FFmpeg: libavformat/lvfdec.c Source File

FFmpeg
lvfdec.c
Go to the documentation of this file.
1 /*
2  * LVF 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 "avformat.h"
24 #include "riff.h"
25 
26  static int lvf_probe(const AVProbeData *p)
27 {
28  if (AV_RL32(p->buf) != MKTAG('L', 'V', 'F', 'F'))
29  return 0;
30 
31  if (!AV_RL32(p->buf + 16) || AV_RL32(p->buf + 16) > 256)
32  return AVPROBE_SCORE_MAX / 8;
33 
34  return AVPROBE_SCORE_EXTENSION;
35 }
36 
37  static int lvf_read_header(AVFormatContext *s)
38 {
39  AVStream *st;
40  int64_t next_offset;
41  unsigned size, nb_streams, id;
42 
43  avio_skip(s->pb, 16);
44  nb_streams = avio_rl32(s->pb);
45  if (!nb_streams)
46  return AVERROR_INVALIDDATA;
47  if (nb_streams > 2) {
48  avpriv_request_sample(s, "%d streams", nb_streams);
49  return AVERROR_PATCHWELCOME;
50  }
51 
52  avio_skip(s->pb, 1012);
53 
54  while (!avio_feof(s->pb)) {
55  id = avio_rl32(s->pb);
56  size = avio_rl32(s->pb);
57  next_offset = avio_tell(s->pb) + size;
58 
59  switch (id) {
60  case MKTAG('0', '0', 'f', 'm'):
61  st = avformat_new_stream(s, 0);
62  if (!st)
63  return AVERROR(ENOMEM);
64 
65  st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
66  avio_skip(s->pb, 4);
67  st->codecpar->width = avio_rl32(s->pb);
68  st->codecpar->height = avio_rl32(s->pb);
69  avio_skip(s->pb, 4);
70  st->codecpar->codec_tag = avio_rl32(s->pb);
71  st->codecpar->codec_id = ff_codec_get_id(ff_codec_bmp_tags,
72  st->codecpar->codec_tag);
73  avpriv_set_pts_info(st, 32, 1, 1000);
74  break;
75  case MKTAG('0', '1', 'f', 'm'):
76  st = avformat_new_stream(s, 0);
77  if (!st)
78  return AVERROR(ENOMEM);
79 
80  st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
81  st->codecpar->codec_tag = avio_rl16(s->pb);
82  st->codecpar->ch_layout.nb_channels = avio_rl16(s->pb);
83  st->codecpar->sample_rate = avio_rl16(s->pb);
84  avio_skip(s->pb, 8);
85  st->codecpar->bits_per_coded_sample = avio_r8(s->pb);
86  st->codecpar->codec_id = ff_codec_get_id(ff_codec_wav_tags,
87  st->codecpar->codec_tag);
88  avpriv_set_pts_info(st, 32, 1, 1000);
89  break;
90  case 0:
91  avio_seek(s->pb, 2048 + 8, SEEK_SET);
92  return 0;
93  default:
94  avpriv_request_sample(s, "id %d", id);
95  return AVERROR_PATCHWELCOME;
96  }
97 
98  avio_seek(s->pb, next_offset, SEEK_SET);
99  }
100 
101  return AVERROR_EOF;
102 }
103 
104  static int lvf_read_packet(AVFormatContext *s, AVPacket *pkt)
105 {
106  unsigned size, flags, timestamp, id;
107  int64_t pos;
108  int ret, is_video = 0;
109  int stream_index;
110 
111  pos = avio_tell(s->pb);
112  while (!avio_feof(s->pb)) {
113  id = avio_rl32(s->pb);
114  size = avio_rl32(s->pb);
115 
116  if (size == 0xFFFFFFFFu)
117  return AVERROR_EOF;
118 
119  switch (id) {
120  case MKTAG('0', '0', 'd', 'c'):
121  is_video = 1;
122  case MKTAG('0', '1', 'w', 'b'):
123  if (size < 8)
124  return AVERROR_INVALIDDATA;
125  stream_index = is_video ? 0 : 1;
126  if (stream_index >= s->nb_streams)
127  return AVERROR_INVALIDDATA;
128  timestamp = avio_rl32(s->pb);
129  flags = avio_rl32(s->pb);
130  ret = av_get_packet(s->pb, pkt, size - 8);
131  if (flags & (1 << 12))
132  pkt->flags |= AV_PKT_FLAG_KEY;
133  pkt->stream_index = stream_index;
134  pkt->pts = timestamp;
135  pkt->pos = pos;
136  return ret;
137  default:
138  ret = avio_skip(s->pb, size);
139  }
140 
141  if (ret < 0)
142  return ret;
143  }
144 
145  return AVERROR_EOF;
146 }
147 
148  const AVInputFormat ff_lvf_demuxer = {
149  .name = "lvf",
150  .long_name = NULL_IF_CONFIG_SMALL("LVF"),
151  .read_probe = lvf_probe,
152  .read_header = lvf_read_header,
153  .read_packet = lvf_read_packet,
154  .extensions = "lvf",
155  .flags = AVFMT_GENERIC_INDEX,
156 };
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
ff_codec_wav_tags
const AVCodecTag ff_codec_wav_tags[]
Definition: riff.c:511
AVCodecParameters::codec_tag
uint32_t codec_tag
Additional information about the codec (corresponds to the AVI FOURCC).
Definition: codec_par.h:65
AVChannelLayout::nb_channels
int nb_channels
Number of channels in this layout.
Definition: channel_layout.h:300
AV_PKT_FLAG_KEY
#define AV_PKT_FLAG_KEY
The packet contains a keyframe.
Definition: packet.h:429
AVPROBE_SCORE_MAX
#define AVPROBE_SCORE_MAX
maximum score
Definition: avformat.h:465
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
avio_rl16
unsigned int avio_rl16(AVIOContext *s)
Definition: aviobuf.c:743
pkt
AVPacket * pkt
Definition: movenc.c:59
AVInputFormat
Definition: avformat.h:656
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: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
AVCodecParameters::width
int width
Video only.
Definition: codec_par.h:127
nb_streams
static int nb_streams
Definition: ffprobe.c:307
AVFormatContext
Format I/O context.
Definition: avformat.h:1213
AVStream::codecpar
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1108
AVERROR_PATCHWELCOME
#define AVERROR_PATCHWELCOME
Not yet implemented in FFmpeg, patches welcome.
Definition: error.h:64
AVProbeData
This structure contains the data a format has to probe a file.
Definition: avformat.h:453
lvf_read_packet
static int lvf_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: lvfdec.c:104
AVCodecParameters::ch_layout
AVChannelLayout ch_layout
Audio only.
Definition: codec_par.h:212
AVPROBE_SCORE_EXTENSION
#define AVPROBE_SCORE_EXTENSION
score for file extension
Definition: avformat.h:463
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:117
id
enum AVCodecID id
Definition: extract_extradata_bsf.c:324
ff_codec_get_id
enum AVCodecID ff_codec_get_id(const AVCodecTag *tags, unsigned int tag)
Definition: utils.c:144
size
int size
Definition: twinvq_data.h:10344
avio_r8
int avio_r8(AVIOContext *s)
Definition: aviobuf.c:632
AVPacket::flags
int flags
A combination of AV_PKT_FLAG values.
Definition: packet.h:380
AVPacket::pts
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: packet.h:367
AVCodecParameters::height
int height
Definition: codec_par.h:128
lvf_read_header
static int lvf_read_header(AVFormatContext *s)
Definition: lvfdec.c:37
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:948
avio_seek
int64_t avio_seek(AVIOContext *s, int64_t offset, int whence)
fseek() equivalent for AVIOContext.
Definition: aviobuf.c:260
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
ff_lvf_demuxer
const AVInputFormat ff_lvf_demuxer
Definition: lvfdec.c:148
ff_codec_bmp_tags
const AVCodecTag ff_codec_bmp_tags[]
Definition: riff.c:36
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
AVMEDIA_TYPE_VIDEO
@ AVMEDIA_TYPE_VIDEO
Definition: avutil.h:201
AVCodecParameters::bits_per_coded_sample
int bits_per_coded_sample
The number of bits per sample in the codedwords.
Definition: codec_par.h:103
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
riff.h
AVPacket::pos
int64_t pos
byte position in stream, -1 if unknown
Definition: packet.h:394
flags
#define flags(name, subs,...)
Definition: cbs_av1.c:561
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
lvf_probe
static int lvf_probe(const AVProbeData *p)
Definition: lvfdec.c:26
avio_feof
int avio_feof(AVIOContext *s)
Similar to feof() but also returns nonzero on read errors.
Definition: aviobuf.c:375
Generated on Wed Aug 24 2022 21:42:15 for FFmpeg by   doxygen 1.8.17

AltStyle によって変換されたページ (->オリジナル) /