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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 {
  30.     int got_first_packet;
  31. } CDGContext;
  32.  
  33. static int read_header(AVFormatContext *s)
  34. {
  35.     AVStream *vst;
  36.     int ret;
  37.  
  38.     vst = avformat_new_stream(s, NULL);
  39.     if (!vst)
  40.         return AVERROR(ENOMEM);
  41.  
  42.     vst->codec->codec_type = AVMEDIA_TYPE_VIDEO;
  43.     vst->codec->codec_id   = AV_CODEC_ID_CDGRAPHICS;
  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.  
  57. static int read_packet(AVFormatContext *s, AVPacket *pkt)
  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.  
  84. AVInputFormat ff_cdg_demuxer = {
  85.     .name           = "cdg",
  86.     .long_name      = NULL_IF_CONFIG_SMALL("CD Graphics"),
  87.     .priv_data_size = sizeof(CDGContext),
  88.     .read_header    = read_header,
  89.     .read_packet    = read_packet,
  90.     .flags          = AVFMT_GENERIC_INDEX,
  91.     .extensions     = "cdg",
  92. };
  93.