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* [FFmpeg-devel] [PR] avformat/whep: add WHEP demuxer support (PR #21603)
@ 2026-01-29 13:11 Artem Smorodin via ffmpeg-devel
  0 siblings, 0 replies; only message in thread
From: Artem Smorodin via ffmpeg-devel @ 2026-01-29 13:11 UTC (permalink / raw)
  To: ffmpeg-devel; +Cc: Artem Smorodin

PR #21603 opened by Artem Smorodin (artem.smorodin.dacast)
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/21603
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/21603.patch

This PR contains the implementation of WHEP (WebRTC-HTTP Egress Protocol).

To implement it, I had to split `whip.c` and separate the RTC/ICE/DTLS/SRTP part (`rtc.c`/`rtc.h`) from it.

WHIP remained almost unchanged (except for the name of the `whip_flags` option). I changed the names of some variables and structures from whip to rtc for consistency, but did not change the logic.

The only important change for WHIP is renaming `whip_flags` to `rtc_flags`. The old name remains in place but is marked as deprecated. Let me know if you find this unacceptable.

As for WHEP:

This demuxer was implemented using the same RTC codebase as whip. During implementation, I also looked at how it was implemented for rtsp.

This demuxer also supports media timeout and an option to set the reordering queue size.

Here are the WHEP-related features that have been implemented:

1. Generation and parsing of SDP offer
2. Full NACK support (NACK PLI implemented, but will not work for H.264 as `need_keyframe` is not implemented for `rtpdec_h264`)
3. RTX support
4. Reorder queue (including drain by max_delay)
5. RTCP feedback

TODO:

1. Only H.264 and OPUS supported right now (to extend it, mainly need to add codecs to SDP generation/parsing)
2. Full ICE is not implemented (same as for WHIP)
3. TWCC and REMB is not implemented
4. Probably many other minor WebRTC features

I tested this using: 

1. ossrs/srs (supports NACK, but not RTX)
2. Cloudflare Streams (supports NACK + RTX)|


@JackLau @lq This may be presumptuous of me, but I would like to ask you, if possible, to prioritize reviewing this PR over working on WHIP, as each merge will be a nightmare for me. Thank you for your understanding.



>From 86ac37cdb4b7b21e0b60d62321a85312e99f9251 Mon Sep 17 00:00:00 2001
From: Artem Smorodin <artem.smorodin@dacast.com>
Date: Thu, 29 Jan 2026 16:04:51 +0300
Subject: [PATCH] avformat/whep: add WHEP demuxer support

avformat/whip: split whip.c to whip and rtc code
---
 configure                |    2 +
 doc/demuxers.texi        |   61 ++
 doc/muxers.texi          |    4 +-
 libavformat/Makefile     |    3 +-
 libavformat/allformats.c |    1 +
 libavformat/rtc.c        | 1105 +++++++++++++++++++++++++
 libavformat/rtc.h        |  274 +++++++
 libavformat/whep.c       | 1119 +++++++++++++++++++++++++
 libavformat/whip.c       | 1660 +++++---------------------------------
 9 files changed, 2761 insertions(+), 1468 deletions(-)
 create mode 100644 libavformat/rtc.c
 create mode 100644 libavformat/rtc.h
 create mode 100644 libavformat/whep.c

diff --git a/configure b/configure
index 6d6e6673dc..ed8fcdf36d 100755
--- a/configure
+++ b/configure
@@ -3902,6 +3902,8 @@ wav_demuxer_select="riffdec"
 wav_muxer_select="riffenc"
 webm_chunk_muxer_select="webm_muxer"
 webm_dash_manifest_demuxer_select="matroska_demuxer"
+whep_demuxer_deps_any="dtls_protocol"
+whep_demuxer_select="rtpdec http_protocol"
 whip_muxer_deps_any="dtls_protocol"
 whip_muxer_select="rtp_muxer http_protocol"
 wtv_demuxer_select="mpegts_demuxer riffdec"
diff --git a/doc/demuxers.texi b/doc/demuxers.texi
index c1dda7f1eb..a4e8beb0ee 100644
--- a/doc/demuxers.texi
+++ b/doc/demuxers.texi
@@ -1179,4 +1179,65 @@ this is set to 0, which means that a sensible value is chosen based on the
 input format.
 @end table
 
+@anchor{whep}
+@section whep
+
+WebRTC (Real-Time Communication) demuxer that supports sub-second latency playback according to
+the WHEP (WebRTC-HTTP Egress Protocol) specification.
+
+This is an experimental feature.
+
+It uses HTTP as a signaling protocol to exchange SDP capabilities and ICE lite candidates. Then,
+it uses STUN binding requests and responses to establish a session over UDP. Subsequently, it
+initiates a DTLS handshake to exchange the SRTP encryption keys. Lastly, it receives RTP packets 
+containing audio and video and decrypt them using SRTP.
+
+Depending on the RTT to the peer, you may need to set the maximum possible delay (max_delay).
+@example
+ffplay -max_delay 500000  -f whep -i http://localhost:1985/rtc/v1/whep/?stream=livestream
+@end example
+
+@subsection Options
+
+This demuxer supports the following options:
+
+@table @option
+
+@item handshake_timeout @var{integer}
+Set the timeout in milliseconds for ICE and DTLS handshake.
+Default value is 5000.
+
+@item media_timeout @var{integer}
+Set the timeout in milliseconds for receiving media packets.
+Default value is 0(disabled).
+
+@item pkt_size @var{integer}
+Set the maximum size, in bytes, of RTP packets that send out.
+Default value is 1200.
+
+@item buffer_size, ts_buffer_size @var{integer}
+Set the buffer size, in bytes, of underlying protocol.
+Default value is -1(auto). The UDP auto selects a reasonable value.
+
+Using the buffer_size option name is deprecated and should not be used.
+
+@item rtc_flags @var{flags}
+Possible values:
+
+@table @samp
+@item dtls_active
+The demuxer will try to set dtls active role and send the first client hello.
+@end table
+
+@item authorization @var{string}
+The optional Bearer token for WHEP Authorization.
+
+@item cert_file @var{string}
+The optional certificate file path for DTLS.
+
+@item key_file @var{string}
+The optional private key file path for DTLS.
+
+@end table
+
 @c man end DEMUXERS
diff --git a/doc/muxers.texi b/doc/muxers.texi
index e1f737b1d9..b0af0494f0 100644
--- a/doc/muxers.texi
+++ b/doc/muxers.texi
@@ -3959,7 +3959,7 @@ Default value is 1200.
 Set the buffer size, in bytes, of underlying protocol.
 Default value is -1(auto). The UDP auto selects a reasonable value.
 
-@item whip_flags @var{flags}
+@item whip_flags, rtc_flags @var{flags}
 Possible values:
 
 @table @samp
@@ -3967,6 +3967,8 @@ Possible values:
 The muxer will try to set dtls active role and send the first client hello.
 @end table
 
+Using the whip_flags option name is deprecated and should not be used.
+
 @item authorization @var{string}
 The optional Bearer token for WHIP Authorization.
 
diff --git a/libavformat/Makefile b/libavformat/Makefile
index 5fd3f7252a..4ef2fae93e 100644
--- a/libavformat/Makefile
+++ b/libavformat/Makefile
@@ -645,7 +645,8 @@ OBJS-$(CONFIG_WEBM_CHUNK_MUXER)          += webm_chunk.o
 OBJS-$(CONFIG_WEBP_MUXER)                += webpenc.o
 OBJS-$(CONFIG_WEBVTT_DEMUXER)            += webvttdec.o subtitles.o
 OBJS-$(CONFIG_WEBVTT_MUXER)              += webvttenc.o
-OBJS-$(CONFIG_WHIP_MUXER)                += whip.o avc.o http.o srtp.o
+OBJS-$(CONFIG_WHEP_DEMUXER)              += whep.o rtc.o http.o srtp.o
+OBJS-$(CONFIG_WHIP_MUXER)                += whip.o rtc.o avc.o http.o srtp.o
 OBJS-$(CONFIG_WSAUD_DEMUXER)             += westwood_aud.o
 OBJS-$(CONFIG_WSAUD_MUXER)               += westwood_audenc.o
 OBJS-$(CONFIG_WSD_DEMUXER)               += wsddec.o rawdec.o
diff --git a/libavformat/allformats.c b/libavformat/allformats.c
index 6ec361fb7b..e2a366cea1 100644
--- a/libavformat/allformats.c
+++ b/libavformat/allformats.c
@@ -518,6 +518,7 @@ extern const FFOutputFormat ff_webp_muxer;
 extern const FFInputFormat  ff_webvtt_demuxer;
 extern const FFOutputFormat ff_webvtt_muxer;
 extern const FFInputFormat  ff_wsaud_demuxer;
+extern const FFInputFormat  ff_whep_demuxer;
 extern const FFOutputFormat ff_whip_muxer;
 extern const FFOutputFormat ff_wsaud_muxer;
 extern const FFInputFormat  ff_wsd_demuxer;
diff --git a/libavformat/rtc.c b/libavformat/rtc.c
new file mode 100644
index 0000000000..40e44d43ca
--- /dev/null
+++ b/libavformat/rtc.c
@@ -0,0 +1,1105 @@
+/*
+ * RTC input/output format
+ * Copyright (c) 2023 The FFmpeg Project
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "avio_internal.h"
+#include "libavutil/base64.h"
+#include "libavutil/bprint.h"
+#include "libavutil/crc.h"
+#include "libavutil/hmac.h"
+#include "libavutil/intreadwrite.h"
+#include "libavutil/mem.h"
+#include "libavutil/random_seed.h"
+#include "libavutil/time.h"
+#include "http.h"
+#include "internal.h"
+#include "mux.h"
+#include "network.h"
+#include "rtp.h"
+#include "rtc.h"
+
+/**
+ * If we try to read from UDP and get EAGAIN, we sleep for 5ms and retry up to 10 times.
+ * This will limit the total duration (in milliseconds, 50ms)
+ */
+#define ICE_DTLS_READ_MAX_RETRY 10
+#define ICE_DTLS_READ_SLEEP_DURATION 5
+
+/* The magic cookie for Session Traversal Utilities for NAT (STUN) messages. */
+#define STUN_MAGIC_COOKIE 0x2112A442
+
+/**
+ * Refer to RFC 8445 5.1.2
+ * priority = (2^24)*(type preference) + (2^8)*(local preference) + (2^0)*(256 - component ID)
+ * host candidate priority is 126 << 24 | 65535 << 8 | 255
+ */
+#define STUN_HOST_CANDIDATE_PRIORITY 126 << 24 | 65535 << 8 | 255
+
+/**
+ * The DTLS content type.
+ * See https://tools.ietf.org/html/rfc2246#section-6.2.1
+ * change_cipher_spec(20), alert(21), handshake(22), application_data(23)
+ */
+#define DTLS_CONTENT_TYPE_CHANGE_CIPHER_SPEC 20
+
+/**
+ * The DTLS record layer header has a total size of 13 bytes, consisting of
+ * ContentType (1 byte), ProtocolVersion (2 bytes), Epoch (2 bytes),
+ * SequenceNumber (6 bytes), and Length (2 bytes).
+ * See https://datatracker.ietf.org/doc/html/rfc9147#section-4
+ */
+#define DTLS_RECORD_LAYER_HEADER_LEN 13
+
+/**
+ * The DTLS version number, which is 0xfeff for DTLS 1.0, or 0xfefd for DTLS 1.2.
+ * See https://datatracker.ietf.org/doc/html/rfc9147#name-the-dtls-record-layer
+ */
+#define DTLS_VERSION_10 0xfeff
+#define DTLS_VERSION_12 0xfefd
+
+/**
+ * The STUN message header, which is 20 bytes long, comprises the
+ * STUNMessageType (1B), MessageLength (2B), MagicCookie (4B),
+ * and TransactionID (12B).
+ * See https://datatracker.ietf.org/doc/html/rfc5389#section-6
+ */
+#define ICE_STUN_HEADER_SIZE 20
+
+/**
+ * The RTP header is 12 bytes long, comprising the Version(1B), PT(1B),
+ * SequenceNumber(2B), Timestamp(4B), and SSRC(4B).
+ * See https://www.rfc-editor.org/rfc/rfc3550#section-5.1
+ */
+#define RTC_RTP_HEADER_SIZE 12
+
+/**
+ * For RTCP, PT is [128, 223] (or without marker [0, 95]). Literally, RTCP starts
+ * from 64 not 0, so PT is [192, 223] (or without marker [64, 95]), see "RTCP Control
+ * Packet Types (PT)" at
+ * https://www.iana.org/assignments/rtp-parameters/rtp-parameters.xhtml#rtp-parameters-4
+ *
+ * For RTP, the PT is [96, 127], or [224, 255] with marker. See "RTP Payload Types (PT)
+ * for standard audio and video encodings" at
+ * https://www.iana.org/assignments/rtp-parameters/rtp-parameters.xhtml#rtp-parameters-1
+ */
+#define RTC_RTCP_PT_START 192
+#define RTC_RTCP_PT_END   223
+
+/* STUN Attribute, comprehension-required range (0x0000-0x7FFF) */
+enum STUNAttr {
+    STUN_ATTR_USERNAME                  = 0x0006, /// shared secret response/bind request
+    STUN_ATTR_PRIORITY                  = 0x0024, /// must be included in a Binding request
+    STUN_ATTR_USE_CANDIDATE             = 0x0025, /// bind request
+    STUN_ATTR_MESSAGE_INTEGRITY         = 0x0008, /// bind request/response
+    STUN_ATTR_FINGERPRINT               = 0x8028, /// rfc5389
+    STUN_ATTR_ICE_CONTROLLING           = 0x802A, /// ICE controlling role
+};
+
+/**
+ * Whether the packet is a DTLS packet.
+ */
+int ff_rtc_is_dtls_packet(uint8_t *b, int size)
+{
+    int ret = 0;
+    if (size > DTLS_RECORD_LAYER_HEADER_LEN) {
+        uint16_t version = AV_RB16(&b[1]);
+        ret = b[0] >= DTLS_CONTENT_TYPE_CHANGE_CIPHER_SPEC &&
+            (version == DTLS_VERSION_10 || version == DTLS_VERSION_12);
+    }
+    return ret;
+}
+
+
+/**
+ * Get or Generate a self-signed certificate and private key for DTLS,
+ * fingerprint for SDP
+ */
+static av_cold int certificate_key_init(AVFormatContext *s)
+{
+    int ret = 0;
+    RTCContext *rtc = s->priv_data;
+
+    if (rtc->cert_file && rtc->key_file) {
+        /* Read the private key and certificate from the file. */
+        if ((ret = ff_ssl_read_key_cert(rtc->key_file, rtc->cert_file,
+                                        rtc->key_buf, sizeof(rtc->key_buf),
+                                        rtc->cert_buf, sizeof(rtc->cert_buf),
+                                        &rtc->dtls_fingerprint)) < 0) {
+            av_log(s, AV_LOG_ERROR, "Failed to read DTLS certificate from cert=%s, key=%s\n",
+                rtc->cert_file, rtc->key_file);
+            return ret;
+        }
+    } else {
+        /* Generate a private key to ctx->dtls_pkey and self-signed certificate. */
+        if ((ret = ff_ssl_gen_key_cert(rtc->key_buf, sizeof(rtc->key_buf),
+                                       rtc->cert_buf, sizeof(rtc->cert_buf),
+                                       &rtc->dtls_fingerprint)) < 0) {
+            av_log(s, AV_LOG_ERROR, "Failed to generate DTLS private key and certificate\n");
+            return ret;
+        }
+    }
+
+    return ret;
+}
+
+static av_cold int dtls_initialize(AVFormatContext *s)
+{
+    int ret = 0;
+    RTCContext *rtc = s->priv_data;
+    int is_dtls_active = rtc->flags & RTC_DTLS_ACTIVE;
+    AVDictionary *opts = NULL;
+    char buf[256];
+
+    ff_url_join(buf, sizeof(buf), "dtls", NULL, rtc->ice_host, rtc->ice_port, NULL);
+    av_dict_set_int(&opts, "mtu", rtc->pkt_size, 0);
+    if (rtc->cert_file) {
+        av_dict_set(&opts, "cert_file", rtc->cert_file, 0);
+    } else
+        av_dict_set(&opts, "cert_pem", rtc->cert_buf, 0);
+
+    if (rtc->key_file) {
+        av_dict_set(&opts, "key_file", rtc->key_file, 0);
+    } else
+        av_dict_set(&opts, "key_pem", rtc->key_buf, 0);
+    av_dict_set_int(&opts, "external_sock", 1, 0);
+    av_dict_set_int(&opts, "use_srtp", 1, 0);
+    av_dict_set_int(&opts, "listen", is_dtls_active ? 0 : 1, 0);
+    ret = ffurl_open_whitelist(&rtc->dtls_uc, buf, AVIO_FLAG_READ_WRITE, &s->interrupt_callback,
+        &opts, s->protocol_whitelist, s->protocol_blacklist, NULL);
+    av_dict_free(&opts);
+    if (ret < 0) {
+        av_log(rtc, AV_LOG_ERROR, "Failed to open DTLS url:%s\n", buf);
+        goto end;
+    }
+    /* reuse the udp created by rtc */
+    ff_tls_set_external_socket(rtc->dtls_uc, rtc->udp);
+end:
+    return ret;
+}
+
+/**
+ * Initialize and check the options for the WebRTC muxer.
+ */
+av_cold int ff_rtc_initialize(AVFormatContext *s)
+{
+    int ret, ideal_pkt_size = 532;
+    RTCContext *rtc = s->priv_data;
+    uint32_t seed;
+
+    rtc->rtc_starttime = av_gettime_relative();
+
+    ret = certificate_key_init(s);
+    if (ret < 0) {
+        av_log(rtc, AV_LOG_ERROR, "Failed to init certificate and key\n");
+        return ret;
+    }
+
+    /* Initialize the random number generator. */
+    seed = av_get_random_seed();
+    av_lfg_init(&rtc->rnd, seed);
+
+    /* 64 bit tie breaker for ICE-CONTROLLING (RFC 8445 16.1) */
+    ret = av_random_bytes((uint8_t *)&rtc->ice_tie_breaker, sizeof(rtc->ice_tie_breaker));
+    if (ret < 0) {
+        av_log(rtc, AV_LOG_ERROR, "Couldn't generate random bytes for ICE tie breaker\n");
+        return ret;
+    }
+
+    rtc->audio_first_seq = av_lfg_get(&rtc->rnd) & 0x0fff;
+    rtc->video_first_seq = rtc->audio_first_seq + 1;
+
+    if (rtc->pkt_size < ideal_pkt_size)
+        av_log(rtc, AV_LOG_WARNING, "pkt_size=%d(<%d) is too small, may cause packet loss\n",
+               rtc->pkt_size, ideal_pkt_size);
+
+    if (rtc->state < RTC_STATE_INIT)
+        rtc->state = RTC_STATE_INIT;
+    rtc->rtc_init_time = av_gettime_relative();
+    av_log(rtc, AV_LOG_VERBOSE, "Init state=%d, handshake_timeout=%dms, pkt_size=%d, seed=%d, elapsed=%.2fms\n",
+        rtc->state, rtc->handshake_timeout, rtc->pkt_size, seed, RTC_ELAPSED(rtc->rtc_starttime, av_gettime_relative()));
+
+    return 0;
+}
+
+/**
+ * Exchange SDP offer with WebRTC peer to get the answer.
+ *
+ * @return 0 if OK, AVERROR_xxx on error
+ */
+static int exchange_sdp(AVFormatContext *s)
+{
+    int ret;
+    char buf[MAX_URL_SIZE];
+    AVBPrint bp;
+    RTCContext *rtc = s->priv_data;
+    /* The URL context is an HTTP transport layer for the WebRTC-HTTP protocol. */
+    URLContext *rtc_uc = NULL;
+    AVDictionary *opts = NULL;
+    char *hex_data = NULL;
+    const char *proto_name = avio_find_protocol_name(s->url);
+
+    /* To prevent a crash during cleanup, always initialize it. */
+    av_bprint_init(&bp, 1, RTC_MAX_SDP_SIZE);
+
+    if (!av_strstart(proto_name, "http", NULL)) {
+        av_log(rtc, AV_LOG_ERROR, "Protocol %s is not supported by RTC, choose http, url is %s\n",
+            proto_name, s->url);
+        ret = AVERROR(EINVAL);
+        goto end;
+    }
+
+    if (!rtc->sdp_offer || !strlen(rtc->sdp_offer)) {
+        av_log(rtc, AV_LOG_ERROR, "No offer to exchange\n");
+        ret = AVERROR(EINVAL);
+        goto end;
+    }
+
+    ret = snprintf(buf, sizeof(buf), "Cache-Control: no-cache\r\nContent-Type: application/sdp\r\n");
+    if (rtc->authorization)
+        ret += snprintf(buf + ret, sizeof(buf) - ret, "Authorization: Bearer %s\r\n", rtc->authorization);
+    if (ret <= 0 || ret >= sizeof(buf)) {
+        av_log(rtc, AV_LOG_ERROR, "Failed to generate headers, size=%d, %s\n", ret, buf);
+        ret = AVERROR(EINVAL);
+        goto end;
+    }
+
+    av_dict_set(&opts, "headers", buf, 0);
+    av_dict_set_int(&opts, "chunked_post", 0, 0);
+
+    hex_data = av_mallocz(2 * strlen(rtc->sdp_offer) + 1);
+    if (!hex_data) {
+        ret = AVERROR(ENOMEM);
+        goto end;
+    }
+    ff_data_to_hex(hex_data, rtc->sdp_offer, strlen(rtc->sdp_offer), 0);
+    av_dict_set(&opts, "post_data", hex_data, 0);
+
+    ret = ffurl_open_whitelist(&rtc_uc, s->url, AVIO_FLAG_READ_WRITE, &s->interrupt_callback,
+        &opts, s->protocol_whitelist, s->protocol_blacklist, NULL);
+    if (ret < 0) {
+        av_log(rtc, AV_LOG_ERROR, "Failed to request url=%s, offer: %s\n", s->url, rtc->sdp_offer);
+        goto end;
+    }
+
+    if (ff_http_get_new_location(rtc_uc)) {
+        rtc->rtc_resource_url = av_strdup(ff_http_get_new_location(rtc_uc));
+        if (!rtc->rtc_resource_url) {
+            ret = AVERROR(ENOMEM);
+            goto end;
+        }
+    }
+
+    while (1) {
+        ret = ffurl_read(rtc_uc, buf, sizeof(buf));
+        if (ret == AVERROR_EOF) {
+            /* Reset the error because we read all response as answer util EOF. */
+            ret = 0;
+            break;
+        }
+        if (ret <= 0) {
+            av_log(rtc, AV_LOG_ERROR, "Failed to read response from url=%s, offer is %s, answer is %s\n",
+                s->url, rtc->sdp_offer, rtc->sdp_answer);
+            goto end;
+        }
+
+        av_bprintf(&bp, "%.*s", ret, buf);
+        if (!av_bprint_is_complete(&bp)) {
+            av_log(rtc, AV_LOG_ERROR, "Answer exceed max size %d, %.*s, %s\n", RTC_MAX_SDP_SIZE, ret, buf, bp.str);
+            ret = AVERROR(EIO);
+            goto end;
+        }
+    }
+
+    if (!av_strstart(bp.str, "v=", NULL)) {
+        av_log(rtc, AV_LOG_ERROR, "Invalid answer: %s\n", bp.str);
+        ret = AVERROR(EINVAL);
+        goto end;
+    }
+
+    rtc->sdp_answer = av_strdup(bp.str);
+    if (!rtc->sdp_answer) {
+        ret = AVERROR(ENOMEM);
+        goto end;
+    }
+
+    if (rtc->state < RTC_STATE_ANSWER)
+        rtc->state = RTC_STATE_ANSWER;
+    av_log(rtc, AV_LOG_VERBOSE, "Got state=%d, answer: %s\n", rtc->state, rtc->sdp_answer);
+
+end:
+    ffurl_closep(&rtc_uc);
+    av_bprint_finalize(&bp, NULL);
+    av_dict_free(&opts);
+    av_freep(&hex_data);
+    return ret;
+}
+
+/**
+ * Parses the ICE ufrag, pwd, and candidates from the SDP answer.
+ *
+ * This function is used to extract the ICE ufrag, pwd, and candidates from the SDP answer.
+ * It returns an error if any of these fields is NULL. The function only uses the first
+ * candidate if there are multiple candidates. However, support for multiple candidates
+ * will be added in the future.
+ *
+ * @param s Pointer to the AVFormatContext
+ * @returns Returns 0 if successful or AVERROR_xxx if an error occurs.
+ */
+static int parse_answer(AVFormatContext *s)
+{
+    int ret = 0;
+    AVIOContext *pb;
+    char line[MAX_URL_SIZE];
+    const char *ptr;
+    int i;
+    RTCContext *rtc = s->priv_data;
+
+    if (!rtc->sdp_answer || !strlen(rtc->sdp_answer)) {
+        av_log(rtc, AV_LOG_ERROR, "No answer to parse\n");
+        ret = AVERROR(EINVAL);
+        goto end;
+    }
+
+    pb = avio_alloc_context(rtc->sdp_answer, strlen(rtc->sdp_answer), 0, NULL, NULL, NULL, NULL);
+    if (!pb)
+        return AVERROR(ENOMEM);
+
+    for (i = 0; !avio_feof(pb); i++) {
+        ff_get_chomp_line(pb, line, sizeof(line));
+        if (av_strstart(line, "a=ice-lite", &ptr))
+            rtc->is_peer_ice_lite = 1;
+        if (av_strstart(line, "a=ice-ufrag:", &ptr) && !rtc->ice_ufrag_remote) {
+            rtc->ice_ufrag_remote = av_strdup(ptr);
+            if (!rtc->ice_ufrag_remote) {
+                ret = AVERROR(ENOMEM);
+                goto end;
+            }
+        } else if (av_strstart(line, "a=ice-pwd:", &ptr) && !rtc->ice_pwd_remote) {
+            rtc->ice_pwd_remote = av_strdup(ptr);
+            if (!rtc->ice_pwd_remote) {
+                ret = AVERROR(ENOMEM);
+                goto end;
+            }
+        } else if (av_strstart(line, "a=candidate:", &ptr) && !rtc->ice_protocol) {
+            if (ptr && av_stristr(ptr, "host")) {
+                /* Refer to RFC 5245 15.1 */
+                char foundation[33], protocol[17], host[129];
+                int component_id, priority, port;
+                ret = sscanf(ptr, "%32s %d %16s %d %128s %d typ host", foundation, &component_id, protocol, &priority, host, &port);
+                if (ret != 6) {
+                    av_log(rtc, AV_LOG_ERROR, "Failed %d to parse line %d %s from %s\n",
+                        ret, i, line, rtc->sdp_answer);
+                    ret = AVERROR(EIO);
+                    goto end;
+                }
+
+                if (av_strcasecmp(protocol, "udp")) {
+                    av_log(rtc, AV_LOG_ERROR, "Protocol %s is not supported by RTC, choose udp, line %d %s of %s\n",
+                        protocol, i, line, rtc->sdp_answer);
+                    ret = AVERROR(EIO);
+                    goto end;
+                }
+
+                rtc->ice_protocol = av_strdup(protocol);
+                rtc->ice_host = av_strdup(host);
+                rtc->ice_port = port;
+                if (!rtc->ice_protocol || !rtc->ice_host) {
+                    ret = AVERROR(ENOMEM);
+                    goto end;
+                }
+            }
+        }
+    }
+
+    if (!rtc->ice_pwd_remote || !strlen(rtc->ice_pwd_remote)) {
+        av_log(rtc, AV_LOG_ERROR, "No remote ice pwd parsed from %s\n", rtc->sdp_answer);
+        ret = AVERROR(EINVAL);
+        goto end;
+    }
+
+    if (!rtc->ice_ufrag_remote || !strlen(rtc->ice_ufrag_remote)) {
+        av_log(rtc, AV_LOG_ERROR, "No remote ice ufrag parsed from %s\n", rtc->sdp_answer);
+        ret = AVERROR(EINVAL);
+        goto end;
+    }
+
+    if (!rtc->ice_protocol || !rtc->ice_host || !rtc->ice_port) {
+        av_log(rtc, AV_LOG_ERROR, "No ice candidate parsed from %s\n", rtc->sdp_answer);
+        ret = AVERROR(EINVAL);
+        goto end;
+    }
+
+    if (rtc->state < RTC_STATE_NEGOTIATED)
+        rtc->state = RTC_STATE_NEGOTIATED;
+    rtc->rtc_answer_time = av_gettime_relative();
+    av_log(rtc, AV_LOG_VERBOSE, "SDP state=%d, offer=%zuB, answer=%zuB, ufrag=%s, pwd=%zuB, transport=%s://%s:%d, elapsed=%.2fms\n",
+        rtc->state, strlen(rtc->sdp_offer), strlen(rtc->sdp_answer), rtc->ice_ufrag_remote, strlen(rtc->ice_pwd_remote),
+        rtc->ice_protocol, rtc->ice_host, rtc->ice_port, RTC_ELAPSED(rtc->rtc_starttime, av_gettime_relative()));
+
+end:
+    avio_context_free(&pb);
+    return ret;
+}
+
+/**
+ * Creates and marshals an ICE binding request packet.
+ *
+ * This function creates and marshals an ICE binding request packet. The function only
+ * generates the username attribute and does not include goog-network-info,
+ * use-candidate. However, some of these attributes may be added in the future.
+ *
+ * @param s Pointer to the AVFormatContext
+ * @param buf Pointer to memory buffer to store the request packet
+ * @param buf_size Size of the memory buffer
+ * @param request_size Pointer to an integer that receives the size of the request packet
+ * @return Returns 0 if successful or AVERROR_xxx if an error occurs.
+ */
+int ff_rtc_ice_create_request(AVFormatContext *s, uint8_t *buf, int buf_size, int *request_size)
+{
+    int ret, size, crc32;
+    char username[128];
+    AVIOContext *pb = NULL;
+    AVHMAC *hmac = NULL;
+    RTCContext *rtc = s->priv_data;
+
+    pb = avio_alloc_context(buf, buf_size, 1, NULL, NULL, NULL, NULL);
+    if (!pb)
+        return AVERROR(ENOMEM);
+
+    hmac = av_hmac_alloc(AV_HMAC_SHA1);
+    if (!hmac) {
+        ret = AVERROR(ENOMEM);
+        goto end;
+    }
+
+    /* Write 20 bytes header */
+    avio_wb16(pb, 0x0001); /* STUN binding request */
+    avio_wb16(pb, 0);      /* length */
+    avio_wb32(pb, STUN_MAGIC_COOKIE); /* magic cookie */
+    avio_wb32(pb, av_lfg_get(&rtc->rnd)); /* transaction ID */
+    avio_wb32(pb, av_lfg_get(&rtc->rnd)); /* transaction ID */
+    avio_wb32(pb, av_lfg_get(&rtc->rnd)); /* transaction ID */
+
+    /* The username is the concatenation of the two ICE ufrag */
+    ret = snprintf(username, sizeof(username), "%s:%s", rtc->ice_ufrag_remote, rtc->ice_ufrag_local);
+    if (ret <= 0 || ret >= sizeof(username)) {
+        av_log(rtc, AV_LOG_ERROR, "Failed to build username %s:%s, max=%zu, ret=%d\n",
+            rtc->ice_ufrag_remote, rtc->ice_ufrag_local, sizeof(username), ret);
+        ret = AVERROR(EIO);
+        goto end;
+    }
+
+    /* Write the username attribute */
+    avio_wb16(pb, STUN_ATTR_USERNAME); /* attribute type username */
+    avio_wb16(pb, ret); /* size of username */
+    avio_write(pb, username, ret); /* bytes of username */
+    ffio_fill(pb, 0, (4 - (ret % 4)) % 4); /* padding */
+
+    /* Write the use-candidate attribute */
+    avio_wb16(pb, STUN_ATTR_USE_CANDIDATE); /* attribute type use-candidate */
+    avio_wb16(pb, 0); /* size of use-candidate */
+
+    avio_wb16(pb, STUN_ATTR_PRIORITY);
+    avio_wb16(pb, 4);
+    avio_wb32(pb, STUN_HOST_CANDIDATE_PRIORITY);
+
+    avio_wb16(pb, STUN_ATTR_ICE_CONTROLLING);
+    avio_wb16(pb, 8);
+    avio_wb64(pb, rtc->ice_tie_breaker);
+
+    /* Build and update message integrity */
+    avio_wb16(pb, STUN_ATTR_MESSAGE_INTEGRITY); /* attribute type message integrity */
+    avio_wb16(pb, 20); /* size of message integrity */
+    ffio_fill(pb, 0, 20); /* fill with zero to directly write and skip it */
+    size = avio_tell(pb);
+    buf[2] = (size - 20) >> 8;
+    buf[3] = (size - 20) & 0xFF;
+    av_hmac_init(hmac, rtc->ice_pwd_remote, strlen(rtc->ice_pwd_remote));
+    av_hmac_update(hmac, buf, size - 24);
+    av_hmac_final(hmac, buf + size - 20, 20);
+
+    /* Write the fingerprint attribute */
+    avio_wb16(pb, STUN_ATTR_FINGERPRINT); /* attribute type fingerprint */
+    avio_wb16(pb, 4); /* size of fingerprint */
+    ffio_fill(pb, 0, 4); /* fill with zero to directly write and skip it */
+    size = avio_tell(pb);
+    buf[2] = (size - 20) >> 8;
+    buf[3] = (size - 20) & 0xFF;
+    /* Refer to the av_hash_alloc("CRC32"), av_hash_init and av_hash_final */
+    crc32 = av_crc(av_crc_get_table(AV_CRC_32_IEEE_LE), 0xFFFFFFFF, buf, size - 8) ^ 0xFFFFFFFF;
+    avio_skip(pb, -4);
+    avio_wb32(pb, crc32 ^ 0x5354554E); /* xor with "STUN" */
+
+    *request_size = size;
+
+end:
+    avio_context_free(&pb);
+    av_hmac_free(hmac);
+    return ret;
+}
+
+/**
+ * Create an ICE binding response.
+ *
+ * This function generates an ICE binding response and writes it to the provided
+ * buffer. The response is signed using the local password for message integrity.
+ *
+ * @param s Pointer to the AVFormatContext structure.
+ * @param tid Pointer to the transaction ID of the binding request. The tid_size should be 12.
+ * @param tid_size The size of the transaction ID, should be 12.
+ * @param buf Pointer to the buffer where the response will be written.
+ * @param buf_size The size of the buffer provided for the response.
+ * @param response_size Pointer to an integer that will store the size of the generated response.
+ * @return Returns 0 if successful or AVERROR_xxx if an error occurs.
+ */
+static int ice_create_response(AVFormatContext *s, char *tid, int tid_size, uint8_t *buf, int buf_size, int *response_size)
+{
+    int ret = 0, size, crc32;
+    AVIOContext *pb = NULL;
+    AVHMAC *hmac = NULL;
+    RTCContext *rtc = s->priv_data;
+
+    if (tid_size != 12) {
+        av_log(rtc, AV_LOG_ERROR, "Invalid transaction ID size. Expected 12, got %d\n", tid_size);
+        return AVERROR(EINVAL);
+    }
+
+    pb = avio_alloc_context(buf, buf_size, 1, NULL, NULL, NULL, NULL);
+    if (!pb)
+        return AVERROR(ENOMEM);
+
+    hmac = av_hmac_alloc(AV_HMAC_SHA1);
+    if (!hmac) {
+        ret = AVERROR(ENOMEM);
+        goto end;
+    }
+
+    /* Write 20 bytes header */
+    avio_wb16(pb, 0x0101); /* STUN binding response */
+    avio_wb16(pb, 0);      /* length */
+    avio_wb32(pb, STUN_MAGIC_COOKIE); /* magic cookie */
+    avio_write(pb, tid, tid_size); /* transaction ID */
+
+    /* Build and update message integrity */
+    avio_wb16(pb, STUN_ATTR_MESSAGE_INTEGRITY); /* attribute type message integrity */
+    avio_wb16(pb, 20); /* size of message integrity */
+    ffio_fill(pb, 0, 20); /* fill with zero to directly write and skip it */
+    size = avio_tell(pb);
+    buf[2] = (size - 20) >> 8;
+    buf[3] = (size - 20) & 0xFF;
+    av_hmac_init(hmac, rtc->ice_pwd_local, strlen(rtc->ice_pwd_local));
+    av_hmac_update(hmac, buf, size - 24);
+    av_hmac_final(hmac, buf + size - 20, 20);
+
+    /* Write the fingerprint attribute */
+    avio_wb16(pb, STUN_ATTR_FINGERPRINT); /* attribute type fingerprint */
+    avio_wb16(pb, 4); /* size of fingerprint */
+    ffio_fill(pb, 0, 4); /* fill with zero to directly write and skip it */
+    size = avio_tell(pb);
+    buf[2] = (size - 20) >> 8;
+    buf[3] = (size - 20) & 0xFF;
+    /* Refer to the av_hash_alloc("CRC32"), av_hash_init and av_hash_final */
+    crc32 = av_crc(av_crc_get_table(AV_CRC_32_IEEE_LE), 0xFFFFFFFF, buf, size - 8) ^ 0xFFFFFFFF;
+    avio_skip(pb, -4);
+    avio_wb32(pb, crc32 ^ 0x5354554E); /* xor with "STUN" */
+
+    *response_size = size;
+
+end:
+    avio_context_free(&pb);
+    av_hmac_free(hmac);
+    return ret;
+}
+
+/**
+ * A Binding request has class=0b00 (request) and method=0b000000000001 (Binding)
+ * and is encoded into the first 16 bits as 0x0001.
+ * See https://datatracker.ietf.org/doc/html/rfc5389#section-6
+ */
+static int ice_is_binding_request(uint8_t *b, int size)
+{
+    return size >= ICE_STUN_HEADER_SIZE && AV_RB16(&b[0]) == 0x0001;
+}
+
+/**
+ * A Binding response has class=0b10 (success response) and method=0b000000000001,
+ * and is encoded into the first 16 bits as 0x0101.
+ */
+int ff_rtc_ice_is_binding_response(uint8_t *b, int size)
+{
+    return size >= ICE_STUN_HEADER_SIZE && AV_RB16(&b[0]) == 0x0101;
+}
+
+/**
+ * In RTP packets, the first byte is represented as 0b10xxxxxx, where the initial
+ * two bits (0b10) indicate the RTP version,
+ * see https://www.rfc-editor.org/rfc/rfc3550#section-5.1
+ * The RTCP packet header is similar to RTP,
+ * see https://www.rfc-editor.org/rfc/rfc3550#section-6.4.1
+ */
+int ff_rtc_media_is_rtp_rtcp(const uint8_t *b, int size)
+{
+    return size >= RTC_RTP_HEADER_SIZE && (b[0] & 0xC0) == 0x80;
+}
+
+/* Whether the packet is RTCP. */
+int ff_rtc_media_is_rtcp(const uint8_t *b, int size)
+{
+    return size >= RTC_RTP_HEADER_SIZE && b[1] >= RTC_RTCP_PT_START && b[1] <= RTC_RTCP_PT_END;
+}
+
+/**
+ * This function handles incoming binding request messages by responding to them.
+ * If the message is not a binding request, it will be ignored.
+ */
+int ff_rtc_ice_handle_binding_request(AVFormatContext *s, char *buf, int buf_size)
+{
+    int ret = 0, size;
+    char tid[12];
+    RTCContext *rtc = s->priv_data;
+
+    /* Ignore if not a binding request. */
+    if (!ice_is_binding_request(buf, buf_size))
+        return ret;
+
+    if (buf_size < ICE_STUN_HEADER_SIZE) {
+        av_log(rtc, AV_LOG_ERROR, "Invalid STUN message, expected at least %d, got %d\n",
+            ICE_STUN_HEADER_SIZE, buf_size);
+        return AVERROR(EINVAL);
+    }
+
+    /* Parse transaction id from binding request in buf. */
+    memcpy(tid, buf + 8, 12);
+
+    /* Build the STUN binding response. */
+    ret = ice_create_response(s, tid, sizeof(tid), rtc->buf, sizeof(rtc->buf), &size);
+    if (ret < 0) {
+        av_log(rtc, AV_LOG_ERROR, "Failed to create STUN binding response, size=%d\n", size);
+        return ret;
+    }
+
+    ret = ffurl_write(rtc->udp, rtc->buf, size);
+    if (ret < 0) {
+        av_log(rtc, AV_LOG_ERROR, "Failed to send STUN binding response, size=%d\n", size);
+        return ret;
+    }
+
+    return 0;
+}
+
+/**
+ * To establish a connection with the UDP server, we utilize ICE-LITE in a Client-Server
+ * mode. In this setup, FFmpeg acts as the UDP client, while the peer functions as the
+ * UDP server.
+ */
+static int udp_connect(AVFormatContext *s)
+{
+    int ret = 0;
+    char url[256];
+    AVDictionary *opts = NULL;
+    RTCContext *rtc = s->priv_data;
+
+    /* Build UDP URL and create the UDP context as transport. */
+    ff_url_join(url, sizeof(url), "udp", NULL, rtc->ice_host, rtc->ice_port, NULL);
+
+    av_dict_set_int(&opts, "connect", 1, 0);
+    av_dict_set_int(&opts, "fifo_size", 0, 0);
+    /* Pass through the pkt_size and buffer_size to underling protocol */
+    av_dict_set_int(&opts, "pkt_size", rtc->pkt_size, 0);
+    av_dict_set_int(&opts, "buffer_size", rtc->ts_buffer_size, 0);
+
+    ret = ffurl_open_whitelist(&rtc->udp, url, AVIO_FLAG_WRITE, &s->interrupt_callback,
+        &opts, s->protocol_whitelist, s->protocol_blacklist, NULL);
+    if (ret < 0) {
+        av_log(rtc, AV_LOG_ERROR, "Failed to connect udp://%s:%d\n", rtc->ice_host, rtc->ice_port);
+        goto end;
+    }
+
+    /* Make the socket non-blocking, set to READ and WRITE mode after connected */
+    ff_socket_nonblock(ffurl_get_file_handle(rtc->udp), 1);
+    rtc->udp->flags |= AVIO_FLAG_READ | AVIO_FLAG_NONBLOCK;
+
+    if (rtc->state < RTC_STATE_UDP_CONNECTED)
+        rtc->state = RTC_STATE_UDP_CONNECTED;
+    rtc->rtc_udp_time = av_gettime_relative();
+    av_log(rtc, AV_LOG_VERBOSE, "UDP state=%d, elapsed=%.2fms, connected to udp://%s:%d\n",
+        rtc->state, RTC_ELAPSED(rtc->rtc_starttime, av_gettime_relative()), rtc->ice_host, rtc->ice_port);
+
+end:
+    av_dict_free(&opts);
+    return ret;
+}
+
+static int ice_dtls_handshake(AVFormatContext *s)
+{
+    int ret = 0, size, i;
+    int64_t starttime = av_gettime_relative(), now;
+    RTCContext *rtc = s->priv_data;
+    int is_dtls_active = rtc->flags & RTC_DTLS_ACTIVE;
+
+    if (rtc->state < RTC_STATE_UDP_CONNECTED || !rtc->udp) {
+        av_log(rtc, AV_LOG_ERROR, "UDP not connected, state=%d, udp=%p\n", rtc->state, rtc->udp);
+        return AVERROR(EINVAL);
+    }
+
+    while (1) {
+        if (rtc->state <= RTC_STATE_ICE_CONNECTING) {
+            /* Build the STUN binding request. */
+            ret = ff_rtc_ice_create_request(s, rtc->buf, sizeof(rtc->buf), &size);
+            if (ret < 0) {
+                av_log(rtc, AV_LOG_ERROR, "Failed to create STUN binding request, size=%d\n", size);
+                goto end;
+            }
+
+            ret = ffurl_write(rtc->udp, rtc->buf, size);
+            if (ret < 0) {
+                av_log(rtc, AV_LOG_ERROR, "Failed to send STUN binding request, size=%d\n", size);
+                goto end;
+            }
+
+            if (rtc->state < RTC_STATE_ICE_CONNECTING)
+                rtc->state = RTC_STATE_ICE_CONNECTING;
+        }
+
+next_packet:
+        if (rtc->state >= RTC_STATE_DTLS_FINISHED)
+            /* DTLS handshake is done, exit the loop. */
+            break;
+
+        now = av_gettime_relative();
+        if (now - starttime >= rtc->handshake_timeout * RTC_US_PER_MS) {
+            av_log(rtc, AV_LOG_ERROR, "DTLS handshake timeout=%dms, cost=%.2fms, elapsed=%.2fms, state=%d\n",
+                rtc->handshake_timeout, RTC_ELAPSED(starttime, now), RTC_ELAPSED(rtc->rtc_starttime, now), rtc->state);
+            ret = AVERROR(ETIMEDOUT);
+            goto end;
+        }
+
+        /* Read the STUN or DTLS messages from peer. */
+        for (i = 0; i < ICE_DTLS_READ_MAX_RETRY; i++) {
+            if (rtc->state > RTC_STATE_ICE_CONNECTED)
+                break;
+            ret = ffurl_read(rtc->udp, rtc->buf, sizeof(rtc->buf));
+            if (ret > 0)
+                break;
+            if (ret == AVERROR(EAGAIN)) {
+                av_usleep(ICE_DTLS_READ_SLEEP_DURATION * RTC_US_PER_MS);
+                continue;
+            }
+            if (is_dtls_active)
+                break;
+            av_log(rtc, AV_LOG_ERROR, "Failed to read message\n");
+            goto end;
+        }
+
+        /* Handle the ICE binding response. */
+        if (ff_rtc_ice_is_binding_response(rtc->buf, ret)) {
+            if (rtc->state < RTC_STATE_ICE_CONNECTED) {
+                if (rtc->is_peer_ice_lite)
+                    rtc->state = RTC_STATE_ICE_CONNECTED;
+            }
+            goto next_packet;
+        }
+
+        /* When a binding request is received, it is necessary to respond immediately. */
+    if (ice_is_binding_request(rtc->buf, ret)) {
+        if ((ret = ff_rtc_ice_handle_binding_request(s, rtc->buf, ret)) < 0)
+            goto end;
+        goto next_packet;
+    }
+
+        /* Handle DTLS handshake */
+        if (ff_rtc_is_dtls_packet(rtc->buf, ret) || is_dtls_active) {
+            rtc->rtc_ice_time = av_gettime_relative();
+            /* Start consent timer when ICE selected */
+            rtc->rtc_last_consent_tx_time = rtc->rtc_last_consent_rx_time = rtc->rtc_ice_time;
+            rtc->state = RTC_STATE_ICE_CONNECTED;
+            av_log(rtc, AV_LOG_VERBOSE, "ICE STUN ok, state=%d, url=udp://%s:%d, location=%s, username=%s:%s, res=%dB, elapsed=%.2fms\n",
+                rtc->state, rtc->ice_host, rtc->ice_port, rtc->rtc_resource_url ? rtc->rtc_resource_url : "",
+                rtc->ice_ufrag_remote, rtc->ice_ufrag_local, ret, RTC_ELAPSED(rtc->rtc_starttime, rtc->rtc_ice_time));
+
+            ret = dtls_initialize(s);
+            if (ret < 0)
+                goto end;
+            ret = ffurl_handshake(rtc->dtls_uc);
+            if (ret < 0) {
+                rtc->state = RTC_STATE_FAILED;
+                av_log(rtc, AV_LOG_ERROR, "DTLS session failed\n");
+                goto end;
+            }
+            if (!ret) {
+                rtc->state = RTC_STATE_DTLS_FINISHED;
+                rtc->rtc_dtls_time = av_gettime_relative();
+                av_log(rtc, AV_LOG_VERBOSE, "DTLS handshake is done, elapsed=%.2fms\n",
+                    RTC_ELAPSED(rtc->rtc_starttime, rtc->rtc_dtls_time));
+            }
+            goto next_packet;
+        }
+    }
+
+end:
+    return ret;
+}
+
+/**
+ * Establish the SRTP context using the keying material exported from DTLS.
+ *
+ * Create separate SRTP contexts for sending video and audio, as their sequences differ
+ * and should not share a single context. Generate a single SRTP context for receiving
+ * RTCP only.
+ *
+ * @return 0 if OK, AVERROR_xxx on error
+ */
+static int setup_srtp(AVFormatContext *s)
+{
+    int ret;
+    char recv_key[DTLS_SRTP_KEY_LEN + DTLS_SRTP_SALT_LEN];
+    char send_key[DTLS_SRTP_KEY_LEN + DTLS_SRTP_SALT_LEN];
+    char buf[AV_BASE64_SIZE(DTLS_SRTP_KEY_LEN + DTLS_SRTP_SALT_LEN)];
+    /**
+     * The profile for OpenSSL's SRTP is SRTP_AES128_CM_SHA1_80, see ssl/d1_srtp.c.
+     * The profile for FFmpeg's SRTP is SRTP_AES128_CM_HMAC_SHA1_80, see libavformat/srtp.c.
+     */
+    const char* suite = "SRTP_AES128_CM_HMAC_SHA1_80";
+    RTCContext *rtc = s->priv_data;
+    int is_dtls_active = rtc->flags & RTC_DTLS_ACTIVE;
+    char *cp = is_dtls_active ? send_key : recv_key;
+    char *sp = is_dtls_active ? recv_key : send_key;
+
+    ret = ff_dtls_export_materials(rtc->dtls_uc, rtc->dtls_srtp_materials, sizeof(rtc->dtls_srtp_materials));
+    if (ret < 0)
+        goto end;
+    /**
+     * This represents the material used to build the SRTP master key. It is
+     * generated by DTLS and has the following layout:
+     *          16B         16B         14B             14B
+     *      client_key | server_key | client_salt | server_salt
+     */
+    char *client_key = rtc->dtls_srtp_materials;
+    char *server_key = rtc->dtls_srtp_materials + DTLS_SRTP_KEY_LEN;
+    char *client_salt = server_key + DTLS_SRTP_KEY_LEN;
+    char *server_salt = client_salt + DTLS_SRTP_SALT_LEN;
+
+    memcpy(cp, client_key, DTLS_SRTP_KEY_LEN);
+    memcpy(cp + DTLS_SRTP_KEY_LEN, client_salt, DTLS_SRTP_SALT_LEN);
+
+    memcpy(sp, server_key, DTLS_SRTP_KEY_LEN);
+    memcpy(sp + DTLS_SRTP_KEY_LEN, server_salt, DTLS_SRTP_SALT_LEN);
+
+    /* Setup SRTP context for outgoing packets */
+    if (!av_base64_encode(buf, sizeof(buf), send_key, sizeof(send_key))) {
+        av_log(rtc, AV_LOG_ERROR, "Failed to encode send key\n");
+        ret = AVERROR(EIO);
+        goto end;
+    }
+
+    ret = ff_srtp_set_crypto(&rtc->srtp_audio_send, suite, buf);
+    if (ret < 0) {
+        av_log(rtc, AV_LOG_ERROR, "Failed to set crypto for audio send\n");
+        goto end;
+    }
+
+    ret = ff_srtp_set_crypto(&rtc->srtp_video_send, suite, buf);
+    if (ret < 0) {
+        av_log(rtc, AV_LOG_ERROR, "Failed to set crypto for video send\n");
+        goto end;
+    }
+
+    ret = ff_srtp_set_crypto(&rtc->srtp_video_rtx_send, suite, buf);
+    if (ret < 0) {
+        av_log(rtc, AV_LOG_ERROR, "Failed to set crypto for video rtx send\n");
+        goto end;
+    }
+
+    ret = ff_srtp_set_crypto(&rtc->srtp_rtcp_send, suite, buf);
+    if (ret < 0) {
+        av_log(rtc, AV_LOG_ERROR, "Failed to set crypto for rtcp send\n");
+        goto end;
+    }
+
+    /* Setup SRTP context for incoming packets */
+    if (!av_base64_encode(buf, sizeof(buf), recv_key, sizeof(recv_key))) {
+        av_log(rtc, AV_LOG_ERROR, "Failed to encode recv key\n");
+        ret = AVERROR(EIO);
+        goto end;
+    }
+
+    ret = ff_srtp_set_crypto(&rtc->srtp_recv, suite, buf);
+    if (ret < 0) {
+        av_log(rtc, AV_LOG_ERROR, "Failed to set crypto for recv\n");
+        goto end;
+    }
+    memcpy(rtc->srtp_recv_key, recv_key, sizeof(recv_key));
+
+    if (rtc->state < RTC_STATE_SRTP_FINISHED)
+        rtc->state = RTC_STATE_SRTP_FINISHED;
+    rtc->rtc_srtp_time = av_gettime_relative();
+    av_log(rtc, AV_LOG_VERBOSE, "SRTP setup done, state=%d, suite=%s, key=%zuB, elapsed=%.2fms\n",
+        rtc->state, suite, sizeof(send_key), RTC_ELAPSED(rtc->rtc_starttime, av_gettime_relative()));
+
+end:
+    return ret;
+}
+
+/**
+ * RTC is connectionless, for it's based on UDP, so it check whether sesison is
+ * timeout. In such case, publishers can't republish the stream util the session
+ * is timeout.
+ * This function is called to notify the server that the stream is ended, server
+ * should expire and close the session immediately, so that publishers can republish
+ * the stream quickly.
+ */
+static int dispose_session(AVFormatContext *s)
+{
+    int ret;
+    char buf[MAX_URL_SIZE];
+    URLContext *rtc_uc = NULL;
+    AVDictionary *opts = NULL;
+    RTCContext *rtc = s->priv_data;
+
+    if (!rtc->rtc_resource_url)
+        return 0;
+
+    ret = snprintf(buf, sizeof(buf), "Cache-Control: no-cache\r\n");
+    if (rtc->authorization)
+        ret += snprintf(buf + ret, sizeof(buf) - ret, "Authorization: Bearer %s\r\n", rtc->authorization);
+    if (ret <= 0 || ret >= sizeof(buf)) {
+        av_log(rtc, AV_LOG_ERROR, "Failed to generate headers, size=%d, %s\n", ret, buf);
+        ret = AVERROR(EINVAL);
+        goto end;
+    }
+
+    av_dict_set(&opts, "headers", buf, 0);
+    av_dict_set_int(&opts, "chunked_post", 0, 0);
+    av_dict_set(&opts, "method", "DELETE", 0);
+    ret = ffurl_open_whitelist(&rtc_uc, rtc->rtc_resource_url, AVIO_FLAG_READ_WRITE, &s->interrupt_callback,
+        &opts, s->protocol_whitelist, s->protocol_blacklist, NULL);
+    if (ret < 0) {
+        av_log(rtc, AV_LOG_ERROR, "Failed to DELETE url=%s\n", rtc->rtc_resource_url);
+        goto end;
+    }
+
+    while (1) {
+        ret = ffurl_read(rtc_uc, buf, sizeof(buf));
+        if (ret == AVERROR_EOF) {
+            ret = 0;
+            break;
+        }
+        if (ret < 0) {
+            av_log(rtc, AV_LOG_ERROR, "Failed to read response from DELETE url=%s\n", rtc->rtc_resource_url);
+            goto end;
+        }
+    }
+
+    av_log(rtc, AV_LOG_INFO, "Dispose resource %s ok\n", rtc->rtc_resource_url);
+
+end:
+    ffurl_closep(&rtc_uc);
+    av_dict_free(&opts);
+    return ret;
+}
+
+av_cold int ff_rtc_connect(AVFormatContext *s)
+{
+    int ret;
+
+    if ((ret = exchange_sdp(s)) < 0)
+        goto end;
+
+    if ((ret = parse_answer(s)) < 0)
+        goto end;
+
+    if ((ret = udp_connect(s)) < 0)
+        goto end;
+
+    if ((ret = ice_dtls_handshake(s)) < 0)
+        goto end;
+
+    if ((ret = setup_srtp(s)) < 0)
+        goto end;
+
+end:
+    return ret;
+}
+
+av_cold void ff_rtc_close(AVFormatContext *s)
+{
+    int i, ret;
+    RTCContext *rtc = s->priv_data;
+
+    ret = dispose_session(s);
+    if (ret < 0)
+        av_log(rtc, AV_LOG_WARNING, "Failed to dispose resource, ret=%d\n", ret);
+
+    for (i = 0; i < s->nb_streams; i++) {
+        AVFormatContext* rtp_ctx = s->streams[i]->priv_data;
+        if (!rtp_ctx)
+            continue;
+
+        av_write_trailer(rtp_ctx);
+        /**
+         * Keep in mind that it is necessary to free the buffer of pb since we allocate
+         * it and pass it to pb using avio_alloc_context, while avio_context_free does
+         * not perform this action.
+         */
+        av_freep(&rtp_ctx->pb->buffer);
+        avio_context_free(&rtp_ctx->pb);
+        avformat_free_context(rtp_ctx);
+        s->streams[i]->priv_data = NULL;
+    }
+
+    av_freep(&rtc->sdp_offer);
+    av_freep(&rtc->sdp_answer);
+    av_freep(&rtc->rtc_resource_url);
+    av_freep(&rtc->ice_ufrag_remote);
+    av_freep(&rtc->ice_pwd_remote);
+    av_freep(&rtc->ice_protocol);
+    av_freep(&rtc->ice_host);
+    av_freep(&rtc->authorization);
+    av_freep(&rtc->cert_file);
+    av_freep(&rtc->key_file);
+    ff_srtp_free(&rtc->srtp_audio_send);
+    ff_srtp_free(&rtc->srtp_video_send);
+    ff_srtp_free(&rtc->srtp_video_rtx_send);
+    ff_srtp_free(&rtc->srtp_rtcp_send);
+    ff_srtp_free(&rtc->srtp_recv);
+    ffurl_close(rtc->dtls_uc);
+    ffurl_closep(&rtc->udp);
+    av_freep(&rtc->dtls_fingerprint);
+}
+
+#define OFFSET(x) offsetof(RTCContext, x)
+#define ENC AV_OPT_FLAG_ENCODING_PARAM
+#define DEC AV_OPT_FLAG_DECODING_PARAM
+#define DEP AV_OPT_FLAG_DEPRECATED
+const AVOption ff_rtc_options[] = {
+    { "handshake_timeout",  "Timeout in milliseconds for ICE and DTLS handshake.",                  OFFSET(handshake_timeout),  AV_OPT_TYPE_INT,    { .i64 = 5000 },    -1, INT_MAX, ENC | DEC },
+    { "media_timeout",      "Timeout in milliseconds for receiving media packets.",                 OFFSET(media_timeout),      AV_OPT_TYPE_INT,    { .i64 = 0 },        0, INT_MAX, DEC },
+    { "pkt_size",           "The maximum size, in bytes, of RTP packets that send out",             OFFSET(pkt_size),           AV_OPT_TYPE_INT,    { .i64 = 1200 },    -1, INT_MAX, ENC | DEC },
+    { "buffer_size",        "The buffer size, in bytes, of underlying protocol",                    OFFSET(ts_buffer_size),        AV_OPT_TYPE_INT,    { .i64 = -1 },      -1, INT_MAX, ENC | DEC | DEP },
+    { "ts_buffer_size",     "The buffer size, in bytes, of underlying protocol",                    OFFSET(ts_buffer_size),        AV_OPT_TYPE_INT,    { .i64 = -1 },      -1, INT_MAX, ENC | DEC },
+    { "reorder_queue_size", "Set number of packets to buffer for handling of reordered packets",    OFFSET(reordering_queue_size), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, INT_MAX, DEC },
+    { "whip_flags",         "Set flags affecting WHIP connection behavior",                         OFFSET(flags),              AV_OPT_TYPE_FLAGS,  { .i64 = 0},         0, UINT_MAX, ENC | DEP, .unit = "flags" },
+    { "rtc_flags",          "Set flags affecting RTC connection behavior",                          OFFSET(flags),              AV_OPT_TYPE_FLAGS,  { .i64 = 0},         0, UINT_MAX, ENC | DEC, .unit = "flags" },
+    { "dtls_active",        "Set dtls role as active",                                              0,                          AV_OPT_TYPE_CONST,  { .i64 = RTC_DTLS_ACTIVE}, 0, UINT_MAX, ENC | DEC, .unit = "flags" },
+    { "authorization",      "The optional Bearer token for Authorization",                          OFFSET(authorization),      AV_OPT_TYPE_STRING, { .str = NULL },     0,       0, ENC | DEC },
+    { "cert_file",          "The optional certificate file path for DTLS",                          OFFSET(cert_file),          AV_OPT_TYPE_STRING, { .str = NULL },     0,       0, ENC | DEC },
+    { "key_file",           "The optional private key file path for DTLS",                          OFFSET(key_file),      AV_OPT_TYPE_STRING, { .str = NULL },     0,       0, ENC | DEC },
+    { NULL },
+};
diff --git a/libavformat/rtc.h b/libavformat/rtc.h
new file mode 100644
index 0000000000..8abdc1ec99
--- /dev/null
+++ b/libavformat/rtc.h
@@ -0,0 +1,274 @@
+/*
+ * RTC definations
+ * Copyright (c) 2023 The FFmpeg Project
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVFORMAT_RTC_H
+#define AVFORMAT_RTC_H
+
+#include "libavutil/opt.h"
+#include "libavutil/lfg.h"
+
+#include "avformat.h"
+#include "srtp.h"
+#include "tls.h"
+#include "url.h"
+
+/**
+ * Maximum size limit of a Session Description Protocol (SDP),
+ * be it an offer or answer.
+ */
+#define RTC_MAX_SDP_SIZE 8192
+
+/**
+ * The maximum size of the Secure Real-time Transport Protocol (SRTP) HMAC checksum
+ * and padding that is appended to the end of the packet. To calculate the maximum
+ * size of the User Datagram Protocol (UDP) packet that can be sent out, subtract
+ * this size from the `pkt_size`.
+ */
+#define DTLS_SRTP_CHECKSUM_LEN 16
+
+/**
+ * The size of the Secure Real-time Transport Protocol (SRTP) master key material
+ * that is exported by Secure Sockets Layer (SSL) after a successful Datagram
+ * Transport Layer Security (DTLS) handshake. This material consists of a key
+ * of 16 bytes and a salt of 14 bytes.
+ */
+#define DTLS_SRTP_KEY_LEN 16
+#define DTLS_SRTP_SALT_LEN 14
+
+/**
+ * Maximum size of the buffer for sending and receiving UDP packets.
+ * Please note that this size does not limit the size of the UDP packet that can be sent.
+ * To set the limit for packet size, modify the `pkt_size` parameter.
+ * For instance, it is possible to set the UDP buffer to 4096 to send or receive packets,
+ * but please keep in mind that the `pkt_size` option limits the packet size to 1400.
+ */
+#define RTC_MAX_UDP_BUFFER_SIZE 4096
+
+/* Referring to Chrome's definition of RTP payload types. */
+#define RTC_RTP_PAYLOAD_TYPE_H264 106
+#define RTC_RTP_PAYLOAD_TYPE_OPUS 111
+#define RTC_RTP_PAYLOAD_TYPE_VIDEO_RTX 105
+
+#define RTC_US_PER_MS 1000
+
+/**
+ * Refer to RFC 7675 5.1,
+ *
+ * To prevent expiry of consent, a STUN binding request can be sent periodically.
+ * Implementations SHOULD set a default interval of 5 seconds(5000ms).
+ *
+ * Consent expires after 30 seconds(30000ms).
+ */
+#define RTC_ICE_CONSENT_CHECK_INTERVAL 5000
+#define RTC_ICE_CONSENT_EXPIRED_TIMER 30000
+
+/**
+ * In the case of ICE-LITE, these fields are not used; instead, they are defined
+ * as constant values.
+ */
+#define RTC_SDP_SESSION_ID "4489045141692799359"
+#define RTC_SDP_CREATOR_IP "127.0.0.1"
+
+/* Calculate the elapsed time from starttime to endtime in milliseconds. */
+#define RTC_ELAPSED(starttime, endtime) ((float)(endtime - starttime) / 1000)
+
+typedef enum RTCFlags {
+    RTC_DTLS_ACTIVE = (1 << 0),
+} RTCFlags;
+
+enum RTCState {
+    RTC_STATE_NONE,
+
+    /* The initial state. */
+    RTC_STATE_INIT,
+    /* The muxer has sent the offer to the peer. */
+    RTC_STATE_OFFER,
+    /* The muxer has received the answer from the peer. */
+    RTC_STATE_ANSWER,
+    /**
+     * After parsing the answer received from the peer, the muxer negotiates the abilities
+     * in the offer that it generated.
+     */
+    RTC_STATE_NEGOTIATED,
+    /* The muxer has connected to the peer via UDP. */
+    RTC_STATE_UDP_CONNECTED,
+    /* The muxer has sent the ICE request to the peer. */
+    RTC_STATE_ICE_CONNECTING,
+    /* The muxer has received the ICE response from the peer. */
+    RTC_STATE_ICE_CONNECTED,
+    /* The muxer has finished the DTLS handshake with the peer. */
+    RTC_STATE_DTLS_FINISHED,
+    /* The muxer has finished the SRTP setup. */
+    RTC_STATE_SRTP_FINISHED,
+    /* The muxer is ready to send/receive media frames. */
+    RTC_STATE_READY,
+    /* The muxer is failed. */
+    RTC_STATE_FAILED,
+};
+
+typedef struct RTCContext {
+    AVClass *av_class;
+
+    uint32_t flags;
+    /* The state of the RTC connection. */
+    enum RTCState state;
+
+    /* Parameters for the input audio and video codecs. */
+    AVCodecParameters *audio_par;
+    AVCodecParameters *video_par;
+
+    /**
+     * The h264_mp4toannexb Bitstream Filter (BSF) bypasses the AnnexB packet;
+     * therefore, it is essential to insert the SPS and PPS before each IDR frame
+     * in such cases.
+     */
+    int h264_annexb_insert_sps_pps;
+
+    /* The random number generator. */
+    AVLFG rnd;
+
+    /* The ICE username and pwd fragment generated by the muxer. */
+    char ice_ufrag_local[9];
+    char ice_pwd_local[33];
+    /* The SSRC of the audio and video stream, generated by the muxer. */
+    uint32_t audio_ssrc;
+    uint32_t video_ssrc;
+    uint32_t video_rtx_ssrc;
+
+    uint16_t audio_first_seq;
+    uint16_t video_first_seq;
+    /* The PT(Payload Type) of stream, generated by the muxer. */
+    uint8_t audio_payload_type;
+    uint8_t video_payload_type;
+    uint8_t video_rtx_payload_type;
+    /**
+     * This is the SDP offer generated by the muxer based on the codec parameters,
+     * DTLS, and ICE information.
+     */
+    char *sdp_offer;
+
+    int is_peer_ice_lite;
+    uint64_t ice_tie_breaker; // random 64 bit, for ICE-CONTROLLING
+    /* The ICE username and pwd from remote server. */
+    char *ice_ufrag_remote;
+    char *ice_pwd_remote;
+    /**
+     * This represents the ICE candidate protocol, priority, host and port.
+     * Currently, we only support one candidate and choose the first UDP candidate.
+     * However, we plan to support multiple candidates in the future.
+     */
+    char *ice_protocol;
+    char *ice_host;
+    int ice_port;
+
+    /* The SDP answer received from the WebRTC server. */
+    char *sdp_answer;
+    /* The resource URL returned in the Location header of WHIP/WHEP HTTP response. */
+    char *rtc_resource_url;
+
+    /* These variables represent timestamps used for calculating and tracking the cost. */
+    int64_t rtc_starttime;
+    int64_t rtc_init_time;
+    int64_t rtc_offer_time;
+    int64_t rtc_answer_time;
+    int64_t rtc_udp_time;
+    int64_t rtc_ice_time;
+    int64_t rtc_dtls_time;
+    int64_t rtc_srtp_time;
+    int64_t rtc_last_consent_tx_time;
+    int64_t rtc_last_consent_rx_time;
+    int64_t rtc_last_media_rx_time;
+
+    /* The certificate and private key content used for DTLS handshake */
+    char cert_buf[MAX_CERTIFICATE_SIZE];
+    char key_buf[MAX_CERTIFICATE_SIZE];
+    /* The fingerprint of certificate, used in SDP offer. */
+    char *dtls_fingerprint;
+    /**
+     * This represents the material used to build the SRTP master key. It is
+     * generated by DTLS and has the following layout:
+     *          16B         16B         14B             14B
+     *      client_key | server_key | client_salt | server_salt
+     */
+    uint8_t dtls_srtp_materials[(DTLS_SRTP_KEY_LEN + DTLS_SRTP_SALT_LEN) * 2];
+
+    /* TODO: Use AVIOContext instead of URLContext */
+    URLContext *dtls_uc;
+
+    /* The SRTP send context, to encrypt outgoing packets. */
+    SRTPContext srtp_audio_send;
+    SRTPContext srtp_video_send;
+    SRTPContext srtp_video_rtx_send;
+    SRTPContext srtp_rtcp_send;
+    /* The SRTP receive context, to decrypt incoming packets. */
+    SRTPContext srtp_recv;
+
+    uint8_t srtp_recv_key[DTLS_SRTP_KEY_LEN + DTLS_SRTP_SALT_LEN];
+
+    /* The UDP transport is used for delivering ICE, DTLS and SRTP packets. */
+    URLContext *udp;
+    /* The buffer for UDP transmission. */
+    char buf[RTC_MAX_UDP_BUFFER_SIZE];
+
+    /* The timeout in milliseconds for ICE and DTLS handshake. */
+    int handshake_timeout;
+    /* The timeout in milliseconds for receiving media packets (RTP). */
+    int media_timeout;
+    /**
+     * The size of RTP packet, should generally be set to MTU.
+     * Note that pion requires a smaller value, for example, 1200.
+     */
+    int pkt_size;
+    int ts_buffer_size;/* Underlying protocol send/receive buffer size */
+
+    int reordering_queue_size; /* RTP reordering queue size */
+    /**
+     * The optional Bearer token for WHIP/WHEP Authorization.
+     * See https://www.ietf.org/archive/id/draft-ietf-wish-whip-08.html#name-authentication-and-authoriz
+     */
+    char* authorization;
+    /* The certificate and private key used for DTLS handshake. */
+    char* cert_file;
+    char* key_file;
+} RTCContext;
+
+int ff_rtc_initialize(AVFormatContext *s);
+
+int ff_rtc_connect(AVFormatContext *s);
+
+void ff_rtc_close(AVFormatContext *s);
+
+int ff_rtc_ice_create_request(AVFormatContext *s, uint8_t *buf, int buf_size, int *request_size);
+
+int ff_rtc_ice_is_binding_response(uint8_t *b, int size);
+
+int ff_rtc_ice_handle_binding_request(AVFormatContext *s, char *buf, int buf_size);
+
+int ff_rtc_is_dtls_packet(uint8_t *b, int size);
+
+int ff_rtc_media_is_rtcp(const uint8_t *b, int size);
+
+int ff_rtc_media_is_rtp_rtcp(const uint8_t *b, int size);
+
+
+extern const AVOption ff_rtc_options[];
+
+#endif /* AVFORMAT_RTC_H */
diff --git a/libavformat/whep.c b/libavformat/whep.c
new file mode 100644
index 0000000000..ee253004a1
--- /dev/null
+++ b/libavformat/whep.c
@@ -0,0 +1,1119 @@
+/*
+ * WebRTC-HTTP egress protocol (WHEP) demuxer
+ * Copyright (c) 2026 Artem Smorodin
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "libavutil/avstring.h"
+#include "libavutil/base64.h"
+#include "libavutil/bprint.h"
+#include "libavutil/channel_layout.h"
+#include "libavutil/intreadwrite.h"
+#include "libavutil/mem.h"
+#include "libavutil/time.h"
+
+#include "libavcodec/codec_desc.h"
+
+#include "avio_internal.h"
+#include "internal.h"
+#include "demux.h"
+#include "network.h"
+#include "rtp.h"
+#include "rtpdec.h"
+#include "rtc.h"
+
+/* If we try to read from UDP and get EAGAIN, we sleep for 5ms and retry up to 10 times. */
+#define WHEP_READ_MAX_RETRY 10
+#define WHEP_READ_SLEEP_DURATION 5
+
+#define DEFAULT_REORDERING_DELAY 100000
+#define WHEP_RTP_REORDER_QUEUE_DEFAULT_SIZE 5000
+
+#define WHEP_DEFAULT_AUDIO_SAMPLERATE 48000
+
+typedef struct WHEPStream {
+    int stream_index;
+    int payload_type;
+    uint32_t ssrc;
+    uint32_t rtx_ssrc;
+    int rtx_payload_type;
+    int rtx_apt;
+
+    RTPDemuxContext *rtp_ctx;
+    const RTPDynamicProtocolHandler *dynamic_handler;
+    PayloadContext *dynamic_protocol_context;
+
+    char delayed_fmtp[2048];
+
+    SRTPContext srtp;
+    int srtp_inited;
+
+    SRTPContext srtp_rtx;
+    int srtp_rtx_inited;
+} WHEPStream;
+
+typedef struct WHEPContext {
+    RTCContext rtc;
+    WHEPStream **streams;
+    int nb_streams;
+    WHEPStream *cur_ws;
+} WHEPContext;
+
+
+static void get_word_until_chars(char *buf, int buf_size,
+                                 const char *sep, const char **pp)
+{
+    const char *p;
+    char *q;
+
+    p = *pp;
+    p += strspn(p, SPACE_CHARS);
+    q = buf;
+    while (!strchr(sep, *p) && *p != '\0') {
+        if ((q - buf) < buf_size - 1)
+            *q++ = *p;
+        p++;
+    }
+    if (buf_size > 0)
+        *q = '\0';
+    *pp = p;
+}
+
+static void get_word_sep(char *buf, int buf_size, const char *sep,
+                         const char **pp)
+{
+    if (**pp == '/') (*pp)++;
+    get_word_until_chars(buf, buf_size, sep, pp);
+}
+
+static void get_word(char *buf, int buf_size, const char **pp)
+{
+    get_word_until_chars(buf, buf_size, SPACE_CHARS, pp);
+}
+
+static WHEPStream *find_stream_by_payload_type(WHEPContext *whep, int payload_type)
+{
+    int i;
+    for (i = 0; i < whep->nb_streams; i++) {
+        if (whep->streams[i]->payload_type == payload_type)
+            return whep->streams[i];
+    }
+    return NULL;
+}
+
+static WHEPStream *find_stream_by_rtx_payload_type(WHEPContext *whep, int payload_type)
+{
+    int i;
+    for (i = 0; i < whep->nb_streams; i++) {
+        if (whep->streams[i]->rtx_payload_type == payload_type)
+            return whep->streams[i];
+    }
+    return NULL;
+}
+
+static WHEPStream *find_stream_by_ssrc(WHEPContext *whep, uint32_t ssrc)
+{
+    int i;
+    for (i = 0; i < whep->nb_streams; i++) {
+        if (whep->streams[i]->ssrc == ssrc)
+            return whep->streams[i];
+    }
+    return NULL;
+}
+
+static WHEPStream *find_stream_by_rtx_ssrc(WHEPContext *whep, uint32_t ssrc)
+{
+    int i;
+    for (i = 0; i < whep->nb_streams; i++) {
+        if (whep->streams[i]->rtx_ssrc == ssrc)
+            return whep->streams[i];
+    }
+    return NULL;
+}
+
+static void init_rtp_handler(const RTPDynamicProtocolHandler *handler,
+                                  WHEPStream *ws, AVStream *st)
+{
+    AVCodecParameters *par = st ? st->codecpar : NULL;
+    if (!handler)
+        return;
+
+    if (par)
+        par->codec_id = handler->codec_id;
+
+    ws->dynamic_handler = handler;
+
+    if (st)
+        ffstream(st)->need_parsing = handler->need_parsing;
+
+    if (handler->priv_data_size) {
+        ws->dynamic_protocol_context = av_mallocz(handler->priv_data_size);
+        if (!ws->dynamic_protocol_context)
+            ws->dynamic_handler = NULL;
+    }
+}
+
+static void finalize_rtp_handler_init(AVFormatContext *s, WHEPStream *ws,
+                                           AVStream *st)
+{
+    if (ws->dynamic_handler && ws->dynamic_handler->init) {
+        int ret = ws->dynamic_handler->init(s, st ? st->index : -1,
+                                            ws->dynamic_protocol_context);
+        if (ret < 0) {
+            if (ws->dynamic_protocol_context) {
+                if (ws->dynamic_handler->close)
+                    ws->dynamic_handler->close(ws->dynamic_protocol_context);
+                av_free(ws->dynamic_protocol_context);
+            }
+            ws->dynamic_protocol_context = NULL;
+            ws->dynamic_handler = NULL;
+        }
+    }
+}
+
+static int parse_rtpmap(AVFormatContext *s, WHEPStream *ws,
+                             int payload_type, const char *p)
+{
+    AVStream *st = s->streams[ws->stream_index];
+    AVCodecParameters *par = st->codecpar;
+    char buf[256];
+    int i;
+    const AVCodecDescriptor *desc;
+    const char *c_name;
+
+    if (ws->payload_type != payload_type) {
+        ws->payload_type = payload_type;
+        if (ws->rtp_ctx)
+            ws->rtp_ctx->payload_type = payload_type;
+    }
+
+    /* See if we can handle this kind of payload */
+    get_word_sep(buf, sizeof(buf), "/ ", &p);
+    if (payload_type < RTP_PT_PRIVATE)
+        par->codec_id = ff_rtp_codec_id(buf, par->codec_type);
+
+    if (par->codec_id == AV_CODEC_ID_NONE) {
+        const RTPDynamicProtocolHandler *handler =
+            ff_rtp_handler_find_by_name(buf, par->codec_type);
+        init_rtp_handler(handler, ws, st);
+        if (!ws->dynamic_handler)
+            par->codec_id = ff_rtp_codec_id(buf, par->codec_type);
+    }
+
+    desc = avcodec_descriptor_get(par->codec_id);
+    c_name = desc && desc->name ? desc->name : "(null)";
+
+    get_word_sep(buf, sizeof(buf), "/", &p);
+    i = atoi(buf);
+    switch (par->codec_type) {
+    case AVMEDIA_TYPE_AUDIO:
+        av_log(s, AV_LOG_DEBUG, "audio codec set to: %s\n", c_name);
+        par->sample_rate = WHEP_DEFAULT_AUDIO_SAMPLERATE;
+        par->ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_MONO;
+        if (i > 0) {
+            par->sample_rate = i;
+            avpriv_set_pts_info(st, 32, 1, par->sample_rate);
+            get_word_sep(buf, sizeof(buf), "/", &p);
+            i = atoi(buf);
+            if (i > 0)
+                av_channel_layout_default(&par->ch_layout, i);
+        }
+        av_log(s, AV_LOG_DEBUG, "audio samplerate set to: %i\n", par->sample_rate);
+        av_log(s, AV_LOG_DEBUG, "audio channels set to: %i\n", par->ch_layout.nb_channels);
+        break;
+    case AVMEDIA_TYPE_VIDEO:
+        av_log(s, AV_LOG_DEBUG, "video codec set to: %s\n", c_name);
+        if (i > 0)
+            avpriv_set_pts_info(st, 32, 1, i);
+        break;
+    default:
+        break;
+    }
+
+    finalize_rtp_handler_init(s, ws, st);
+    if (ws->dynamic_handler)
+        ff_rtp_parse_set_dynamic_protocol(ws->rtp_ctx,
+                                          ws->dynamic_protocol_context,
+                                          ws->dynamic_handler);
+
+    if (ws->delayed_fmtp[0] && ws->dynamic_handler &&
+        ws->dynamic_handler->parse_sdp_a_line) {
+        ws->dynamic_handler->parse_sdp_a_line(s, st->index,
+                                              ws->dynamic_protocol_context,
+                                              ws->delayed_fmtp);
+        ws->delayed_fmtp[0] = '\0';
+    }
+
+    return 0;
+}
+
+static int add_stream(AVFormatContext *s, enum AVMediaType codec_type,
+                           int payload_type, WHEPStream **out)
+{
+    int ret = 0;
+    int queue_size;
+    WHEPContext *whep = s->priv_data;
+    RTCContext *rtc = &whep->rtc;
+    WHEPStream *ws = NULL;
+    AVStream *st = NULL;
+
+    if (s->nb_streams >= s->max_streams) {
+        av_log(s, AV_LOG_ERROR, "Too many streams, max=%d\n", s->max_streams);
+        return AVERROR(ENOSYS);
+    }
+
+    st = avformat_new_stream(s, NULL);
+    if (!st)
+        return AVERROR(ENOMEM);
+
+    st->id = whep->nb_streams;
+    st->codecpar->codec_type = codec_type;
+
+    ws = av_mallocz(sizeof(*ws));
+    if (!ws) {
+        ret = AVERROR(ENOMEM);
+        goto end;
+    }
+    ws->payload_type = payload_type;
+    ws->rtx_payload_type = -1;
+    ws->rtx_apt = -1;
+    ws->stream_index = st->index;
+
+    queue_size = s->max_delay ? rtc->reordering_queue_size : 0;
+    ws->rtp_ctx = ff_rtp_parse_open(s, st, payload_type, queue_size);
+    if (!ws->rtp_ctx) {
+        ret = AVERROR(ENOMEM);
+        goto end;
+    }
+
+    dynarray_add(&whep->streams, &whep->nb_streams, ws);
+    if (out)
+        *out = ws;
+    ws = NULL;
+
+end:
+    if (ws) {
+        ff_rtp_parse_close(ws->rtp_ctx);
+        av_free(ws);
+    }
+    return ret;
+}
+
+static int parse_sdp_answer(AVFormatContext *s)
+{
+    int ret = 0, i;
+    AVIOContext *pb = NULL;
+    char line[MAX_URL_SIZE];
+    const char *p;
+    WHEPContext *whep = s->priv_data;
+    RTCContext *rtc = &whep->rtc;
+    WHEPStream *cur = NULL;
+
+    if (!rtc->sdp_answer || !strlen(rtc->sdp_answer)) {
+        av_log(rtc, AV_LOG_ERROR, "No answer to parse\n");
+        return AVERROR(EINVAL);
+    }
+
+    pb = avio_alloc_context(rtc->sdp_answer, strlen(rtc->sdp_answer), 0,
+                            NULL, NULL, NULL, NULL);
+    if (!pb)
+        return AVERROR(ENOMEM);
+
+    while (!avio_feof(pb)) {
+        ff_get_chomp_line(pb, line, sizeof(line));
+        if (!line[0])
+            continue;
+
+        if (av_strstart(line, "m=", &p)) {
+            char media[16], port[16], proto[64], fmt[16];
+            enum AVMediaType codec_type = AVMEDIA_TYPE_UNKNOWN;
+            int payload_type = -1;
+            int expected_payload_type = -1;
+
+            get_word(media, sizeof(media), &p);
+            get_word(port, sizeof(port), &p);
+            get_word(proto, sizeof(proto), &p);
+            if (!media[0])
+                continue;
+
+            if (!strcmp(media, "audio")) {
+                codec_type = AVMEDIA_TYPE_AUDIO;
+                expected_payload_type = rtc->audio_payload_type;
+            } else if (!strcmp(media, "video")) {
+                codec_type = AVMEDIA_TYPE_VIDEO;
+                expected_payload_type = rtc->video_payload_type;
+            } else {
+                cur = NULL;
+
+                continue;
+            }
+
+            while (1) {
+                int pt;
+                get_word(fmt, sizeof(fmt), &p);
+                if (!fmt[0])
+                    break;
+                pt = atoi(fmt);
+                if (payload_type < 0)
+                    payload_type = pt;
+                if (expected_payload_type >= 0 && pt == expected_payload_type)
+                    payload_type = pt;
+            }
+            if (payload_type < 0)
+                continue;
+
+            ret = add_stream(s, codec_type, payload_type, &cur);
+            if (ret < 0)
+                goto end;
+            continue;
+        }
+
+        if (av_strstart(line, "a=rtpmap:", &p)) {
+            char pt_buf[16];
+            char codec_name[32];
+            int payload_type;
+            WHEPStream *ws;
+
+            get_word(pt_buf, sizeof(pt_buf), &p);
+            payload_type = atoi(pt_buf);
+            p += strspn(p, SPACE_CHARS);
+            {
+                const char *p2 = p;
+                get_word_sep(codec_name, sizeof(codec_name), "/ ", &p2);
+                if (!av_strcasecmp(codec_name, "rtx"))
+                    continue;
+            }
+            ws = find_stream_by_payload_type(whep, payload_type);
+            if (!ws)
+                continue;
+            ret = parse_rtpmap(s, ws, payload_type, p);
+            if (ret < 0)
+                goto end;
+            continue;
+        }
+
+        if (av_strstart(line, "a=fmtp:", &p)) {
+            char pt_buf[16];
+            int payload_type;
+            int apt_payload_type;
+            WHEPStream *ws;
+            const char *fmtp_attr = line + 2;
+            const char *apt;
+
+            get_word(pt_buf, sizeof(pt_buf), &p);
+            payload_type = atoi(pt_buf);
+            apt = strstr(fmtp_attr, "apt=");
+            if (apt) {
+                apt_payload_type = atoi(apt + 4);
+                ws = find_stream_by_payload_type(whep, apt_payload_type);
+                if (!ws && cur && cur->payload_type == apt_payload_type)
+                    ws = cur;
+                if (ws) {
+                    ws->rtx_payload_type = payload_type;
+                    ws->rtx_apt = apt_payload_type;
+                }
+                continue;
+            }
+
+            ws = find_stream_by_payload_type(whep, payload_type);
+            if (!ws)
+                continue;
+            if (ws->dynamic_handler && ws->dynamic_handler->parse_sdp_a_line) {
+                ws->dynamic_handler->parse_sdp_a_line(s, ws->stream_index,
+                                                      ws->dynamic_protocol_context, fmtp_attr);
+            } else if (!ws->delayed_fmtp[0]) {
+                av_strlcpy(ws->delayed_fmtp, fmtp_attr, sizeof(ws->delayed_fmtp));
+            }
+            continue;
+        }
+
+        if (av_strstart(line, "a=ssrc-group:", &p)) {
+            char semantics[16], ssrc1_buf[32], ssrc2_buf[32];
+            uint32_t ssrc1, ssrc2;
+
+            get_word(semantics, sizeof(semantics), &p);
+            if (av_strcasecmp(semantics, "FID"))
+                continue;
+
+            get_word(ssrc1_buf, sizeof(ssrc1_buf), &p);
+            get_word(ssrc2_buf, sizeof(ssrc2_buf), &p);
+            if (!ssrc1_buf[0] || !ssrc2_buf[0])
+                continue;
+
+            ssrc1 = strtoul(ssrc1_buf, NULL, 10);
+            ssrc2 = strtoul(ssrc2_buf, NULL, 10);
+
+            if (cur) {
+                if (!cur->ssrc || cur->ssrc == ssrc2)
+                    cur->ssrc = ssrc1;
+                cur->rtx_ssrc = ssrc2;
+            }
+            continue;
+        }
+
+        if (av_strstart(line, "a=ssrc:", &p)) {
+            uint32_t ssrc = strtoul(p, NULL, 10);
+            if (cur && !cur->ssrc)
+                cur->ssrc = ssrc;
+            continue;
+        }
+
+        if (av_strstart(line, "a=", &p)) {
+            if (cur && cur->dynamic_handler && cur->dynamic_handler->parse_sdp_a_line) {
+                cur->dynamic_handler->parse_sdp_a_line(s, cur->stream_index,
+                                                       cur->dynamic_protocol_context, p);
+            }
+        }
+
+        if (av_strstart(line, "s=", &p)) {
+            av_dict_set(&s->metadata, "title", p, 0);
+        }
+    }
+
+    for (i = 0; i < whep->nb_streams; i++) {
+        WHEPStream *ws = whep->streams[i];
+        if (!ws)
+            continue;
+        if (ws->rtx_payload_type >= 0 || ws->rtx_ssrc) {
+            av_log(rtc, AV_LOG_VERBOSE,
+                   "RTX negotiated stream=%d pt=%d ssrc=%u rtx_pt=%d rtx_ssrc=%u\n",
+                   ws->stream_index, ws->payload_type, ws->ssrc,
+                   ws->rtx_payload_type, ws->rtx_ssrc);
+        }
+    }
+
+    if (!whep->nb_streams) {
+        av_log(rtc, AV_LOG_ERROR, "No media streams parsed from answer\n");
+        ret = AVERROR(EINVAL);
+        goto end;
+    }
+
+end:
+    avio_context_free(&pb);
+    return ret;
+}
+
+static int init_srtp_streams(AVFormatContext *s)
+{
+    int i, ret;
+    char keybuf[AV_BASE64_SIZE(DTLS_SRTP_KEY_LEN + DTLS_SRTP_SALT_LEN)];
+    const char *suite = "SRTP_AES128_CM_HMAC_SHA1_80";
+    WHEPContext *whep = s->priv_data;
+    RTCContext *rtc = &whep->rtc;
+
+    if (!av_base64_encode(keybuf, sizeof(keybuf),
+                          rtc->srtp_recv_key, sizeof(rtc->srtp_recv_key))) {
+        av_log(rtc, AV_LOG_ERROR, "Failed to encode recv key\n");
+        return AVERROR(EIO);
+    }
+
+    for (i = 0; i < whep->nb_streams; i++) {
+        WHEPStream *ws = whep->streams[i];
+        if (!ws)
+            continue;
+        ret = ff_srtp_set_crypto(&ws->srtp, suite, keybuf);
+        if (ret < 0) {
+            av_log(rtc, AV_LOG_ERROR, "Failed to set crypto for stream %d\n", i);
+            return ret;
+        }
+        ws->srtp_inited = 1;
+
+        ret = ff_srtp_set_crypto(&ws->srtp_rtx, suite, keybuf);
+        if (ret < 0) {
+            av_log(rtc, AV_LOG_ERROR, "Failed to set crypto for rtx stream %d\n", i);
+            return ret;
+        }
+        ws->srtp_rtx_inited = 1;
+    }
+
+    return 0;
+}
+
+static int generate_sdp_offer(AVFormatContext *s)
+{
+    int ret = 0;
+    AVBPrint bp;
+    WHEPContext *whep = s->priv_data;
+    RTCContext *rtc = &whep->rtc;
+    int is_dtls_active = rtc->flags & RTC_DTLS_ACTIVE;
+
+    /* To prevent a crash during cleanup, always initialize it. */
+    av_bprint_init(&bp, 1, RTC_MAX_SDP_SIZE);
+
+    if (rtc->sdp_offer) {
+        av_log(rtc, AV_LOG_ERROR, "SDP offer is already set\n");
+        ret = AVERROR(EINVAL);
+        goto end;
+    }
+
+    snprintf(rtc->ice_ufrag_local, sizeof(rtc->ice_ufrag_local), "%08x",
+             av_lfg_get(&rtc->rnd));
+    snprintf(rtc->ice_pwd_local, sizeof(rtc->ice_pwd_local), "%08x%08x%08x%08x",
+             av_lfg_get(&rtc->rnd), av_lfg_get(&rtc->rnd), av_lfg_get(&rtc->rnd),
+             av_lfg_get(&rtc->rnd));
+
+    rtc->audio_payload_type = RTC_RTP_PAYLOAD_TYPE_OPUS;
+    rtc->video_payload_type = RTC_RTP_PAYLOAD_TYPE_H264;
+    rtc->video_rtx_payload_type = RTC_RTP_PAYLOAD_TYPE_VIDEO_RTX;
+
+    av_bprintf(&bp, ""
+        "v=0\r\n"
+        "o=FFmpeg %s 2 IN IP4 %s\r\n"
+        "s=FFmpegPlaySession\r\n"
+        "t=0 0\r\n"
+        "a=group:BUNDLE 0 1\r\n"
+        "a=extmap-allow-mixed\r\n"
+        "a=msid-semantic: WMS\r\n",
+        RTC_SDP_SESSION_ID,
+        RTC_SDP_CREATOR_IP);
+
+    av_bprintf(&bp, ""
+        "m=audio 9 UDP/TLS/RTP/SAVPF %u\r\n"
+        "c=IN IP4 0.0.0.0\r\n"
+        "a=ice-ufrag:%s\r\n"
+        "a=ice-pwd:%s\r\n"
+        "a=fingerprint:sha-256 %s\r\n"
+        "a=setup:%s\r\n"
+        "a=mid:0\r\n"
+        "a=recvonly\r\n"
+        "a=rtcp-mux\r\n"
+        "a=rtpmap:%u opus/48000/2\r\n",
+        rtc->audio_payload_type,
+        rtc->ice_ufrag_local,
+        rtc->ice_pwd_local,
+        rtc->dtls_fingerprint,
+        is_dtls_active ? "active" : "passive",
+        rtc->audio_payload_type);
+
+    av_bprintf(&bp, ""
+        "m=video 9 UDP/TLS/RTP/SAVPF %u %u\r\n"
+        "c=IN IP4 0.0.0.0\r\n"
+        "a=ice-ufrag:%s\r\n"
+        "a=ice-pwd:%s\r\n"
+        "a=fingerprint:sha-256 %s\r\n"
+        "a=setup:%s\r\n"
+        "a=mid:1\r\n"
+        "a=recvonly\r\n"
+        "a=rtcp-mux\r\n"
+        "a=rtcp-rsize\r\n"
+        "a=rtpmap:%u H264/90000\r\n"
+        "a=fmtp:%u level-asymmetry-allowed=1;packetization-mode=1;profile-level-id=42e01f\r\n"
+        "a=rtcp-fb:%u nack\r\n"
+        "a=rtcp-fb:%u nack pli\r\n"
+        "a=rtpmap:%u rtx/90000\r\n"
+        "a=fmtp:%u apt=%u\r\n",
+        rtc->video_payload_type,
+        rtc->video_rtx_payload_type,
+        rtc->ice_ufrag_local,
+        rtc->ice_pwd_local,
+        rtc->dtls_fingerprint,
+        is_dtls_active ? "active" : "passive",
+        rtc->video_payload_type,
+        rtc->video_payload_type,
+        rtc->video_payload_type,
+        rtc->video_payload_type,
+        rtc->video_rtx_payload_type,
+        rtc->video_rtx_payload_type,
+        rtc->video_payload_type);
+
+    if (!av_bprint_is_complete(&bp)) {
+        av_log(rtc, AV_LOG_ERROR, "Offer exceed max %d, %s\n", RTC_MAX_SDP_SIZE, bp.str);
+        ret = AVERROR(EIO);
+        goto end;
+    }
+
+    rtc->sdp_offer = av_strdup(bp.str);
+    if (!rtc->sdp_offer) {
+        ret = AVERROR(ENOMEM);
+        goto end;
+    }
+
+    if (rtc->state < RTC_STATE_OFFER)
+        rtc->state = RTC_STATE_OFFER;
+    rtc->rtc_offer_time = av_gettime_relative();
+    av_log(rtc, AV_LOG_VERBOSE, "Generated state=%d, offer: %s\n",
+           rtc->state, rtc->sdp_offer);
+
+end:
+    av_bprint_finalize(&bp, NULL);
+    return ret;
+}
+
+static int send_rtcp_rr(AVFormatContext *s, WHEPStream *ws, int count)
+{
+    int ret;
+    int len;
+    int cipher_len;
+    uint8_t *buf = NULL;
+    AVIOContext *pb = NULL;
+    WHEPContext *whep = s->priv_data;
+    RTCContext *rtc = &whep->rtc;
+
+    if ((ret = avio_open_dyn_buf(&pb)) < 0)
+        return ret;
+
+    ret = ff_rtp_check_and_send_back_rr(ws->rtp_ctx, NULL, pb, count);
+    len = avio_close_dyn_buf(pb, &buf);
+    if (ret < 0 || len <= 0 || !buf) {
+        av_free(buf);
+        return 0;
+    }
+
+    cipher_len = ff_srtp_encrypt(&rtc->srtp_rtcp_send, buf, len, rtc->buf, sizeof(rtc->buf));
+    if (cipher_len <= 0 || cipher_len < len) {
+        av_log(rtc, AV_LOG_WARNING, "Failed to encrypt rtcp packet=%dB, cipher=%dB\n",
+               len, cipher_len);
+        av_free(buf);
+        return 0;
+    }
+
+    av_log(rtc, AV_LOG_TRACE, "Sending SRTCP RR stream=%d plain=%dB cipher=%dB\n",
+           ws->stream_index, len, cipher_len);
+    ret = ffurl_write(rtc->udp, rtc->buf, cipher_len);
+    if (ret < 0)
+        av_log(rtc, AV_LOG_ERROR, "Failed to send rtcp packet=%dB, ret=%d\n", cipher_len, ret);
+
+    av_free(buf);
+    return ret < 0 ? ret : 0;
+}
+
+static int send_rtcp_feedback(AVFormatContext *s, WHEPStream *ws)
+{
+    int ret;
+    int len;
+    int cipher_len;
+    uint8_t *buf = NULL;
+    AVIOContext *pb = NULL;
+    WHEPContext *whep = s->priv_data;
+    RTCContext *rtc = &whep->rtc;
+
+    if ((ret = avio_open_dyn_buf(&pb)) < 0)
+        return ret;
+
+    ret = ff_rtp_send_rtcp_feedback(ws->rtp_ctx, NULL, pb);
+    len = avio_close_dyn_buf(pb, &buf);
+    if (ret < 0 || len <= 0 || !buf) {
+        av_free(buf);
+        return 0;
+    }
+
+    cipher_len = ff_srtp_encrypt(&rtc->srtp_rtcp_send, buf, len,
+                                rtc->buf, sizeof(rtc->buf));
+    if (cipher_len <= 0 || cipher_len < len) {
+        av_log(rtc, AV_LOG_WARNING,
+               "Failed to encrypt rtcp feedback packet=%dB, cipher=%dB\n",
+               len, cipher_len);
+        av_free(buf);
+        return 0;
+    }
+
+    av_log(rtc, AV_LOG_TRACE,
+           "Sending SRTCP feedback stream=%d plain=%dB cipher=%dB\n",
+           ws->stream_index, len, cipher_len);
+    ret = ffurl_write(rtc->udp, rtc->buf, cipher_len);
+    if (ret < 0)
+        av_log(rtc, AV_LOG_ERROR,
+               "Failed to send rtcp feedback packet=%dB, ret=%d\n",
+               cipher_len, ret);
+
+    av_free(buf);
+    return ret < 0 ? ret : 0;
+}
+
+static av_cold int whep_read_header(AVFormatContext *s)
+{
+    int ret;
+    WHEPContext *whep = s->priv_data;
+    RTCContext *rtc = &whep->rtc;
+
+    if (s->max_delay < 0) /* Not set by the caller */
+        s->max_delay = DEFAULT_REORDERING_DELAY;
+
+    if (rtc->reordering_queue_size <= 0)
+        rtc->reordering_queue_size = WHEP_RTP_REORDER_QUEUE_DEFAULT_SIZE;
+
+    if ((ret = ff_rtc_initialize(s)) < 0)
+        goto end;
+
+    if ((ret = generate_sdp_offer(s)) < 0)
+        goto end;
+
+    if ((ret = ff_rtc_connect(s)) < 0)
+        goto end;
+
+    if ((ret = parse_sdp_answer(s)) < 0)
+        goto end;
+
+    if ((ret = init_srtp_streams(s)) < 0)
+        goto end;
+
+    if (rtc->state < RTC_STATE_READY)
+        rtc->state = RTC_STATE_READY;
+
+    rtc->rtc_last_media_rx_time = av_gettime_relative();
+
+    av_log(rtc, AV_LOG_INFO, "Demuxer state=%d, elapsed=%.2fms(init:%.2f,offer:%.2f,answer:%.2f,udp:%.2f,ice:%.2f,dtls:%.2f,srtp:%.2f)\n",
+        rtc->state, RTC_ELAPSED(rtc->rtc_starttime, av_gettime_relative()),
+        RTC_ELAPSED(rtc->rtc_starttime, rtc->rtc_init_time),
+        RTC_ELAPSED(rtc->rtc_init_time, rtc->rtc_offer_time),
+        RTC_ELAPSED(rtc->rtc_offer_time, rtc->rtc_answer_time),
+        RTC_ELAPSED(rtc->rtc_answer_time, rtc->rtc_udp_time),
+        RTC_ELAPSED(rtc->rtc_udp_time, rtc->rtc_ice_time),
+        RTC_ELAPSED(rtc->rtc_ice_time, rtc->rtc_dtls_time),
+        RTC_ELAPSED(rtc->rtc_dtls_time, rtc->rtc_srtp_time));
+
+end:
+    if (ret < 0)
+        rtc->state = RTC_STATE_FAILED;
+    return ret;
+}
+
+static int get_rtp_payload_offset(const uint8_t *buf, int len, int *offset)
+{
+    int csrc, ext;
+    int header_len;
+
+    if (len < 12)
+        return AVERROR_INVALIDDATA;
+    if ((buf[0] >> 6) != RTP_VERSION)
+        return AVERROR_INVALIDDATA;
+
+    csrc = buf[0] & 0x0f;
+    ext  = buf[0] & 0x10;
+
+    header_len = 12 + 4 * csrc;
+    if (len < header_len)
+        return AVERROR_INVALIDDATA;
+
+    if (ext) {
+        int ext_len;
+
+        if (len < header_len + 4)
+            return AVERROR_INVALIDDATA;
+        /* See RFC 3550 Section 5.3.1 RTP Header Extension handling */
+        ext_len = (AV_RB16(buf + header_len + 2) + 1) * 4;
+        if (len < header_len + ext_len)
+            return AVERROR_INVALIDDATA;
+        header_len += ext_len;
+    }
+
+    *offset = header_len;
+    return 0;
+}
+
+static int whep_unwrap_rtx_packet(AVFormatContext *s, WHEPStream *ws,
+                                 uint8_t *buf, int *size)
+{
+    int ret, payload_offset;
+    uint16_t osn;
+    uint32_t media_ssrc;
+    int apt = ws->rtx_apt >= 0 ? ws->rtx_apt : ws->payload_type;
+
+    ret = get_rtp_payload_offset(buf, *size, &payload_offset);
+    if (ret < 0)
+        return ret;
+
+    if (*size - payload_offset < 2)
+        return AVERROR_INVALIDDATA;
+
+    osn = AV_RB16(buf + payload_offset);
+
+    memmove(buf + payload_offset, buf + payload_offset + 2, *size - payload_offset - 2);
+    *size -= 2;
+
+    AV_WB16(buf + 2, osn);
+    buf[1] = (buf[1] & 0x80) | (apt & 0x7f);
+
+    media_ssrc = ws->ssrc;
+    if (!media_ssrc && ws->rtp_ctx && ws->rtp_ctx->ssrc)
+        media_ssrc = ws->ssrc = ws->rtp_ctx->ssrc;
+    if (!media_ssrc) {
+        av_log(s, AV_LOG_DEBUG, "Cannot unwrap RTX before media SSRC is known\n");
+        return AVERROR(EAGAIN);
+    }
+
+    AV_WB32(buf + 8, media_ssrc);
+    return 0;
+}
+
+static int whep_read_packet(AVFormatContext *s, AVPacket *pkt)
+{
+    int ret, i;
+    int64_t now;
+    int64_t first_queue_time;
+    int size;
+    uint8_t *buf;
+    WHEPContext *whep = s->priv_data;
+    RTCContext *rtc = &whep->rtc;
+    WHEPStream *ws;
+    WHEPStream *first_queue_ws;
+    uint32_t ssrc;
+    int payload_type;
+    int is_rtcp;
+    int is_rtx;
+    SRTPContext *srtp_ctx;
+    int64_t wait_end;
+
+    while (1) {
+        if (ff_check_interrupt(&s->interrupt_callback))
+            return AVERROR_EXIT;
+
+        ws = whep->cur_ws;
+        if (ws) {
+            ret = ff_rtp_parse_packet(ws->rtp_ctx, pkt, NULL, 0);
+            if (ret >= 0) {
+                if (!ws->ssrc && ws->rtp_ctx->ssrc)
+                    ws->ssrc = ws->rtp_ctx->ssrc;
+                send_rtcp_feedback(s, ws);
+                if (ret == 0)
+                    whep->cur_ws = NULL;
+                return 0;
+            }
+            whep->cur_ws = NULL;
+        }
+
+        now = av_gettime_relative();
+        if (rtc->media_timeout > 0 && rtc->rtc_last_media_rx_time &&
+            now - rtc->rtc_last_media_rx_time > rtc->media_timeout * RTC_US_PER_MS) {
+            av_log(rtc, AV_LOG_ERROR,
+                   "Media timeout after %.2fms (limited %dms), terminate session\n",
+                   RTC_ELAPSED(rtc->rtc_last_media_rx_time, now), rtc->media_timeout);
+            rtc->state = RTC_STATE_FAILED;
+            return AVERROR(ETIMEDOUT);
+        }
+        first_queue_time = 0;
+        first_queue_ws = NULL;
+        if (s->max_delay > 0) {
+            for (i = 0; i < whep->nb_streams; i++) {
+                int64_t queue_time = ff_rtp_queued_packet_time(whep->streams[i]->rtp_ctx);
+                if (queue_time && (!first_queue_time || queue_time < first_queue_time)) {
+                    first_queue_time = queue_time;
+                    first_queue_ws = whep->streams[i];
+                }
+            }
+        }
+        wait_end = first_queue_time ? first_queue_time + s->max_delay : 0;
+        if (wait_end && now > wait_end && first_queue_ws) {
+            ret = ff_rtp_parse_packet(first_queue_ws->rtp_ctx, pkt, NULL, 0);
+            if (ret >= 0) {
+                if (!first_queue_ws->ssrc && first_queue_ws->rtp_ctx->ssrc)
+                    first_queue_ws->ssrc = first_queue_ws->rtp_ctx->ssrc;
+                send_rtcp_feedback(s, first_queue_ws);
+                whep->cur_ws = ret ? first_queue_ws : NULL;
+                return 0;
+            }
+        }
+        if (now - rtc->rtc_last_consent_rx_time > RTC_ICE_CONSENT_EXPIRED_TIMER * RTC_US_PER_MS) {
+            av_log(rtc, AV_LOG_ERROR,
+                "Consent Freshness expired after %.2fms (limited %dms), terminate session\n",
+                RTC_ELAPSED(rtc->rtc_last_consent_rx_time, now), RTC_ICE_CONSENT_EXPIRED_TIMER);
+            rtc->state = RTC_STATE_FAILED;
+            return AVERROR(ETIMEDOUT);
+        }
+        if (now - rtc->rtc_last_consent_tx_time > RTC_ICE_CONSENT_CHECK_INTERVAL * RTC_US_PER_MS) {
+            ret = ff_rtc_ice_create_request(s, rtc->buf, sizeof(rtc->buf), &size);
+            if (ret < 0) {
+                av_log(rtc, AV_LOG_ERROR, "Failed to create STUN binding request, size=%d\n", size);
+                return ret;
+            }
+            ret = ffurl_write(rtc->udp, rtc->buf, size);
+            if (ret < 0) {
+                av_log(rtc, AV_LOG_ERROR, "Failed to send STUN binding request, size=%d\n", size);
+                return ret;
+            }
+            rtc->rtc_last_consent_tx_time = now;
+            av_log(rtc, AV_LOG_DEBUG, "Consent Freshness check sent\n");
+        }
+
+        for (i = 0; i < WHEP_READ_MAX_RETRY; i++) {
+            ret = ffurl_read(rtc->udp, rtc->buf, sizeof(rtc->buf));
+            if (ret > 0)
+                break;
+            if (ret == AVERROR(EAGAIN)) {
+                if (s->flags & AVFMT_FLAG_NONBLOCK)
+                    return AVERROR(EAGAIN);
+                if (wait_end) {
+                    now = av_gettime_relative();
+                    if (now > wait_end && first_queue_ws) {
+                        ret = ff_rtp_parse_packet(first_queue_ws->rtp_ctx, pkt, NULL, 0);
+                        if (ret >= 0) {
+                            if (!first_queue_ws->ssrc && first_queue_ws->rtp_ctx->ssrc)
+                                first_queue_ws->ssrc = first_queue_ws->rtp_ctx->ssrc;
+                            send_rtcp_feedback(s, first_queue_ws);
+                            whep->cur_ws = ret ? first_queue_ws : NULL;
+                            return 0;
+                        }
+                    }
+                    if (now < wait_end) {
+                        int64_t sleep_us = FFMIN((int64_t)WHEP_READ_SLEEP_DURATION * RTC_US_PER_MS,
+                                                 wait_end - now);
+                        av_usleep(sleep_us);
+                        continue;
+                    }
+                }
+                av_usleep(WHEP_READ_SLEEP_DURATION * RTC_US_PER_MS);
+                continue;
+            }
+            if (ret < 0)
+                return ret;
+            if (!ret)
+                return AVERROR_EOF;
+        }
+        if (ret <= 0)
+            continue;
+
+        if (ff_rtc_ice_is_binding_response(rtc->buf, ret)) {
+            rtc->rtc_last_consent_rx_time = av_gettime_relative();
+            av_log(rtc, AV_LOG_DEBUG, "Consent Freshness check received\n");
+            continue;
+        }
+
+        if (ff_rtc_is_dtls_packet(rtc->buf, ret)) {
+            if ((ret = ffurl_write(rtc->dtls_uc, rtc->buf, ret)) < 0) {
+                av_log(rtc, AV_LOG_ERROR, "Failed to handle DTLS message\n");
+                return ret;
+            }
+            continue;
+        }
+
+        if (!ff_rtc_media_is_rtp_rtcp(rtc->buf, ret)) {
+            ff_rtc_ice_handle_binding_request(s, rtc->buf, ret);
+            continue;
+        }
+
+        is_rtcp = ff_rtc_media_is_rtcp(rtc->buf, ret);
+        if (is_rtcp) {
+            ssrc = ret >= 8 ? AV_RB32(&rtc->buf[4]) : 0;
+            ws = find_stream_by_ssrc(whep, ssrc);
+            if (!ws)
+                ws = find_stream_by_rtx_ssrc(whep, ssrc);
+        } else {
+            payload_type = rtc->buf[1] & 0x7f;
+            ssrc = ret >= 12 ? AV_RB32(&rtc->buf[8]) : 0;
+            ws = find_stream_by_ssrc(whep, ssrc);
+            if (!ws)
+                ws = find_stream_by_rtx_ssrc(whep, ssrc);
+            if (!ws)
+                ws = find_stream_by_payload_type(whep, payload_type);
+            if (!ws)
+                ws = find_stream_by_rtx_payload_type(whep, payload_type);
+        }
+        if (!ws && whep->nb_streams == 1)
+            ws = whep->streams[0];
+        if (!ws)
+            continue;
+        if (!is_rtcp)
+            rtc->rtc_last_media_rx_time = av_gettime_relative();
+
+        is_rtx = !is_rtcp &&
+                 ((ws->rtx_ssrc && ssrc == ws->rtx_ssrc) ||
+                  (ws->rtx_payload_type >= 0 && payload_type == ws->rtx_payload_type));
+        srtp_ctx = is_rtx ? &ws->srtp_rtx : &ws->srtp;
+
+        if (!ws->srtp_inited || (is_rtx && !ws->srtp_rtx_inited))
+            continue;
+
+        size = ret;
+        if ((ret = ff_srtp_decrypt(srtp_ctx, rtc->buf, &size)) < 0) {
+            av_log(rtc, AV_LOG_WARNING, "Failed to decrypt srtp packet, ret=%d\n", ret);
+            continue;
+        }
+
+        if (ff_rtc_media_is_rtcp(rtc->buf, size)) {
+            uint8_t *pkt_buf = av_memdup(rtc->buf, size);
+            if (!pkt_buf)
+                return AVERROR(ENOMEM);
+            buf = pkt_buf;
+            ff_rtp_parse_packet(ws->rtp_ctx, pkt, &buf, size);
+            if (buf)
+                av_freep(&pkt_buf);
+            continue;
+        }
+
+        if (size > 0) {
+            int pkt_size = size;
+            uint8_t *pkt_buf = av_memdup(rtc->buf, pkt_size);
+            if (!pkt_buf)
+                return AVERROR(ENOMEM);
+            buf = pkt_buf;
+
+            if (is_rtx) {
+                ret = whep_unwrap_rtx_packet(s, ws, buf, &pkt_size);
+                if (ret < 0) {
+                    av_free(pkt_buf);
+                    continue;
+                }
+            }
+
+            ret = ff_rtp_parse_packet(ws->rtp_ctx, pkt, &buf, pkt_size);
+            if (buf)
+                av_freep(&pkt_buf);
+            send_rtcp_feedback(s, ws);
+            send_rtcp_rr(s, ws, pkt_size);
+            if (ret >= 0) {
+                if (!ws->ssrc && ws->rtp_ctx->ssrc)
+                    ws->ssrc = ws->rtp_ctx->ssrc;
+                whep->cur_ws = ret ? ws : NULL;
+                return 0;
+            }
+        }
+    }
+}
+
+static av_cold int whep_read_close(AVFormatContext *s)
+{
+    int i;
+    WHEPContext *whep = s->priv_data;
+
+    for (i = 0; i < whep->nb_streams; i++) {
+        WHEPStream *ws = whep->streams[i];
+        if (!ws)
+            continue;
+        if (ws->dynamic_handler && ws->dynamic_protocol_context) {
+            if (ws->dynamic_handler->close)
+                ws->dynamic_handler->close(ws->dynamic_protocol_context);
+            av_free(ws->dynamic_protocol_context);
+        }
+        ff_srtp_free(&ws->srtp);
+        ff_srtp_free(&ws->srtp_rtx);
+        ff_rtp_parse_close(ws->rtp_ctx);
+        av_free(ws);
+    }
+    av_freep(&whep->streams);
+
+    ff_rtc_close(s);
+    return 0;
+}
+
+static const AVClass whep_demuxer_class = {
+    .class_name = "WHEP demuxer",
+    .item_name  = av_default_item_name,
+    .option     = ff_rtc_options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
+const FFInputFormat ff_whep_demuxer = {
+    .p.name         = "whep",
+    .p.long_name    = NULL_IF_CONFIG_SMALL("WHEP(WebRTC-HTTP egress protocol) demuxer"),
+    .p.flags        = AVFMT_NOFILE | AVFMT_EXPERIMENTAL,
+    .p.priv_class   = &whep_demuxer_class,
+    .priv_data_size = sizeof(WHEPContext),
+    .read_header    = whep_read_header,
+    .read_packet    = whep_read_packet,
+    .read_close     = whep_read_close,
+};
diff --git a/libavformat/whip.c b/libavformat/whip.c
index 8aed0c31e5..a0fc07d5cd 100644
--- a/libavformat/whip.c
+++ b/libavformat/whip.c
@@ -21,443 +21,19 @@
 
 #include "libavcodec/h264.h"
 #include "libavcodec/startcode.h"
-#include "libavutil/avassert.h"
-#include "libavutil/base64.h"
 #include "libavutil/bprint.h"
-#include "libavutil/crc.h"
-#include "libavutil/hmac.h"
-#include "libavutil/intreadwrite.h"
-#include "libavutil/lfg.h"
-#include "libavutil/opt.h"
+#include "libavutil/avassert.h"
 #include "libavutil/mem.h"
-#include "libavutil/random_seed.h"
 #include "libavutil/time.h"
+#include "libavutil/intreadwrite.h"
+
+#include "internal.h"
+#include "avio_internal.h"
 #include "avc.h"
 #include "nal.h"
-#include "avio_internal.h"
-#include "http.h"
-#include "internal.h"
+#include "rtc.h"
 #include "mux.h"
-#include "network.h"
 #include "rtp.h"
-#include "srtp.h"
-#include "tls.h"
-
-/**
- * Maximum size limit of a Session Description Protocol (SDP),
- * be it an offer or answer.
- */
-#define MAX_SDP_SIZE 8192
-
-/**
- * The size of the Secure Real-time Transport Protocol (SRTP) master key material
- * that is exported by Secure Sockets Layer (SSL) after a successful Datagram
- * Transport Layer Security (DTLS) handshake. This material consists of a key
- * of 16 bytes and a salt of 14 bytes.
- */
-#define DTLS_SRTP_KEY_LEN 16
-#define DTLS_SRTP_SALT_LEN 14
-
-/**
- * The maximum size of the Secure Real-time Transport Protocol (SRTP) HMAC checksum
- * and padding that is appended to the end of the packet. To calculate the maximum
- * size of the User Datagram Protocol (UDP) packet that can be sent out, subtract
- * this size from the `pkt_size`.
- */
-#define DTLS_SRTP_CHECKSUM_LEN 16
-
-#define WHIP_US_PER_MS 1000
-
-/**
- * If we try to read from UDP and get EAGAIN, we sleep for 5ms and retry up to 10 times.
- * This will limit the total duration (in milliseconds, 50ms)
- */
-#define ICE_DTLS_READ_MAX_RETRY 10
-#define ICE_DTLS_READ_SLEEP_DURATION 5
-
-/* The magic cookie for Session Traversal Utilities for NAT (STUN) messages. */
-#define STUN_MAGIC_COOKIE 0x2112A442
-
-/**
- * Refer to RFC 8445 5.1.2
- * priority = (2^24)*(type preference) + (2^8)*(local preference) + (2^0)*(256 - component ID)
- * host candidate priority is 126 << 24 | 65535 << 8 | 255
- */
-#define STUN_HOST_CANDIDATE_PRIORITY 126 << 24 | 65535 << 8 | 255
-
-/**
- * The DTLS content type.
- * See https://tools.ietf.org/html/rfc2246#section-6.2.1
- * change_cipher_spec(20), alert(21), handshake(22), application_data(23)
- */
-#define DTLS_CONTENT_TYPE_CHANGE_CIPHER_SPEC 20
-
-/**
- * The DTLS record layer header has a total size of 13 bytes, consisting of
- * ContentType (1 byte), ProtocolVersion (2 bytes), Epoch (2 bytes),
- * SequenceNumber (6 bytes), and Length (2 bytes).
- * See https://datatracker.ietf.org/doc/html/rfc9147#section-4
- */
-#define DTLS_RECORD_LAYER_HEADER_LEN 13
-
-/**
- * The DTLS version number, which is 0xfeff for DTLS 1.0, or 0xfefd for DTLS 1.2.
- * See https://datatracker.ietf.org/doc/html/rfc9147#name-the-dtls-record-layer
- */
-#define DTLS_VERSION_10 0xfeff
-#define DTLS_VERSION_12 0xfefd
-
-/**
- * Maximum size of the buffer for sending and receiving UDP packets.
- * Please note that this size does not limit the size of the UDP packet that can be sent.
- * To set the limit for packet size, modify the `pkt_size` parameter.
- * For instance, it is possible to set the UDP buffer to 4096 to send or receive packets,
- * but please keep in mind that the `pkt_size` option limits the packet size to 1400.
- */
-#define MAX_UDP_BUFFER_SIZE 4096
-
-/* Referring to Chrome's definition of RTP payload types. */
-#define WHIP_RTP_PAYLOAD_TYPE_H264 106
-#define WHIP_RTP_PAYLOAD_TYPE_OPUS 111
-#define WHIP_RTP_PAYLOAD_TYPE_VIDEO_RTX 105
-
-/**
- * The STUN message header, which is 20 bytes long, comprises the
- * STUNMessageType (1B), MessageLength (2B), MagicCookie (4B),
- * and TransactionID (12B).
- * See https://datatracker.ietf.org/doc/html/rfc5389#section-6
- */
-#define ICE_STUN_HEADER_SIZE 20
-
-/**
- * The RTP header is 12 bytes long, comprising the Version(1B), PT(1B),
- * SequenceNumber(2B), Timestamp(4B), and SSRC(4B).
- * See https://www.rfc-editor.org/rfc/rfc3550#section-5.1
- */
-#define WHIP_RTP_HEADER_SIZE 12
-
-/**
- * For RTCP, PT is [128, 223] (or without marker [0, 95]). Literally, RTCP starts
- * from 64 not 0, so PT is [192, 223] (or without marker [64, 95]), see "RTCP Control
- * Packet Types (PT)" at
- * https://www.iana.org/assignments/rtp-parameters/rtp-parameters.xhtml#rtp-parameters-4
- *
- * For RTP, the PT is [96, 127], or [224, 255] with marker. See "RTP Payload Types (PT)
- * for standard audio and video encodings" at
- * https://www.iana.org/assignments/rtp-parameters/rtp-parameters.xhtml#rtp-parameters-1
- */
-#define WHIP_RTCP_PT_START 192
-#define WHIP_RTCP_PT_END   223
-
-/**
- * In the case of ICE-LITE, these fields are not used; instead, they are defined
- * as constant values.
- */
-#define WHIP_SDP_SESSION_ID "4489045141692799359"
-#define WHIP_SDP_CREATOR_IP "127.0.0.1"
-
-/**
- * Refer to RFC 7675 5.1,
- *
- * To prevent expiry of consent, a STUN binding request can be sent periodically.
- * Implementations SHOULD set a default interval of 5 seconds(5000ms).
- *
- * Consent expires after 30 seconds(30000ms).
- */
-#define WHIP_ICE_CONSENT_CHECK_INTERVAL 5000
-#define WHIP_ICE_CONSENT_EXPIRED_TIMER 30000
-
-/* Calculate the elapsed time from starttime to endtime in milliseconds. */
-#define ELAPSED(starttime, endtime) ((float)(endtime - starttime) / 1000)
-
-/* STUN Attribute, comprehension-required range (0x0000-0x7FFF) */
-enum STUNAttr {
-    STUN_ATTR_USERNAME                  = 0x0006, /// shared secret response/bind request
-    STUN_ATTR_PRIORITY                  = 0x0024, /// must be included in a Binding request
-    STUN_ATTR_USE_CANDIDATE             = 0x0025, /// bind request
-    STUN_ATTR_MESSAGE_INTEGRITY         = 0x0008, /// bind request/response
-    STUN_ATTR_FINGERPRINT               = 0x8028, /// rfc5389
-    STUN_ATTR_ICE_CONTROLLING           = 0x802A, /// ICE controlling role
-};
-
-enum WHIPState {
-    WHIP_STATE_NONE,
-
-    /* The initial state. */
-    WHIP_STATE_INIT,
-    /* The muxer has sent the offer to the peer. */
-    WHIP_STATE_OFFER,
-    /* The muxer has received the answer from the peer. */
-    WHIP_STATE_ANSWER,
-    /**
-     * After parsing the answer received from the peer, the muxer negotiates the abilities
-     * in the offer that it generated.
-     */
-    WHIP_STATE_NEGOTIATED,
-    /* The muxer has connected to the peer via UDP. */
-    WHIP_STATE_UDP_CONNECTED,
-    /* The muxer has sent the ICE request to the peer. */
-    WHIP_STATE_ICE_CONNECTING,
-    /* The muxer has received the ICE response from the peer. */
-    WHIP_STATE_ICE_CONNECTED,
-    /* The muxer has finished the DTLS handshake with the peer. */
-    WHIP_STATE_DTLS_FINISHED,
-    /* The muxer has finished the SRTP setup. */
-    WHIP_STATE_SRTP_FINISHED,
-    /* The muxer is ready to send/receive media frames. */
-    WHIP_STATE_READY,
-    /* The muxer is failed. */
-    WHIP_STATE_FAILED,
-};
-
-typedef enum WHIPFlags {
-    WHIP_DTLS_ACTIVE = (1 << 0),
-} WHIPFlags;
-
-typedef struct WHIPContext {
-    AVClass *av_class;
-
-    uint32_t flags;
-    /* The state of the RTC connection. */
-    enum WHIPState state;
-
-    /* Parameters for the input audio and video codecs. */
-    AVCodecParameters *audio_par;
-    AVCodecParameters *video_par;
-
-    /**
-     * The h264_mp4toannexb Bitstream Filter (BSF) bypasses the AnnexB packet;
-     * therefore, it is essential to insert the SPS and PPS before each IDR frame
-     * in such cases.
-     */
-    int h264_annexb_insert_sps_pps;
-
-    /* The random number generator. */
-    AVLFG rnd;
-
-    /* The ICE username and pwd fragment generated by the muxer. */
-    char ice_ufrag_local[9];
-    char ice_pwd_local[33];
-    /* The SSRC of the audio and video stream, generated by the muxer. */
-    uint32_t audio_ssrc;
-    uint32_t video_ssrc;
-    uint32_t video_rtx_ssrc;
-
-    uint16_t audio_first_seq;
-    uint16_t video_first_seq;
-    /* The PT(Payload Type) of stream, generated by the muxer. */
-    uint8_t audio_payload_type;
-    uint8_t video_payload_type;
-    uint8_t video_rtx_payload_type;
-    /**
-     * This is the SDP offer generated by the muxer based on the codec parameters,
-     * DTLS, and ICE information.
-     */
-    char *sdp_offer;
-
-    int is_peer_ice_lite;
-    uint64_t ice_tie_breaker; // random 64 bit, for ICE-CONTROLLING
-    /* The ICE username and pwd from remote server. */
-    char *ice_ufrag_remote;
-    char *ice_pwd_remote;
-    /**
-     * This represents the ICE candidate protocol, priority, host and port.
-     * Currently, we only support one candidate and choose the first UDP candidate.
-     * However, we plan to support multiple candidates in the future.
-     */
-    char *ice_protocol;
-    char *ice_host;
-    int ice_port;
-
-    /* The SDP answer received from the WebRTC server. */
-    char *sdp_answer;
-    /* The resource URL returned in the Location header of WHIP HTTP response. */
-    char *whip_resource_url;
-
-    /* These variables represent timestamps used for calculating and tracking the cost. */
-    int64_t whip_starttime;
-    int64_t whip_init_time;
-    int64_t whip_offer_time;
-    int64_t whip_answer_time;
-    int64_t whip_udp_time;
-    int64_t whip_ice_time;
-    int64_t whip_dtls_time;
-    int64_t whip_srtp_time;
-    int64_t whip_last_consent_tx_time;
-    int64_t whip_last_consent_rx_time;
-
-    /* The certificate and private key content used for DTLS handshake */
-    char cert_buf[MAX_CERTIFICATE_SIZE];
-    char key_buf[MAX_CERTIFICATE_SIZE];
-    /* The fingerprint of certificate, used in SDP offer. */
-    char *dtls_fingerprint;
-    /**
-     * This represents the material used to build the SRTP master key. It is
-     * generated by DTLS and has the following layout:
-     *          16B         16B         14B             14B
-     *      client_key | server_key | client_salt | server_salt
-     */
-    uint8_t dtls_srtp_materials[(DTLS_SRTP_KEY_LEN + DTLS_SRTP_SALT_LEN) * 2];
-
-    /* TODO: Use AVIOContext instead of URLContext */
-    URLContext *dtls_uc;
-
-    /* The SRTP send context, to encrypt outgoing packets. */
-    SRTPContext srtp_audio_send;
-    SRTPContext srtp_video_send;
-    SRTPContext srtp_video_rtx_send;
-    SRTPContext srtp_rtcp_send;
-    /* The SRTP receive context, to decrypt incoming packets. */
-    SRTPContext srtp_recv;
-
-    /* The UDP transport is used for delivering ICE, DTLS and SRTP packets. */
-    URLContext *udp;
-    /* The buffer for UDP transmission. */
-    char buf[MAX_UDP_BUFFER_SIZE];
-
-    /* The timeout in milliseconds for ICE and DTLS handshake. */
-    int handshake_timeout;
-    /**
-     * The size of RTP packet, should generally be set to MTU.
-     * Note that pion requires a smaller value, for example, 1200.
-     */
-    int pkt_size;
-    int ts_buffer_size;/* Underlying protocol send/receive buffer size */
-    /**
-     * The optional Bearer token for WHIP Authorization.
-     * See https://www.ietf.org/archive/id/draft-ietf-wish-whip-08.html#name-authentication-and-authoriz
-     */
-    char* authorization;
-    /* The certificate and private key used for DTLS handshake. */
-    char* cert_file;
-    char* key_file;
-} WHIPContext;
-
-/**
- * Whether the packet is a DTLS packet.
- */
-static int is_dtls_packet(uint8_t *b, int size)
-{
-    int ret = 0;
-    if (size > DTLS_RECORD_LAYER_HEADER_LEN) {
-        uint16_t version = AV_RB16(&b[1]);
-        ret = b[0] >= DTLS_CONTENT_TYPE_CHANGE_CIPHER_SPEC &&
-            (version == DTLS_VERSION_10 || version == DTLS_VERSION_12);
-    }
-    return ret;
-}
-
-
-/**
- * Get or Generate a self-signed certificate and private key for DTLS,
- * fingerprint for SDP
- */
-static av_cold int certificate_key_init(AVFormatContext *s)
-{
-    int ret = 0;
-    WHIPContext *whip = s->priv_data;
-
-    if (whip->cert_file && whip->key_file) {
-        /* Read the private key and certificate from the file. */
-        if ((ret = ff_ssl_read_key_cert(whip->key_file, whip->cert_file,
-                                        whip->key_buf, sizeof(whip->key_buf),
-                                        whip->cert_buf, sizeof(whip->cert_buf),
-                                        &whip->dtls_fingerprint)) < 0) {
-            av_log(s, AV_LOG_ERROR, "Failed to read DTLS certificate from cert=%s, key=%s\n",
-                whip->cert_file, whip->key_file);
-            return ret;
-        }
-    } else {
-        /* Generate a private key to ctx->dtls_pkey and self-signed certificate. */
-        if ((ret = ff_ssl_gen_key_cert(whip->key_buf, sizeof(whip->key_buf),
-                                       whip->cert_buf, sizeof(whip->cert_buf),
-                                       &whip->dtls_fingerprint)) < 0) {
-            av_log(s, AV_LOG_ERROR, "Failed to generate DTLS private key and certificate\n");
-            return ret;
-        }
-    }
-
-    return ret;
-}
-
-static av_cold int dtls_initialize(AVFormatContext *s)
-{
-    int ret = 0;
-    WHIPContext *whip = s->priv_data;
-    int is_dtls_active = whip->flags & WHIP_DTLS_ACTIVE;
-    AVDictionary *opts = NULL;
-    char buf[256];
-
-    ff_url_join(buf, sizeof(buf), "dtls", NULL, whip->ice_host, whip->ice_port, NULL);
-    av_dict_set_int(&opts, "mtu", whip->pkt_size, 0);
-    if (whip->cert_file) {
-        av_dict_set(&opts, "cert_file", whip->cert_file, 0);
-    } else
-        av_dict_set(&opts, "cert_pem", whip->cert_buf, 0);
-
-    if (whip->key_file) {
-        av_dict_set(&opts, "key_file", whip->key_file, 0);
-    } else
-        av_dict_set(&opts, "key_pem", whip->key_buf, 0);
-    av_dict_set_int(&opts, "external_sock", 1, 0);
-    av_dict_set_int(&opts, "use_srtp", 1, 0);
-    av_dict_set_int(&opts, "listen", is_dtls_active ? 0 : 1, 0);
-    ret = ffurl_open_whitelist(&whip->dtls_uc, buf, AVIO_FLAG_READ_WRITE, &s->interrupt_callback,
-        &opts, s->protocol_whitelist, s->protocol_blacklist, NULL);
-    av_dict_free(&opts);
-    if (ret < 0) {
-        av_log(whip, AV_LOG_ERROR, "Failed to open DTLS url:%s\n", buf);
-        goto end;
-    }
-    /* reuse the udp created by whip */
-    ff_tls_set_external_socket(whip->dtls_uc, whip->udp);
-end:
-    return ret;
-}
-
-/**
- * Initialize and check the options for the WebRTC muxer.
- */
-static av_cold int initialize(AVFormatContext *s)
-{
-    int ret, ideal_pkt_size = 532;
-    WHIPContext *whip = s->priv_data;
-    uint32_t seed;
-
-    whip->whip_starttime = av_gettime_relative();
-
-    ret = certificate_key_init(s);
-    if (ret < 0) {
-        av_log(whip, AV_LOG_ERROR, "Failed to init certificate and key\n");
-        return ret;
-    }
-
-    /* Initialize the random number generator. */
-    seed = av_get_random_seed();
-    av_lfg_init(&whip->rnd, seed);
-
-    /* 64 bit tie breaker for ICE-CONTROLLING (RFC 8445 16.1) */
-    ret = av_random_bytes((uint8_t *)&whip->ice_tie_breaker, sizeof(whip->ice_tie_breaker));
-    if (ret < 0) {
-        av_log(whip, AV_LOG_ERROR, "Couldn't generate random bytes for ICE tie breaker\n");
-        return ret;
-    }
-
-    whip->audio_first_seq = av_lfg_get(&whip->rnd) & 0x0fff;
-    whip->video_first_seq = whip->audio_first_seq + 1;
-
-    if (whip->pkt_size < ideal_pkt_size)
-        av_log(whip, AV_LOG_WARNING, "pkt_size=%d(<%d) is too small, may cause packet loss\n",
-               whip->pkt_size, ideal_pkt_size);
-
-    if (whip->state < WHIP_STATE_INIT)
-        whip->state = WHIP_STATE_INIT;
-    whip->whip_init_time = av_gettime_relative();
-    av_log(whip, AV_LOG_VERBOSE, "Init state=%d, handshake_timeout=%dms, pkt_size=%d, seed=%d, elapsed=%.2fms\n",
-        whip->state, whip->handshake_timeout, whip->pkt_size, seed, ELAPSED(whip->whip_starttime, av_gettime_relative()));
-
-    return 0;
-}
 
 /**
  * When duplicating a stream, the demuxer has already set the extradata, profile, and
@@ -477,7 +53,7 @@ static int parse_profile_level(AVFormatContext *s, AVCodecParameters *par)
     const uint8_t *r = par->extradata, *r1, *end = par->extradata + par->extradata_size;
     H264SPS seq, *const sps = &seq;
     uint32_t state;
-    WHIPContext *whip = s->priv_data;
+    RTCContext *rtc = s->priv_data;
 
     if (par->codec_id != AV_CODEC_ID_H264)
         return ret;
@@ -486,7 +62,7 @@ static int parse_profile_level(AVFormatContext *s, AVCodecParameters *par)
         return ret;
 
     if (!par->extradata || par->extradata_size <= 0) {
-        av_log(whip, AV_LOG_ERROR, "Unable to parse profile from empty extradata=%p, size=%d\n",
+        av_log(rtc, AV_LOG_ERROR, "Unable to parse profile from empty extradata=%p, size=%d\n",
             par->extradata, par->extradata_size);
         return AVERROR(EINVAL);
     }
@@ -500,12 +76,12 @@ static int parse_profile_level(AVFormatContext *s, AVCodecParameters *par)
         if ((state & 0x1f) == H264_NAL_SPS) {
             ret = ff_avc_decode_sps(sps, r, r1 - r);
             if (ret < 0) {
-                av_log(whip, AV_LOG_ERROR, "Failed to decode SPS, state=%x, size=%d\n",
+                av_log(rtc, AV_LOG_ERROR, "Failed to decode SPS, state=%x, size=%d\n",
                     state, (int)(r1 - r));
                 return ret;
             }
 
-            av_log(whip, AV_LOG_VERBOSE, "Parse profile=%d, level=%d from SPS\n",
+            av_log(rtc, AV_LOG_VERBOSE, "Parse profile=%d, level=%d from SPS\n",
                 sps->profile_idc, sps->level_idc);
             par->profile = sps->profile_idc;
             par->level = sps->level_idc;
@@ -541,44 +117,44 @@ static int parse_profile_level(AVFormatContext *s, AVCodecParameters *par)
 static int parse_codec(AVFormatContext *s)
 {
     int i, ret = 0;
-    WHIPContext *whip = s->priv_data;
+    RTCContext *rtc = s->priv_data;
 
     for (i = 0; i < s->nb_streams; i++) {
         AVCodecParameters *par = s->streams[i]->codecpar;
         switch (par->codec_type) {
         case AVMEDIA_TYPE_VIDEO:
-            whip->video_par = par;
+            rtc->video_par = par;
 
             if (par->video_delay > 0) {
-                av_log(whip, AV_LOG_ERROR, "Unsupported B frames by RTC\n");
+                av_log(rtc, AV_LOG_ERROR, "Unsupported B frames by RTC\n");
                 return AVERROR_PATCHWELCOME;
             }
 
             if ((ret = parse_profile_level(s, par)) < 0) {
-                av_log(whip, AV_LOG_ERROR, "Failed to parse SPS/PPS from extradata\n");
+                av_log(rtc, AV_LOG_ERROR, "Failed to parse SPS/PPS from extradata\n");
                 return AVERROR(EINVAL);
             }
 
             if (par->profile == AV_PROFILE_UNKNOWN) {
-                av_log(whip, AV_LOG_WARNING, "No profile found in extradata, consider baseline\n");
+                av_log(rtc, AV_LOG_WARNING, "No profile found in extradata, consider baseline\n");
                 return AVERROR(EINVAL);
             }
             if (par->level == AV_LEVEL_UNKNOWN) {
-                av_log(whip, AV_LOG_WARNING, "No level found in extradata, consider 3.1\n");
+                av_log(rtc, AV_LOG_WARNING, "No level found in extradata, consider 3.1\n");
                 return AVERROR(EINVAL);
             }
             break;
         case AVMEDIA_TYPE_AUDIO:
-            whip->audio_par = par;
+            rtc->audio_par = par;
 
             if (par->ch_layout.nb_channels != 2) {
-                av_log(whip, AV_LOG_ERROR, "Unsupported audio channels %d by RTC, choose stereo\n",
+                av_log(rtc, AV_LOG_ERROR, "Unsupported audio channels %d by RTC, choose stereo\n",
                     par->ch_layout.nb_channels);
                 return AVERROR_PATCHWELCOME;
             }
 
             if (par->sample_rate != 48000) {
-                av_log(whip, AV_LOG_ERROR, "Unsupported audio sample rate %d by RTC, choose 48000\n", par->sample_rate);
+                av_log(rtc, AV_LOG_ERROR, "Unsupported audio sample rate %d by RTC, choose 48000\n", par->sample_rate);
                 return AVERROR_PATCHWELCOME;
             }
             break;
@@ -605,37 +181,37 @@ static int generate_sdp_offer(AVFormatContext *s)
     char bundle[4];
     int bundle_index = 0;
     AVBPrint bp;
-    WHIPContext *whip = s->priv_data;
-    int is_dtls_active = whip->flags & WHIP_DTLS_ACTIVE;
+    RTCContext *rtc = s->priv_data;
+    int is_dtls_active = rtc->flags & RTC_DTLS_ACTIVE;
 
     /* To prevent a crash during cleanup, always initialize it. */
-    av_bprint_init(&bp, 1, MAX_SDP_SIZE);
+    av_bprint_init(&bp, 1, RTC_MAX_SDP_SIZE);
 
-    if (whip->sdp_offer) {
-        av_log(whip, AV_LOG_ERROR, "SDP offer is already set\n");
+    if (rtc->sdp_offer) {
+        av_log(rtc, AV_LOG_ERROR, "SDP offer is already set\n");
         ret = AVERROR(EINVAL);
         goto end;
     }
 
-    snprintf(whip->ice_ufrag_local, sizeof(whip->ice_ufrag_local), "%08x",
-        av_lfg_get(&whip->rnd));
-    snprintf(whip->ice_pwd_local, sizeof(whip->ice_pwd_local), "%08x%08x%08x%08x",
-        av_lfg_get(&whip->rnd), av_lfg_get(&whip->rnd), av_lfg_get(&whip->rnd),
-        av_lfg_get(&whip->rnd));
+    snprintf(rtc->ice_ufrag_local, sizeof(rtc->ice_ufrag_local), "%08x",
+        av_lfg_get(&rtc->rnd));
+    snprintf(rtc->ice_pwd_local, sizeof(rtc->ice_pwd_local), "%08x%08x%08x%08x",
+        av_lfg_get(&rtc->rnd), av_lfg_get(&rtc->rnd), av_lfg_get(&rtc->rnd),
+        av_lfg_get(&rtc->rnd));
 
-    whip->audio_ssrc = av_lfg_get(&whip->rnd);
-    whip->video_ssrc = whip->audio_ssrc + 1;
-    whip->video_rtx_ssrc = whip->video_ssrc + 1;
+    rtc->audio_ssrc = av_lfg_get(&rtc->rnd);
+    rtc->video_ssrc = rtc->audio_ssrc + 1;
+    rtc->video_rtx_ssrc = rtc->video_ssrc + 1;
 
-    whip->audio_payload_type = WHIP_RTP_PAYLOAD_TYPE_OPUS;
-    whip->video_payload_type = WHIP_RTP_PAYLOAD_TYPE_H264;
-    whip->video_rtx_payload_type = WHIP_RTP_PAYLOAD_TYPE_VIDEO_RTX;
+    rtc->audio_payload_type = RTC_RTP_PAYLOAD_TYPE_OPUS;
+    rtc->video_payload_type = RTC_RTP_PAYLOAD_TYPE_H264;
+    rtc->video_rtx_payload_type = RTC_RTP_PAYLOAD_TYPE_VIDEO_RTX;
 
-    if (whip->audio_par) {
+    if (rtc->audio_par) {
         bundle[bundle_index++] = '0';
         bundle[bundle_index++] = ' ';
     }
-    if (whip->video_par) {
+    if (rtc->video_par) {
         bundle[bundle_index++] = '1';
         bundle[bundle_index++] = ' ';
     }
@@ -649,12 +225,12 @@ static int generate_sdp_offer(AVFormatContext *s)
         "a=group:BUNDLE %s\r\n"
         "a=extmap-allow-mixed\r\n"
         "a=msid-semantic: WMS\r\n",
-        WHIP_SDP_SESSION_ID,
-        WHIP_SDP_CREATOR_IP,
+        RTC_SDP_SESSION_ID,
+        RTC_SDP_CREATOR_IP,
         bundle);
 
-    if (whip->audio_par) {
-        if (whip->audio_par->codec_id == AV_CODEC_ID_OPUS)
+    if (rtc->audio_par) {
+        if (rtc->audio_par->codec_id == AV_CODEC_ID_OPUS)
             acodec_name = "opus";
 
         av_bprintf(&bp, ""
@@ -671,26 +247,26 @@ static int generate_sdp_offer(AVFormatContext *s)
             "a=rtpmap:%u %s/%d/%d\r\n"
             "a=ssrc:%u cname:FFmpeg\r\n"
             "a=ssrc:%u msid:FFmpeg audio\r\n",
-            whip->audio_payload_type,
-            whip->ice_ufrag_local,
-            whip->ice_pwd_local,
-            whip->dtls_fingerprint,
+            rtc->audio_payload_type,
+            rtc->ice_ufrag_local,
+            rtc->ice_pwd_local,
+            rtc->dtls_fingerprint,
             is_dtls_active ? "active" : "passive",
-            whip->audio_payload_type,
+            rtc->audio_payload_type,
             acodec_name,
-            whip->audio_par->sample_rate,
-            whip->audio_par->ch_layout.nb_channels,
-            whip->audio_ssrc,
-            whip->audio_ssrc);
+            rtc->audio_par->sample_rate,
+            rtc->audio_par->ch_layout.nb_channels,
+            rtc->audio_ssrc,
+            rtc->audio_ssrc);
     }
 
-    if (whip->video_par) {
-        level = whip->video_par->level;
-        if (whip->video_par->codec_id == AV_CODEC_ID_H264) {
+    if (rtc->video_par) {
+        level = rtc->video_par->level;
+        if (rtc->video_par->codec_id == AV_CODEC_ID_H264) {
             vcodec_name = "H264";
-            profile_iop |= whip->video_par->profile & AV_PROFILE_H264_CONSTRAINED ? 1 << 6 : 0;
-            profile_iop |= whip->video_par->profile & AV_PROFILE_H264_INTRA ? 1 << 4 : 0;
-            profile_idc = whip->video_par->profile & 0x00ff;
+            profile_iop |= rtc->video_par->profile & AV_PROFILE_H264_CONSTRAINED ? 1 << 6 : 0;
+            profile_iop |= rtc->video_par->profile & AV_PROFILE_H264_INTRA ? 1 << 4 : 0;
+            profile_idc = rtc->video_par->profile & 0x00ff;
         }
 
         av_bprintf(&bp, ""
@@ -713,768 +289,50 @@ static int generate_sdp_offer(AVFormatContext *s)
             "a=ssrc-group:FID %u %u\r\n"
             "a=ssrc:%u cname:FFmpeg\r\n"
             "a=ssrc:%u msid:FFmpeg video\r\n",
-            whip->video_payload_type,
-            whip->video_rtx_payload_type,
-            whip->ice_ufrag_local,
-            whip->ice_pwd_local,
-            whip->dtls_fingerprint,
+            rtc->video_payload_type,
+            rtc->video_rtx_payload_type,
+            rtc->ice_ufrag_local,
+            rtc->ice_pwd_local,
+            rtc->dtls_fingerprint,
             is_dtls_active ? "active" : "passive",
-            whip->video_payload_type,
+            rtc->video_payload_type,
             vcodec_name,
-            whip->video_payload_type,
+            rtc->video_payload_type,
             profile_idc,
             profile_iop,
             level,
-            whip->video_payload_type,
-            whip->video_rtx_payload_type,
-            whip->video_rtx_payload_type,
-            whip->video_payload_type,
-            whip->video_ssrc,
-            whip->video_rtx_ssrc,
-            whip->video_ssrc,
-            whip->video_ssrc);
+            rtc->video_payload_type,
+            rtc->video_rtx_payload_type,
+            rtc->video_rtx_payload_type,
+            rtc->video_payload_type,
+            rtc->video_ssrc,
+            rtc->video_rtx_ssrc,
+            rtc->video_ssrc,
+            rtc->video_ssrc);
     }
 
     if (!av_bprint_is_complete(&bp)) {
-        av_log(whip, AV_LOG_ERROR, "Offer exceed max %d, %s\n", MAX_SDP_SIZE, bp.str);
+        av_log(rtc, AV_LOG_ERROR, "Offer exceed max %d, %s\n", RTC_MAX_SDP_SIZE, bp.str);
         ret = AVERROR(EIO);
         goto end;
     }
 
-    whip->sdp_offer = av_strdup(bp.str);
-    if (!whip->sdp_offer) {
+    rtc->sdp_offer = av_strdup(bp.str);
+    if (!rtc->sdp_offer) {
         ret = AVERROR(ENOMEM);
         goto end;
     }
 
-    if (whip->state < WHIP_STATE_OFFER)
-        whip->state = WHIP_STATE_OFFER;
-    whip->whip_offer_time = av_gettime_relative();
-    av_log(whip, AV_LOG_VERBOSE, "Generated state=%d, offer: %s\n", whip->state, whip->sdp_offer);
+    if (rtc->state < RTC_STATE_OFFER)
+        rtc->state = RTC_STATE_OFFER;
+    rtc->rtc_offer_time = av_gettime_relative();
+    av_log(rtc, AV_LOG_VERBOSE, "Generated state=%d, offer: %s\n", rtc->state, rtc->sdp_offer);
 
 end:
     av_bprint_finalize(&bp, NULL);
     return ret;
 }
 
-/**
- * Exchange SDP offer with WebRTC peer to get the answer.
- *
- * @return 0 if OK, AVERROR_xxx on error
- */
-static int exchange_sdp(AVFormatContext *s)
-{
-    int ret;
-    char buf[MAX_URL_SIZE];
-    AVBPrint bp;
-    WHIPContext *whip = s->priv_data;
-    /* The URL context is an HTTP transport layer for the WHIP protocol. */
-    URLContext *whip_uc = NULL;
-    AVDictionary *opts = NULL;
-    char *hex_data = NULL;
-    const char *proto_name = avio_find_protocol_name(s->url);
-
-    /* To prevent a crash during cleanup, always initialize it. */
-    av_bprint_init(&bp, 1, MAX_SDP_SIZE);
-
-    if (!av_strstart(proto_name, "http", NULL)) {
-        av_log(whip, AV_LOG_ERROR, "Protocol %s is not supported by RTC, choose http, url is %s\n",
-            proto_name, s->url);
-        ret = AVERROR(EINVAL);
-        goto end;
-    }
-
-    if (!whip->sdp_offer || !strlen(whip->sdp_offer)) {
-        av_log(whip, AV_LOG_ERROR, "No offer to exchange\n");
-        ret = AVERROR(EINVAL);
-        goto end;
-    }
-
-    ret = snprintf(buf, sizeof(buf), "Cache-Control: no-cache\r\nContent-Type: application/sdp\r\n");
-    if (whip->authorization)
-        ret += snprintf(buf + ret, sizeof(buf) - ret, "Authorization: Bearer %s\r\n", whip->authorization);
-    if (ret <= 0 || ret >= sizeof(buf)) {
-        av_log(whip, AV_LOG_ERROR, "Failed to generate headers, size=%d, %s\n", ret, buf);
-        ret = AVERROR(EINVAL);
-        goto end;
-    }
-
-    av_dict_set(&opts, "headers", buf, 0);
-    av_dict_set_int(&opts, "chunked_post", 0, 0);
-
-    hex_data = av_mallocz(2 * strlen(whip->sdp_offer) + 1);
-    if (!hex_data) {
-        ret = AVERROR(ENOMEM);
-        goto end;
-    }
-    ff_data_to_hex(hex_data, whip->sdp_offer, strlen(whip->sdp_offer), 0);
-    av_dict_set(&opts, "post_data", hex_data, 0);
-
-    ret = ffurl_open_whitelist(&whip_uc, s->url, AVIO_FLAG_READ_WRITE, &s->interrupt_callback,
-        &opts, s->protocol_whitelist, s->protocol_blacklist, NULL);
-    if (ret < 0) {
-        av_log(whip, AV_LOG_ERROR, "Failed to request url=%s, offer: %s\n", s->url, whip->sdp_offer);
-        goto end;
-    }
-
-    if (ff_http_get_new_location(whip_uc)) {
-        whip->whip_resource_url = av_strdup(ff_http_get_new_location(whip_uc));
-        if (!whip->whip_resource_url) {
-            ret = AVERROR(ENOMEM);
-            goto end;
-        }
-    }
-
-    while (1) {
-        ret = ffurl_read(whip_uc, buf, sizeof(buf));
-        if (ret == AVERROR_EOF) {
-            /* Reset the error because we read all response as answer util EOF. */
-            ret = 0;
-            break;
-        }
-        if (ret <= 0) {
-            av_log(whip, AV_LOG_ERROR, "Failed to read response from url=%s, offer is %s, answer is %s\n",
-                s->url, whip->sdp_offer, whip->sdp_answer);
-            goto end;
-        }
-
-        av_bprintf(&bp, "%.*s", ret, buf);
-        if (!av_bprint_is_complete(&bp)) {
-            av_log(whip, AV_LOG_ERROR, "Answer exceed max size %d, %.*s, %s\n", MAX_SDP_SIZE, ret, buf, bp.str);
-            ret = AVERROR(EIO);
-            goto end;
-        }
-    }
-
-    if (!av_strstart(bp.str, "v=", NULL)) {
-        av_log(whip, AV_LOG_ERROR, "Invalid answer: %s\n", bp.str);
-        ret = AVERROR(EINVAL);
-        goto end;
-    }
-
-    whip->sdp_answer = av_strdup(bp.str);
-    if (!whip->sdp_answer) {
-        ret = AVERROR(ENOMEM);
-        goto end;
-    }
-
-    if (whip->state < WHIP_STATE_ANSWER)
-        whip->state = WHIP_STATE_ANSWER;
-    av_log(whip, AV_LOG_VERBOSE, "Got state=%d, answer: %s\n", whip->state, whip->sdp_answer);
-
-end:
-    ffurl_closep(&whip_uc);
-    av_bprint_finalize(&bp, NULL);
-    av_dict_free(&opts);
-    av_freep(&hex_data);
-    return ret;
-}
-
-/**
- * Parses the ICE ufrag, pwd, and candidates from the SDP answer.
- *
- * This function is used to extract the ICE ufrag, pwd, and candidates from the SDP answer.
- * It returns an error if any of these fields is NULL. The function only uses the first
- * candidate if there are multiple candidates. However, support for multiple candidates
- * will be added in the future.
- *
- * @param s Pointer to the AVFormatContext
- * @returns Returns 0 if successful or AVERROR_xxx if an error occurs.
- */
-static int parse_answer(AVFormatContext *s)
-{
-    int ret = 0;
-    AVIOContext *pb;
-    char line[MAX_URL_SIZE];
-    const char *ptr;
-    int i;
-    WHIPContext *whip = s->priv_data;
-
-    if (!whip->sdp_answer || !strlen(whip->sdp_answer)) {
-        av_log(whip, AV_LOG_ERROR, "No answer to parse\n");
-        ret = AVERROR(EINVAL);
-        goto end;
-    }
-
-    pb = avio_alloc_context(whip->sdp_answer, strlen(whip->sdp_answer), 0, NULL, NULL, NULL, NULL);
-    if (!pb)
-        return AVERROR(ENOMEM);
-
-    for (i = 0; !avio_feof(pb); i++) {
-        ff_get_chomp_line(pb, line, sizeof(line));
-        if (av_strstart(line, "a=ice-lite", &ptr))
-            whip->is_peer_ice_lite = 1;
-        if (av_strstart(line, "a=ice-ufrag:", &ptr) && !whip->ice_ufrag_remote) {
-            whip->ice_ufrag_remote = av_strdup(ptr);
-            if (!whip->ice_ufrag_remote) {
-                ret = AVERROR(ENOMEM);
-                goto end;
-            }
-        } else if (av_strstart(line, "a=ice-pwd:", &ptr) && !whip->ice_pwd_remote) {
-            whip->ice_pwd_remote = av_strdup(ptr);
-            if (!whip->ice_pwd_remote) {
-                ret = AVERROR(ENOMEM);
-                goto end;
-            }
-        } else if (av_strstart(line, "a=candidate:", &ptr) && !whip->ice_protocol) {
-            if (ptr && av_stristr(ptr, "host")) {
-                /* Refer to RFC 5245 15.1 */
-                char foundation[33], protocol[17], host[129];
-                int component_id, priority, port;
-                ret = sscanf(ptr, "%32s %d %16s %d %128s %d typ host", foundation, &component_id, protocol, &priority, host, &port);
-                if (ret != 6) {
-                    av_log(whip, AV_LOG_ERROR, "Failed %d to parse line %d %s from %s\n",
-                        ret, i, line, whip->sdp_answer);
-                    ret = AVERROR(EIO);
-                    goto end;
-                }
-
-                if (av_strcasecmp(protocol, "udp")) {
-                    av_log(whip, AV_LOG_ERROR, "Protocol %s is not supported by RTC, choose udp, line %d %s of %s\n",
-                        protocol, i, line, whip->sdp_answer);
-                    ret = AVERROR(EIO);
-                    goto end;
-                }
-
-                whip->ice_protocol = av_strdup(protocol);
-                whip->ice_host = av_strdup(host);
-                whip->ice_port = port;
-                if (!whip->ice_protocol || !whip->ice_host) {
-                    ret = AVERROR(ENOMEM);
-                    goto end;
-                }
-            }
-        }
-    }
-
-    if (!whip->ice_pwd_remote || !strlen(whip->ice_pwd_remote)) {
-        av_log(whip, AV_LOG_ERROR, "No remote ice pwd parsed from %s\n", whip->sdp_answer);
-        ret = AVERROR(EINVAL);
-        goto end;
-    }
-
-    if (!whip->ice_ufrag_remote || !strlen(whip->ice_ufrag_remote)) {
-        av_log(whip, AV_LOG_ERROR, "No remote ice ufrag parsed from %s\n", whip->sdp_answer);
-        ret = AVERROR(EINVAL);
-        goto end;
-    }
-
-    if (!whip->ice_protocol || !whip->ice_host || !whip->ice_port) {
-        av_log(whip, AV_LOG_ERROR, "No ice candidate parsed from %s\n", whip->sdp_answer);
-        ret = AVERROR(EINVAL);
-        goto end;
-    }
-
-    if (whip->state < WHIP_STATE_NEGOTIATED)
-        whip->state = WHIP_STATE_NEGOTIATED;
-    whip->whip_answer_time = av_gettime_relative();
-    av_log(whip, AV_LOG_VERBOSE, "SDP state=%d, offer=%zuB, answer=%zuB, ufrag=%s, pwd=%zuB, transport=%s://%s:%d, elapsed=%.2fms\n",
-        whip->state, strlen(whip->sdp_offer), strlen(whip->sdp_answer), whip->ice_ufrag_remote, strlen(whip->ice_pwd_remote),
-        whip->ice_protocol, whip->ice_host, whip->ice_port, ELAPSED(whip->whip_starttime, av_gettime_relative()));
-
-end:
-    avio_context_free(&pb);
-    return ret;
-}
-
-/**
- * Creates and marshals an ICE binding request packet.
- *
- * This function creates and marshals an ICE binding request packet. The function only
- * generates the username attribute and does not include goog-network-info,
- * use-candidate. However, some of these attributes may be added in the future.
- *
- * @param s Pointer to the AVFormatContext
- * @param buf Pointer to memory buffer to store the request packet
- * @param buf_size Size of the memory buffer
- * @param request_size Pointer to an integer that receives the size of the request packet
- * @return Returns 0 if successful or AVERROR_xxx if an error occurs.
- */
-static int ice_create_request(AVFormatContext *s, uint8_t *buf, int buf_size, int *request_size)
-{
-    int ret, size, crc32;
-    char username[128];
-    AVIOContext *pb = NULL;
-    AVHMAC *hmac = NULL;
-    WHIPContext *whip = s->priv_data;
-
-    pb = avio_alloc_context(buf, buf_size, 1, NULL, NULL, NULL, NULL);
-    if (!pb)
-        return AVERROR(ENOMEM);
-
-    hmac = av_hmac_alloc(AV_HMAC_SHA1);
-    if (!hmac) {
-        ret = AVERROR(ENOMEM);
-        goto end;
-    }
-
-    /* Write 20 bytes header */
-    avio_wb16(pb, 0x0001); /* STUN binding request */
-    avio_wb16(pb, 0);      /* length */
-    avio_wb32(pb, STUN_MAGIC_COOKIE); /* magic cookie */
-    avio_wb32(pb, av_lfg_get(&whip->rnd)); /* transaction ID */
-    avio_wb32(pb, av_lfg_get(&whip->rnd)); /* transaction ID */
-    avio_wb32(pb, av_lfg_get(&whip->rnd)); /* transaction ID */
-
-    /* The username is the concatenation of the two ICE ufrag */
-    ret = snprintf(username, sizeof(username), "%s:%s", whip->ice_ufrag_remote, whip->ice_ufrag_local);
-    if (ret <= 0 || ret >= sizeof(username)) {
-        av_log(whip, AV_LOG_ERROR, "Failed to build username %s:%s, max=%zu, ret=%d\n",
-            whip->ice_ufrag_remote, whip->ice_ufrag_local, sizeof(username), ret);
-        ret = AVERROR(EIO);
-        goto end;
-    }
-
-    /* Write the username attribute */
-    avio_wb16(pb, STUN_ATTR_USERNAME); /* attribute type username */
-    avio_wb16(pb, ret); /* size of username */
-    avio_write(pb, username, ret); /* bytes of username */
-    ffio_fill(pb, 0, (4 - (ret % 4)) % 4); /* padding */
-
-    /* Write the use-candidate attribute */
-    avio_wb16(pb, STUN_ATTR_USE_CANDIDATE); /* attribute type use-candidate */
-    avio_wb16(pb, 0); /* size of use-candidate */
-
-    avio_wb16(pb, STUN_ATTR_PRIORITY);
-    avio_wb16(pb, 4);
-    avio_wb32(pb, STUN_HOST_CANDIDATE_PRIORITY);
-
-    avio_wb16(pb, STUN_ATTR_ICE_CONTROLLING);
-    avio_wb16(pb, 8);
-    avio_wb64(pb, whip->ice_tie_breaker);
-
-    /* Build and update message integrity */
-    avio_wb16(pb, STUN_ATTR_MESSAGE_INTEGRITY); /* attribute type message integrity */
-    avio_wb16(pb, 20); /* size of message integrity */
-    ffio_fill(pb, 0, 20); /* fill with zero to directly write and skip it */
-    size = avio_tell(pb);
-    buf[2] = (size - 20) >> 8;
-    buf[3] = (size - 20) & 0xFF;
-    av_hmac_init(hmac, whip->ice_pwd_remote, strlen(whip->ice_pwd_remote));
-    av_hmac_update(hmac, buf, size - 24);
-    av_hmac_final(hmac, buf + size - 20, 20);
-
-    /* Write the fingerprint attribute */
-    avio_wb16(pb, STUN_ATTR_FINGERPRINT); /* attribute type fingerprint */
-    avio_wb16(pb, 4); /* size of fingerprint */
-    ffio_fill(pb, 0, 4); /* fill with zero to directly write and skip it */
-    size = avio_tell(pb);
-    buf[2] = (size - 20) >> 8;
-    buf[3] = (size - 20) & 0xFF;
-    /* Refer to the av_hash_alloc("CRC32"), av_hash_init and av_hash_final */
-    crc32 = av_crc(av_crc_get_table(AV_CRC_32_IEEE_LE), 0xFFFFFFFF, buf, size - 8) ^ 0xFFFFFFFF;
-    avio_skip(pb, -4);
-    avio_wb32(pb, crc32 ^ 0x5354554E); /* xor with "STUN" */
-
-    *request_size = size;
-
-end:
-    avio_context_free(&pb);
-    av_hmac_free(hmac);
-    return ret;
-}
-
-/**
- * Create an ICE binding response.
- *
- * This function generates an ICE binding response and writes it to the provided
- * buffer. The response is signed using the local password for message integrity.
- *
- * @param s Pointer to the AVFormatContext structure.
- * @param tid Pointer to the transaction ID of the binding request. The tid_size should be 12.
- * @param tid_size The size of the transaction ID, should be 12.
- * @param buf Pointer to the buffer where the response will be written.
- * @param buf_size The size of the buffer provided for the response.
- * @param response_size Pointer to an integer that will store the size of the generated response.
- * @return Returns 0 if successful or AVERROR_xxx if an error occurs.
- */
-static int ice_create_response(AVFormatContext *s, char *tid, int tid_size, uint8_t *buf, int buf_size, int *response_size)
-{
-    int ret = 0, size, crc32;
-    AVIOContext *pb = NULL;
-    AVHMAC *hmac = NULL;
-    WHIPContext *whip = s->priv_data;
-
-    if (tid_size != 12) {
-        av_log(whip, AV_LOG_ERROR, "Invalid transaction ID size. Expected 12, got %d\n", tid_size);
-        return AVERROR(EINVAL);
-    }
-
-    pb = avio_alloc_context(buf, buf_size, 1, NULL, NULL, NULL, NULL);
-    if (!pb)
-        return AVERROR(ENOMEM);
-
-    hmac = av_hmac_alloc(AV_HMAC_SHA1);
-    if (!hmac) {
-        ret = AVERROR(ENOMEM);
-        goto end;
-    }
-
-    /* Write 20 bytes header */
-    avio_wb16(pb, 0x0101); /* STUN binding response */
-    avio_wb16(pb, 0);      /* length */
-    avio_wb32(pb, STUN_MAGIC_COOKIE); /* magic cookie */
-    avio_write(pb, tid, tid_size); /* transaction ID */
-
-    /* Build and update message integrity */
-    avio_wb16(pb, STUN_ATTR_MESSAGE_INTEGRITY); /* attribute type message integrity */
-    avio_wb16(pb, 20); /* size of message integrity */
-    ffio_fill(pb, 0, 20); /* fill with zero to directly write and skip it */
-    size = avio_tell(pb);
-    buf[2] = (size - 20) >> 8;
-    buf[3] = (size - 20) & 0xFF;
-    av_hmac_init(hmac, whip->ice_pwd_local, strlen(whip->ice_pwd_local));
-    av_hmac_update(hmac, buf, size - 24);
-    av_hmac_final(hmac, buf + size - 20, 20);
-
-    /* Write the fingerprint attribute */
-    avio_wb16(pb, STUN_ATTR_FINGERPRINT); /* attribute type fingerprint */
-    avio_wb16(pb, 4); /* size of fingerprint */
-    ffio_fill(pb, 0, 4); /* fill with zero to directly write and skip it */
-    size = avio_tell(pb);
-    buf[2] = (size - 20) >> 8;
-    buf[3] = (size - 20) & 0xFF;
-    /* Refer to the av_hash_alloc("CRC32"), av_hash_init and av_hash_final */
-    crc32 = av_crc(av_crc_get_table(AV_CRC_32_IEEE_LE), 0xFFFFFFFF, buf, size - 8) ^ 0xFFFFFFFF;
-    avio_skip(pb, -4);
-    avio_wb32(pb, crc32 ^ 0x5354554E); /* xor with "STUN" */
-
-    *response_size = size;
-
-end:
-    avio_context_free(&pb);
-    av_hmac_free(hmac);
-    return ret;
-}
-
-/**
- * A Binding request has class=0b00 (request) and method=0b000000000001 (Binding)
- * and is encoded into the first 16 bits as 0x0001.
- * See https://datatracker.ietf.org/doc/html/rfc5389#section-6
- */
-static int ice_is_binding_request(uint8_t *b, int size)
-{
-    return size >= ICE_STUN_HEADER_SIZE && AV_RB16(&b[0]) == 0x0001;
-}
-
-/**
- * A Binding response has class=0b10 (success response) and method=0b000000000001,
- * and is encoded into the first 16 bits as 0x0101.
- */
-static int ice_is_binding_response(uint8_t *b, int size)
-{
-    return size >= ICE_STUN_HEADER_SIZE && AV_RB16(&b[0]) == 0x0101;
-}
-
-/**
- * In RTP packets, the first byte is represented as 0b10xxxxxx, where the initial
- * two bits (0b10) indicate the RTP version,
- * see https://www.rfc-editor.org/rfc/rfc3550#section-5.1
- * The RTCP packet header is similar to RTP,
- * see https://www.rfc-editor.org/rfc/rfc3550#section-6.4.1
- */
-static int media_is_rtp_rtcp(const uint8_t *b, int size)
-{
-    return size >= WHIP_RTP_HEADER_SIZE && (b[0] & 0xC0) == 0x80;
-}
-
-/* Whether the packet is RTCP. */
-static int media_is_rtcp(const uint8_t *b, int size)
-{
-    return size >= WHIP_RTP_HEADER_SIZE && b[1] >= WHIP_RTCP_PT_START && b[1] <= WHIP_RTCP_PT_END;
-}
-
-/**
- * This function handles incoming binding request messages by responding to them.
- * If the message is not a binding request, it will be ignored.
- */
-static int ice_handle_binding_request(AVFormatContext *s, char *buf, int buf_size)
-{
-    int ret = 0, size;
-    char tid[12];
-    WHIPContext *whip = s->priv_data;
-
-    /* Ignore if not a binding request. */
-    if (!ice_is_binding_request(buf, buf_size))
-        return ret;
-
-    if (buf_size < ICE_STUN_HEADER_SIZE) {
-        av_log(whip, AV_LOG_ERROR, "Invalid STUN message, expected at least %d, got %d\n",
-            ICE_STUN_HEADER_SIZE, buf_size);
-        return AVERROR(EINVAL);
-    }
-
-    /* Parse transaction id from binding request in buf. */
-    memcpy(tid, buf + 8, 12);
-
-    /* Build the STUN binding response. */
-    ret = ice_create_response(s, tid, sizeof(tid), whip->buf, sizeof(whip->buf), &size);
-    if (ret < 0) {
-        av_log(whip, AV_LOG_ERROR, "Failed to create STUN binding response, size=%d\n", size);
-        return ret;
-    }
-
-    ret = ffurl_write(whip->udp, whip->buf, size);
-    if (ret < 0) {
-        av_log(whip, AV_LOG_ERROR, "Failed to send STUN binding response, size=%d\n", size);
-        return ret;
-    }
-
-    return 0;
-}
-
-/**
- * To establish a connection with the UDP server, we utilize ICE-LITE in a Client-Server
- * mode. In this setup, FFmpeg acts as the UDP client, while the peer functions as the
- * UDP server.
- */
-static int udp_connect(AVFormatContext *s)
-{
-    int ret = 0;
-    char url[256];
-    AVDictionary *opts = NULL;
-    WHIPContext *whip = s->priv_data;
-
-    /* Build UDP URL and create the UDP context as transport. */
-    ff_url_join(url, sizeof(url), "udp", NULL, whip->ice_host, whip->ice_port, NULL);
-
-    av_dict_set_int(&opts, "connect", 1, 0);
-    av_dict_set_int(&opts, "fifo_size", 0, 0);
-    /* Pass through the pkt_size and buffer_size to underling protocol */
-    av_dict_set_int(&opts, "pkt_size", whip->pkt_size, 0);
-    av_dict_set_int(&opts, "buffer_size", whip->ts_buffer_size, 0);
-
-    ret = ffurl_open_whitelist(&whip->udp, url, AVIO_FLAG_WRITE, &s->interrupt_callback,
-        &opts, s->protocol_whitelist, s->protocol_blacklist, NULL);
-    if (ret < 0) {
-        av_log(whip, AV_LOG_ERROR, "Failed to connect udp://%s:%d\n", whip->ice_host, whip->ice_port);
-        goto end;
-    }
-
-    /* Make the socket non-blocking, set to READ and WRITE mode after connected */
-    ff_socket_nonblock(ffurl_get_file_handle(whip->udp), 1);
-    whip->udp->flags |= AVIO_FLAG_READ | AVIO_FLAG_NONBLOCK;
-
-    if (whip->state < WHIP_STATE_UDP_CONNECTED)
-        whip->state = WHIP_STATE_UDP_CONNECTED;
-    whip->whip_udp_time = av_gettime_relative();
-    av_log(whip, AV_LOG_VERBOSE, "UDP state=%d, elapsed=%.2fms, connected to udp://%s:%d\n",
-        whip->state, ELAPSED(whip->whip_starttime, av_gettime_relative()), whip->ice_host, whip->ice_port);
-
-end:
-    av_dict_free(&opts);
-    return ret;
-}
-
-static int ice_dtls_handshake(AVFormatContext *s)
-{
-    int ret = 0, size, i;
-    int64_t starttime = av_gettime_relative(), now;
-    WHIPContext *whip = s->priv_data;
-    int is_dtls_active = whip->flags & WHIP_DTLS_ACTIVE;
-
-    if (whip->state < WHIP_STATE_UDP_CONNECTED || !whip->udp) {
-        av_log(whip, AV_LOG_ERROR, "UDP not connected, state=%d, udp=%p\n", whip->state, whip->udp);
-        return AVERROR(EINVAL);
-    }
-
-    while (1) {
-        if (whip->state <= WHIP_STATE_ICE_CONNECTING) {
-            /* Build the STUN binding request. */
-            ret = ice_create_request(s, whip->buf, sizeof(whip->buf), &size);
-            if (ret < 0) {
-                av_log(whip, AV_LOG_ERROR, "Failed to create STUN binding request, size=%d\n", size);
-                goto end;
-            }
-
-            ret = ffurl_write(whip->udp, whip->buf, size);
-            if (ret < 0) {
-                av_log(whip, AV_LOG_ERROR, "Failed to send STUN binding request, size=%d\n", size);
-                goto end;
-            }
-
-            if (whip->state < WHIP_STATE_ICE_CONNECTING)
-                whip->state = WHIP_STATE_ICE_CONNECTING;
-        }
-
-next_packet:
-        if (whip->state >= WHIP_STATE_DTLS_FINISHED)
-            /* DTLS handshake is done, exit the loop. */
-            break;
-
-        now = av_gettime_relative();
-        if (now - starttime >= whip->handshake_timeout * WHIP_US_PER_MS) {
-            av_log(whip, AV_LOG_ERROR, "DTLS handshake timeout=%dms, cost=%.2fms, elapsed=%.2fms, state=%d\n",
-                whip->handshake_timeout, ELAPSED(starttime, now), ELAPSED(whip->whip_starttime, now), whip->state);
-            ret = AVERROR(ETIMEDOUT);
-            goto end;
-        }
-
-        /* Read the STUN or DTLS messages from peer. */
-        for (i = 0; i < ICE_DTLS_READ_MAX_RETRY; i++) {
-            if (whip->state > WHIP_STATE_ICE_CONNECTED)
-                break;
-            ret = ffurl_read(whip->udp, whip->buf, sizeof(whip->buf));
-            if (ret > 0)
-                break;
-            if (ret == AVERROR(EAGAIN)) {
-                av_usleep(ICE_DTLS_READ_SLEEP_DURATION * WHIP_US_PER_MS);
-                continue;
-            }
-            if (is_dtls_active)
-                break;
-            av_log(whip, AV_LOG_ERROR, "Failed to read message\n");
-            goto end;
-        }
-
-        /* Handle the ICE binding response. */
-        if (ice_is_binding_response(whip->buf, ret)) {
-            if (whip->state < WHIP_STATE_ICE_CONNECTED) {
-                if (whip->is_peer_ice_lite)
-                    whip->state = WHIP_STATE_ICE_CONNECTED;
-            }
-            goto next_packet;
-        }
-
-        /* When a binding request is received, it is necessary to respond immediately. */
-        if (ice_is_binding_request(whip->buf, ret)) {
-            if ((ret = ice_handle_binding_request(s, whip->buf, ret)) < 0)
-                goto end;
-            goto next_packet;
-        }
-
-        /* Handle DTLS handshake */
-        if (is_dtls_packet(whip->buf, ret) || is_dtls_active) {
-            whip->whip_ice_time = av_gettime_relative();
-            /* Start consent timer when ICE selected */
-            whip->whip_last_consent_tx_time = whip->whip_last_consent_rx_time = whip->whip_ice_time;
-            whip->state = WHIP_STATE_ICE_CONNECTED;
-            av_log(whip, AV_LOG_VERBOSE, "ICE STUN ok, state=%d, url=udp://%s:%d, location=%s, username=%s:%s, res=%dB, elapsed=%.2fms\n",
-                whip->state, whip->ice_host, whip->ice_port, whip->whip_resource_url ? whip->whip_resource_url : "",
-                whip->ice_ufrag_remote, whip->ice_ufrag_local, ret, ELAPSED(whip->whip_starttime, whip->whip_ice_time));
-
-            ret = dtls_initialize(s);
-            if (ret < 0)
-                goto end;
-            ret = ffurl_handshake(whip->dtls_uc);
-            if (ret < 0) {
-                whip->state = WHIP_STATE_FAILED;
-                av_log(whip, AV_LOG_ERROR, "DTLS session failed\n");
-                goto end;
-            }
-            if (!ret) {
-                whip->state = WHIP_STATE_DTLS_FINISHED;
-                whip->whip_dtls_time = av_gettime_relative();
-                av_log(whip, AV_LOG_VERBOSE, "DTLS handshake is done, elapsed=%.2fms\n",
-                    ELAPSED(whip->whip_starttime, whip->whip_dtls_time));
-            }
-            goto next_packet;
-        }
-    }
-
-end:
-    return ret;
-}
-
-/**
- * Establish the SRTP context using the keying material exported from DTLS.
- *
- * Create separate SRTP contexts for sending video and audio, as their sequences differ
- * and should not share a single context. Generate a single SRTP context for receiving
- * RTCP only.
- *
- * @return 0 if OK, AVERROR_xxx on error
- */
-static int setup_srtp(AVFormatContext *s)
-{
-    int ret;
-    char recv_key[DTLS_SRTP_KEY_LEN + DTLS_SRTP_SALT_LEN];
-    char send_key[DTLS_SRTP_KEY_LEN + DTLS_SRTP_SALT_LEN];
-    char buf[AV_BASE64_SIZE(DTLS_SRTP_KEY_LEN + DTLS_SRTP_SALT_LEN)];
-    /**
-     * The profile for OpenSSL's SRTP is SRTP_AES128_CM_SHA1_80, see ssl/d1_srtp.c.
-     * The profile for FFmpeg's SRTP is SRTP_AES128_CM_HMAC_SHA1_80, see libavformat/srtp.c.
-     */
-    const char* suite = "SRTP_AES128_CM_HMAC_SHA1_80";
-    WHIPContext *whip = s->priv_data;
-    int is_dtls_active = whip->flags & WHIP_DTLS_ACTIVE;
-    char *cp = is_dtls_active ? send_key : recv_key;
-    char *sp = is_dtls_active ? recv_key : send_key;
-
-    ret = ff_dtls_export_materials(whip->dtls_uc, whip->dtls_srtp_materials, sizeof(whip->dtls_srtp_materials));
-    if (ret < 0)
-        goto end;
-    /**
-     * This represents the material used to build the SRTP master key. It is
-     * generated by DTLS and has the following layout:
-     *          16B         16B         14B             14B
-     *      client_key | server_key | client_salt | server_salt
-     */
-    char *client_key = whip->dtls_srtp_materials;
-    char *server_key = whip->dtls_srtp_materials + DTLS_SRTP_KEY_LEN;
-    char *client_salt = server_key + DTLS_SRTP_KEY_LEN;
-    char *server_salt = client_salt + DTLS_SRTP_SALT_LEN;
-
-    memcpy(cp, client_key, DTLS_SRTP_KEY_LEN);
-    memcpy(cp + DTLS_SRTP_KEY_LEN, client_salt, DTLS_SRTP_SALT_LEN);
-
-    memcpy(sp, server_key, DTLS_SRTP_KEY_LEN);
-    memcpy(sp + DTLS_SRTP_KEY_LEN, server_salt, DTLS_SRTP_SALT_LEN);
-
-    /* Setup SRTP context for outgoing packets */
-    if (!av_base64_encode(buf, sizeof(buf), send_key, sizeof(send_key))) {
-        av_log(whip, AV_LOG_ERROR, "Failed to encode send key\n");
-        ret = AVERROR(EIO);
-        goto end;
-    }
-
-    ret = ff_srtp_set_crypto(&whip->srtp_audio_send, suite, buf);
-    if (ret < 0) {
-        av_log(whip, AV_LOG_ERROR, "Failed to set crypto for audio send\n");
-        goto end;
-    }
-
-    ret = ff_srtp_set_crypto(&whip->srtp_video_send, suite, buf);
-    if (ret < 0) {
-        av_log(whip, AV_LOG_ERROR, "Failed to set crypto for video send\n");
-        goto end;
-    }
-
-    ret = ff_srtp_set_crypto(&whip->srtp_video_rtx_send, suite, buf);
-    if (ret < 0) {
-        av_log(whip, AV_LOG_ERROR, "Failed to set crypto for video rtx send\n");
-        goto end;
-    }
-
-    ret = ff_srtp_set_crypto(&whip->srtp_rtcp_send, suite, buf);
-    if (ret < 0) {
-        av_log(whip, AV_LOG_ERROR, "Failed to set crypto for rtcp send\n");
-        goto end;
-    }
-
-    /* Setup SRTP context for incoming packets */
-    if (!av_base64_encode(buf, sizeof(buf), recv_key, sizeof(recv_key))) {
-        av_log(whip, AV_LOG_ERROR, "Failed to encode recv key\n");
-        ret = AVERROR(EIO);
-        goto end;
-    }
-
-    ret = ff_srtp_set_crypto(&whip->srtp_recv, suite, buf);
-    if (ret < 0) {
-        av_log(whip, AV_LOG_ERROR, "Failed to set crypto for recv\n");
-        goto end;
-    }
-
-    if (whip->state < WHIP_STATE_SRTP_FINISHED)
-        whip->state = WHIP_STATE_SRTP_FINISHED;
-    whip->whip_srtp_time = av_gettime_relative();
-    av_log(whip, AV_LOG_VERBOSE, "SRTP setup done, state=%d, suite=%s, key=%zuB, elapsed=%.2fms\n",
-        whip->state, suite, sizeof(send_key), ELAPSED(whip->whip_starttime, av_gettime_relative()));
-
-end:
-    return ret;
-}
-
 /**
  * Callback triggered by the RTP muxer when it creates and sends out an RTP packet.
  *
@@ -1487,33 +345,33 @@ static int on_rtp_write_packet(void *opaque, const uint8_t *buf, int buf_size)
     int ret, cipher_size, is_rtcp, is_video;
     uint8_t payload_type;
     AVFormatContext *s = opaque;
-    WHIPContext *whip = s->priv_data;
+    RTCContext *rtc = s->priv_data;
     SRTPContext *srtp;
 
     /* Ignore if not RTP or RTCP packet. */
-    if (!media_is_rtp_rtcp(buf, buf_size))
+    if (!ff_rtc_media_is_rtp_rtcp(buf, buf_size))
         return 0;
 
     /* Only support audio, video and rtcp. */
-    is_rtcp = media_is_rtcp(buf, buf_size);
+    is_rtcp = ff_rtc_media_is_rtcp(buf, buf_size);
     payload_type = buf[1] & 0x7f;
-    is_video = payload_type == whip->video_payload_type;
-    if (!is_rtcp && payload_type != whip->video_payload_type && payload_type != whip->audio_payload_type)
+    is_video = payload_type == rtc->video_payload_type;
+    if (!is_rtcp && payload_type != rtc->video_payload_type && payload_type != rtc->audio_payload_type)
         return 0;
 
     /* Get the corresponding SRTP context. */
-    srtp = is_rtcp ? &whip->srtp_rtcp_send : (is_video? &whip->srtp_video_send : &whip->srtp_audio_send);
+    srtp = is_rtcp ? &rtc->srtp_rtcp_send : (is_video? &rtc->srtp_video_send : &rtc->srtp_audio_send);
 
     /* Encrypt by SRTP and send out. */
-    cipher_size = ff_srtp_encrypt(srtp, buf, buf_size, whip->buf, sizeof(whip->buf));
+    cipher_size = ff_srtp_encrypt(srtp, buf, buf_size, rtc->buf, sizeof(rtc->buf));
     if (cipher_size <= 0 || cipher_size < buf_size) {
-        av_log(whip, AV_LOG_WARNING, "Failed to encrypt packet=%dB, cipher=%dB\n", buf_size, cipher_size);
+        av_log(rtc, AV_LOG_WARNING, "Failed to encrypt packet=%dB, cipher=%dB\n", buf_size, cipher_size);
         return 0;
     }
 
-    ret = ffurl_write(whip->udp, whip->buf, cipher_size);
+    ret = ffurl_write(rtc->udp, rtc->buf, cipher_size);
     if (ret < 0) {
-        av_log(whip, AV_LOG_ERROR, "Failed to write packet=%dB, ret=%d\n", cipher_size, ret);
+        av_log(rtc, AV_LOG_ERROR, "Failed to write packet=%dB, ret=%d\n", cipher_size, ret);
         return ret;
     }
 
@@ -1538,20 +396,20 @@ static int create_rtp_muxer(AVFormatContext *s)
     AVDictionary *opts = NULL;
     uint8_t *buffer = NULL;
     char buf[64];
-    WHIPContext *whip = s->priv_data;
-    whip->udp->flags |= AVIO_FLAG_NONBLOCK;
+    RTCContext *rtc = s->priv_data;
+    rtc->udp->flags |= AVIO_FLAG_NONBLOCK;
 
     const AVOutputFormat *rtp_format = av_guess_format("rtp", NULL, NULL);
     if (!rtp_format) {
-        av_log(whip, AV_LOG_ERROR, "Failed to guess rtp muxer\n");
+        av_log(rtc, AV_LOG_ERROR, "Failed to guess rtp muxer\n");
         ret = AVERROR(ENOSYS);
         goto end;
     }
 
     /* The UDP buffer size, may greater than MTU. */
-    buffer_size = MAX_UDP_BUFFER_SIZE;
+    buffer_size = RTC_MAX_UDP_BUFFER_SIZE;
     /* The RTP payload max size. Reserved some bytes for SRTP checksum and padding. */
-    max_packet_size = whip->pkt_size - DTLS_SRTP_CHECKSUM_LEN;
+    max_packet_size = rtc->pkt_size - DTLS_SRTP_CHECKSUM_LEN;
 
     for (i = 0; i < s->nb_streams; i++) {
         rtp_ctx = avformat_alloc_context();
@@ -1604,15 +462,15 @@ static int create_rtp_muxer(AVFormatContext *s)
         rtp_ctx->pb->av_class = &ff_avio_class;
 
         is_video = s->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO;
-        snprintf(buf, sizeof(buf), "%d", is_video? whip->video_payload_type : whip->audio_payload_type);
+        snprintf(buf, sizeof(buf), "%d", is_video? rtc->video_payload_type : rtc->audio_payload_type);
         av_dict_set(&opts, "payload_type", buf, 0);
-        snprintf(buf, sizeof(buf), "%d", is_video? whip->video_ssrc : whip->audio_ssrc);
+        snprintf(buf, sizeof(buf), "%d", is_video? rtc->video_ssrc : rtc->audio_ssrc);
         av_dict_set(&opts, "ssrc", buf, 0);
-        av_dict_set_int(&opts, "seq", is_video ? whip->video_first_seq : whip->audio_first_seq, 0);
+        av_dict_set_int(&opts, "seq", is_video ? rtc->video_first_seq : rtc->audio_first_seq, 0);
 
         ret = avformat_write_header(rtp_ctx, &opts);
         if (ret < 0) {
-            av_log(whip, AV_LOG_ERROR, "Failed to write rtp header\n");
+            av_log(rtc, AV_LOG_ERROR, "Failed to write rtp header\n");
             goto end;
         }
 
@@ -1622,18 +480,18 @@ static int create_rtp_muxer(AVFormatContext *s)
         rtp_ctx = NULL;
     }
 
-    if (whip->state < WHIP_STATE_READY)
-        whip->state = WHIP_STATE_READY;
-    av_log(whip, AV_LOG_INFO, "Muxer state=%d, buffer_size=%d, max_packet_size=%d, "
+    if (rtc->state < RTC_STATE_READY)
+        rtc->state = RTC_STATE_READY;
+    av_log(rtc, AV_LOG_INFO, "Muxer state=%d, buffer_size=%d, max_packet_size=%d, "
                            "elapsed=%.2fms(init:%.2f,offer:%.2f,answer:%.2f,udp:%.2f,ice:%.2f,dtls:%.2f,srtp:%.2f)\n",
-        whip->state, buffer_size, max_packet_size, ELAPSED(whip->whip_starttime, av_gettime_relative()),
-        ELAPSED(whip->whip_starttime,   whip->whip_init_time),
-        ELAPSED(whip->whip_init_time,   whip->whip_offer_time),
-        ELAPSED(whip->whip_offer_time,  whip->whip_answer_time),
-        ELAPSED(whip->whip_answer_time, whip->whip_udp_time),
-        ELAPSED(whip->whip_udp_time,    whip->whip_ice_time),
-        ELAPSED(whip->whip_ice_time,    whip->whip_dtls_time),
-        ELAPSED(whip->whip_dtls_time,   whip->whip_srtp_time));
+        rtc->state, buffer_size, max_packet_size, RTC_ELAPSED(rtc->rtc_starttime, av_gettime_relative()),
+        RTC_ELAPSED(rtc->rtc_starttime,   rtc->rtc_init_time),
+        RTC_ELAPSED(rtc->rtc_init_time,   rtc->rtc_offer_time),
+        RTC_ELAPSED(rtc->rtc_offer_time,  rtc->rtc_answer_time),
+        RTC_ELAPSED(rtc->rtc_answer_time, rtc->rtc_udp_time),
+        RTC_ELAPSED(rtc->rtc_udp_time,    rtc->rtc_ice_time),
+        RTC_ELAPSED(rtc->rtc_ice_time,    rtc->rtc_dtls_time),
+        RTC_ELAPSED(rtc->rtc_dtls_time,   rtc->rtc_srtp_time));
 
 end:
     if (rtp_ctx) {
@@ -1646,64 +504,69 @@ end:
     return ret;
 }
 
-/**
- * RTC is connectionless, for it's based on UDP, so it check whether sesison is
- * timeout. In such case, publishers can't republish the stream util the session
- * is timeout.
- * This function is called to notify the server that the stream is ended, server
- * should expire and close the session immediately, so that publishers can republish
- * the stream quickly.
- */
-static int dispose_session(AVFormatContext *s)
+static av_cold int whip_init(AVFormatContext *s)
 {
     int ret;
-    char buf[MAX_URL_SIZE];
-    URLContext *whip_uc = NULL;
-    AVDictionary *opts = NULL;
-    WHIPContext *whip = s->priv_data;
+    RTCContext *rtc = s->priv_data;
 
-    if (!whip->whip_resource_url)
-        return 0;
-
-    ret = snprintf(buf, sizeof(buf), "Cache-Control: no-cache\r\n");
-    if (whip->authorization)
-        ret += snprintf(buf + ret, sizeof(buf) - ret, "Authorization: Bearer %s\r\n", whip->authorization);
-    if (ret <= 0 || ret >= sizeof(buf)) {
-        av_log(whip, AV_LOG_ERROR, "Failed to generate headers, size=%d, %s\n", ret, buf);
-        ret = AVERROR(EINVAL);
+    if ((ret = ff_rtc_initialize(s)) < 0)
         goto end;
-    }
 
-    av_dict_set(&opts, "headers", buf, 0);
-    av_dict_set_int(&opts, "chunked_post", 0, 0);
-    av_dict_set(&opts, "method", "DELETE", 0);
-    ret = ffurl_open_whitelist(&whip_uc, whip->whip_resource_url, AVIO_FLAG_READ_WRITE, &s->interrupt_callback,
-        &opts, s->protocol_whitelist, s->protocol_blacklist, NULL);
-    if (ret < 0) {
-        av_log(whip, AV_LOG_ERROR, "Failed to DELETE url=%s\n", whip->whip_resource_url);
+    if ((ret = parse_codec(s)) < 0)
         goto end;
-    }
 
-    while (1) {
-        ret = ffurl_read(whip_uc, buf, sizeof(buf));
-        if (ret == AVERROR_EOF) {
-            ret = 0;
-            break;
-        }
-        if (ret < 0) {
-            av_log(whip, AV_LOG_ERROR, "Failed to read response from DELETE url=%s\n", whip->whip_resource_url);
-            goto end;
-        }
-    }
+    if ((ret = generate_sdp_offer(s)) < 0)
+        goto end;
 
-    av_log(whip, AV_LOG_INFO, "Dispose resource %s ok\n", whip->whip_resource_url);
+    if ((ret = ff_rtc_connect(s)) < 0)
+        goto end;
+
+    if ((ret = create_rtp_muxer(s)) < 0)
+        goto end;
 
 end:
-    ffurl_closep(&whip_uc);
-    av_dict_free(&opts);
+    if (ret < 0)
+        rtc->state = RTC_STATE_FAILED;
     return ret;
 }
 
+static void handle_nack_rtx(AVFormatContext *s, int size)
+{
+    int ret;
+    RTCContext *rtc = s->priv_data;
+    uint8_t *buf = NULL;
+    int rtcp_len, srtcp_len, header_len = 12/*RFC 4585 6.1*/;
+
+    /**
+     * Refer to RFC 3550 6.4.1
+     * The length of this RTCP packet in 32 bit words minus one,
+     * including the header and any padding.
+     */
+    rtcp_len = (AV_RB16(&rtc->buf[2]) + 1) * 4;
+    if (rtcp_len <= header_len) {
+        av_log(rtc, AV_LOG_WARNING, "NACK packet is broken, size: %d\n", rtcp_len);
+        goto error;
+    }
+    /* SRTCP index(4 bytes) + HMAC(SRTP_ARS128_CM_SHA1_80) 10bytes */
+    srtcp_len = rtcp_len + 4 + 10;
+    if (srtcp_len != size) {
+        av_log(rtc, AV_LOG_WARNING, "NACK packet size not match, srtcp_len:%d, size:%d\n", srtcp_len, size);
+        goto error;
+    }
+    buf = av_memdup(rtc->buf, srtcp_len);
+    if (!buf)
+        goto error;
+    if ((ret = ff_srtp_decrypt(&rtc->srtp_recv, buf, &srtcp_len)) < 0) {
+        av_log(rtc, AV_LOG_WARNING, "NACK packet decrypt failed: %d\n", ret);
+        goto error;
+    }
+    goto end;
+error:
+    av_log(rtc, AV_LOG_WARNING, "Failed to handle NACK and RTX, Skip...\n");
+end:
+    av_freep(&buf);
+}
+
 /**
  * Since the h264_mp4toannexb filter only processes the MP4 ISOM format and bypasses
  * the annexb format, it is necessary to manually insert encoder metadata before each
@@ -1785,85 +648,10 @@ fail:
     return ret;
 }
 
-static av_cold int whip_init(AVFormatContext *s)
-{
-    int ret;
-    WHIPContext *whip = s->priv_data;
-
-    if ((ret = initialize(s)) < 0)
-        goto end;
-
-    if ((ret = parse_codec(s)) < 0)
-        goto end;
-
-    if ((ret = generate_sdp_offer(s)) < 0)
-        goto end;
-
-    if ((ret = exchange_sdp(s)) < 0)
-        goto end;
-
-    if ((ret = parse_answer(s)) < 0)
-        goto end;
-
-    if ((ret = udp_connect(s)) < 0)
-        goto end;
-
-    if ((ret = ice_dtls_handshake(s)) < 0)
-        goto end;
-
-    if ((ret = setup_srtp(s)) < 0)
-        goto end;
-
-    if ((ret = create_rtp_muxer(s)) < 0)
-        goto end;
-
-end:
-    if (ret < 0)
-        whip->state = WHIP_STATE_FAILED;
-    return ret;
-}
-
-static void handle_nack_rtx(AVFormatContext *s, int size)
-{
-    int ret;
-    WHIPContext *whip = s->priv_data;
-    uint8_t *buf = NULL;
-    int rtcp_len, srtcp_len, header_len = 12/*RFC 4585 6.1*/;
-
-    /**
-     * Refer to RFC 3550 6.4.1
-     * The length of this RTCP packet in 32 bit words minus one,
-     * including the header and any padding.
-     */
-    rtcp_len = (AV_RB16(&whip->buf[2]) + 1) * 4;
-    if (rtcp_len <= header_len) {
-        av_log(whip, AV_LOG_WARNING, "NACK packet is broken, size: %d\n", rtcp_len);
-        goto error;
-    }
-    /* SRTCP index(4 bytes) + HMAC(SRTP_ARS128_CM_SHA1_80) 10bytes */
-    srtcp_len = rtcp_len + 4 + 10;
-    if (srtcp_len != size) {
-        av_log(whip, AV_LOG_WARNING, "NACK packet size not match, srtcp_len:%d, size:%d\n", srtcp_len, size);
-        goto error;
-    }
-    buf = av_memdup(whip->buf, srtcp_len);
-    if (!buf)
-        goto error;
-    if ((ret = ff_srtp_decrypt(&whip->srtp_recv, buf, &srtcp_len)) < 0) {
-        av_log(whip, AV_LOG_WARNING, "NACK packet decrypt failed: %d\n", ret);
-        goto error;
-    }
-    goto end;
-error:
-    av_log(whip, AV_LOG_WARNING, "Failed to handle NACK and RTX, Skip...\n");
-end:
-    av_freep(&buf);
-}
-
 static int whip_write_packet(AVFormatContext *s, AVPacket *pkt)
 {
     int ret;
-    WHIPContext *whip = s->priv_data;
+    RTCContext *rtc = s->priv_data;
     AVStream *st = s->streams[pkt->stream_index];
     AVFormatContext *rtp_ctx = st->priv_data;
     int64_t now = av_gettime_relative();
@@ -1871,50 +659,50 @@ static int whip_write_packet(AVFormatContext *s, AVPacket *pkt)
      * Refer to RFC 7675
      * Periodically send Consent Freshness STUN Binding Request
      */
-    if (now - whip->whip_last_consent_tx_time > WHIP_ICE_CONSENT_CHECK_INTERVAL * WHIP_US_PER_MS) {
+    if (now - rtc->rtc_last_consent_tx_time > RTC_ICE_CONSENT_CHECK_INTERVAL * RTC_US_PER_MS) {
         int size;
-        ret = ice_create_request(s, whip->buf, sizeof(whip->buf), &size);
+        ret = ff_rtc_ice_create_request(s, rtc->buf, sizeof(rtc->buf), &size);
         if (ret < 0) {
-            av_log(whip, AV_LOG_ERROR, "Failed to create STUN binding request, size=%d\n", size);
+            av_log(rtc, AV_LOG_ERROR, "Failed to create STUN binding request, size=%d\n", size);
             goto end;
         }
-        ret = ffurl_write(whip->udp, whip->buf, size);
+        ret = ffurl_write(rtc->udp, rtc->buf, size);
         if (ret < 0) {
-            av_log(whip, AV_LOG_ERROR, "Failed to send STUN binding request, size=%d\n", size);
+            av_log(rtc, AV_LOG_ERROR, "Failed to send STUN binding request, size=%d\n", size);
             goto end;
         }
-        whip->whip_last_consent_tx_time = now;
-        av_log(whip, AV_LOG_DEBUG, "Consent Freshness check sent\n");
+        rtc->rtc_last_consent_tx_time = now;
+        av_log(rtc, AV_LOG_DEBUG, "Consent Freshness check sent\n");
     }
 
     /**
      * Receive packets from the server such as ICE binding requests, DTLS messages,
      * and RTCP like PLI requests, then respond to them.
      */
-    ret = ffurl_read(whip->udp, whip->buf, sizeof(whip->buf));
+    ret = ffurl_read(rtc->udp, rtc->buf, sizeof(rtc->buf));
     if (ret < 0) {
         if (ret == AVERROR(EAGAIN))
             goto write_packet;
-        av_log(whip, AV_LOG_ERROR, "Failed to read from UDP socket\n");
+        av_log(rtc, AV_LOG_ERROR, "Failed to read from UDP socket\n");
         goto end;
     }
     if (!ret) {
-        av_log(whip, AV_LOG_ERROR, "Receive EOF from UDP socket\n");
+        av_log(rtc, AV_LOG_ERROR, "Receive EOF from UDP socket\n");
         goto end;
     }
-    if (ice_is_binding_response(whip->buf, ret)) {
-        whip->whip_last_consent_rx_time = av_gettime_relative();
-        av_log(whip, AV_LOG_DEBUG, "Consent Freshness check received\n");
+    if (ff_rtc_ice_is_binding_response(rtc->buf, ret)) {
+        rtc->rtc_last_consent_rx_time = av_gettime_relative();
+        av_log(rtc, AV_LOG_DEBUG, "Consent Freshness check received\n");
     }
-    if (is_dtls_packet(whip->buf, ret)) {
-        if ((ret = ffurl_write(whip->dtls_uc, whip->buf, ret)) < 0) {
-            av_log(whip, AV_LOG_ERROR, "Failed to handle DTLS message\n");
+    if (ff_rtc_is_dtls_packet(rtc->buf, ret)) {
+        if ((ret = ffurl_write(rtc->dtls_uc, rtc->buf, ret)) < 0) {
+            av_log(rtc, AV_LOG_ERROR, "Failed to handle DTLS message\n");
             goto end;
         }
     }
-    if (media_is_rtcp(whip->buf, ret)) {
-        uint8_t fmt = whip->buf[0] & 0x1f;
-        uint8_t pt = whip->buf[1];
+    if (ff_rtc_media_is_rtcp(rtc->buf, ret)) {
+        uint8_t fmt = rtc->buf[0] & 0x1f;
+        uint8_t pt = rtc->buf[1];
         /**
          * Handle RTCP NACK packet
          * Refer to RFC 4585 6.2.1
@@ -1927,16 +715,16 @@ static int whip_write_packet(AVFormatContext *s, AVPacket *pkt)
     }
 write_packet:
     now = av_gettime_relative();
-    if (now - whip->whip_last_consent_rx_time > WHIP_ICE_CONSENT_EXPIRED_TIMER * WHIP_US_PER_MS) {
-        av_log(whip, AV_LOG_ERROR,
+    if (now - rtc->rtc_last_consent_rx_time > RTC_ICE_CONSENT_EXPIRED_TIMER * RTC_US_PER_MS) {
+        av_log(rtc, AV_LOG_ERROR,
             "Consent Freshness expired after %.2fms (limited %dms), terminate session\n",
-            ELAPSED(whip->whip_last_consent_rx_time, now), WHIP_ICE_CONSENT_EXPIRED_TIMER);
+            RTC_ELAPSED(rtc->rtc_last_consent_rx_time, now), RTC_ICE_CONSENT_EXPIRED_TIMER);
         ret = AVERROR(ETIMEDOUT);
         goto end;
     }
-    if (whip->h264_annexb_insert_sps_pps && st->codecpar->codec_id == AV_CODEC_ID_H264) {
+    if (rtc->h264_annexb_insert_sps_pps && st->codecpar->codec_id == AV_CODEC_ID_H264) {
         if ((ret = h264_annexb_insert_sps_pps(s, pkt)) < 0) {
-            av_log(whip, AV_LOG_ERROR, "Failed to insert SPS/PPS before IDR\n");
+            av_log(rtc, AV_LOG_ERROR, "Failed to insert SPS/PPS before IDR\n");
             goto end;
         }
     }
@@ -1944,104 +732,44 @@ write_packet:
     ret = ff_write_chained(rtp_ctx, 0, pkt, s, 0);
     if (ret < 0) {
         if (ret == AVERROR(EINVAL)) {
-            av_log(whip, AV_LOG_WARNING, "Ignore failed to write packet=%dB, ret=%d\n", pkt->size, ret);
+            av_log(rtc, AV_LOG_WARNING, "Ignore failed to write packet=%dB, ret=%d\n", pkt->size, ret);
             ret = 0;
         } else if (ret == AVERROR(EAGAIN)) {
-            av_log(whip, AV_LOG_ERROR, "UDP send blocked, please increase the buffer via -ts_buffer_size\n");
+            av_log(rtc, AV_LOG_ERROR, "UDP send blocked, please increase the buffer via -ts_buffer_size\n");
         } else
-            av_log(whip, AV_LOG_ERROR, "Failed to write packet, size=%d, ret=%d\n", pkt->size, ret);
+            av_log(rtc, AV_LOG_ERROR, "Failed to write packet, size=%d, ret=%d\n", pkt->size, ret);
         goto end;
     }
 
 end:
     if (ret < 0)
-        whip->state = WHIP_STATE_FAILED;
+        rtc->state = RTC_STATE_FAILED;
     return ret;
 }
 
-static av_cold void whip_deinit(AVFormatContext *s)
-{
-    int i, ret;
-    WHIPContext *whip = s->priv_data;
-
-    ret = dispose_session(s);
-    if (ret < 0)
-        av_log(whip, AV_LOG_WARNING, "Failed to dispose resource, ret=%d\n", ret);
-
-    for (i = 0; i < s->nb_streams; i++) {
-        AVFormatContext* rtp_ctx = s->streams[i]->priv_data;
-        if (!rtp_ctx)
-            continue;
-
-        av_write_trailer(rtp_ctx);
-        /**
-         * Keep in mind that it is necessary to free the buffer of pb since we allocate
-         * it and pass it to pb using avio_alloc_context, while avio_context_free does
-         * not perform this action.
-         */
-        av_freep(&rtp_ctx->pb->buffer);
-        avio_context_free(&rtp_ctx->pb);
-        avformat_free_context(rtp_ctx);
-        s->streams[i]->priv_data = NULL;
-    }
-
-    av_freep(&whip->sdp_offer);
-    av_freep(&whip->sdp_answer);
-    av_freep(&whip->whip_resource_url);
-    av_freep(&whip->ice_ufrag_remote);
-    av_freep(&whip->ice_pwd_remote);
-    av_freep(&whip->ice_protocol);
-    av_freep(&whip->ice_host);
-    av_freep(&whip->authorization);
-    av_freep(&whip->cert_file);
-    av_freep(&whip->key_file);
-    ff_srtp_free(&whip->srtp_audio_send);
-    ff_srtp_free(&whip->srtp_video_send);
-    ff_srtp_free(&whip->srtp_video_rtx_send);
-    ff_srtp_free(&whip->srtp_rtcp_send);
-    ff_srtp_free(&whip->srtp_recv);
-    ffurl_close(whip->dtls_uc);
-    ffurl_closep(&whip->udp);
-    av_freep(&whip->dtls_fingerprint);
-}
-
 static int whip_check_bitstream(AVFormatContext *s, AVStream *st, const AVPacket *pkt)
 {
     int ret = 1, extradata_isom = 0;
     uint8_t *b = pkt->data;
-    WHIPContext *whip = s->priv_data;
+    RTCContext *rtc = s->priv_data;
 
     if (st->codecpar->codec_id == AV_CODEC_ID_H264) {
         extradata_isom = st->codecpar->extradata_size > 0 && st->codecpar->extradata[0] == 1;
         if (pkt->size >= 5 && AV_RB32(b) != 0x0000001 && (AV_RB24(b) != 0x000001 || extradata_isom)) {
             ret = ff_stream_add_bitstream_filter(st, "h264_mp4toannexb", NULL);
-            av_log(whip, AV_LOG_VERBOSE, "Enable BSF h264_mp4toannexb, packet=[%x %x %x %x %x ...], extradata_isom=%d\n",
+            av_log(rtc, AV_LOG_VERBOSE, "Enable BSF h264_mp4toannexb, packet=[%x %x %x %x %x ...], extradata_isom=%d\n",
                 b[0], b[1], b[2], b[3], b[4], extradata_isom);
         } else
-            whip->h264_annexb_insert_sps_pps = 1;
+            rtc->h264_annexb_insert_sps_pps = 1;
     }
 
     return ret;
 }
 
-#define OFFSET(x) offsetof(WHIPContext, x)
-#define ENC AV_OPT_FLAG_ENCODING_PARAM
-static const AVOption options[] = {
-    { "handshake_timeout",  "Timeout in milliseconds for ICE and DTLS handshake.",      OFFSET(handshake_timeout),  AV_OPT_TYPE_INT,    { .i64 = 5000 },    -1, INT_MAX, ENC },
-    { "pkt_size",           "The maximum size, in bytes, of RTP packets that send out", OFFSET(pkt_size),           AV_OPT_TYPE_INT,    { .i64 = 1200 },    -1, INT_MAX, ENC },
-    { "ts_buffer_size",     "The buffer size, in bytes, of underlying protocol",        OFFSET(ts_buffer_size),        AV_OPT_TYPE_INT,    { .i64 = -1 },      -1, INT_MAX, ENC },
-    { "whip_flags",         "Set flags affecting WHIP connection behavior",             OFFSET(flags),              AV_OPT_TYPE_FLAGS,  { .i64 = 0},         0, UINT_MAX, ENC, .unit = "flags" },
-    { "dtls_active",        "Set dtls role as active",                                  0,                          AV_OPT_TYPE_CONST,  { .i64 = WHIP_DTLS_ACTIVE}, 0, UINT_MAX, ENC, .unit = "flags" },
-    { "authorization",      "The optional Bearer token for WHIP Authorization",         OFFSET(authorization),      AV_OPT_TYPE_STRING, { .str = NULL },     0,       0, ENC },
-    { "cert_file",          "The optional certificate file path for DTLS",              OFFSET(cert_file),          AV_OPT_TYPE_STRING, { .str = NULL },     0,       0, ENC },
-    { "key_file",           "The optional private key file path for DTLS",              OFFSET(key_file),      AV_OPT_TYPE_STRING, { .str = NULL },     0,       0, ENC },
-    { NULL },
-};
-
 static const AVClass whip_muxer_class = {
     .class_name = "WHIP muxer",
     .item_name  = av_default_item_name,
-    .option     = options,
+    .option     = ff_rtc_options,
     .version    = LIBAVUTIL_VERSION_INT,
 };
 
@@ -2054,9 +782,9 @@ const FFOutputFormat ff_whip_muxer = {
     .p.flags            = AVFMT_GLOBALHEADER | AVFMT_NOFILE | AVFMT_EXPERIMENTAL,
     .p.priv_class       = &whip_muxer_class,
     .flags_internal     = FF_OFMT_FLAG_ONLY_DEFAULT_CODECS | FF_OFMT_FLAG_MAX_ONE_OF_EACH,
-    .priv_data_size     = sizeof(WHIPContext),
+    .priv_data_size     = sizeof(RTCContext),
     .init               = whip_init,
     .write_packet       = whip_write_packet,
-    .deinit             = whip_deinit,
+    .deinit             = ff_rtc_close,
     .check_bitstream    = whip_check_bitstream,
-};
+};
\ No newline at end of file
-- 
2.52.0

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2026-01-29 13:11 [FFmpeg-devel] [PR] avformat/whep: add WHEP demuxer support (PR #21603) Artem Smorodin via ffmpeg-devel

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