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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  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 
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);
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)
66  else if (st->codec->channels == 4)
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 
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 
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 };