func: int avfilter_register(AVFilter *filter)
  
  {
  
      if (next_registered_avfilter_idx == MAX_REGISTERED_AVFILTERS_NB)
  
          return -1;
  
  
  
      registered_avfilters[next_registered_avfilter_idx++] = filter;
  
      return 0;
  
  }
  