func: static av_cold int png_dec_end(AVCodecContext *avctx)
  
  {
  
      PNGDecContext *s = avctx->priv_data;
  
  
  
      ff_thread_release_buffer(avctx, &s->previous_picture);
  
      av_frame_free(&s->previous_picture.f);
  
      ff_thread_release_buffer(avctx, &s->last_picture);
  
      av_frame_free(&s->last_picture.f);
  
      ff_thread_release_buffer(avctx, &s->picture);
  
      av_frame_free(&s->picture.f);
  
      av_freep(&s->buffer);
  
      s->buffer_size = 0;
  
      av_freep(&s->last_row);
  
      s->last_row_size = 0;
  
      av_freep(&s->tmp_row);
  
      s->tmp_row_size = 0;
  
      av_freep(&s->extra_data);
  
      s->extra_data_size = 0;
  
  
  
      return 0;
  
  }
  