Audio Mixer and Audio Mixer Groups - Unity Official Tutorials

The audio mixer asset in Unity allows us

a great deal of control over the signal flow

of audio in our projects.

By default our main camera

is assigned an audio listener component.

The audio listener component is where audio

is output from the scene

to the headphones or the speakers of the listener

In Unity all audio starts at an audio source.

Here we have a game object called Base

and it's got an audio source on it which has a clip

of a baseline loaded,

which is also set to play on awake and loop.

There are 3 other objects

which contain other musical parts including

an arpeggio kick and percussion.

When we play the scene we're going to hear these

first 3 parts play directly through

the audio listener component.

If we want to get more control over how

our audio is processed we can create an

audio mixer asset, so choose Create

Audio Mixer

and then we can either double click on it

to make it visible

or we can go to Window - Audio Mixer

or choose command-8

on Mac or control-8 on PC.

The audio mixer can be docked

like many of the other windows,

I'm going to dock it down here on the bottom of my screen

and I'm going to expand

to give myself a little bit more real estate.

The default state for an audio mixer

is that it's created only

with a master group here.

In Unity's audio system we refer to channels

as groups because they provide a little

bit of additional audio functionality

that a normal mixer channel would not.

Now, we've got our master

and currently nothing is assigned to it.

If we play we'll see

no movement in the meters.

If we choose our

game objects here we can edit

for all of them the output parameter here

and we can assign it by clicking on it

to the master channel of audio mixer 1.

Now when we play

we've setup some signal flow,

our signal is now passing from

our audio sources through the master

to the audio listener on the main camera.

By default the master group

is created with an attenuation effect applied to it.

The attenuation effect is what allows

us to control the volume of the signal

passing through the master group.

If we want to adjust that while we're playing

we're going to need to click Edit In Play Mode.

Now we can adjust the volume

and we can see in the inspector on the right

that the change is being reflected.

Changes made while editing

during play mode will be saved

to the audio mixer asset.

Unlike scene changes, which will revert

when exiting play mode.

Currently audio mixer 1 has only 1 group

the master.

To create a more flexible signal flow

we're going to go over here to the Groups area

and click the + button twice.

When we click the + button a new group

will be created that is the child

of the currently selected group.

Notice that in the channel strip view

group A and group B have appeared.

With multiple groups in our mixer we can

now assign some of our parts to different groups

Let's assign the kick drum

by clicking on the output parameter

to group A.

Now if we play

activate Edit In Play Mode.

You'll notice that when we turn down group A

we can turn down the kick drum independently because

it's now on it's own group.

And when we turn down the master we can

turn down everything.

This is because group A is routed

through the master so the master controls

everything which is routed through it..

That's because of the way

that the groups are arranged in the groups

area down here.

We can see that group A is a child

of the master group and group B is in turn

a child of group A.

So if we assign our arpeggio

using it's output to group B

we can now test again

and we'll see that turning down group A

now turns down

both the kick and the arpeggio

because group B is a child of group A.

So here we have what's called a

serial signal flow routing,

meaning group B passes through group A

and then passes through the master.

We can also create a parallel signal flow

by changing the routing of group B.

If we click on group B in the groups area

and drag it's name on to the master

we can now make group B

a child of the master and pass it's signal

directly to the master, and we can test that out.

So now we have the kick in group A.

The arpeggio in group B.

And everything being run through the master.

While we're working in the mixer we may want to check

parts of our mix individually.

We can do this using the solo, mute and bypass

buttons on each of the groups.

When we click solo

all the other tracks are temporarily muted

so that we can hear that track by itself

and make any changes we need to make.

When we click mute the opposite happens.

The one track we've muted becomes silent

and we can hear anything else that we need to hear.

Bypass allows us to bypass any

audio effects that we've applied to the channel.

Let's go down and click Add

Low Pass Simple.

This is a low pass filter which will remove

high frequencies from our arpeggio sound.

Here's the arpeggio soloed.

Here's the bypass.

So if we're having problems with one of our effects

or we want to check something we can bypass.

It's worth noting that solo, mute and bypass

are not intended to be used at runtime

they're supposed to be used in

setting up your mix and designing your sounds.

But not to be controlled by the

engine while the game is playing.

Additionally each group has it's own pitch control.

If we look in the inspector we'll see

that the pitch is currently set

to 100 for this group,

our arpeggio,

let's set it to 50%.

So we can adjust the pitch not just

at the individual sound level using

audio source pitch control but also

at the group level.

In addition to controlling signal flow

with groups we can also control

signal flow with multiple mixers.

By using multiple mixers for each

category of sounds in our mix

we can then route those mixers

to groups in audio mixer 1

to control the overall balance of the mix.

If we create another mixer by

clicking the + button,

we'll call this one

Drum Mixer.

We can now create two groups within this.

We'll configure this in a

parallel routing

and we will assign our kick

to the drum mixer kick channel

and we'll activate our percussion source here

and assign that to the percussion channel.

In order to be able to control the volume balance

between those two sets of elements let's

create a third group

and route it to the master output.

Now if we grab our drum mixer

and drop it on to audio mixer 1

we can choose drum group as an input.

When we play the scene

We can see that our entire drum mixer

is now being routed through drum group

to the master output.

As you're working in the mixer and your project's

grow more complex you may find

that you want to manage the view of the mixer.

This can be done using the visibility

controls down here, let's say we want to make

groups A and B invisible and just view the

drum group and the master,

we can do that by clicking these eye icons

beside the group names.

Once we've made them visible we can save that in a view.

Here we currently only have one view,

let's click the + button to make another.

Now in view View Simple we have

these two groups turned off

and in our main view

we could have them turned back on

by clicking on the view name we can toggle

between different views of the mixer.

Snapshots allow us to store

and recall the state of the mixer.

We'll cover snapshots in their own dedicated lesson.

Please see the link below for more information.

So far we've taken a look at

controlling our signal flow for our game music.

Let's take a look at an example which includes

some sound effects as well.

Here we have the Nightmares project

which is available for download on the asset store.

What we've done is we've setup two mixers.

One is the master mixer and another

is a sound effects mixer.

In the master mixer we have two groups,

one for music and one for our sound effects.

We've also got our vocal effects

for when the player gets hurt routed

to a vocal effects group also on

the sound effects mixer.

Our background music is routed directly

to the music channel of the master mixer

since there's only one channel for the

music in this case.

If we play our scene we can see this in action.

Using this approach we can then

balance each separate set of effects,

gun shots, vocal effects

against our music easily

using one overall volume for sound effects

and one overall volume for music.