FFmpeg
cdg.c
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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 
30 {
31  AVStream *vst;
32  int ret;
33 
34  vst = avformat_new_stream(s, NULL);
35  if (!vst)
36  return AVERROR(ENOMEM);
37 
40 
41  /// 75 sectors/sec * 4 packets/sector = 300 packets/sec
42  avpriv_set_pts_info(vst, 32, 1, 300);
43 
44  ret = avio_size(s->pb);
45  if (ret < 0) {
46  av_log(s, AV_LOG_WARNING, "Cannot calculate duration as file size cannot be determined\n");
47  } else
48  vst->duration = (ret * (int64_t)vst->time_base.den) / (CDG_PACKET_SIZE * 300);
49 
50  return 0;
51 }
52 
54 {
55  int ret;
56 
57  ret = av_get_packet(s->pb, pkt, CDG_PACKET_SIZE);
58  pkt->stream_index = 0;
59  pkt->dts=
60  pkt->pts= pkt->pos / CDG_PACKET_SIZE;
61 
62  if (!pkt->pos || (ret > 5 &&
63  (pkt->data[0] & CDG_MASK) == CDG_COMMAND &&
64  (pkt->data[1] & CDG_MASK) == 1 && !(pkt->data[2+2+1] & 0x0F))) {
65  pkt->flags = AV_PKT_FLAG_KEY;
66  }
67  return ret;
68 }
69 
71  .name = "cdg",
72  .long_name = NULL_IF_CONFIG_SMALL("CD Graphics"),
73  .read_header = read_header,
74  .read_packet = read_packet,
75  .flags = AVFMT_GENERIC_INDEX,
76  .extensions = "cdg",
77 };
#define NULL
Definition: coverity.c:32
int64_t avio_size(AVIOContext *s)
Get the filesize.
Definition: aviobuf.c:346
#define CDG_COMMAND
Definition: cdg.c:26
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:200
int64_t pos
byte position in stream, -1 if unknown
Definition: packet.h:383
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:4869
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: codec_par.h:60
static AVPacket pkt
Format I/O context.
Definition: avformat.h:1355
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:4450
uint8_t * data
Definition: packet.h:363
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:305
#define av_log(a,...)
#define AV_PKT_FLAG_KEY
The packet contains a keyframe.
Definition: packet.h:401
#define CDG_MASK
Definition: cdg.c:27
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:153
enum AVMediaType codec_type
General type of the encoded data.
Definition: codec_par.h:56
int flags
A combination of AV_PKT_FLAG values.
Definition: packet.h:369
AVInputFormat ff_cdg_demuxer
Definition: cdg.c:70
#define s(width, name)
Definition: cbs_vp9.c:257
Stream structure.
Definition: avformat.h:880
AVIOContext * pb
I/O context.
Definition: avformat.h:1397
#define AVFMT_GENERIC_INDEX
Use generic index building code.
Definition: avformat.h:463
int64_t duration
Decoding: duration of the stream, in stream time base.
Definition: avformat.h:929
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:29
int64_t dts
Decompression timestamp in AVStream->time_base units; the time at which the packet is decompressed...
Definition: packet.h:362
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:652
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1027
int stream_index
Definition: packet.h:365
AVRational time_base
This is the fundamental unit of time (in seconds) in terms of which frame timestamps are represented...
Definition: avformat.h:909
static int read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: cdg.c:53
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
This structure stores compressed data.
Definition: packet.h:340
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: packet.h:356