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  1. /*
  2.  * AST demuxer
  3.  * Copyright (c) 2012 Paul B Mahol
  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. #include "libavutil/channel_layout.h"
  23. #include "libavutil/intreadwrite.h"
  24. #include "avformat.h"
  25. #include "internal.h"
  26. #include "ast.h"
  27.  
  28. static int ast_probe(AVProbeData *p)
  29. {
  30.     if (AV_RL32(p->buf) != MKTAG('S','T','R','M'))
  31.         return 0;
  32.  
  33.     if (!AV_RB16(p->buf + 10) ||
  34.         !AV_RB16(p->buf + 12) || AV_RB16(p->buf + 12) > 256 ||
  35.         !AV_RB32(p->buf + 16) || AV_RB32(p->buf + 16) > 8*48000)
  36.         return AVPROBE_SCORE_MAX / 8;
  37.  
  38.     return AVPROBE_SCORE_MAX / 3 * 2;
  39. }
  40.  
  41. static int ast_read_header(AVFormatContext *s)
  42. {
  43.     int depth;
  44.     AVStream *st;
  45.  
  46.     st = avformat_new_stream(s, NULL);
  47.     if (!st)
  48.         return AVERROR(ENOMEM);
  49.  
  50.     avio_skip(s->pb, 8);
  51.     st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
  52.     st->codec->codec_id   = ff_codec_get_id(ff_codec_ast_tags, avio_rb16(s->pb));
  53.  
  54.     depth = avio_rb16(s->pb);
  55.     if (depth != 16) {
  56.         avpriv_request_sample(s, "depth %d", depth);
  57.         return AVERROR_INVALIDDATA;
  58.     }
  59.  
  60.     st->codec->channels = avio_rb16(s->pb);
  61.     if (!st->codec->channels)
  62.         return AVERROR_INVALIDDATA;
  63.  
  64.     if (st->codec->channels == 2)
  65.         st->codec->channel_layout = AV_CH_LAYOUT_STEREO;
  66.     else if (st->codec->channels == 4)
  67.         st->codec->channel_layout = AV_CH_LAYOUT_4POINT0;
  68.  
  69.     avio_skip(s->pb, 2);
  70.     st->codec->sample_rate = avio_rb32(s->pb);
  71.     if (st->codec->sample_rate <= 0)
  72.         return AVERROR_INVALIDDATA;
  73.     st->start_time         = 0;
  74.     st->duration           = avio_rb32(s->pb);
  75.     avio_skip(s->pb, 40);
  76.     avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate);
  77.  
  78.     return 0;
  79. }
  80.  
  81. static int ast_read_packet(AVFormatContext *s, AVPacket *pkt)
  82. {
  83.     uint32_t type, size;
  84.     int64_t pos;
  85.     int ret;
  86.  
  87.     if (avio_feof(s->pb))
  88.         return AVERROR_EOF;
  89.  
  90.     pos  = avio_tell(s->pb);
  91.     type = avio_rl32(s->pb);
  92.     size = avio_rb32(s->pb);
  93.     if (size > INT_MAX / s->streams[0]->codec->channels)
  94.         return AVERROR_INVALIDDATA;
  95.  
  96.     size *= s->streams[0]->codec->channels;
  97.     if ((ret = avio_skip(s->pb, 24)) < 0) // padding
  98.         return ret;
  99.  
  100.     if (type == MKTAG('B','L','C','K')) {
  101.         ret = av_get_packet(s->pb, pkt, size);
  102.         pkt->stream_index = 0;
  103.         pkt->pos = pos;
  104.     } else {
  105.         av_log(s, AV_LOG_ERROR, "unknown chunk %x\n", type);
  106.         avio_skip(s->pb, size);
  107.         ret = AVERROR_INVALIDDATA;
  108.     }
  109.  
  110.     return ret;
  111. }
  112.  
  113. AVInputFormat ff_ast_demuxer = {
  114.     .name           = "ast",
  115.     .long_name      = NULL_IF_CONFIG_SMALL("AST (Audio Stream)"),
  116.     .read_probe     = ast_probe,
  117.     .read_header    = ast_read_header,
  118.     .read_packet    = ast_read_packet,
  119.     .extensions     = "ast",
  120.     .flags          = AVFMT_GENERIC_INDEX,
  121.     .codec_tag      = (const AVCodecTag* const []){ff_codec_ast_tags, 0},
  122. };
  123.