FFmpeg  2.1.1
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 
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  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  avpriv_request_sample(s, "depth %d", 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 };
const char * s
Definition: avisynth_c.h:668
int size
static int ast_read_header(AVFormatContext *s)
Definition: astdec.c:38
enum AVCodecID ff_codec_get_id(const AVCodecTag *tags, unsigned int tag)
Definition: utils.c:2556
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:478
int64_t pos
byte position in stream, -1 if unknown
Definition: avcodec.h:1092
void avpriv_set_pts_info(AVStream *s, int pts_wrap_bits, unsigned int pts_num, unsigned int pts_den)
Set the time base and wrapping info for a given stream.
Definition: utils.c:3922
static int ast_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: astdec.c:78
AVCodecContext * codec
Codec context associated with this stream.
Definition: avformat.h:686
unsigned int avio_rl32(AVIOContext *s)
Definition: aviobuf.c:593
void av_log(void *avcl, int level, const char *fmt,...) av_printf_format(3
Send the specified message to the log if the level is less than or equal to the current av_log_level...
#define AV_CH_LAYOUT_4POINT0
unsigned int avio_rb32(AVIOContext *s)
Definition: aviobuf.c:624
#define AV_CH_LAYOUT_STEREO
static int ast_probe(AVProbeData *p)
Definition: astdec.c:28
Format I/O context.
Definition: avformat.h:968
void void avpriv_request_sample(void *avc, const char *msg,...) av_printf_format(2
Log a generic warning message about a missing feature.
#define AV_RB16(x)
Definition: intreadwrite.h:232
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:336
static av_always_inline int64_t avio_tell(AVIOContext *s)
ftell() equivalent for AVIOContext.
Definition: avio.h:248
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:3348
int av_get_packet(AVIOContext *s, AVPacket *pkt, int size)
Allocate and read the payload of a packet and initialize its fields with default values.
Definition: utils.c:200
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: avcodec.h:4147
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:151
int depth
Definition: v4l.c:61
#define AVFMT_GENERIC_INDEX
Use generic index building code.
Definition: avformat.h:355
uint64_t channel_layout
Audio channel layout.
Definition: avcodec.h:1934
ret
Definition: avfilter.c:961
AVStream ** streams
Definition: avformat.h:1016
Stream structure.
Definition: avformat.h:667
enum AVMediaType codec_type
Definition: avcodec.h:1154
enum AVCodecID codec_id
Definition: avcodec.h:1157
int sample_rate
samples per second
Definition: avcodec.h:1873
AVIOContext * pb
I/O context.
Definition: avformat.h:1001
#define MKTAG(a, b, c, d)
AVInputFormat ff_ast_demuxer
Definition: astdec.c:110
This structure contains the data a format has to probe a file.
Definition: avformat.h:334
int64_t avio_skip(AVIOContext *s, int64_t offset)
Skip given number of bytes forward.
Definition: aviobuf.c:256
#define type
#define AVERROR_EOF
#define AVPROBE_SCORE_MAX
maximum score
Definition: avformat.h:342
int64_t duration
Decoding: duration of the stream, in stream time base.
Definition: avformat.h:720
int url_feof(AVIOContext *s)
feof() equivalent for AVIOContext.
Definition: aviobuf.c:280
int64_t start_time
Decoding: pts of the first frame of the stream in presentation order, in stream time base...
Definition: avformat.h:713
Main libavformat public API header.
#define AV_RB32(x)
Definition: intreadwrite.h:258
#define AVERROR_INVALIDDATA
#define AV_RL32(x)
Definition: intreadwrite.h:275
const AVCodecTag ff_codec_ast_tags[]
Definition: ast.c:25
int channels
number of audio channels
Definition: avcodec.h:1874
#define AVERROR(e)
unsigned int avio_rb16(AVIOContext *s)
Definition: aviobuf.c:609
static AVPacket pkt
Definition: demuxing.c:52
int stream_index
Definition: avcodec.h:1065
This structure stores compressed data.
Definition: avcodec.h:1040