Audio AudioMixer updated via slider, but non-linear?

Hi all,

I was wondering whether anyone could help with the following query.

I followed Unity's AudioMixer tutorial and am happy that I can influence the volume of an audio mixer via a slider, but if you move the slider to halfway, this isn't half of the volume.

Having had a look around online there is mention of using

Mathf.Log10(sliderValue) * 20

, and having a slider value between 0.0001 and 1.

What I find when using this approach is that the maximum volume, as displayed in dB in the AudioMixer will never be above 0, and having the volume drop to -80dB seems a little unnecessary as it seems to become inaudible in excess of -40dB.

So, how can I apply a linear slider to a non-linear volume? I'm assuming someone must have already done this, although a quick search of the forums seemed to show a lot of examples just popping the float value straight in.

Any help would be appreciated.

----------
Have been referring to these;

• https://unity3d.com/learn/tutorials/topics/audio/exposed-audiomixer-parameters?playlist=17096
• https://johnleonardfrench.com/artic...slider-in-unity-using-logarithmic-conversion/
• http://www.playdotsound.com/portfol...making-sense-of-linear-values-in-audio-tools/

 

You can't ... unfortunately Unity devs are retarded with the units they use for Audio. There's literally no reason why they couldn't present the audio volume as a logarithmic dB scale instead of a float from 0.0f - 1.0f but because they are programmers they only care about floats!

You have to manually convert dB to float in order to know the dB equivalent.

Here's a Linear Float to Decibel calculator that you will have to use ...

http://www.playdotsound.com/portfol...making-sense-of-linear-values-in-audio-tools/

Going from 1.0f to 0.5f is only reducing the volume by -6 dB ... you get used to it eventually.

Just wait until you see the units they use in the SFX_Reverb plugin on the audio mixers ... there are dB AND mB ... MilliBELS!

 

Here's how I did it.

Open the Audio Mixer via: Window > Audio > Audio Mixer and doc it to the right pane (so it's visible when you play)
Expose a parameter, call it "Volume"
Drag the Audio Mixer (created in the root of Assets folder) to the following script
Create a slider with MinValue=0, MaxValue=1 and set its OnValueChanged event to the SetVolume() of the script

I made a small tweak to the slider's volume when it was 0, otherwise the volume would decrease until it reaches zero and then rose to maximal volume.

Code (CSharp):

1. using UnityEngine;
2.  
3. public class OptionsMenu : MonoBehaviour
4. {
5.     public UnityEngine.Audio.AudioMixer audioMixer;
6.  
7.     public void SetVolume(float decimalVolume)
8.     {
9.         var dbVolume = Mathf.Log10(decimalVolume) * 20;
10.         if (decimalVolume == 0.0f)
11.         {
12.             dbVolume = -80.0f;
13.         }
14.         audioMixer.SetFloat("Volume", dbVolume);
15.     }
16. }
17.  

 

Hi Stephane,

Thank you for the reply and code example, appreciated.

I don't think the above solution covers exactly what I mean though. For example;

When the slider value is at 1 the AudioMixer db register as 0db, instead of 20.
When the slider value is at 0.5 the AudioMixer db registers as -6db

I think what this perhaps needs is the ability to covert the slider value from the range of 0 to 1 to a correct value between 20 and -40db.

 

If someone bump into this, i found a solution on another thread:

Code (CSharp):

1. using UnityEngine;
2. using UnityEngine.UI;
3. using UnityEngine.Audio;
4. public class MixerControl : MonoBehaviour
5. {
6.     public AudioMixer audioMixer;
7.     public Slider volumeSlider;
8.     private void Start() {
9.         volumeSlider.onValueChanged.AddListener((sliderValue) => {
10.             audioMixer.SetFloat("Volume", remap(sliderValue, 0f, 1f, -40f, 20f, false, false, false, false));
11.         });
12.     }
13.     public static float remap(float val, float in1, float in2, float out1, float out2,
14.         bool in1Clamped, bool in2Clamped, bool out1Clamped, bool out2Clamped) {
15.         if (in1Clamped == true && val < in1) val = in1;
16.         if (in2Clamped == true && val > in2) val = in2;
17.  
18.         float result = out1 + (val - in1) * (out2 - out1) / (in2 - in1);
19.  
20.         if (out1Clamped == true && result < out1) result = out1;
21.         if (out2Clamped == true && result > out2) result = out2;
22.  
23.         return result;
24.     }
25. }

 

I think you can simply multiply the sliderValue by 8, this will double the slider value 4 times ( 1,2,4,8 ), each doubling adds 6 db to the resulting db value ( from 0 to 6 to 12 to 18 )
Mathf.Log10(sliderValue*8) * 20 // this will change your slider value to be from -80 db to 18 db