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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 
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_free_packet(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 };