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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  vst->duration = (ret * vst->time_base.den) / (CDG_PACKET_SIZE * 300);
47 
48  return 0;
49 }
50 
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  pkt->dts=
64  pkt->pts= pkt->pos / CDG_PACKET_SIZE;
65 
66  if(ret>5 && (pkt->data[0]&0x3F) == 9 && (pkt->data[1]&0x3F)==1 && !(pkt->data[2+2+1] & 0x0F)){
67  pkt->flags = AV_PKT_FLAG_KEY;
68  }
69  return ret;
70 }
71 
73  .name = "cdg",
74  .long_name = NULL_IF_CONFIG_SMALL("CD Graphics"),
75  .read_header = read_header,
76  .read_packet = read_packet,
77  .flags = AVFMT_GENERIC_INDEX,
78  .extensions = "cdg",
79 };