Libav
cdg.c
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1 /*
2  * CD Graphics Demuxer
3  * Copyright (c) 2009 Michael Tison
4  *
5  * This file is part of Libav.
6  *
7  * Libav 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  * Libav 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 Libav; 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 
46  avpriv_set_pts_info(vst, 32, 1, 300);
47 
48  ret = avio_size(s->pb);
49  if (ret < 0)
50  return ret;
51 
52  vst->duration = (ret * vst->time_base.den) / (CDG_PACKET_SIZE * 300);
53  return 0;
54 }
55 
56 static int read_packet(AVFormatContext *s, AVPacket *pkt)
57 {
58  CDGContext *priv = s->priv_data;
59  int ret;
60 
61  while (1) {
62  ret = av_get_packet(s->pb, pkt, CDG_PACKET_SIZE);
63  if (ret < 1 || (pkt->data[0] & CDG_MASK) == CDG_COMMAND)
64  break;
65  av_free_packet(pkt);
66  }
67 
68  if (!priv->got_first_packet) {
69  pkt->flags |= AV_PKT_FLAG_KEY;
70  priv->got_first_packet = 1;
71  }
72 
73  pkt->stream_index = 0;
74  return ret;
75 }
76 
78  .name = "cdg",
79  .long_name = NULL_IF_CONFIG_SMALL("CD Graphics"),
80  .priv_data_size = sizeof(CDGContext),
83  .extensions = "cdg",
84 };
int64_t avio_size(AVIOContext *s)
Get the filesize.
Definition: aviobuf.c:241
void av_free_packet(AVPacket *pkt)
Free a packet.
Definition: avpacket.c:243
#define CDG_COMMAND
Definition: cdg.c:26
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:2821
Format I/O context.
Definition: avformat.h:922
Definition: cdg.c:29
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:2518
uint8_t * data
Definition: avcodec.h:973
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:117
#define AV_PKT_FLAG_KEY
The packet contains a keyframe.
Definition: avcodec.h:1019
#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:150
int flags
A combination of AV_PKT_FLAG values.
Definition: avcodec.h:979
AVCodecContext * codec
Codec context associated with this stream.
Definition: avformat.h:718
AVInputFormat ff_cdg_demuxer
Definition: cdg.c:77
int got_first_packet
Definition: cdg.c:30
Stream structure.
Definition: avformat.h:699
NULL
Definition: eval.c:55
enum AVMediaType codec_type
Definition: avcodec.h:1058
enum AVCodecID codec_id
Definition: avcodec.h:1067
AVIOContext * pb
I/O context.
Definition: avformat.h:964
int64_t duration
Decoding: duration of the stream, in stream time base.
Definition: avformat.h:756
Main libavformat public API header.
#define CDG_PACKET_SIZE
Definition: cdg.c:25
int den
denominator
Definition: rational.h:45
static int read_header(AVFormatContext *s)
Definition: cdg.c:33
void * priv_data
Format private data.
Definition: avformat.h:950
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:525
int stream_index
Definition: avcodec.h:975
AVRational time_base
This is the fundamental unit of time (in seconds) in terms of which frame timestamps are represented...
Definition: avformat.h:741
static int read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: cdg.c:56
This structure stores compressed data.
Definition: avcodec.h:950