[FFmpeg-devel] [PATCH 3/5] avformat/lc3: Add file format for LC3/LC3plus transport

[Antoine Soulier via ffmpeg-devel <ffmpeg-devel@ffmpeg.org>]

A file format is described in Bluetooth SIG LC3 and ETSI TS 103 634, for
test purpose. This is the format implemented here.

Signed-off-by: Antoine Soulier <asoulier@google.com>
Signed-off-by: Antoine SOULIER <asoulier@google.com>
---
 libavformat/Makefile     |   3 +
 libavformat/allformats.c |   3 +
 libavformat/lc3dec.c     | 140 +++++++++++++++++++++++++++++++++++++++
 libavformat/lc3enc.c     | 118 +++++++++++++++++++++++++++++++++
 4 files changed, 264 insertions(+)
 create mode 100644 libavformat/lc3dec.c
 create mode 100644 libavformat/lc3enc.c

diff --git a/libavformat/Makefile b/libavformat/Makefile
index 94a949f555..29a38c1d94 100644
--- a/libavformat/Makefile
+++ b/libavformat/Makefile
@@ -332,6 +332,9 @@ OBJS-$(CONFIG_KVAG_DEMUXER)              += kvag.o
 OBJS-$(CONFIG_KVAG_MUXER)                += kvag.o rawenc.o
 OBJS-$(CONFIG_LAF_DEMUXER)               += lafdec.o
 OBJS-$(CONFIG_LATM_MUXER)                += latmenc.o rawenc.o
+OBJS-$(CONFIG_LC3_DEMUXER)               += lc3dec.o
+OBJS-$(CONFIG_LC3_MUXER)                 += lc3enc.o
+OBJS-$(CONFIG_LC3_PLUS_MUXER)            += lc3enc.o
 OBJS-$(CONFIG_LMLM4_DEMUXER)             += lmlm4.o
 OBJS-$(CONFIG_LOAS_DEMUXER)              += loasdec.o rawdec.o
 OBJS-$(CONFIG_LUODAT_DEMUXER)            += luodatdec.o
diff --git a/libavformat/allformats.c b/libavformat/allformats.c
index e15d0fa6d7..551b0f0d7b 100644
--- a/libavformat/allformats.c
+++ b/libavformat/allformats.c
@@ -252,6 +252,9 @@ extern const FFInputFormat  ff_kvag_demuxer;
 extern const FFOutputFormat ff_kvag_muxer;
 extern const FFInputFormat  ff_laf_demuxer;
 extern const FFOutputFormat ff_latm_muxer;
+extern const FFInputFormat  ff_lc3_demuxer;
+extern const FFOutputFormat ff_lc3_muxer;
+extern const FFOutputFormat ff_lc3_plus_muxer;
 extern const FFInputFormat  ff_lmlm4_demuxer;
 extern const FFInputFormat  ff_loas_demuxer;
 extern const FFInputFormat  ff_luodat_demuxer;
diff --git a/libavformat/lc3dec.c b/libavformat/lc3dec.c
new file mode 100644
index 0000000000..563384f786
--- /dev/null
+++ b/libavformat/lc3dec.c
@@ -0,0 +1,140 @@
+/*
+ * LC3 demuxer
+ * Copyright (C) 2024  Antoine Soulier <asoulier@google.com>
+ *
+ * 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
+ */
+
+/**
+ * @file
+ * Based on the file format specified by :
+ *
+ * - Bluetooth SIG - Low Complexity Communication Codec Test Suite
+ *   https://www.bluetooth.org/docman/handlers/downloaddoc.ashx?doc_id=502301
+ *   3.2.8.2 Reference LC3 Codec Bitstream Format
+ *
+ * - ETSI TI 103 634 V1.4.1 - Low Complexity Communication Codec plus
+ *   https://www.etsi.org/deliver/etsi_ts/103600_103699/103634/01.04.01_60/ts_103634v010401p.pdf
+ *   LC3plus conformance script package
+ */
+
+#include <lc3.h>
+
+#include "libavcodec/avcodec.h"
+#include "libavcodec/packet.h"
+#include "libavutil/intreadwrite.h"
+
+#include "avformat.h"
+#include "avio.h"
+#include "demux.h"
+#include "internal.h"
+
+typedef struct LC3DemuxContext {
+    int frame_samples;
+    int64_t position;
+    int64_t length;
+} LC3DemuxContext;
+
+static int lc3_read_header(AVFormatContext *s)
+{
+    LC3DemuxContext *lc3 = s->priv_data;
+    AVStream *st = NULL;
+    uint16_t tag, hdr_size;
+    uint16_t frame_us;
+    uint32_t length;
+    bool ep_mode, hr_mode;
+    int srate_hz, channels, bit_rate;
+    int num_extra_params, ret;
+
+    tag = avio_rb16(s->pb);
+    hdr_size = avio_rl16(s->pb);
+
+    if (tag != 0x1ccc || hdr_size < 9 * sizeof(uint16_t))
+        return AVERROR_INVALIDDATA;
+
+    num_extra_params = hdr_size / sizeof(uint16_t) - 9;
+
+    srate_hz = avio_rl16(s->pb) * 100;
+    bit_rate = avio_rl16(s->pb) * 100;
+    channels = avio_rl16(s->pb);
+    frame_us = avio_rl16(s->pb) * 10;
+    ep_mode  = avio_rl16(s->pb) != 0;
+    length   = avio_rl32(s->pb);
+    hr_mode  = num_extra_params >= 1 && avio_rl16(s->pb);
+
+    st = avformat_new_stream(s, NULL);
+    if (!st)
+        return AVERROR(ENOMEM);
+
+    avpriv_set_pts_info(st, 32, 1, srate_hz);
+    st->duration = length;
+
+    st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
+    st->codecpar->codec_id = frame_us <= 5000 || ep_mode || hr_mode ?
+                             AV_CODEC_ID_LC3_PLUS : AV_CODEC_ID_LC3;
+    st->codecpar->sample_rate = srate_hz;
+    st->codecpar->bit_rate = bit_rate;
+    st->codecpar->ch_layout.nb_channels = channels;
+
+    if ((ret = ff_alloc_extradata(st->codecpar, 6)) < 0) {
+        av_log(s, AV_LOG_ERROR, "Could not allocate extradata.\n");
+        return ret;
+    }
+
+    AV_WL16(st->codecpar->extradata + 0, frame_us);
+    AV_WL16(st->codecpar->extradata + 2, ep_mode);
+    AV_WL16(st->codecpar->extradata + 4, hr_mode);
+
+    lc3->frame_samples = lc3_hr_frame_samples(hr_mode, frame_us, srate_hz);
+    lc3->position = 0;
+    lc3->length = st->duration +
+        lc3_hr_delay_samples(hr_mode, frame_us, srate_hz);
+
+    return 0;
+}
+
+static int lc3_read_packet(AVFormatContext *s, AVPacket *pkt)
+{
+    LC3DemuxContext *lc3 = s->priv_data;
+    AVIOContext *pb = s->pb;
+    int ret;
+
+    if ((ret = av_get_packet(s->pb, pkt, avio_rl16(pb))) < 0)
+        return ret;
+
+    pkt->duration = lc3->frame_samples;
+    lc3->position += lc3->frame_samples;
+    if (lc3->position > lc3->length) {
+        pkt->duration -= lc3->position - lc3->length;
+        lc3->position = lc3->length;
+    }
+
+    return 0;
+}
+
+const FFInputFormat ff_lc3_demuxer = {
+    .p.name         = "lc3",
+    .p.long_name    = NULL_IF_CONFIG_SMALL(
+           "LC3 / LC3plus (Low Complexity Communication Codec)"),
+    .p.extensions   = "lc3",
+    .p.flags        = AVFMT_GENERIC_INDEX |
+                      AVFMT_NOTIMESTAMPS  |
+                      AVFMT_NO_BYTE_SEEK,
+    .priv_data_size = sizeof(LC3DemuxContext),
+    .read_header    = lc3_read_header,
+    .read_packet    = lc3_read_packet,
+};
diff --git a/libavformat/lc3enc.c b/libavformat/lc3enc.c
new file mode 100644
index 0000000000..e6a9ddb35d
--- /dev/null
+++ b/libavformat/lc3enc.c
@@ -0,0 +1,118 @@
+/*
+ * LC3 muxer
+ * Copyright (C) 2024  Antoine Soulier <asoulier@google.com>
+ *
+ * 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
+ */
+
+/**
+ * @file
+ * Based on the file format specified by :
+ *
+ * - Bluetooth SIG - Low Complexity Communication Codec Test Suite
+ *   https://www.bluetooth.org/docman/handlers/downloaddoc.ashx?doc_id=502301
+ *   3.2.8.2 Reference LC3 Codec Bitstream Format
+ *
+ * - ETSI TI 103 634 V1.4.1 - Low Complexity Communication Codec plus
+ *   https://www.etsi.org/deliver/etsi_ts/103600_103699/103634/01.04.01_60/ts_103634v010401p.pdf
+ *   LC3plus conformance script package
+ */
+
+#include <lc3.h>
+
+#include "libavutil/intreadwrite.h"
+#include "libavutil/opt.h"
+
+#include "avformat.h"
+#include "avio.h"
+#include "mux.h"
+#include "internal.h"
+
+static av_cold int lc3_init(AVFormatContext *s)
+{
+    if (s->nb_streams != 1) {
+        av_log(s, AV_LOG_ERROR, "This muxer only supports a single stream.\n");
+        return AVERROR(EINVAL);
+    }
+
+    return 0;
+}
+
+static int lc3_write_header(AVFormatContext *s)
+{
+    AVStream *st = s->streams[0];
+    int channels = st->codecpar->ch_layout.nb_channels;
+    int srate_hz = st->codecpar->sample_rate;
+    int bit_rate = st->codecpar->bit_rate;
+    uint16_t frame_us = 10000;
+    bool ep_mode = false, hr_mode = false;
+    uint32_t nb_samples = av_rescale_q(
+        st->duration, st->time_base, (AVRational){ 1, srate_hz });
+
+    if (st->codecpar->extradata_size >= 2)
+        frame_us = AV_RL16(st->codecpar->extradata + 0);
+    if (st->codecpar->extradata_size >= 4)
+        ep_mode = AV_RL16(st->codecpar->extradata + 2);
+    if (st->codecpar->extradata_size >= 6)
+        hr_mode = AV_RL16(st->codecpar->extradata + 4);
+
+    avio_wb16(s->pb, 0x1ccc);
+    avio_wl16(s->pb, (9 + hr_mode) * sizeof(uint16_t));
+    avio_wl16(s->pb, srate_hz / 100);
+    avio_wl16(s->pb, bit_rate / 100);
+    avio_wl16(s->pb, channels);
+    avio_wl16(s->pb, frame_us / 10);
+    avio_wl16(s->pb, ep_mode);
+    avio_wl32(s->pb, nb_samples);
+    if (hr_mode)
+        avio_wl16(s->pb, hr_mode);
+
+    return 0;
+}
+
+static int lc3_write_packet(AVFormatContext *s, AVPacket *pkt)
+{
+    avio_wl16(s->pb, pkt->size);
+    avio_write(s->pb, pkt->data, pkt->size);
+    return 0;
+}
+
+const FFOutputFormat ff_lc3_muxer = {
+    .p.name        = "lc3",
+    .p.long_name   = NULL_IF_CONFIG_SMALL(
+           "LC3 (Low Complexity Communication Codec)"),
+    .p.extensions  = "lc3",
+    .p.audio_codec = AV_CODEC_ID_LC3,
+    .p.video_codec = AV_CODEC_ID_NONE,
+    .p.flags       = AVFMT_NOTIMESTAMPS,
+    .init          = lc3_init,
+    .write_header  = lc3_write_header,
+    .write_packet  = lc3_write_packet,
+};
+
+const FFOutputFormat ff_lc3_plus_muxer = {
+    .p.name        = "lc3_plus",
+    .p.long_name   = NULL_IF_CONFIG_SMALL(
+           "LC3Plus (Low Complexity Communication Codec plus)"),
+    .p.extensions  = "lc3",
+    .p.audio_codec = AV_CODEC_ID_LC3_PLUS,
+    .p.video_codec = AV_CODEC_ID_NONE,
+    .p.flags       = AVFMT_NOTIMESTAMPS,
+    .init          = lc3_init,
+    .write_header  = lc3_write_header,
+    .write_packet  = lc3_write_packet,
+};
-- 
2.44.0.396.g6e790dbe36-goog

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