FFmpeg
mgsts.c
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1 /*
2  * Metar Gear Solid: The Twin Snakes 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/intreadwrite.h"
23 #include "libavutil/intfloat.h"
24 #include "avformat.h"
25 #include "riff.h"
26 
27 static int read_probe(const AVProbeData *p)
28 {
29  if (AV_RB32(p->buf ) != 0x000E ||
30  AV_RB32(p->buf + 4) != 0x0050 ||
31  AV_RB32(p->buf + 12) != 0x0034)
32  return 0;
33  return AVPROBE_SCORE_MAX;
34 }
35 
36 static int read_header(AVFormatContext *s)
37 {
38  AVIOContext *pb = s->pb;
39  AVStream *st;
40  AVRational fps;
41  uint32_t chunk_size;
42 
43  avio_skip(pb, 4);
44  chunk_size = avio_rb32(pb);
45  if (chunk_size != 80)
46  return AVERROR(EIO);
47  avio_skip(pb, 20);
48 
49  st = avformat_new_stream(s, 0);
50  if (!st)
51  return AVERROR(ENOMEM);
52 
53  ffstream(st)->need_parsing = AVSTREAM_PARSE_HEADERS;
54  st->start_time = 0;
55  st->nb_frames =
56  st->duration = avio_rb32(pb);
57  fps = av_d2q(av_int2float(avio_rb32(pb)), INT_MAX);
58  st->codecpar->width = avio_rb32(pb);
59  st->codecpar->height = avio_rb32(pb);
60  avio_skip(pb, 12);
61  st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
62  st->codecpar->codec_tag = avio_rb32(pb);
63  st->codecpar->codec_id = ff_codec_get_id(ff_codec_bmp_tags,
64  st->codecpar->codec_tag);
65  avpriv_set_pts_info(st, 64, fps.den, fps.num);
66  avio_skip(pb, 20);
67 
68  return 0;
69 }
70 
71 static int read_packet(AVFormatContext *s, AVPacket *pkt)
72 {
73  AVIOContext *pb = s->pb;
74  uint32_t chunk_size, payload_size;
75  int ret;
76 
77  if (avio_feof(pb))
78  return AVERROR_EOF;
79 
80  avio_skip(pb, 4);
81  chunk_size = avio_rb32(pb);
82  avio_skip(pb, 4);
83  payload_size = avio_rb32(pb);
84 
85  if (chunk_size < payload_size + 16)
86  return AVERROR(EIO);
87 
88  ret = av_get_packet(pb, pkt, payload_size);
89  if (ret < 0)
90  return ret;
91 
92  pkt->pos -= 16;
93  pkt->duration = 1;
94  avio_skip(pb, chunk_size - (ret + 16));
95 
96  return ret;
97 }
98 
99 const AVInputFormat ff_mgsts_demuxer = {
100  .name = "mgsts",
101  .long_name = NULL_IF_CONFIG_SMALL("Metal Gear Solid: The Twin Snakes"),
102  .read_probe = read_probe,
103  .read_header = read_header,
104  .read_packet = read_packet,
105  .flags = AVFMT_GENERIC_INDEX,
106 };
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:243
AVCodecParameters::codec_type
enum AVMediaType codec_type
General type of the encoded data.
Definition: codec_par.h:58
read_probe
static int read_probe(const AVProbeData *p)
Definition: mgsts.c:27
AVERROR_EOF
#define AVERROR_EOF
End of file.
Definition: error.h:57
AVPacket::duration
int64_t duration
Duration of this packet in AVStream->time_base units, 0 if unknown.
Definition: packet.h:392
AVCodecParameters::codec_tag
uint32_t codec_tag
Additional information about the codec (corresponds to the AVI FOURCC).
Definition: codec_par.h:66
intfloat.h
read_header
static int read_header(AVFormatContext *s)
Definition: mgsts.c:36
AVPROBE_SCORE_MAX
#define AVPROBE_SCORE_MAX
maximum score
Definition: avformat.h:463
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:771
ffstream
static av_always_inline FFStream * ffstream(AVStream *st)
Definition: internal.h:413
av_int2float
static av_always_inline float av_int2float(uint32_t i)
Reinterpret a 32-bit integer as a float.
Definition: intfloat.h:40
AVFMT_GENERIC_INDEX
#define AVFMT_GENERIC_INDEX
Use generic index building code.
Definition: avformat.h:480
AVStream::duration
int64_t duration
Decoding: duration of the stream, in stream time base.
Definition: avformat.h:897
AVRational::num
int num
Numerator.
Definition: rational.h:59
avio_rb32
unsigned int avio_rb32(AVIOContext *s)
Definition: aviobuf.c:782
pkt
AVPacket * pkt
Definition: movenc.c:59
AVInputFormat
Definition: avformat.h:546
intreadwrite.h
s
#define s(width, name)
Definition: cbs_vp9.c:256
AVInputFormat::name
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:551
AVProbeData::buf
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:453
AVCodecParameters::width
int width
Video only.
Definition: codec_par.h:128
FFStream::need_parsing
enum AVStreamParseType need_parsing
Definition: internal.h:386
AVFormatContext
Format I/O context.
Definition: avformat.h:1104
AVStream::codecpar
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:861
ff_mgsts_demuxer
const AVInputFormat ff_mgsts_demuxer
Definition: mgsts.c:99
AVRational
Rational number (pair of numerator and denominator).
Definition: rational.h:58
AVProbeData
This structure contains the data a format has to probe a file.
Definition: avformat.h:451
AVStream::nb_frames
int64_t nb_frames
number of frames in this stream if known or 0
Definition: avformat.h:899
AVIOContext
Bytestream IO Context.
Definition: avio.h:166
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:115
ff_codec_get_id
enum AVCodecID ff_codec_get_id(const AVCodecTag *tags, unsigned int tag)
Definition: utils.c:144
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
read_packet
static int read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: mgsts.c:71
AVCodecParameters::height
int height
Definition: codec_par.h:129
av_d2q
AVRational av_d2q(double d, int max)
Convert a double precision floating point number to a rational.
Definition: rational.c:106
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
ret
ret
Definition: filter_design.txt:187
AVStream
Stream structure.
Definition: avformat.h:838
AVSTREAM_PARSE_HEADERS
@ AVSTREAM_PARSE_HEADERS
Only parse headers, do not repack.
Definition: avformat.h:689
avformat.h
ff_codec_bmp_tags
const AVCodecTag ff_codec_bmp_tags[]
Definition: riff.c:36
AVRational::den
int den
Denominator.
Definition: rational.h:60
avio_skip
int64_t avio_skip(AVIOContext *s, int64_t offset)
Skip given number of bytes forward.
Definition: aviobuf.c:339
AVMEDIA_TYPE_VIDEO
@ AVMEDIA_TYPE_VIDEO
Definition: avutil.h:201
AVCodecParameters::codec_id
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: codec_par.h:62
AVPacket
This structure stores compressed data.
Definition: packet.h:351
riff.h
AVPacket::pos
int64_t pos
byte position in stream, -1 if unknown
Definition: packet.h:394
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:887
avio_feof
int avio_feof(AVIOContext *s)
Similar to feof() but also returns nonzero on read errors.
Definition: aviobuf.c:367
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