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astdec.c
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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 
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  AV_RB16(p->buf + 10) &&
32  AV_RB16(p->buf + 12) &&
33  AV_RB32(p->buf + 16))
34  return AVPROBE_SCORE_MAX / 3 * 2;
35  return 0;
36 }
37 
39 {
40  int depth;
41  AVStream *st;
42 
43  st = avformat_new_stream(s, NULL);
44  if (!st)
45  return AVERROR(ENOMEM);
46 
47  avio_skip(s->pb, 8);
50 
51  depth = avio_rb16(s->pb);
52  if (depth != 16) {
53  av_log_ask_for_sample(s, "unsupported depth %d\n", depth);
54  return AVERROR_INVALIDDATA;
55  }
56 
57  st->codec->channels = avio_rb16(s->pb);
58  if (!st->codec->channels)
59  return AVERROR_INVALIDDATA;
60 
61  if (st->codec->channels == 2)
63  else if (st->codec->channels == 4)
65 
66  avio_skip(s->pb, 2);
67  st->codec->sample_rate = avio_rb32(s->pb);
68  if (st->codec->sample_rate <= 0)
69  return AVERROR_INVALIDDATA;
70  st->start_time = 0;
71  st->duration = avio_rb32(s->pb);
72  avio_skip(s->pb, 40);
73  avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate);
74 
75  return 0;
76 }
77 
79 {
80  uint32_t type, size;
81  int64_t pos;
82  int ret;
83 
84  if (url_feof(s->pb))
85  return AVERROR_EOF;
86 
87  pos = avio_tell(s->pb);
88  type = avio_rl32(s->pb);
89  size = avio_rb32(s->pb);
90  if (size > INT_MAX / s->streams[0]->codec->channels)
91  return AVERROR_INVALIDDATA;
92 
93  size *= s->streams[0]->codec->channels;
94  if ((ret = avio_skip(s->pb, 24)) < 0) // padding
95  return ret;
96 
97  if (type == MKTAG('B','L','C','K')) {
98  ret = av_get_packet(s->pb, pkt, size);
99  pkt->stream_index = 0;
100  pkt->pos = pos;
101  } else {
102  av_log(s, AV_LOG_ERROR, "unknown chunk %x\n", type);
103  avio_skip(s->pb, size);
104  ret = AVERROR_INVALIDDATA;
105  }
106 
107  return ret;
108 }
109 
111  .name = "ast",
112  .long_name = NULL_IF_CONFIG_SMALL("AST (Audio Stream)"),
113  .read_probe = ast_probe,
114  .read_header = ast_read_header,
115  .read_packet = ast_read_packet,
116  .extensions = "ast",
117  .flags = AVFMT_GENERIC_INDEX,
118  .codec_tag = (const AVCodecTag* const []){ff_codec_ast_tags, 0},
119 };