ffmpeg/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 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 "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 & 0xfffffe00)
  37             continue;
  38         if (temp_buffer < 2)
  39             continue;
  40
  41         if (temp_buffer == VOP_START_CODE)
  42             VOP++;
  43         else if (temp_buffer == VISUAL_OBJECT_START_CODE)
  44             VISO++;
  45         else if (temp_buffer >= 0x100 && temp_buffer < 0x120)
  46             VO++;
  47         else if (temp_buffer >= 0x120 && temp_buffer < 0x130)
  48             VOL++;
  49         else if (!(0x1AF < temp_buffer && temp_buffer < 0x1B7) &&
  50                  !(0x1B9 < temp_buffer && temp_buffer < 0x1C4))
  51             res++;
  52     }
  53
  54     if (VOP >= VISO && VOP >= VOL && VO >= VOL && VOL > 0 && res == 0)
  55         return VOP+VO > 4 ? AVPROBE_SCORE_EXTENSION : AVPROBE_SCORE_EXTENSION/2;
  56     return 0;
  57 }
  58
  59 FF_DEF_RAWVIDEO_DEMUXER2(m4v, "raw MPEG-4 video", mpeg4video_probe, "m4v",
  60                          AV_CODEC_ID_MPEG4, AVFMT_GENERIC_INDEX | AVFMT_TS_DISCONT)