4 channel audio not fully working

Unity Engine
,
1

Hi!
I’m trying to figure out how to do multi channel audio in unity, and it looks like something isn’t working correctly.

here is my setup:

  • Blank unity project (unity 2020.3.0f1)
  • Set project settings > audio > default speaker mode to “Quad”
  • Create a 4-channel audio clip with audacity (1 “click” on each channel, one at a time)
  • Import the clip into unity with default settings

7968651--1022070--upload_2022-3-16_16-56-31.png
7968651--1022070--upload_2022-3-16_16-56-31.png846×430 25 KB

I don’t have an external sound card (yet) so I’m using VB-Cable as a virtual 4-channel output

VB-Cable provides a Control panel where I can see the levels for each channel.
Playing back the source file with quicktime, I can see the channel 1,2,3 and 4 levels moving as I expect.
However, playing back the imported audio clip in unity’s asset preview merges channel 1 with 3, and 2 with 4. The same thing happens when playing the audio in-game.

Another setup I’ve tried is the same as above, but setting up my computer to use an “aggregate audio device”:

With this setup, playing back the clip in Quicktime or in the unity asset preview works as expected (I hear the channels 1 and 2 through the Built-in output and “see” the channels 3 and 4 on the VB-Cable control panel).
Playing the clip in-game however, only the channels 1,2 and 3 seem to work. Nothing happens on channel 4 (Even using a unity audio mixer, I can see channels 1,2 and 3 “lighting up” but 4 stays silent)

I know changing audio config with unity opened is not guaranteed to work, so for every test I do, I quit and restart Unity.

I hope I’ve explained the issue properly. If not, I’ve attached a zip file with the test unity project (including the 4 channel audio track), and screen recording of different tests I’ve made. If you need more info, I’ll be happy to provide it for you

System:
MacBook Pro (Retina, 13-inch, Late 2013)
MacOS 11.6.2
16GB RAM
2,8 GHz Dual-Core Intel Core i7

7968651–1022040–unity audio bug.zip (1.6 MB)

7968651--1022070--upload_2022-3-16_16-56-31.png
7968651--1022070--upload_2022-3-16_16-56-31.png846×430 25 KB

2

this fixed it for me: https://thomasmountainborn.com/2016/06/10/sending-audio-directly-to-a-speaker-in-unity/

Channels 3 and 4 are for center and bass. you have to use channels 5 & 6 for back left and back right speakers.

3

Your link is broken. I have tried audio clips with audio on 1,2,3,4 and 1,2,5,6 and neither works. I still only get 1,2 and 3 during playback in Unity, but not in asset preview.

4

Hi ! Yes indeed the link is broken.

I’m currently facing the same issue on Unity (6000.0.45f1)

Here is a 4.0 file that has basically 4 mono channels at the same level, but when it’s played only the 1,2,3 channels are fed, the 4 is silent :

Quad_Speaker_Mode
Quad_Speaker_Mode150×354 8.91 KB

If I change the speaker mode to “Surround” in the audio settings, it seems to work better but I can’t afford 5 outputs.

Surround_Speaker_Mode
Surround_Speaker_Mode141×356 9.58 KB

Maybe a lead to fix that issue would be in the fact that Unity seems to import the Audio Clip as a 3.1 channel layout instead of the 4.0 we want. We can see it displayed in the Audio Clip asset infos at the bottom of your capture (Vorbis, 44100 Hz, 3.1, 00:03.823). I have exactly the same 3.1 instead of 4.0 info.

Quad_Audio_File
Quad_Audio_File1069×208 53.2 KB

I’ve tried to encode the channel order in the metadata of the audio file with different layout/naming using ffmpeg but none seems to work, it’s always displayed as a “3.1” file in Unity (in other audio Software the Quad in recognize as a 4.0).

Maybe a Unity Dev could tell us what channel order/layout/encapsulation would be needed in the metadata of the Audio File for Unity to recognize it as a 4.0(L,R,SL,SR) and not 3.1 (L,R,C,Lfe) ?