FFmpeg: libavformat/cdg.c Source File

FFmpeg
cdg.c
Go to the documentation of this file.
1 /*
2  * CD Graphics Demuxer
3  * Copyright (c) 2009 Michael Tison
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 "avformat.h"
23 #include "demux.h"
24 #include "internal.h"
25 
26  #define CDG_PACKET_SIZE 24
27  #define CDG_COMMAND 0x09
28  #define CDG_MASK 0x3F
29 
30  static int read_probe(const AVProbeData *p)
31 {
32  const int cnt = p->buf_size / CDG_PACKET_SIZE;
33  int score = 0;
34 
35  for (int i = 0; i < cnt; i++) {
36  const int x = p->buf[i * CDG_PACKET_SIZE] & CDG_MASK;
37 
38  score += x == CDG_COMMAND;
39  if (x != CDG_COMMAND && x != 0)
40  return 0;
41  }
42 
43  return FFMIN(score, AVPROBE_SCORE_MAX);
44 }
45 
46  static int read_header(AVFormatContext *s)
47 {
48  AVStream *vst;
49  int64_t ret;
50 
51  vst = avformat_new_stream(s, NULL);
52  if (!vst)
53  return AVERROR(ENOMEM);
54 
55  vst->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
56  vst->codecpar->codec_id = AV_CODEC_ID_CDGRAPHICS;
57 
58  /// 75 sectors/sec * 4 packets/sector = 300 packets/sec
59  avpriv_set_pts_info(vst, 32, 1, 300);
60 
61  ret = avio_size(s->pb);
62  if (ret < 0) {
63  av_log(s, AV_LOG_WARNING, "Cannot calculate duration as file size cannot be determined\n");
64  } else
65  vst->duration = (ret * (int64_t)vst->time_base.den) / (CDG_PACKET_SIZE * 300);
66 
67  return 0;
68 }
69 
70  static int read_packet(AVFormatContext *s, AVPacket *pkt)
71 {
72  int ret;
73 
74  ret = av_get_packet(s->pb, pkt, CDG_PACKET_SIZE);
75  pkt->stream_index = 0;
76  pkt->dts=
77  pkt->pts= pkt->pos / CDG_PACKET_SIZE;
78 
79  if (!pkt->pos || (ret > 5 &&
80  (pkt->data[0] & CDG_MASK) == CDG_COMMAND &&
81  (pkt->data[1] & CDG_MASK) == 1 && !(pkt->data[2+2+1] & 0x0F))) {
82  pkt->flags = AV_PKT_FLAG_KEY;
83  }
84  return ret;
85 }
86 
87  const FFInputFormat ff_cdg_demuxer = {
88  .p.name = "cdg",
89  .p.long_name = NULL_IF_CONFIG_SMALL("CD Graphics"),
90  .p.flags = AVFMT_GENERIC_INDEX,
91  .p.extensions = "cdg",
92  .read_probe = read_probe,
93  .read_header = read_header,
94  .read_packet = read_packet,
95 };
AV_LOG_WARNING
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:216
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
AVCodecParameters::codec_type
enum AVMediaType codec_type
General type of the encoded data.
Definition: codec_par.h:51
avformat_new_stream
AVStream * avformat_new_stream(AVFormatContext *s, const struct AVCodec *c)
Add a new stream to a media file.
int64_t
long long int64_t
Definition: coverity.c:34
read_header
static int read_header(AVFormatContext *s)
Definition: cdg.c:46
AVPacket::data
uint8_t * data
Definition: packet.h:588
avio_size
int64_t avio_size(AVIOContext *s)
Get the filesize.
Definition: aviobuf.c:326
AV_PKT_FLAG_KEY
#define AV_PKT_FLAG_KEY
The packet contains a keyframe.
Definition: packet.h:643
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:777
AVFMT_GENERIC_INDEX
#define AVFMT_GENERIC_INDEX
Use generic index building code.
Definition: avformat.h:479
read_packet
static int read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: cdg.c:70
AVStream::duration
int64_t duration
Decoding: duration of the stream, in stream time base.
Definition: avformat.h:803
pkt
AVPacket * pkt
Definition: movenc.c:60
s
#define s(width, name)
Definition: cbs_vp9.c:198
AVInputFormat::name
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:549
AVFormatContext
Format I/O context.
Definition: avformat.h:1264
internal.h
AVStream::codecpar
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:767
AVStream::time_base
AVRational time_base
This is the fundamental unit of time (in seconds) in terms of which frame timestamps are represented.
Definition: avformat.h:783
NULL
#define NULL
Definition: coverity.c:32
ff_cdg_demuxer
const FFInputFormat ff_cdg_demuxer
Definition: cdg.c:87
AVProbeData
This structure contains the data a format has to probe a file.
Definition: avformat.h:451
AV_CODEC_ID_CDGRAPHICS
@ AV_CODEC_ID_CDGRAPHICS
Definition: codec_id.h:184
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:94
FFInputFormat::p
AVInputFormat p
The public AVInputFormat.
Definition: demux.h:51
AVPacket::dts
int64_t dts
Decompression timestamp in AVStream->time_base units; the time at which the packet is decompressed.
Definition: packet.h:587
CDG_MASK
#define CDG_MASK
Definition: cdg.c:28
AVPacket::flags
int flags
A combination of AV_PKT_FLAG values.
Definition: packet.h:594
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:256
AVPacket::pts
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: packet.h:581
FFMIN
#define FFMIN(a, b)
Definition: macros.h:49
demux.h
CDG_COMMAND
#define CDG_COMMAND
Definition: cdg.c:27
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:98
CDG_PACKET_SIZE
#define CDG_PACKET_SIZE
Definition: cdg.c:26
ret
ret
Definition: filter_design.txt:187
AVStream
Stream structure.
Definition: avformat.h:744
avformat.h
AVRational::den
int den
Denominator.
Definition: rational.h:60
Windows::Graphics::DirectX::Direct3D11::p
IDirect3DDxgiInterfaceAccess _COM_Outptr_ void ** p
Definition: vsrc_gfxcapture_winrt.hpp:53
AVPacket::stream_index
int stream_index
Definition: packet.h:590
AVMEDIA_TYPE_VIDEO
@ AVMEDIA_TYPE_VIDEO
Definition: avutil.h:200
read_probe
static int read_probe(const AVProbeData *p)
Definition: cdg.c:30
AVCodecParameters::codec_id
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: codec_par.h:55
AVPacket
This structure stores compressed data.
Definition: packet.h:565
AVPacket::pos
int64_t pos
byte position in stream, -1 if unknown
Definition: packet.h:608
FFInputFormat
Definition: demux.h:47
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:27
Generated on Tue Nov 18 2025 19:23:24 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) /