libavformat/lc3.c

   1 /*
   2  * LC3 muxer and demuxer
   3  * Copyright (C) 2024  Antoine Soulier <asoulier@google.com>
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /**
  23  * @file
  24  * Based on the file format specified by :
  25  *
  26  * - Bluetooth SIG - Low Complexity Communication Codec Test Suite
  27  *   https://www.bluetooth.org/docman/handlers/downloaddoc.ashx?doc_id=502301
  28  *   3.2.8.2 Reference LC3 Codec Bitstream Format
  29  *
  30  * - ETSI TI 103 634 V1.4.1 - Low Complexity Communication Codec plus
  31  *   https://www.etsi.org/deliver/etsi_ts/103600_103699/103634/01.04.01_60/ts_103634v010401p.pdf
  32  *   LC3plus conformance script package
  33  */
  34
  35 #include "config_components.h"
  36
  37 #include "libavcodec/packet.h"
  38 #include "libavutil/intreadwrite.h"
  39
  40 #include "avformat.h"
  41 #include "avio.h"
  42 #include "demux.h"
  43 #include "internal.h"
  44 #include "mux.h"
  45
  46 static int check_frame_length(void *avcl, int srate_hz, int frame_us)
  47 {
  48     if (srate_hz !=  8000 && srate_hz != 16000 && srate_hz != 24000 &&
  49         srate_hz != 32000 && srate_hz != 48000 && srate_hz != 96000) {
  50         if (avcl)
  51             av_log(avcl, AV_LOG_ERROR,
  52                    "Invalid LC3 sample rate: %d Hz.\n", srate_hz);
  53         return -1;
  54     }
  55
  56     if (frame_us != 2500 && frame_us !=  5000 &&
  57         frame_us != 7500 && frame_us != 10000) {
  58         if (avcl)
  59             av_log(avcl, AV_LOG_ERROR,
  60                    "Invalid LC3 frame duration: %.1f ms.\n", frame_us / 1000.f);
  61         return -1;
  62     }
  63
  64     return 0;
  65 }
  66
  67 #if CONFIG_LC3_DEMUXER
  68
  69 typedef struct LC3DemuxContext {
  70     int frame_samples;
  71     int64_t end_dts;
  72 } LC3DemuxContext;
  73
  74 static int lc3_read_probe(const AVProbeData *p)
  75 {
  76     int frame_us, srate_hz;
  77
  78     if (p->buf_size < 12)
  79         return 0;
  80
  81     if (AV_RB16(p->buf + 0) != 0x1ccc ||
  82         AV_RL16(p->buf + 2) <  9 * sizeof(uint16_t))
  83         return 0;
  84
  85     srate_hz = AV_RL16(p->buf + 4) * 100;
  86     frame_us = AV_RL16(p->buf + 10) * 10;
  87     if (check_frame_length(NULL, srate_hz, frame_us) < 0)
  88         return 0;
  89
  90     return AVPROBE_SCORE_MAX;
  91 }
  92
  93 static int lc3_read_header(AVFormatContext *s)
  94 {
  95     LC3DemuxContext *lc3 = s->priv_data;
  96     AVStream *st = NULL;
  97     uint16_t tag, hdr_size;
  98     uint32_t length;
  99     int srate_hz, frame_us, channels, bit_rate;
 100     int ep_mode, hr_mode;
 101     int num_extra_params;
 102     int delay, ret;
 103
 104     tag = avio_rb16(s->pb);
 105     hdr_size = avio_rl16(s->pb);
 106
 107     if (tag != 0x1ccc || hdr_size < 9 * sizeof(uint16_t))
 108         return AVERROR_INVALIDDATA;
 109
 110     num_extra_params = hdr_size / sizeof(uint16_t) - 9;
 111
 112     srate_hz = avio_rl16(s->pb) * 100;
 113     bit_rate = avio_rl16(s->pb) * 100;
 114     channels = avio_rl16(s->pb);
 115     frame_us = avio_rl16(s->pb) * 10;
 116     ep_mode  = avio_rl16(s->pb) != 0;
 117     length   = avio_rl32(s->pb);
 118     hr_mode  = num_extra_params >= 1 && avio_rl16(s->pb);
 119
 120     if (check_frame_length(s, srate_hz, frame_us) < 0)
 121         return AVERROR_INVALIDDATA;
 122
 123     st = avformat_new_stream(s, NULL);
 124     if (!st)
 125         return AVERROR(ENOMEM);
 126
 127     avpriv_set_pts_info(st, 64, 1, srate_hz);
 128     avpriv_update_cur_dts(s, st, 0);
 129     st->duration = length;
 130
 131     st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
 132     st->codecpar->codec_id = AV_CODEC_ID_LC3;
 133     st->codecpar->sample_rate = srate_hz;
 134     st->codecpar->bit_rate = bit_rate;
 135     st->codecpar->ch_layout.nb_channels = channels;
 136
 137     if ((ret = ff_alloc_extradata(st->codecpar, 6)) < 0)
 138         return ret;
 139
 140     AV_WL16(st->codecpar->extradata + 0, frame_us / 10);
 141     AV_WL16(st->codecpar->extradata + 2, ep_mode);
 142     AV_WL16(st->codecpar->extradata + 4, hr_mode);
 143
 144     lc3->frame_samples = av_rescale(frame_us, srate_hz, 1000*1000);
 145
 146     delay = av_rescale(frame_us == 7500 ? 4000 : 2500, srate_hz, 1000*1000);
 147     lc3->end_dts = length ? length + delay : -1;
 148
 149     return 0;
 150 }
 151
 152 static int lc3_read_packet(AVFormatContext *s, AVPacket *pkt)
 153 {
 154     LC3DemuxContext *lc3 = s->priv_data;
 155     AVStream *st = s->streams[0];
 156     AVIOContext *pb = s->pb;
 157     int64_t pos = avio_tell(pb);
 158     int64_t remaining_samples;
 159     int ret;
 160
 161     ret = av_get_packet(s->pb, pkt, avio_rl16(pb));
 162     if (ret < 0)
 163         return ret;
 164
 165     pkt->pos = pos;
 166
 167     remaining_samples = lc3->end_dts < 0 ? lc3->frame_samples :
 168                         FFMAX(lc3->end_dts - ffstream(st)->cur_dts, 0);
 169     pkt->duration = FFMIN(lc3->frame_samples, remaining_samples);
 170
 171     return 0;
 172 }
 173
 174 const FFInputFormat ff_lc3_demuxer = {
 175     .p.name         = "lc3",
 176     .p.long_name    = NULL_IF_CONFIG_SMALL("LC3 (Low Complexity Communication Codec)"),
 177     .p.extensions   = "lc3",
 178     .p.flags        = AVFMT_GENERIC_INDEX,
 179     .priv_data_size = sizeof(LC3DemuxContext),
 180     .read_probe     = lc3_read_probe,
 181     .read_header    = lc3_read_header,
 182     .read_packet    = lc3_read_packet,
 183 };
 184
 185 #endif /* CONFIG_LC3_DEMUXER */
 186
 187 #if CONFIG_LC3_MUXER
 188
 189 static int lc3_write_header(AVFormatContext *s)
 190 {
 191     AVStream *st = s->streams[0];
 192     int channels = st->codecpar->ch_layout.nb_channels;
 193     int srate_hz = st->codecpar->sample_rate;
 194     int bit_rate = st->codecpar->bit_rate;
 195     int frame_us, ep_mode, hr_mode;
 196     uint32_t nb_samples = av_rescale_q(
 197         st->duration, st->time_base, (AVRational){ 1, srate_hz });
 198
 199     if (st->codecpar->extradata_size < 6)
 200         return AVERROR_INVALIDDATA;
 201
 202     frame_us = AV_RL16(st->codecpar->extradata + 0) * 10;
 203     ep_mode = AV_RL16(st->codecpar->extradata + 2) != 0;
 204     hr_mode = AV_RL16(st->codecpar->extradata + 4) != 0;
 205
 206     if (check_frame_length(s, srate_hz, frame_us) < 0)
 207         return AVERROR_INVALIDDATA;
 208
 209     avio_wb16(s->pb, 0x1ccc);
 210     avio_wl16(s->pb, (9 + hr_mode) * sizeof(uint16_t));
 211     avio_wl16(s->pb, srate_hz / 100);
 212     avio_wl16(s->pb, bit_rate / 100);
 213     avio_wl16(s->pb, channels);
 214     avio_wl16(s->pb, frame_us / 10);
 215     avio_wl16(s->pb, ep_mode);
 216     avio_wl32(s->pb, nb_samples);
 217     if (hr_mode)
 218         avio_wl16(s->pb, hr_mode);
 219
 220     return 0;
 221 }
 222
 223 static int lc3_write_packet(AVFormatContext *s, AVPacket *pkt)
 224 {
 225     avio_wl16(s->pb, pkt->size);
 226     avio_write(s->pb, pkt->data, pkt->size);
 227     return 0;
 228 }
 229
 230 const FFOutputFormat ff_lc3_muxer = {
 231     .p.name        = "lc3",
 232     .p.long_name   = NULL_IF_CONFIG_SMALL("LC3 (Low Complexity Communication Codec)"),
 233     .p.extensions  = "lc3",
 234     .p.audio_codec = AV_CODEC_ID_LC3,
 235     .p.video_codec = AV_CODEC_ID_NONE,
 236     .p.subtitle_codec = AV_CODEC_ID_NONE,
 237     .p.flags       = AVFMT_NOTIMESTAMPS,
 238     .flags_internal   = FF_OFMT_FLAG_MAX_ONE_OF_EACH |
 239                         FF_OFMT_FLAG_ONLY_DEFAULT_CODECS,
 240     .write_header  = lc3_write_header,
 241     .write_packet  = lc3_write_packet,
 242 };
 243
 244 #endif /* CONFIG_LC3_MUXER */