Hey all! I’m new to FMOD and I’m using it to create an audio visualizer in Unity (so I’m using c#). I have the visualizer working using the getSpectrum function from Unity’s native audio engine, but I’d like to switch to FMOD. Unfortunately, I’m unsure of how exactly to do this.

From what I understand, I need to create a custom DSP, add it to my master channel, and then use the getParameterData function on it in update in order to get the frequency spectrum at every frame.

I suppose my question is…where exactly in my code am I supposed to add the DSP? From looking through the code, it seems the system created by FMOD is only accessible in some editor scripts (from which I cannot call functions), and in a script called “RuntimeManager.cs.” Is RuntimeManager.cs where I’m supposed to add the DSP? Thanks in advanced!

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Best Answer

Here’s an example I wrote but never included in the docs due to lack of polish

using System;
using UnityEngine;
using System.Runtime.InteropServices;

class ScriptUsageLowLevel : MonoBehaviour
    FMOD.Studio.EventInstance musicInstance;
    FMOD.DSP fft;

    LineRenderer lineRenderer;

    const int WindowSize = 1024;

    void Start()
        lineRenderer = gameObject.AddComponent<LineRenderer>();
        lineRenderer.SetWidth(.1f, .1f);

        musicInstance = FMODUnity.RuntimeManager.CreateInstance("event:/Music/Basic/Random Layered");

        FMODUnity.RuntimeManager.LowlevelSystem.createDSPByType(FMOD.DSP_TYPE.FFT, out fft);
        fft.setParameterInt((int)FMOD.DSP_FFT.WINDOWTYPE, (int)FMOD.DSP_FFT_WINDOW.HANNING);
        fft.setParameterInt((int)FMOD.DSP_FFT.WINDOWSIZE, WindowSize * 2);

        FMOD.ChannelGroup channelGroup;
        FMODUnity.RuntimeManager.LowlevelSystem.getMasterChannelGroup(out channelGroup);
        channelGroup.addDSP(FMOD.CHANNELCONTROL_DSP_INDEX.HEAD, fft);


    const float WIDTH = 10.0f;
    const float HEIGHT = 0.1f;

    void Update()
        IntPtr unmanagedData;
        uint length;
        fft.getParameterData((int)FMOD.DSP_FFT.SPECTRUMDATA, out unmanagedData, out length);
        FMOD.DSP_PARAMETER_FFT fftData = (FMOD.DSP_PARAMETER_FFT)Marshal.PtrToStructure(unmanagedData, typeof(FMOD.DSP_PARAMETER_FFT));
        var spectrum = fftData.spectrum;

        if (fftData.numchannels > 0)
            var pos =;
            pos.x = WIDTH * -0.5f;

            for (int i = 0; i < WindowSize; ++i)
                pos.x += (WIDTH / WindowSize);

                float level = lin2dB(spectrum[0][i]);
                pos.y = (80 + level) * HEIGHT;

                lineRenderer.SetPosition(i, pos);

    float lin2dB(float linear)
        return Mathf.Clamp(Mathf.Log10(linear) * 20.0f, -80.0f, 0.0f);
  • Thomas

    You are a lifesaver! Thanks a bunch :)

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