libavformat/spdifdec.c

   1 /*
   2  * IEC 61937 demuxer
   3  * Copyright (c) 2010 Anssi Hannula <anssi.hannula at iki.fi>
   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  * IEC 61937 demuxer, used for compressed data in S/PDIF
  25  * @author Anssi Hannula
  26  */
  27
  28 #include "libavutil/bswap.h"
  29
  30 #include "libavcodec/ac3defs.h"
  31 #include "libavcodec/adts_parser.h"
  32
  33 #include "avformat.h"
  34 #include "demux.h"
  35 #include "internal.h"
  36 #include "spdif.h"
  37
  38 static int spdif_get_offset_and_codec(AVFormatContext *s,
  39                                       enum IEC61937DataType data_type,
  40                                       const char *buf, int *offset,
  41                                       enum AVCodecID *codec)
  42 {
  43     uint32_t samples;
  44     uint8_t frames;
  45     int ret;
  46
  47     switch (data_type & 0xff) {
  48     case IEC61937_AC3:
  49         *offset = AC3_FRAME_SIZE << 2;
  50         *codec = AV_CODEC_ID_AC3;
  51         break;
  52     case IEC61937_MPEG1_LAYER1:
  53         *offset = spdif_mpeg_pkt_offset[1][0];
  54         *codec = AV_CODEC_ID_MP1;
  55         break;
  56     case IEC61937_MPEG1_LAYER23:
  57         *offset = spdif_mpeg_pkt_offset[1][0];
  58         *codec = AV_CODEC_ID_MP3;
  59         break;
  60     case IEC61937_MPEG2_EXT:
  61         *offset = 4608;
  62         *codec = AV_CODEC_ID_MP3;
  63         break;
  64     case IEC61937_MPEG2_AAC:
  65         ret = av_adts_header_parse(buf, &samples, &frames);
  66         if (ret < 0) {
  67             if (s) /* be silent during a probe */
  68                 av_log(s, AV_LOG_ERROR, "Invalid AAC packet in IEC 61937\n");
  69             return ret;
  70         }
  71         *offset = samples << 2;
  72         *codec = AV_CODEC_ID_AAC;
  73         break;
  74     case IEC61937_MPEG2_LAYER1_LSF:
  75         *offset = spdif_mpeg_pkt_offset[0][0];
  76         *codec = AV_CODEC_ID_MP1;
  77         break;
  78     case IEC61937_MPEG2_LAYER2_LSF:
  79         *offset = spdif_mpeg_pkt_offset[0][1];
  80         *codec = AV_CODEC_ID_MP2;
  81         break;
  82     case IEC61937_MPEG2_LAYER3_LSF:
  83         *offset = spdif_mpeg_pkt_offset[0][2];
  84         *codec = AV_CODEC_ID_MP3;
  85         break;
  86     case IEC61937_DTS1:
  87         *offset = 2048;
  88         *codec = AV_CODEC_ID_DTS;
  89         break;
  90     case IEC61937_DTS2:
  91         *offset = 4096;
  92         *codec = AV_CODEC_ID_DTS;
  93         break;
  94     case IEC61937_DTS3:
  95         *offset = 8192;
  96         *codec = AV_CODEC_ID_DTS;
  97         break;
  98     case IEC61937_EAC3:
  99         *offset = 24576;
 100         *codec = AV_CODEC_ID_EAC3;
 101         break;
 102     default:
 103         if (s) { /* be silent during a probe */
 104             avpriv_request_sample(s, "Data type 0x%04x in IEC 61937",
 105                                   data_type);
 106         }
 107         return AVERROR_PATCHWELCOME;
 108     }
 109     return 0;
 110 }
 111
 112 /* Largest offset between bursts we currently handle, i.e. AAC with
 113    samples = 4096 */
 114 #define SPDIF_MAX_OFFSET 16384
 115
 116 static int spdif_probe(const AVProbeData *p)
 117 {
 118     enum AVCodecID codec;
 119     return ff_spdif_probe (p->buf, p->buf_size, &codec);
 120 }
 121
 122 int ff_spdif_probe(const uint8_t *p_buf, int buf_size, enum AVCodecID *codec)
 123 {
 124     const uint8_t *buf = p_buf;
 125     const uint8_t *probe_end = p_buf + FFMIN(2 * SPDIF_MAX_OFFSET, buf_size - 1);
 126     const uint8_t *expected_code = buf + 7;
 127     uint32_t state = 0;
 128     int sync_codes = 0;
 129     int consecutive_codes = 0;
 130     int offset;
 131
 132     for (; buf < probe_end; buf++) {
 133         state = (state << 8) | *buf;
 134
 135         if (state == (AV_BSWAP16C(SYNCWORD1) << 16 | AV_BSWAP16C(SYNCWORD2))
 136                 && buf[1] < 0x37) {
 137             sync_codes++;
 138
 139             if (buf == expected_code) {
 140                 if (++consecutive_codes >= 2)
 141                     return AVPROBE_SCORE_MAX;
 142             } else
 143                 consecutive_codes = 0;
 144
 145             if (buf + 4 + AV_AAC_ADTS_HEADER_SIZE > p_buf + buf_size)
 146                 break;
 147
 148             /* continue probing to find more sync codes */
 149             probe_end = FFMIN(buf + SPDIF_MAX_OFFSET, p_buf + buf_size - 1);
 150
 151             /* skip directly to the next sync code */
 152             if (!spdif_get_offset_and_codec(NULL, (buf[2] << 8) | buf[1],
 153                                             &buf[5], &offset, codec)) {
 154                 if (buf + offset >= p_buf + buf_size)
 155                     break;
 156                 expected_code = buf + offset;
 157                 buf = expected_code - 7;
 158             }
 159         }
 160     }
 161
 162     if (!sync_codes)
 163         return 0;
 164
 165     if (sync_codes >= 6)
 166         /* good amount of sync codes but with unexpected offsets */
 167         return AVPROBE_SCORE_EXTENSION;
 168
 169     /* some sync codes were found */
 170     return AVPROBE_SCORE_EXTENSION / 4;
 171 }
 172
 173 static int spdif_read_header(AVFormatContext *s)
 174 {
 175     s->ctx_flags |= AVFMTCTX_NOHEADER;
 176     return 0;
 177 }
 178
 179 static int spdif_get_pkt_size_bits(int type, int code)
 180 {
 181     switch (type & 0xff) {
 182     case IEC61937_EAC3:
 183         return code << 3;
 184     default:
 185         return code;
 186     }
 187 }
 188
 189 int ff_spdif_read_packet(AVFormatContext *s, AVPacket *pkt)
 190 {
 191     AVIOContext *pb = s->pb;
 192     enum IEC61937DataType data_type;
 193     enum AVCodecID codec_id;
 194     uint32_t state = 0;
 195     int pkt_size_bits, offset, ret;
 196
 197     while (state != (AV_BSWAP16C(SYNCWORD1) << 16 | AV_BSWAP16C(SYNCWORD2))) {
 198         state = (state << 8) | avio_r8(pb);
 199         if (avio_feof(pb))
 200             return AVERROR_EOF;
 201     }
 202
 203     data_type = avio_rl16(pb);
 204     pkt_size_bits = spdif_get_pkt_size_bits(data_type, avio_rl16(pb));
 205
 206     if (pkt_size_bits % 16)
 207         avpriv_request_sample(s, "Packet not ending at a 16-bit boundary");
 208
 209     ret = av_new_packet(pkt, FFALIGN(pkt_size_bits, 16) >> 3);
 210     if (ret)
 211         return ret;
 212
 213     pkt->pos = avio_tell(pb) - BURST_HEADER_SIZE;
 214
 215     if (avio_read(pb, pkt->data, pkt->size) < pkt->size) {
 216         return AVERROR_EOF;
 217     }
 218     ff_spdif_bswap_buf16((uint16_t *)pkt->data, (uint16_t *)pkt->data, pkt->size >> 1);
 219
 220     ret = spdif_get_offset_and_codec(s, data_type, pkt->data,
 221                                      &offset, &codec_id);
 222     if (ret < 0) {
 223         return ret;
 224     }
 225
 226     /* skip over the padding to the beginning of the next frame */
 227     avio_skip(pb, offset - pkt->size - BURST_HEADER_SIZE);
 228
 229     if (!s->nb_streams) {
 230         /* first packet, create a stream */
 231         AVStream *st = avformat_new_stream(s, NULL);
 232         if (!st) {
 233             return AVERROR(ENOMEM);
 234         }
 235         st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
 236         st->codecpar->codec_id = codec_id;
 237         if (codec_id == AV_CODEC_ID_EAC3)
 238             ffstream(st)->need_parsing = AVSTREAM_PARSE_FULL;
 239         else
 240             ffstream(st)->need_parsing = AVSTREAM_PARSE_HEADERS;
 241     } else if (codec_id != s->streams[0]->codecpar->codec_id) {
 242         avpriv_report_missing_feature(s, "Codec change in IEC 61937");
 243         return AVERROR_PATCHWELCOME;
 244     }
 245
 246     if (!s->bit_rate && s->streams[0]->codecpar->sample_rate)
 247         /* stream bitrate matches 16-bit stereo PCM bitrate for currently
 248            supported codecs */
 249         s->bit_rate = 2 * 16LL * s->streams[0]->codecpar->sample_rate;
 250
 251     return 0;
 252 }
 253
 254 const FFInputFormat ff_spdif_demuxer = {
 255     .p.name         = "spdif",
 256     .p.long_name    = NULL_IF_CONFIG_SMALL("IEC 61937 (compressed data in S/PDIF)"),
 257     .p.flags        = AVFMT_GENERIC_INDEX,
 258     .read_probe     = spdif_probe,
 259     .read_header    = spdif_read_header,
 260     .read_packet    = ff_spdif_read_packet,
 261 };