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 
30 {
31  AVStream *vst;
32  int ret;
33 
34  vst = avformat_new_stream(s, NULL);
35  if (!vst)
36  return AVERROR(ENOMEM);
37 
40 
42  avpriv_set_pts_info(vst, 32, 1, 300);
43 
44  ret = avio_size(s->pb);
45  if (ret > 0)
46  vst->duration = (ret * vst->time_base.den) / (CDG_PACKET_SIZE * 300);
47 
48  return 0;
49 }
50 
51 static int read_packet(AVFormatContext *s, AVPacket *pkt)
52 {
53  int ret;
54 
55  while (1) {
56  ret = av_get_packet(s->pb, pkt, CDG_PACKET_SIZE);
57  if (ret < 1 || (pkt->data[0] & CDG_MASK) == CDG_COMMAND)
58  break;
59  av_free_packet(pkt);
60  }
61 
62  pkt->stream_index = 0;
63  return ret;
64 }
65 
67  .name = "cdg",
68  .long_name = NULL_IF_CONFIG_SMALL("CD Graphics"),
69  .read_header = read_header,
70  .read_packet = read_packet,
71  .extensions = "cdg",
72 };
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:242
#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:3208
Format I/O context.
Definition: avformat.h:871
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:118
#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:142
AVStream * avformat_new_stream(AVFormatContext *s, AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:2662
AVCodecContext * codec
Codec context associated with this stream.
Definition: avformat.h:702
AVInputFormat ff_cdg_demuxer
Definition: cdg.c:66
Stream structure.
Definition: avformat.h:683
NULL
Definition: eval.c:55
enum AVMediaType codec_type
Definition: avcodec.h:1062
enum AVCodecID codec_id
Definition: avcodec.h:1065
AVIOContext * pb
I/O context.
Definition: avformat.h:913
int64_t duration
Decoding: duration of the stream, in stream time base.
Definition: avformat.h:734
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:29
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:516
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:719
static int read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: cdg.c:51
This structure stores compressed data.
Definition: avcodec.h:950