func: static int output_frame(H264Context *h, AVFrame *dst, AVFrame *src)
  
  {
  
      int i;
  
      int ret = av_frame_ref(dst, src);
  
      if (ret < 0)
  
          return ret;
  
  
  
      if (!h->sps.crop)
  
          return 0;
  
  
  
      for (i = 0; i < 3; i++) {
  
          int hshift = (i > 0) ? h->chroma_x_shift : 0;
  
          int vshift = (i > 0) ? h->chroma_y_shift : 0;
  
          int off    = ((h->sps.crop_left >> hshift) << h->pixel_shift) +
  
              (h->sps.crop_top  >> vshift) * dst->linesize[i];
  
          dst->data[i] += off;
  
      }
  
      return 0;
  
  }
  