FFmpeg
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(const 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 
61  if (!st->codecpar->ch_layout.nb_channels)
62  return AVERROR_INVALIDDATA;
63 
64  if (st->codecpar->ch_layout.nb_channels == 2)
66  else if (st->codecpar->ch_layout.nb_channels == 4)
68 
69  avio_skip(s->pb, 2);
70  st->codecpar->sample_rate = avio_rb32(s->pb);
71  if (st->codecpar->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->codecpar->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 (!s->streams[0]->codecpar->ch_layout.nb_channels ||
94  size > INT_MAX / s->streams[0]->codecpar->ch_layout.nb_channels)
95  return AVERROR_INVALIDDATA;
96 
97  size *= s->streams[0]->codecpar->ch_layout.nb_channels;
98  if ((ret = avio_skip(s->pb, 24)) < 0) // padding
99  return ret;
100 
101  if (type == MKTAG('B','L','C','K')) {
102  ret = av_get_packet(s->pb, pkt, size);
103  pkt->stream_index = 0;
104  pkt->pos = pos;
105  } else {
106  av_log(s, AV_LOG_ERROR, "unknown chunk %"PRIx32"\n", type);
107  avio_skip(s->pb, size);
109  }
110 
111  return ret;
112 }
113 
115  .name = "ast",
116  .long_name = NULL_IF_CONFIG_SMALL("AST (Audio Stream)"),
117  .read_probe = ast_probe,
118  .read_header = ast_read_header,
119  .read_packet = ast_read_packet,
120  .extensions = "ast",
121  .flags = AVFMT_GENERIC_INDEX,
122  .codec_tag = ff_ast_codec_tags_list,
123 };
AVERROR
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
avformat_new_stream
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: options.c:237
AVCodecParameters::codec_type
enum AVMediaType codec_type
General type of the encoded data.
Definition: codec_par.h:57
AVERROR_EOF
#define AVERROR_EOF
End of file.
Definition: error.h:57
AV_CHANNEL_LAYOUT_4POINT0
#define AV_CHANNEL_LAYOUT_4POINT0
Definition: channel_layout.h:359
AV_CHANNEL_LAYOUT_STEREO
#define AV_CHANNEL_LAYOUT_STEREO
Definition: channel_layout.h:354
AVChannelLayout::nb_channels
int nb_channels
Number of channels in this layout.
Definition: channel_layout.h:300
AVPROBE_SCORE_MAX
#define AVPROBE_SCORE_MAX
maximum score
Definition: avformat.h:465
ast.h
avpriv_set_pts_info
void avpriv_set_pts_info(AVStream *st, int pts_wrap_bits, unsigned int pts_num, unsigned int pts_den)
Set the time base and wrapping info for a given stream.
Definition: avformat.c:697
avio_tell
static av_always_inline int64_t avio_tell(AVIOContext *s)
ftell() equivalent for AVIOContext.
Definition: avio.h:505
AVFMT_GENERIC_INDEX
#define AVFMT_GENERIC_INDEX
Use generic index building code.
Definition: avformat.h:482
type
it s the only field you need to keep assuming you have a context There is some magic you don t need to care about around this just let it vf type
Definition: writing_filters.txt:86
AVStream::duration
int64_t duration
Decoding: duration of the stream, in stream time base.
Definition: avformat.h:998
ast_read_header
static int ast_read_header(AVFormatContext *s)
Definition: astdec.c:41
avio_rb32
unsigned int avio_rb32(AVIOContext *s)
Definition: aviobuf.c:790
pkt
AVPacket * pkt
Definition: movenc.c:59
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:180
AVInputFormat
Definition: avformat.h:656
intreadwrite.h
s
#define s(width, name)
Definition: cbs_vp9.c:256
ff_codec_ast_tags
const AVCodecTag ff_codec_ast_tags[]
Definition: ast.c:26
AVInputFormat::name
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:661
AVProbeData::buf
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:455
AVMEDIA_TYPE_AUDIO
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
AVFormatContext
Format I/O context.
Definition: avformat.h:1213
internal.h
AVStream::codecpar
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1108
NULL
#define NULL
Definition: coverity.c:32
AVProbeData
This structure contains the data a format has to probe a file.
Definition: avformat.h:453
AVCodecParameters::ch_layout
AVChannelLayout ch_layout
Audio only.
Definition: codec_par.h:212
AVCodecParameters::sample_rate
int sample_rate
Audio only.
Definition: codec_par.h:177
avio_rl32
unsigned int avio_rl32(AVIOContext *s)
Definition: aviobuf.c:759
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:116
ff_codec_get_id
enum AVCodecID ff_codec_get_id(const AVCodecTag *tags, unsigned int tag)
Definition: utils.c:144
AVChannelLayout
An AVChannelLayout holds information about the channel layout of audio data.
Definition: channel_layout.h:290
size
int size
Definition: twinvq_data.h:10344
AV_RB32
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_WL16 uint64_t_TMPL AV_WB64 unsigned int_TMPL AV_RB32
Definition: bytestream.h:96
ff_ast_demuxer
const AVInputFormat ff_ast_demuxer
Definition: astdec.c:114
ast_probe
static int ast_probe(const AVProbeData *p)
Definition: astdec.c:28
av_get_packet
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:102
ff_ast_codec_tags_list
const AVCodecTag *const ff_ast_codec_tags_list[]
Definition: ast.c:32
ret
ret
Definition: filter_design.txt:187
AVStream
Stream structure.
Definition: avformat.h:948
avio_rb16
unsigned int avio_rb16(AVIOContext *s)
Definition: aviobuf.c:775
pos
unsigned int pos
Definition: spdifenc.c:412
avformat.h
AV_RL32
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_RL32
Definition: bytestream.h:92
channel_layout.h
AVPacket::stream_index
int stream_index
Definition: packet.h:376
avio_skip
int64_t avio_skip(AVIOContext *s, int64_t offset)
Skip given number of bytes forward.
Definition: aviobuf.c:347
avpriv_request_sample
#define avpriv_request_sample(...)
Definition: tableprint_vlc.h:36
AVCodecParameters::codec_id
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: codec_par.h:61
AVPacket
This structure stores compressed data.
Definition: packet.h:351
AVPacket::pos
int64_t pos
byte position in stream, -1 if unknown
Definition: packet.h:394
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:27
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:61
MKTAG
#define MKTAG(a, b, c, d)
Definition: macros.h:55
AVStream::start_time
int64_t start_time
Decoding: pts of the first frame of the stream in presentation order, in stream time base.
Definition: avformat.h:988
ast_read_packet
static int ast_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: astdec.c:81
AV_RB16
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_WL16 uint64_t_TMPL AV_WB64 unsigned int_TMPL AV_WB32 unsigned int_TMPL AV_WB24 unsigned int_TMPL AV_RB16
Definition: bytestream.h:98
avio_feof
int avio_feof(AVIOContext *s)
Similar to feof() but also returns nonzero on read errors.
Definition: aviobuf.c:375