func: static int seek_test(const char *input_filename, const char *start, const char *end)
  
  {
  
      AVCodec *codec = NULL;
  
      AVCodecContext *ctx= NULL;
  
      AVCodecParameters *origin_par = NULL;
  
      AVFrame *fr = NULL;
  
      AVFormatContext *fmt_ctx = NULL;
  
      int video_stream;
  
      int result;
  
      int i, j;
  
      long int start_ts, end_ts;
  
  
  
      size_of_array = 0;
  
      number_of_elements = 0;
  
      crc_array = pts_array = NULL;
  
  
  
      result = avformat_open_input(&fmt_ctx, input_filename, NULL, NULL);
  
      if (result < 0) {
  
          av_log(NULL, AV_LOG_ERROR, "Can't open file\n");
  
          return result;
  
      }
  
  
  
      result = avformat_find_stream_info(fmt_ctx, NULL);
  
      if (result < 0) {
  
          av_log(NULL, AV_LOG_ERROR, "Can't get stream info\n");
  
          return result;
  
      }
  
  
  
      start_ts = read_seek_range(start);
  
      end_ts = read_seek_range(end);
  
      if ((start_ts < 0) || (end_ts < 0))
  
          return -1;
  
  
  
      //TODO: add ability to work with audio format
  
      video_stream = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, NULL, 0);
  
      if (video_stream < 0) {
  
        av_log(NULL, AV_LOG_ERROR, "Can't find video stream in input file\n");
  
        return -1;
  
      }
  
  
  
      origin_par = fmt_ctx->streams[video_stream]->codecpar;
  
  
  
      codec = avcodec_find_decoder(origin_par->codec_id);
  
      if (!codec) {
  
          av_log(NULL, AV_LOG_ERROR, "Can't find decoder\n");
  
          return -1;
  
      }
  
  
  
      ctx = avcodec_alloc_context3(codec);
  
      if (!ctx) {
  
          av_log(NULL, AV_LOG_ERROR, "Can't allocate decoder context\n");
  
          return AVERROR(ENOMEM);
  
      }
  
  
  
      result = avcodec_parameters_to_context(ctx, origin_par);
  
      if (result) {
  
          av_log(NULL, AV_LOG_ERROR, "Can't copy decoder context\n");
  
          return result;
  
      }
  
  
  
      result = avcodec_open2(ctx, codec, NULL);
  
      if (result < 0) {
  
          av_log(ctx, AV_LOG_ERROR, "Can't open decoder\n");
  
          return result;
  
      }
  
  
  
      fr = av_frame_alloc();
  
      if (!fr) {
  
          av_log(NULL, AV_LOG_ERROR, "Can't allocate frame\n");
  
          return AVERROR(ENOMEM);
  
      }
  
  
  
      result = compute_crc_of_packets(fmt_ctx, video_stream, ctx, fr, i, j, 1);
  
      if (result != 0)
  
          return -1;
  
  
  
      for (i = start_ts; i < end_ts; i += 100) {
  
          for (j = i + 100; j < end_ts; j += 100)
  
          result = compute_crc_of_packets(fmt_ctx, video_stream, ctx, fr, i, j, 0);
  
          if (result != 0)
  
              return -1;
  
      }
  
  
  
      av_freep(&crc_array);
  
      av_freep(&pts_array);
  
      av_frame_free(&fr);
  
      avcodec_close(ctx);
  
      avformat_close_input(&fmt_ctx);
  
      avcodec_free_context(&ctx);
  
      return 0;
  
  }
  