libavformat/m4vdec.c

   1 /*
   2  * RAW MPEG-4 video demuxer
   3  * Copyright (c) 2006  Thijs Vermeir <thijs.vermeir@barco.com>
   4  *
   5  * This file is part of Libav.
   6  *
   7  * Libav 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  * Libav 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 Libav; 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 "rawdec.h"
  24
  25 #define VISUAL_OBJECT_START_CODE       0x000001b5
  26 #define VOP_START_CODE                 0x000001b6
  27
  28 static int mpeg4video_probe(AVProbeData *probe_packet)
  29 {
  30     uint32_t temp_buffer= -1;
  31     int VO=0, VOL=0, VOP = 0, VISO = 0, res=0;
  32     int i;
  33
  34     for(i=0; i<probe_packet->buf_size; i++){
  35         temp_buffer = (temp_buffer<<8) + probe_packet->buf[i];
  36         if ((temp_buffer & 0xffffff00) != 0x100)
  37             continue;
  38
  39         if (temp_buffer == VOP_START_CODE)                         VOP++;
  40         else if (temp_buffer == VISUAL_OBJECT_START_CODE)          VISO++;
  41         else if (temp_buffer < 0x120)                              VO++;
  42         else if (temp_buffer < 0x130)                              VOL++;
  43         else if (   !(0x1AF < temp_buffer && temp_buffer < 0x1B7)
  44                  && !(0x1B9 < temp_buffer && temp_buffer < 0x1C4)) res++;
  45     }
  46
  47     if (VOP >= VISO && VOP >= VOL && VO >= VOL && VOL > 0 && res==0)
  48         return AVPROBE_SCORE_MAX/2;
  49     return 0;
  50 }
  51
  52 FF_DEF_RAWVIDEO_DEMUXER(m4v, "raw MPEG-4 video", mpeg4video_probe, "m4v", AV_CODEC_ID_MPEG4)