libavformat/mpegvideodec.c

   1 /*
   2  * RAW MPEG video demuxer
   3  * Copyright (c) 2002-2003 Fabrice Bellard
   4  * Copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
   5  *
   6  * This file is part of Libav.
   7  *
   8  * Libav is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * Libav is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with Libav; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include "avformat.h"
  24 #include "rawdec.h"
  25
  26 #define SEQ_START_CODE          0x000001b3
  27 #define GOP_START_CODE          0x000001b8
  28 #define PICTURE_START_CODE      0x00000100
  29 #define SLICE_START_CODE        0x00000101
  30 #define PACK_START_CODE         0x000001ba
  31 #define VIDEO_ID                0x000001e0
  32 #define AUDIO_ID                0x000001c0
  33
  34 static int mpegvideo_probe(AVProbeData *p)
  35 {
  36     uint32_t code= -1;
  37     int pic=0, seq=0, slice=0, pspack=0, pes=0;
  38     int i;
  39
  40     for(i=0; i<p->buf_size; i++){
  41         code = (code<<8) + p->buf[i];
  42         if ((code & 0xffffff00) == 0x100) {
  43             switch(code){
  44             case     SEQ_START_CODE:   seq++; break;
  45             case PICTURE_START_CODE:   pic++; break;
  46             case   SLICE_START_CODE: slice++; break;
  47             case    PACK_START_CODE: pspack++; break;
  48             }
  49             if     ((code & 0x1f0) == VIDEO_ID)   pes++;
  50             else if((code & 0x1e0) == AUDIO_ID)   pes++;
  51         }
  52     }
  53     if(seq && seq*9<=pic*10 && pic*9<=slice*10 && !pspack && !pes)
  54         return pic>1 ? AVPROBE_SCORE_MAX/2+1 : AVPROBE_SCORE_MAX/4; // +1 for .mpg
  55     return 0;
  56 }
  57
  58 FF_DEF_RAWVIDEO_DEMUXER(mpegvideo, "raw MPEG video", mpegvideo_probe, NULL, AV_CODEC_ID_MPEG1VIDEO)