func: static av_cold int roq_dpcm_encode_init(AVCodecContext *avctx)
  
  {
  
      ROQDPCMContext *context = avctx->priv_data;
  
  
  
      if (avctx->channels > 2) {
  
          av_log(avctx, AV_LOG_ERROR, "Audio must be mono or stereo\n");
  
          return -1;
  
      }
  
      if (avctx->sample_rate != 22050) {
  
          av_log(avctx, AV_LOG_ERROR, "Audio must be 22050 Hz\n");
  
          return -1;
  
      }
  
      if (avctx->sample_fmt != AV_SAMPLE_FMT_S16) {
  
          av_log(avctx, AV_LOG_ERROR, "Audio must be signed 16-bit\n");
  
          return -1;
  
      }
  
  
  
      avctx->frame_size = ROQ_FIRST_FRAME_SIZE;
  
  
  
      context->lastSample[0] = context->lastSample[1] = 0;
  
  
  
      avctx->coded_frame= avcodec_alloc_frame();
  
  
  
  
  
      return 0;
  
  }