[FFmpeg-devel] [PATCH 4/6] libavformat/webrtc: add common code for WebRTC streaming

[Michael Riedl <michael.riedl@nativewaves.com>]

Signed-off-by: Michael Riedl <michael.riedl@nativewaves.com>
---
 libavformat/webrtc.c | 398 +++++++++++++++++++++++++++++++++++++++++++
 libavformat/webrtc.h |  70 ++++++++
 2 files changed, 468 insertions(+)
 create mode 100644 libavformat/webrtc.c
 create mode 100644 libavformat/webrtc.h

diff --git a/libavformat/webrtc.c b/libavformat/webrtc.c
new file mode 100644
index 00000000000..75884eac46f
--- /dev/null
+++ b/libavformat/webrtc.c
@@ -0,0 +1,398 @@
+/*
+ * WebRTC-HTTP ingestion/egress protocol (WHIP/WHEP) common code
+ *
+ * Copyright (C) 2023 NativeWaves GmbH <contact@nativewaves.com>
+ * This work is supported by FFG project 47168763.
+ *
+ * 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/opt.h"
+#include "libavutil/uuid.h"
+#include "libavutil/random_seed.h"
+#include "rtpenc_chain.h"
+#include "rtsp.h"
+#include "webrtc.h"
+
+static const char* webrtc_get_state_name(const rtcState state)
+{
+    switch (state)
+    {
+        case RTC_NEW:
+            return "RTC_NEW";
+        case RTC_CONNECTING:
+            return "RTC_CONNECTING";
+        case RTC_CONNECTED:
+            return "RTC_CONNECTED";
+        case RTC_DISCONNECTED:
+            return "RTC_DISCONNECTED";
+        case RTC_FAILED:
+            return "RTC_FAILED";
+        case RTC_CLOSED:
+            return "RTC_CLOSED";
+        default:
+            return "UNKNOWN";
+    }
+}
+
+static void webrtc_log(const rtcLogLevel rtcLevel, const char *const message)
+{
+    int level = AV_LOG_VERBOSE;
+    switch (rtcLevel)
+    {
+        case RTC_LOG_NONE:
+            level = AV_LOG_QUIET;
+            break;
+        case RTC_LOG_DEBUG:
+        case RTC_LOG_VERBOSE:
+            level = AV_LOG_DEBUG;
+            break;
+        case RTC_LOG_INFO:
+            level = AV_LOG_VERBOSE;
+            break;
+        case RTC_LOG_WARNING:
+            level = AV_LOG_WARNING;
+            break;
+        case RTC_LOG_ERROR:
+            level = AV_LOG_ERROR;
+            break;
+        case RTC_LOG_FATAL:
+            level = AV_LOG_FATAL;
+            break;
+    }
+
+    av_log(NULL, level, "[libdatachannel] %s\n", message);
+}
+
+void webrtc_init_logger(void)
+{
+    rtcLogLevel level = RTC_LOG_VERBOSE;
+    switch (av_log_get_level())
+    {
+        case AV_LOG_QUIET:
+            level = RTC_LOG_NONE;
+            break;
+        case AV_LOG_DEBUG:
+            level = RTC_LOG_DEBUG;
+            break;
+        case AV_LOG_VERBOSE:
+            level = RTC_LOG_VERBOSE;
+            break;
+        case AV_LOG_WARNING:
+            level = RTC_LOG_WARNING;
+            break;
+        case AV_LOG_ERROR:
+            level = RTC_LOG_ERROR;
+            break;
+        case AV_LOG_FATAL:
+            level = RTC_LOG_FATAL;
+            break;
+    }
+
+    rtcInitLogger(level, webrtc_log);
+}
+
+int webrtc_generate_media_stream_id(char media_stream_id[37])
+{
+    int ret;
+    AVUUID uuid;
+
+    ret = av_random_bytes(uuid, sizeof(uuid));
+    if (ret < 0) {
+        goto fail;
+    }
+    av_uuid_unparse(uuid, media_stream_id);
+    return 0;
+
+fail:
+    return ret;
+}
+
+int webrtc_create_resource(DataChannelContext*const ctx)
+{
+    int ret;
+    URLContext* h = NULL;
+    char* headers;
+    char offer_sdp[SDP_MAX_SIZE] = { 0 };
+    char response_sdp[SDP_MAX_SIZE] = { 0 };
+
+    /* set local description */
+    if (rtcSetLocalDescription(ctx->peer_connection, "offer") != RTC_ERR_SUCCESS) {
+        av_log(ctx->avctx, AV_LOG_ERROR, "Failed to set local description\n");
+        ret = AVERROR_EXTERNAL;
+        goto fail;
+    }
+
+    /* create offer */
+    ret = rtcGetLocalDescription(ctx->peer_connection, offer_sdp, sizeof(offer_sdp));
+    if (ret < 0) {
+        av_log(ctx->avctx, AV_LOG_ERROR, "Failed to get local description\n");
+        ret = AVERROR_EXTERNAL;
+        goto fail;
+    }
+    av_log(ctx->avctx, AV_LOG_VERBOSE, "offer_sdp: %s\n", offer_sdp);
+
+    /* alloc the http context */
+    if ((ret = ffurl_alloc(&h, ctx->avctx->url, AVIO_FLAG_READ_WRITE, NULL)) < 0) {
+        av_log(ctx->avctx, AV_LOG_ERROR, "ffurl_alloc failed\n");
+        goto fail;
+    }
+
+    /* set options */
+    headers = av_asprintf("Content-type: application/sdp\r\n");
+    if (ctx->bearer_token) {
+        headers = av_asprintf("%sAuthorization: Bearer %s\r\n", headers, ctx->bearer_token);
+    }
+    av_log(ctx->avctx, AV_LOG_VERBOSE, "headers: %s\n", headers);
+    av_opt_set(h->priv_data, "headers", headers, 0);
+    av_opt_set(h->priv_data, "method", "POST", 0);
+    av_opt_set_bin(h->priv_data, "post_data", (uint8_t*)offer_sdp, strlen(offer_sdp), 0);
+
+    /* open the http context */
+    if ((ret = ffurl_connect(h, NULL)) < 0) {
+        av_log(ctx->avctx, AV_LOG_ERROR, "ffurl_connect failed\n");
+        goto fail;
+    }
+
+    /* read the server reply */
+    ret = ffurl_read_complete(h, (unsigned char*)response_sdp, sizeof(response_sdp));
+    if (ret < 0) {
+        av_log(ctx->avctx, AV_LOG_ERROR, "ffurl_read_complete failed\n");
+        goto fail;
+    }
+
+    av_log(ctx->avctx, AV_LOG_VERBOSE, "response: %s\n", response_sdp);
+
+    /* set remote description */
+    ret = rtcSetRemoteDescription(ctx->peer_connection, response_sdp, "answer");
+    if (ret < 0) {
+        av_log(ctx->avctx, AV_LOG_ERROR, "Failed to set remote description\n");
+        goto fail;
+    }
+
+    /* save resource location for later use */
+    av_opt_get(h->priv_data, "new_location", AV_OPT_SEARCH_CHILDREN, (uint8_t**)&ctx->resource_location);
+    av_log(ctx->avctx, AV_LOG_VERBOSE, "resource_location: %s\n", ctx->resource_location);
+
+    /* close the http context */
+    if ((ret = ffurl_closep(&h)) < 0) {
+        av_log(ctx->avctx, AV_LOG_ERROR, "ffurl_closep failed\n");
+        goto fail;
+    }
+
+    av_freep(&headers);
+    return 0;
+
+fail:
+    if (h) {
+        ffurl_closep(&h);
+    }
+    av_freep(&headers);
+    return ret;
+}
+
+int webrtc_close_resource(DataChannelContext*const ctx)
+{
+    int ret;
+    URLContext* h = NULL;
+    char* headers = NULL;
+
+    if (!ctx->resource_location) {
+        return 0;
+    }
+
+    /* alloc the http context */
+    if ((ret = ffurl_alloc(&h, ctx->resource_location, AVIO_FLAG_READ_WRITE, NULL)) < 0) {
+        av_log(ctx->avctx, AV_LOG_ERROR, "ffurl_alloc failed\n");
+        goto fail;
+    }
+
+    /* set options */
+    if (ctx->bearer_token) {
+        headers = av_asprintf("Authorization: Bearer %s\r\n", ctx->bearer_token);
+        av_log(ctx->avctx, AV_LOG_VERBOSE, "headers: %s\n", headers);
+    }
+    av_opt_set(h->priv_data, "method", "DELETE", 0);
+
+    /* open the http context */
+    if ((ret = ffurl_connect(h, NULL)) < 0) {
+        av_log(ctx->avctx, AV_LOG_ERROR, "ffurl_connect failed\n");
+        goto fail;
+    }
+
+    /* close the http context */
+    if ((ret = ffurl_closep(&h)) < 0) {
+        av_log(ctx->avctx, AV_LOG_ERROR, "ffurl_close failed\n");
+        goto fail;
+    }
+
+fail:
+    if (h) {
+        ffurl_closep(&h);
+    }
+    av_freep(&ctx->resource_location);
+    av_freep(&headers);
+    return ret;
+}
+
+/* callback for receiving data */
+static int webrtc_read(URLContext *h, unsigned char *buf, int size)
+{
+    const DataChannelTrack*const ctx = (const DataChannelTrack*const)h->priv_data;
+    int ret;
+
+    ret = rtcReceiveMessage(ctx->track_id, (char*)buf, &size);
+    if (ret == RTC_ERR_NOT_AVAIL) {
+        return AVERROR(EAGAIN);
+    }
+    else if (ret == RTC_ERR_TOO_SMALL) {
+        return AVERROR_BUFFER_TOO_SMALL;
+    }
+    else if (ret != RTC_ERR_SUCCESS) {
+        av_log(ctx->avctx, AV_LOG_ERROR, "rtcReceiveMessage failed: %d\n", ret);
+        return AVERROR_EOF;
+    }
+    return size;
+}
+
+/* callback for sending data */
+static int webrtc_write(URLContext *h, const unsigned char *buf, int size)
+{
+    const DataChannelTrack*const ctx = (const DataChannelTrack*const)h->priv_data;
+    int ret;
+
+    ret = rtcSendMessage(ctx->track_id, (const char*)buf, size);
+    if (ret != RTC_ERR_SUCCESS) {
+        av_log(ctx->avctx, AV_LOG_ERROR, "rtcSendMessage failed: %d\n", ret);
+        return AVERROR_EXTERNAL;
+    }
+    return size;
+}
+
+static const URLProtocol ff_webrtc_protocol = {
+    .name            = "webrtc",
+    .url_read        = webrtc_read,
+    .url_write       = webrtc_write,
+};
+
+int webrtc_init_urlcontext(DataChannelContext*const ctx, int track_idx)
+{
+    DataChannelTrack*const track = &ctx->tracks[track_idx];
+
+    track->rtp_url_context = av_mallocz(sizeof(URLContext));
+    if (!track->rtp_url_context) {
+        return AVERROR(ENOMEM);
+    }
+
+    track->rtp_url_context->prot = &ff_webrtc_protocol;
+    track->rtp_url_context->priv_data = track;
+    track->rtp_url_context->max_packet_size = RTP_MAX_PACKET_SIZE;
+    track->rtp_url_context->flags = AVIO_FLAG_READ_WRITE;
+    track->rtp_url_context->rw_timeout = ctx->rw_timeout;
+    return 0;
+}
+
+static void webrtc_on_state_change(int pc, rtcState state, void* ptr)
+{
+    DataChannelContext*const ctx = (DataChannelContext*const)ptr;
+
+    av_log(ctx->avctx, AV_LOG_VERBOSE, "Connection state changed from %s to %s\n", webrtc_get_state_name(ctx->state), webrtc_get_state_name(state));
+    ctx->state = state;
+}
+
+int webrtc_init_connection(DataChannelContext *const ctx)
+{
+    int ret;
+    rtcConfiguration config = { 0 };
+
+    if (!(ctx->peer_connection = rtcCreatePeerConnection(&config))) {
+        av_log(ctx->avctx, AV_LOG_ERROR, "Failed to create PeerConnection\n");
+        return AVERROR_EXTERNAL;
+    }
+
+    rtcSetUserPointer(ctx->peer_connection, ctx);
+
+    if (rtcSetStateChangeCallback(ctx->peer_connection, webrtc_on_state_change)) {
+        av_log(ctx->avctx, AV_LOG_ERROR, "Failed to set state change callback\n");
+        ret = AVERROR_EXTERNAL;
+        goto fail;
+    }
+
+    return 0;
+
+fail:
+    rtcDeletePeerConnection(ctx->peer_connection);
+    return ret;
+}
+
+int webrtc_convert_codec(enum AVCodecID codec_id, rtcCodec* rtc_codec)
+{
+    switch (codec_id)
+    {
+        case AV_CODEC_ID_H264:
+            *rtc_codec = RTC_CODEC_H264;
+            break;
+        case AV_CODEC_ID_HEVC:
+            *rtc_codec = RTC_CODEC_H265;
+            break;
+        case AV_CODEC_ID_AV1:
+            *rtc_codec = RTC_CODEC_AV1;
+            break;
+        case AV_CODEC_ID_VP9:
+            *rtc_codec = RTC_CODEC_VP9;
+            break;
+        case AV_CODEC_ID_OPUS:
+            *rtc_codec = RTC_CODEC_OPUS;
+            break;
+        case AV_CODEC_ID_AAC:
+            *rtc_codec = RTC_CODEC_AAC;
+            break;
+        case AV_CODEC_ID_PCM_ALAW:
+            *rtc_codec = RTC_CODEC_PCMA;
+            break;
+        case AV_CODEC_ID_PCM_MULAW:
+            *rtc_codec = RTC_CODEC_PCMU;
+            break;
+        default:
+            *rtc_codec = -1;
+            return AVERROR(EINVAL);
+    }
+
+    return 0;
+}
+
+void webrtc_deinit(DataChannelContext*const ctx)
+{
+    if (ctx->tracks) {
+        for (int i = 0; i < ctx->nb_tracks; ++i) {
+            if (ctx->tracks[i].rtp_ctx)
+                avformat_free_context(ctx->tracks[i].rtp_ctx);
+            if (ctx->tracks[i].rtp_url_context)
+                av_freep(&ctx->tracks[i].rtp_url_context);
+            if (ctx->tracks[i].track_id)
+                rtcDeleteTrack(ctx->tracks[i].track_id);
+        }
+        av_freep(&ctx->tracks);
+    }
+    if (ctx->peer_connection) {
+        rtcDeletePeerConnection(ctx->peer_connection);
+        ctx->peer_connection = 0;
+    }
+    if (ctx->resource_location)
+        av_freep(&ctx->resource_location);
+}
\ No newline at end of file
diff --git a/libavformat/webrtc.h b/libavformat/webrtc.h
new file mode 100644
index 00000000000..f7d81f3dd0b
--- /dev/null
+++ b/libavformat/webrtc.h
@@ -0,0 +1,70 @@
+/*
+ * WebRTC-HTTP ingestion/egress protocol (WHIP/WHEP) common code
+ *
+ * Copyright (C) 2023 NativeWaves GmbH <contact@nativewaves.com>
+ * This work is supported by FFG project 47168763.
+ *
+ * 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_WEBRTC_H
+#define AVFORMAT_WEBRTC_H
+
+#include "avformat.h"
+#include "avio_internal.h"
+#include "libavcodec/codec_id.h"
+#include "url.h"
+#include "rtc/rtc.h"
+
+#define RTP_MAX_PACKET_SIZE 1450
+
+typedef struct DataChannelTrack {
+    AVFormatContext *avctx;
+    int track_id;
+    AVFormatContext *rtp_ctx;
+    URLContext *rtp_url_context;
+} DataChannelTrack;
+
+typedef struct DataChannelContext {
+    AVFormatContext *avctx;
+    int peer_connection;
+    rtcState state;
+    DataChannelTrack *tracks;
+    int nb_tracks;
+    const char *resource_location;
+
+    /* options */
+    char* bearer_token;
+    int64_t connection_timeout;
+    int64_t rw_timeout;
+} DataChannelContext;
+
+#define WEBRTC_OPTIONS(FLAGS, offset) \
+    { "bearer_token", "optional Bearer token for authentication and authorization", offset+offsetof(DataChannelContext, bearer_token), AV_OPT_TYPE_STRING, { .str = NULL }, 0, 0, FLAGS }, \
+    { "connection_timeout", "timeout for establishing a connection", offset+offsetof(DataChannelContext, connection_timeout), AV_OPT_TYPE_DURATION, { .i64 = 10000000 }, 1, INT_MAX, FLAGS }, \
+    { "rw_timeout", "timeout for receiving/writing data", offset+offsetof(DataChannelContext, rw_timeout), AV_OPT_TYPE_DURATION, { .i64 = 1000000 }, 1, INT_MAX, FLAGS }
+
+extern int webrtc_close_resource(DataChannelContext*const ctx);
+extern int webrtc_convert_codec(enum AVCodecID codec_id, rtcCodec* rtc_codec);
+extern int webrtc_create_resource(DataChannelContext*const ctx);
+extern void webrtc_deinit(DataChannelContext*const ctx);
+extern int webrtc_generate_media_stream_id(char media_stream_id[37]);
+extern int webrtc_init_connection(DataChannelContext*const ctx);
+extern void webrtc_init_logger(void);
+extern int webrtc_init_urlcontext(DataChannelContext*const ctx, int track_idx);
+
+#endif /* AVFORMAT_WEBRTC_H */
-- 
2.39.2

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