func: int avcodec_decode_audio(AVCodecContext *avctx, int16_t *samples,
  
                           int *frame_size_ptr,
  
                           uint8_t *buf, int buf_size)
  
  {
  
      int ret;
  
  
  
      *frame_size_ptr= 0;
  
      if((avctx->codec->capabilities & CODEC_CAP_DELAY) || buf_size){
  
          ret = avctx->codec->decode(avctx, samples, frame_size_ptr,
  
                                  buf, buf_size);
  
          avctx->frame_number++;
  
      }else
  
          ret= 0;
  
      return ret;
  
  }
  