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/*
* LC3 muxer and 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 "config_components.h"
#include "libavcodec/packet.h"
#include "libavutil/intreadwrite.h"
#include "avformat.h"
#include "avio.h"
#include "demux.h"
#include "internal.h"
#include "mux.h"
static int check_frame_length(void *avcl, int srate_hz, int frame_us)
{
if (srate_hz != 8000 && srate_hz != 16000 && srate_hz != 24000 &&
srate_hz != 32000 && srate_hz != 48000 && srate_hz != 96000) {
if (avcl)
av_log(avcl, AV_LOG_ERROR,
"Invalid LC3 sample rate: %d Hz.\n", srate_hz);
return -1;
}
if (frame_us != 2500 && frame_us != 5000 &&
frame_us != 7500 && frame_us != 10000) {
if (avcl)
av_log(avcl, AV_LOG_ERROR,
"Invalid LC3 frame duration: %.1f ms.\n", frame_us / 1000.f);
return -1;
}
return 0;
}
#if CONFIG_LC3_DEMUXER
typedef struct LC3DemuxContext {
int frame_samples;
int64_t end_dts;
} LC3DemuxContext;
static int lc3_read_probe(const AVProbeData *p)
{
int frame_us, srate_hz;
if (p->buf_size < 12)
return 0;
if (AV_RB16(p->buf + 0) != 0x1ccc ||
AV_RL16(p->buf + 2) < 9 * sizeof(uint16_t))
return 0;
srate_hz = AV_RL16(p->buf + 4) * 100;
frame_us = AV_RL16(p->buf + 10) * 10;
if (check_frame_length(NULL, srate_hz, frame_us) < 0)
return 0;
return AVPROBE_SCORE_MAX;
}
static int lc3_read_header(AVFormatContext *s)
{
LC3DemuxContext *lc3 = s->priv_data;
AVStream *st = NULL;
uint16_t tag, hdr_size;
uint32_t length;
int srate_hz, frame_us, channels, bit_rate;
int ep_mode, hr_mode;
int num_extra_params;
int delay, 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);
if (check_frame_length(s, srate_hz, frame_us) < 0)
return AVERROR_INVALIDDATA;
st = avformat_new_stream(s, NULL);
if (!st)
return AVERROR(ENOMEM);
avpriv_set_pts_info(st, 64, 1, srate_hz);
avpriv_update_cur_dts(s, st, 0);
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)
return ret;
AV_WL16(st->codecpar->extradata + 0, frame_us / 10);
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);
delay = av_rescale(frame_us == 7500 ? 4000 : 2500, srate_hz, 1000*1000);
lc3->end_dts = length ? length + delay : -1;
return 0;
}
static int lc3_read_packet(AVFormatContext *s, AVPacket *pkt)
{
LC3DemuxContext *lc3 = s->priv_data;
AVStream *st = s->streams[0];
AVIOContext *pb = s->pb;
int64_t pos = avio_tell(pb);
int64_t remaining_samples;
int ret;
ret = av_get_packet(s->pb, pkt, avio_rl16(pb));
if (ret < 0)
return ret;
pkt->pos = pos;
remaining_samples = lc3->end_dts < 0 ? lc3->frame_samples :
FFMAX(lc3->end_dts - ffstream(st)->cur_dts, 0);
pkt->duration = FFMIN(lc3->frame_samples, remaining_samples);
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_probe = lc3_read_probe,
.read_header = lc3_read_header,
.read_packet = lc3_read_packet,
};
#endif /* CONFIG_LC3_DEMUXER */
#if CONFIG_LC3_MUXER
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;
if (check_frame_length(s, srate_hz, frame_us) < 0)
return AVERROR_INVALIDDATA;
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.subtitle_codec = AV_CODEC_ID_NONE,
.p.flags = AVFMT_NOTIMESTAMPS,
.flags_internal = FF_OFMT_FLAG_MAX_ONE_OF_EACH |
FF_OFMT_FLAG_ONLY_DEFAULT_CODECS,
.write_header = lc3_write_header,
.write_packet = lc3_write_packet,
};
#endif /* CONFIG_LC3_MUXER */
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