/*
  * RAW MPEG video demuxer
  * Copyright (c) 2002-2003 Fabrice Bellard
  * Copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #include "avformat.h"

 #include "rawdec.h"

 #include "libavutil/intreadwrite.h"

 #include "libavcodec/internal.h"

 #define SEQ_START_CODE          0x000001b3
 #define GOP_START_CODE          0x000001b8
 #define PICTURE_START_CODE      0x00000100
 #define SLICE_START_CODE        0x00000101
 #define PACK_START_CODE         0x000001ba
 #define VIDEO_ID                0x000001e0
 #define AUDIO_ID                0x000001c0
 

 static int mpegvideo_probe(const AVProbeData *p)

 {
     uint32_t code= -1;

     int pic=0, seq=0, slice=0, pspack=0, vpes=0, apes=0, res=0, sicle=0;

     const uint8_t *ptr = p->buf, *end = ptr + p->buf_size;

     uint32_t last = 0;

     int j;

     while (ptr < end) {
         ptr = avpriv_find_start_code(ptr, end, &code);

         if ((code & 0xffffff00) == 0x100) {
             switch(code){

             case     SEQ_START_CODE:

                 if (!(ptr[3 + 1 + 2] & 0x20))

                     break;

                 j = -1;
                 if (ptr[j + 8] & 2)

                     j+= 64;

                 if (j >= end - ptr)

                     break;

                 if (ptr[j + 8] & 1)

                     j+= 64;

                 if (j >= end - ptr)

                     break;

                 if (AV_RB24(ptr + j + 9) & 0xFFFFFE)

                     break;
                 seq++;
             break;

             case PICTURE_START_CODE:   pic++; break;
             case    PACK_START_CODE: pspack++; break;

             case              0x1b6:
                                         res++; break;

             }

             if (code >= SLICE_START_CODE && code <= 0x1af) {
                 if (last >= SLICE_START_CODE && last <= 0x1af) {
                     if (code >= last) slice++;
                     else              sicle++;
                 }else{
                     if (code == SLICE_START_CODE) slice++;
                     else                          sicle++;
                 }
             }

             if     ((code & 0x1f0) == VIDEO_ID)   vpes++;
             else if((code & 0x1e0) == AUDIO_ID)   apes++;

             last = code;

         }
     }

     if(seq && seq*9<=pic*10 && pic*9<=slice*10 && !pspack && !apes && !res && slice > sicle) {

         if(vpes) return AVPROBE_SCORE_EXTENSION / 4;
         else     return pic>1 ? AVPROBE_SCORE_EXTENSION + 1 : AVPROBE_SCORE_EXTENSION / 2; // +1 for .mpg

     }

     return 0;
 }
 

 FF_DEF_RAWVIDEO_DEMUXER(mpegvideo, "raw MPEG video", mpegvideo_probe, NULL, AV_CODEC_ID_MPEG1VIDEO)