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ffmpeg-4.2.2/libavformat/cavsvideodec.c 2.44 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * RAW Chinese AVS video demuxer
   * Copyright (c) 2009  Stefan Gehrer <stefan.gehrer@gmx.de>
   *
   * 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 "libavcodec/internal.h"
  
  #define CAVS_SEQ_START_CODE       0x000001b0
  #define CAVS_PIC_I_START_CODE     0x000001b3
  #define CAVS_UNDEF_START_CODE     0x000001b4
  #define CAVS_PIC_PB_START_CODE    0x000001b6
  #define CAVS_VIDEO_EDIT_CODE      0x000001b7
  #define CAVS_PROFILE_JIZHUN       0x20
  
  static int cavsvideo_probe(const AVProbeData *p)
  {
      uint32_t code= -1;
      int pic=0, seq=0, slice_pos = 0;
      const uint8_t *ptr = p->buf, *end = p->buf + p->buf_size;
  
      while (ptr < end) {
          ptr = avpriv_find_start_code(ptr, end, &code);
          if ((code & 0xffffff00) == 0x100) {
              if(code < CAVS_SEQ_START_CODE) {
                  /* slices have to be consecutive */
                  if(code < slice_pos)
                      return 0;
                  slice_pos = code;
              } else {
                  slice_pos = 0;
              }
              if (code == CAVS_SEQ_START_CODE) {
                  seq++;
                  /* check for the only currently supported profile */
                  if (*ptr != CAVS_PROFILE_JIZHUN)
                      return 0;
              } else if ((code == CAVS_PIC_I_START_CODE) ||
                         (code == CAVS_PIC_PB_START_CODE)) {
                  pic++;
              } else if ((code == CAVS_UNDEF_START_CODE) ||
                         (code >  CAVS_VIDEO_EDIT_CODE)) {
                  return 0;
              }
          }
      }
      if(seq && seq*9<=pic*10)
          return AVPROBE_SCORE_EXTENSION+1;
      return 0;
  }
  
  FF_DEF_RAWVIDEO_DEMUXER(cavsvideo, "raw Chinese AVS (Audio Video Standard)", cavsvideo_probe, NULL, AV_CODEC_ID_CAVS)