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 Libav.
   6  *
   7  * Libav 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  * Libav 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 Libav; 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 "avformat.h"
  29 #include "spdif.h"
  30 #include "libavcodec/ac3.h"
  31 #include "libavcodec/aacadtsdec.h"
  32
  33 static int spdif_get_offset_and_codec(AVFormatContext *s,
  34                                       enum IEC61937DataType data_type,
  35                                       const char *buf, int *offset,
  36                                       enum AVCodecID *codec)
  37 {
  38     AACADTSHeaderInfo aac_hdr;
  39     GetBitContext gbc;
  40
  41     switch (data_type & 0xff) {
  42     case IEC61937_AC3:
  43         *offset = AC3_FRAME_SIZE << 2;
  44         *codec = AV_CODEC_ID_AC3;
  45         break;
  46     case IEC61937_MPEG1_LAYER1:
  47         *offset = spdif_mpeg_pkt_offset[1][0];
  48         *codec = AV_CODEC_ID_MP1;
  49         break;
  50     case IEC61937_MPEG1_LAYER23:
  51         *offset = spdif_mpeg_pkt_offset[1][0];
  52         *codec = AV_CODEC_ID_MP3;
  53         break;
  54     case IEC61937_MPEG2_EXT:
  55         *offset = 4608;
  56         *codec = AV_CODEC_ID_MP3;
  57         break;
  58     case IEC61937_MPEG2_AAC:
  59         init_get_bits(&gbc, buf, AAC_ADTS_HEADER_SIZE * 8);
  60         if (avpriv_aac_parse_header(&gbc, &aac_hdr)) {
  61             if (s) /* be silent during a probe */
  62                 av_log(s, AV_LOG_ERROR, "Invalid AAC packet in IEC 61937\n");
  63             return AVERROR_INVALIDDATA;
  64         }
  65         *offset = aac_hdr.samples << 2;
  66         *codec = AV_CODEC_ID_AAC;
  67         break;
  68     case IEC61937_MPEG2_LAYER1_LSF:
  69         *offset = spdif_mpeg_pkt_offset[0][0];
  70         *codec = AV_CODEC_ID_MP1;
  71         break;
  72     case IEC61937_MPEG2_LAYER2_LSF:
  73         *offset = spdif_mpeg_pkt_offset[0][1];
  74         *codec = AV_CODEC_ID_MP2;
  75         break;
  76     case IEC61937_MPEG2_LAYER3_LSF:
  77         *offset = spdif_mpeg_pkt_offset[0][2];
  78         *codec = AV_CODEC_ID_MP3;
  79         break;
  80     case IEC61937_DTS1:
  81         *offset = 2048;
  82         *codec = AV_CODEC_ID_DTS;
  83         break;
  84     case IEC61937_DTS2:
  85         *offset = 4096;
  86         *codec = AV_CODEC_ID_DTS;
  87         break;
  88     case IEC61937_DTS3:
  89         *offset = 8192;
  90         *codec = AV_CODEC_ID_DTS;
  91         break;
  92     default:
  93         if (s) { /* be silent during a probe */
  94             av_log(s, AV_LOG_WARNING, "Data type 0x%04x", data_type);
  95             av_log_missing_feature(s, " in IEC 61937", 1);
  96         }
  97         return AVERROR_PATCHWELCOME;
  98     }
  99     return 0;
 100 }
 101
 102 /* Largest offset between bursts we currently handle, i.e. AAC with
 103    aac_hdr.samples = 4096 */
 104 #define SPDIF_MAX_OFFSET 16384
 105
 106 static int spdif_probe(AVProbeData *p)
 107 {
 108     const uint8_t *buf = p->buf;
 109     const uint8_t *probe_end = p->buf + FFMIN(2 * SPDIF_MAX_OFFSET, p->buf_size - 1);
 110     const uint8_t *expected_code = buf + 7;
 111     uint32_t state = 0;
 112     int sync_codes = 0;
 113     int consecutive_codes = 0;
 114     int offset;
 115     enum AVCodecID codec;
 116
 117     for (; buf < probe_end; buf++) {
 118         state = (state << 8) | *buf;
 119
 120         if (state == (AV_BSWAP16C(SYNCWORD1) << 16 | AV_BSWAP16C(SYNCWORD2))
 121                 && buf[1] < 0x37) {
 122             sync_codes++;
 123
 124             if (buf == expected_code) {
 125                 if (++consecutive_codes >= 2)
 126                     return AVPROBE_SCORE_MAX;
 127             } else
 128                 consecutive_codes = 0;
 129
 130             if (buf + 4 + AAC_ADTS_HEADER_SIZE > p->buf + p->buf_size)
 131                 break;
 132
 133             /* continue probing to find more sync codes */
 134             probe_end = FFMIN(buf + SPDIF_MAX_OFFSET, p->buf + p->buf_size - 1);
 135
 136             /* skip directly to the next sync code */
 137             if (!spdif_get_offset_and_codec(NULL, (buf[2] << 8) | buf[1],
 138                                             &buf[5], &offset, &codec)) {
 139                 if (buf + offset >= p->buf + p->buf_size)
 140                     break;
 141                 expected_code = buf + offset;
 142                 buf = expected_code - 7;
 143             }
 144         }
 145     }
 146
 147     if (!sync_codes)
 148         return 0;
 149
 150     if (sync_codes >= 6)
 151         /* good amount of sync codes but with unexpected offsets */
 152         return AVPROBE_SCORE_MAX / 2;
 153
 154     /* some sync codes were found */
 155     return AVPROBE_SCORE_MAX / 8;
 156 }
 157
 158 static int spdif_read_header(AVFormatContext *s)
 159 {
 160     s->ctx_flags |= AVFMTCTX_NOHEADER;
 161     return 0;
 162 }
 163
 164 static int spdif_read_packet(AVFormatContext *s, AVPacket *pkt)
 165 {
 166     AVIOContext *pb = s->pb;
 167     enum IEC61937DataType data_type;
 168     enum AVCodecID codec_id;
 169     uint32_t state = 0;
 170     int pkt_size_bits, offset, ret;
 171
 172     while (state != (AV_BSWAP16C(SYNCWORD1) << 16 | AV_BSWAP16C(SYNCWORD2))) {
 173         state = (state << 8) | avio_r8(pb);
 174         if (pb->eof_reached)
 175             return AVERROR_EOF;
 176     }
 177
 178     data_type = avio_rl16(pb);
 179     pkt_size_bits = avio_rl16(pb);
 180
 181     if (pkt_size_bits % 16)
 182         av_log_ask_for_sample(s, "Packet does not end to a 16-bit boundary.");
 183
 184     ret = av_new_packet(pkt, FFALIGN(pkt_size_bits, 16) >> 3);
 185     if (ret)
 186         return ret;
 187
 188     pkt->pos = avio_tell(pb) - BURST_HEADER_SIZE;
 189
 190     if (avio_read(pb, pkt->data, pkt->size) < pkt->size) {
 191         av_free_packet(pkt);
 192         return AVERROR_EOF;
 193     }
 194     ff_spdif_bswap_buf16((uint16_t *)pkt->data, (uint16_t *)pkt->data, pkt->size >> 1);
 195
 196     ret = spdif_get_offset_and_codec(s, data_type, pkt->data,
 197                                      &offset, &codec_id);
 198     if (ret) {
 199         av_free_packet(pkt);
 200         return ret;
 201     }
 202
 203     /* skip over the padding to the beginning of the next frame */
 204     avio_skip(pb, offset - pkt->size - BURST_HEADER_SIZE);
 205
 206     if (!s->nb_streams) {
 207         /* first packet, create a stream */
 208         AVStream *st = avformat_new_stream(s, NULL);
 209         if (!st) {
 210             av_free_packet(pkt);
 211             return AVERROR(ENOMEM);
 212         }
 213         st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
 214         st->codec->codec_id = codec_id;
 215     } else if (codec_id != s->streams[0]->codec->codec_id) {
 216         av_log_missing_feature(s, "Codec change in IEC 61937", 0);
 217         return AVERROR_PATCHWELCOME;
 218     }
 219
 220     if (!s->bit_rate && s->streams[0]->codec->sample_rate)
 221         /* stream bitrate matches 16-bit stereo PCM bitrate for currently
 222            supported codecs */
 223         s->bit_rate = 2 * 16 * s->streams[0]->codec->sample_rate;
 224
 225     return 0;
 226 }
 227
 228 AVInputFormat ff_spdif_demuxer = {
 229     .name           = "spdif",
 230     .long_name      = NULL_IF_CONFIG_SMALL("IEC 61937 (compressed data in S/PDIF)"),
 231     .read_probe     = spdif_probe,
 232     .read_header    = spdif_read_header,
 233     .read_packet    = spdif_read_packet,
 234     .flags          = AVFMT_GENERIC_INDEX,
 235 };