[FFmpeg-devel] [PATCH 2/2] avformat/lc3: Add file format for LC3/LC3plus transport
Antoine Soulier
asoulier at google.com
Thu Apr 4 19:54:16 EEST 2024
In a previous patch, I modified the duration of the packet. But since, we
now support seeking, I don't know how to obtain the pts of the packet (or
sample position since start), without an implementation of a `read_seek()`
function.
Can you help me on how I can derive the pts of the packet?
Thanks.
On Thu, Apr 4, 2024, 9:30 AM Andreas Rheinhardt <
andreas.rheinhardt at outlook.com> wrote:
> Antoine Soulier via ffmpeg-devel:
> > 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 | 127 +++++++++++++++++++++++++++++++++++++++
> > libavformat/lc3enc.c | 100 ++++++++++++++++++++++++++++++
> > 6 files changed, 238 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..7232e9847e
> > --- /dev/null
> > +++ b/libavformat/lc3dec.c
> > @@ -0,0 +1,127 @@
> > +/*
> > + * 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;
> > +} LC3DemuxContext;
> > +
> > +static int lc3_read_header(AVFormatContext *s)
> > +{
> > + LC3DemuxContext *lc3 = s->priv_data;
> > + AVStream *st = NULL;
> > + uint16_t tag, hdr_size;
> > + uint16_t frame_10us;
> > + 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_10us = avio_rl16(s->pb);
> > + 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, 64, 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, 10)) < 0) {
> > + av_log(s, AV_LOG_ERROR, "Could not allocate extradata.\n");
>
> Still pointless error message.
>
> > + return ret;
> > + }
> > +
> > + AV_WL16(st->codecpar->extradata + 0, frame_10us);
> > + AV_WL16(st->codecpar->extradata + 2, ep_mode);
> > + AV_WL16(st->codecpar->extradata + 4, hr_mode);
> > + AV_WL32(st->codecpar->extradata + 6, length);
> > +
> > + lc3->frame_samples = av_rescale(frame_10us, srate_hz, 100*1000);
> > +
> > + return 0;
> > +}
> > +
> > +static int lc3_read_packet(AVFormatContext *s, AVPacket *pkt)
> > +{
> > + LC3DemuxContext *lc3 = s->priv_data;
> > + AVIOContext *pb = s->pb;
> > + int64_t pos = avio_tell(pb);
> > + int ret;
> > +
> > + ret = av_get_packet(s->pb, pkt, avio_rl16(pb));
> > + if (ret < 0)
> > + return ret;
> > +
> > + pkt->pos = pos;
> > + pkt->duration = lc3->frame_samples;
>
> This should set AV_PKT_DATA_SKIP_SAMPLES side data to the packet that
> crosses the number of samples specified in the header.
>
> > +
> > + 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_GENERIC_INDEX,
> > + .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..e768212f63
> > --- /dev/null
> > +++ b/libavformat/lc3enc.c
> > @@ -0,0 +1,100 @@
> > +/*
> > + * 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;
> > + int frame_us, ep_mode, hr_mode;
> > + uint32_t nb_samples = av_rescale_q(
> > + st->duration, st->time_base, (AVRational){ 1, srate_hz });
> > +
> > + if (st->codecpar->extradata_size < 6)
> > + return AVERROR_INVALIDDATA;
> > +
> > + frame_us = AV_RL16(st->codecpar->extradata + 0) * 10;
> > + ep_mode = AV_RL16(st->codecpar->extradata + 2) != 0;
> > + hr_mode = AV_RL16(st->codecpar->extradata + 4) != 0;
> > +
> > + 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,
> > +};
>
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