Adding DSP Causes WASAPI Starvation

FMOD Engine
22

Just as a follow up: it seems the errors periodically happen even while simply just letting the game play in the editor.

This happens with the code from https://www.fmod.com/docs/2.02/unity/examples-dsp-capture.html so I don’t think it comes from any coding error, unless the example is incorrect.

23

I’m getting the starvation warning from the following code run in unity specifically on ending playmode. No actual audio needs to be played.


using System;
using FMOD;
using FMODUnity;
using UnityEngine;

class ExactExample : MonoBehaviour
{
  private DSP mCaptureDSP;
  private uint mBufferLength;
  private int mChannels = 0;
  
  void Start()
  {
    
    DSP_DESCRIPTION desc = new DSP_DESCRIPTION
    {
      numinputbuffers  = 1,
      numoutputbuffers = 1,
      // most other callbacks will not produce the starvation warning
      // although process callback fires a raw exception even when empty
      read             = CaptureDSPReadCallback 
    };

    RuntimeManager.CoreSystem.getMasterChannelGroup( out var masterCG );
    RuntimeManager.CoreSystem.createDSP( ref desc, out mCaptureDSP );
    masterCG.addDSP( 0, mCaptureDSP );
  }

  [AOT.MonoPInvokeCallback( typeof(DSP_READ_CALLBACK) )]
  static RESULT CaptureDSPReadCallback( ref DSP_STATE dsp_state, IntPtr inbuffer, IntPtr outbuffer, uint length, int inchannels, ref int outchannels )
  {
    return RESULT.OK;
  }

  private void OnDisable()
  {
    if( mCaptureDSP.hasHandle() )
    {
      if( RuntimeManager.CoreSystem.getMasterChannelGroup( out var channelGroup ) == RESULT.OK ) 
        channelGroup.removeDSP( mCaptureDSP );
      
      mCaptureDSP.release();
      mCaptureDSP.clearHandle();
    }
  }
}

If the read callback is set, the warning will fire when exiting playmode.

I’ve tried a bunch of variations. None will prevent the warning on shutdown.

Worth noting that assigning the process callback will throw a marshal type exception and lock the editor:


  [AOT.MonoPInvokeCallback( typeof(DSP_PROCESS_CALLBACK) )]
  private RESULT ProcessCallback( ref DSP_STATE dsp_state, uint length, ref DSP_BUFFER_ARRAY inbufferarray, ref DSP_BUFFER_ARRAY outbufferarray, bool inputsidle, DSP_PROCESS_OPERATION op )
  {
    return RESULT.OK;
  }

.....
MarshalDirectiveException: Structure field of type Int32[] can't be marshalled as LPArray
  at (wrapper native-to-managed) ExactExample.ProcessCallback(FMOD.DSP_STATE&,uint,FMOD.DSP_BUFFER_ARRAY&,FMOD.DSP_BUFFER_ARRAY&,int,FMOD.DSP_PROCESS_OPERATION)

Super annoying.

Am I doing something incredibly wrong here or is this just a bug in fmod’s unity api?

EDIT:
Tested with an older project and the starvation warning does not happen with 2.02.15 it does happen with 2.02.22.

25

For anyone following this response follow through to Adding signal DSP causes starvation - Unity - FMOD Forums