[FFmpeg-devel] [PATCH 2/2] avformat/lc3: Add file format for LC3/LC3plus transport
Antoine Soulier
asoulier at google.com
Thu Mar 28 23:35:59 EET 2024
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 at google.com>
---
Changelog | 1 +
doc/muxers.texi | 6 ++
libavformat/Makefile | 2 +
libavformat/allformats.c | 2 +
libavformat/lc3dec.c | 135 +++++++++++++++++++++++++++++++++++++++
libavformat/lc3enc.c | 102 +++++++++++++++++++++++++++++
6 files changed, 248 insertions(+)
create mode 100644 libavformat/lc3dec.c
create mode 100644 libavformat/lc3enc.c
diff --git a/Changelog b/Changelog
index 83a4cf7888..08c200a41d 100644
--- a/Changelog
+++ b/Changelog
@@ -2,6 +2,7 @@ Entries are sorted chronologically from oldest to youngest within each release,
releases are sorted from youngest to oldest.
version <next>:
+- LC3/LC3plus demuxer and muxer
- LC3/LC3plus decoding/encoding using external library liblc3
diff --git a/doc/muxers.texi b/doc/muxers.texi
index a10a8e216f..9687746c30 100644
--- a/doc/muxers.texi
+++ b/doc/muxers.texi
@@ -2612,6 +2612,12 @@ WebDAV server every second:
ffmpeg -f x11grab -framerate 1 -i :0.0 -q:v 6 -update 1 -protocol_opts method=PUT http://example.com/desktop.jpg
@end example
+ at section lc3
+Bluetooth SIG Low Complexity Communication Codec audio (LC3), or
+ETSI TS 103 634 Low Complexity Communication Codec plus (LC3plus).
+
+This muxer accepts a single @code{lc3} audio stream.
+
@section matroska
Matroska container muxer.
diff --git a/libavformat/Makefile b/libavformat/Makefile
index 44aa485029..4961c42852 100644
--- a/libavformat/Makefile
+++ b/libavformat/Makefile
@@ -332,6 +332,8 @@ 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-$(CONFIG_LMLM4_DEMUXER) += lmlm4.o
OBJS-$(CONFIG_LOAS_DEMUXER) += loasdec.o rawdec.o
OBJS-$(CONFIG_LUODAT_DEMUXER) += luodatdec.o
diff --git a/libavformat/allformats.c b/libavformat/allformats.c
index 9df42bb87a..0b36a7c3eb 100644
--- a/libavformat/allformats.c
+++ b/libavformat/allformats.c
@@ -252,6 +252,8 @@ 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 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..9ca9825f1b
--- /dev/null
+++ b/libavformat/lc3dec.c
@@ -0,0 +1,135 @@
+/*
+ * LC3 demuxer
+ * Copyright (C) 2024 Antoine Soulier <asoulier at 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 "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;
+ int 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 = 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 = av_rescale(frame_us, srate_hz, 1000*1000);
+
+ lc3->position = 0;
+ lc3->length = st->duration +
+ av_rescale(frame_us == 7500 ? 4000 : 2500, srate_hz, 1000*1000);
+
+ return 0;
+}
+
+static int lc3_read_packet(AVFormatContext *s, AVPacket *pkt)
+{
+ LC3DemuxContext *lc3 = s->priv_data;
+ AVIOContext *pb = s->pb;
+ int ret;
+
+ ret = av_get_packet(s->pb, pkt, avio_rl16(pb));
+ if (ret < 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 (Low Complexity Communication Codec)"),
+ .p.extensions = "lc3",
+ .p.flags = AVFMT_NOBINSEARCH | AVFMT_NOGENSEARCH | AVFMT_NO_BYTE_SEEK | AVFMT_NOTIMESTAMPS,
+ .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..a7e3e3f4f7
--- /dev/null
+++ b/libavformat/lc3enc.c
@@ -0,0 +1,102 @@
+/*
+ * LC3 muxer
+ * Copyright (C) 2024 Antoine Soulier <asoulier at 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 "libavutil/intreadwrite.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;
+ int ep_mode = 0, hr_mode = 0;
+ 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 >= 6) {
+ ep_mode = AV_RL16(st->codecpar->extradata + 2);
+ 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,
+};
--
2.44.0.478.gd926399ef9-goog
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