How to use FMOD_WAVWRITER in Unity for Android/iOS platforms

Unity
, ,
4

To use the WAVWRITER_NRT output type you will need to make a minor change to the RuntimeManager initialization code to allow it to mix from update:

//Assets\Plugins\FMOD\src\RuntimeManager.cs
private FMOD.RESULT Initialize()
{
... // Line ~376
+   result = studioSystem.initialize(virtualChannels, studioInitFlags, FMOD.INITFLAGS.MIX_FROM_UPDATE, IntPtr.Zero);
    if (result != FMOD.RESULT.OK && initResult == FMOD.RESULT.OK)
...
}

With that you can set you can now switch between the WAVWRITER_NRT and other output types, depending on whether you want to export or playback your scene in Unity. Here is a basic script demonstrating how to export the audio from a Unity scene using WAVWRITER_NRT:

Bounce.cs 
using UnityEngine;

public class Bounce : MonoBehaviour
{
    [SerializeField]
    bool bounce = false;

    [SerializeField]
    int durationSeconds = 25;

    void Start()
    {
        if (bounce)
        {
            FMODUnity.RuntimeManager.CoreSystem.getOutput(out FMOD.OUTPUTTYPE output);

            FMODUnity.RuntimeManager.CoreSystem.getMasterChannelGroup(out FMOD.ChannelGroup cg);
            cg.getDSPClock(out ulong child, out _);

            FMODUnity.RuntimeManager.CoreSystem.getSoftwareFormat(out int sampleRate, out _, out _);
            ulong future = child + (ulong)sampleRate * (uint)durationSeconds;
            FMODUnity.RuntimeManager.CoreSystem.setOutput(FMOD.OUTPUTTYPE.WAVWRITER_NRT);
            while (child < future)
            {
                FMODUnity.RuntimeManager.StudioSystem.update();
                cg.getDSPClock(out child, out _);
            }
            FMODUnity.RuntimeManager.CoreSystem.setOutput(output);
        }
    }
}

That will then produce a file called “fmodoutput.wav”, which I believe should be the application’s persistent data path in Unity. Otherwise you could potentially override the FMOD file system with System::setFileSystem to save it to a different location without reinitializing your system object just to change the path.

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