libavformat/m4vdec.c
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00001 /*
00002  * RAW MPEG-4 video demuxer
00003  * Copyright (c) 2006  Thijs Vermeir <thijs.vermeir@barco.com>
00004  *
00005  * This file is part of Libav.
00006  *
00007  * Libav is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * Libav is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with Libav; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00022 #include "avformat.h"
00023 #include "rawdec.h"
00024 
00025 #define VISUAL_OBJECT_START_CODE       0x000001b5
00026 #define VOP_START_CODE                 0x000001b6
00027 
00028 static int mpeg4video_probe(AVProbeData *probe_packet)
00029 {
00030     uint32_t temp_buffer= -1;
00031     int VO=0, VOL=0, VOP = 0, VISO = 0, res=0;
00032     int i;
00033 
00034     for(i=0; i<probe_packet->buf_size; i++){
00035         temp_buffer = (temp_buffer<<8) + probe_packet->buf[i];
00036         if ((temp_buffer & 0xffffff00) != 0x100)
00037             continue;
00038 
00039         if (temp_buffer == VOP_START_CODE)                         VOP++;
00040         else if (temp_buffer == VISUAL_OBJECT_START_CODE)          VISO++;
00041         else if (temp_buffer < 0x120)                              VO++;
00042         else if (temp_buffer < 0x130)                              VOL++;
00043         else if (   !(0x1AF < temp_buffer && temp_buffer < 0x1B7)
00044                  && !(0x1B9 < temp_buffer && temp_buffer < 0x1C4)) res++;
00045     }
00046 
00047     if (VOP >= VISO && VOP >= VOL && VO >= VOL && VOL > 0 && res==0)
00048         return AVPROBE_SCORE_MAX/2;
00049     return 0;
00050 }
00051 
00052 FF_DEF_RAWVIDEO_DEMUXER(m4v, "raw MPEG-4 video format", mpeg4video_probe, "m4v", CODEC_ID_MPEG4)