FFmpeg  4.0
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 "internal.h"
24 
25 #define CDG_PACKET_SIZE 24
26 #define CDG_COMMAND 0x09
27 #define CDG_MASK 0x3F
28 
29 typedef struct CDGContext {
31 } CDGContext;
32 
34 {
35  AVStream *vst;
36  int ret;
37 
38  vst = avformat_new_stream(s, NULL);
39  if (!vst)
40  return AVERROR(ENOMEM);
41 
44 
45  /// 75 sectors/sec * 4 packets/sector = 300 packets/sec
46  avpriv_set_pts_info(vst, 32, 1, 300);
47 
48  ret = avio_size(s->pb);
49  if (ret < 0) {
50  av_log(s, AV_LOG_WARNING, "Cannot calculate duration as file size cannot be determined\n");
51  } else
52  vst->duration = (ret * vst->time_base.den) / (CDG_PACKET_SIZE * 300);
53 
54  return 0;
55 }
56 
58 {
59  CDGContext *priv = s->priv_data;
60  int ret;
61 
62  while (1) {
63  ret = av_get_packet(s->pb, pkt, CDG_PACKET_SIZE);
64  if (ret < 1 || (pkt->data[0] & CDG_MASK) == CDG_COMMAND)
65  break;
66  av_packet_unref(pkt);
67  }
68 
69  if (!priv->got_first_packet) {
70  pkt->flags |= AV_PKT_FLAG_KEY;
71  priv->got_first_packet = 1;
72  }
73 
74  pkt->stream_index = 0;
75  pkt->dts=
76  pkt->pts= pkt->pos / CDG_PACKET_SIZE;
77 
78  if(ret>5 && (pkt->data[0]&0x3F) == 9 && (pkt->data[1]&0x3F)==1 && !(pkt->data[2+2+1] & 0x0F)){
79  pkt->flags = AV_PKT_FLAG_KEY;
80  }
81  return ret;
82 }
83 
85  .name = "cdg",
86  .long_name = NULL_IF_CONFIG_SMALL("CD Graphics"),
87  .priv_data_size = sizeof(CDGContext),
91  .extensions = "cdg",
92 };
#define NULL
Definition: coverity.c:32
const char * s
Definition: avisynth_c.h:768
int64_t avio_size(AVIOContext *s)
Get the filesize.
Definition: aviobuf.c:336
#define CDG_COMMAND
Definition: cdg.c:26
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:182
int64_t pos
byte position in stream, -1 if unknown
Definition: avcodec.h:1450
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:4811
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: avcodec.h:3884
static AVPacket pkt
Format I/O context.
Definition: avformat.h:1342
Definition: cdg.c:29
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:4441
uint8_t * data
Definition: avcodec.h:1430
static int flags
Definition: log.c:55
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:310
#define av_log(a,...)
#define AV_PKT_FLAG_KEY
The packet contains a keyframe.
Definition: avcodec.h:1462
#define CDG_MASK
Definition: cdg.c:27
#define AVERROR(e)
Definition: error.h:43
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:186
enum AVMediaType codec_type
General type of the encoded data.
Definition: avcodec.h:3880
int flags
A combination of AV_PKT_FLAG values.
Definition: avcodec.h:1436
AVInputFormat ff_cdg_demuxer
Definition: cdg.c:84
int got_first_packet
Definition: cdg.c:30
Stream structure.
Definition: avformat.h:873
AVIOContext * pb
I/O context.
Definition: avformat.h:1384
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
Definition: avpacket.c:592
#define AVFMT_GENERIC_INDEX
Use generic index building code.
Definition: avformat.h:470
int64_t duration
Decoding: duration of the stream, in stream time base.
Definition: avformat.h:922
Main libavformat public API header.
#define CDG_PACKET_SIZE
Definition: cdg.c:25
int den
Denominator.
Definition: rational.h:60
static int read_header(AVFormatContext *s)
Definition: cdg.c:33
void * priv_data
Format private data.
Definition: avformat.h:1370
int64_t dts
Decompression timestamp in AVStream->time_base units; the time at which the packet is decompressed...
Definition: avcodec.h:1429
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:647
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1020
int stream_index
Definition: avcodec.h:1432
AVRational time_base
This is the fundamental unit of time (in seconds) in terms of which frame timestamps are represented...
Definition: avformat.h:902
static int read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: cdg.c:57
This structure stores compressed data.
Definition: avcodec.h:1407
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: avcodec.h:1423