Prerolling a stream allows the source stream handlers to start and fill the buffers. An application can then start the streams for better real-time response and initial synchronization of streams. This is accomplished by the SpiStartStream function with the SPI_START_PREROLL flag.

However, if a stream is already paused (STOP_PAUSED), the stream is already cued so there is no need to call SpiStartStream to refill the buffers. The following example illustrates how to check to see if a stream is in a paused state.

  /************************************
  * If the stream is paused, there is no
  * sense in cueing it since the buffers
  * are full anyway
  **************************************/

  if ( STRMSTATE == MCI_PAUSE  ||
       STRMSTATE == STOP_PAUSED )

      {
      /***********************************************
      ** If the stream is going the right way
      ** then we have the ability to avoid the cue
      ** since the buffers have been filled up before
      ** we did the pause
      **********************************************/

      if ( AMPMIX.ulOperation == OPERATION_RECORD &&
           fCueInput )
         {
         ulpInstance->ulCreateFlag = PREROLL_STATE;
         STRMSTATE = CUERECD_STATE;
         return ( MCIERR_SUCCESS );
         }

      /*************************************************
      * If the current stream is cued for playback and
      * we have a cue_output request, our work is done
      **************************************************/

      else if ( AMPMIX.ulOperation == OPERATION_PLAY &&
                fCueOutput )
         {

         ulpInstance->ulCreateFlag = PREROLL_STATE;
         STRMSTATE = CUEPLAY_STATE;
         return ( MCIERR_SUCCESS );
         }

      }   /* If the stream may be in cue state */