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You can use the properties of a bus to make global changes to the audio or motion in your game. When defining the properties of a bus, you can do the following:
Since the busses are the last level of control, any changes you make will affect the entire group of objects below them.
As is the case for objects, you can also apply effects, use RTPCs, assign states, and set advanced properties for busses. For more information, refer to the following sections:
Relative properties can be defined for each bus within your hierarchy. Relative properties are cumulative, which means that the property values for a bus are added to the child objects below it.
There are relative properties that you can modify for busses:
Bus Volume - The attenuation directly applied in the bus.
Voice Volume - The attenuation applied to audio structures playing in the bus.
Voice Pitch - The playback speed of the audio structures playing in the bus.
You can edit these properties for several busses at the same time in the Multi Editor. Multiselect the busses in the Audio tab of the Project Explorer and from the shortcut menu, choose Show in Multi Editor. You can also tweak and fine-tune these properties in real time while connected to your game.
To define the relative properties of a bus:
Load a bus into the Property Editor.
Type a value or drag the corresponding slider to set a value to one of the relative properties.
![[Note]](/images/2023.1.8_8601/?source=Help&id=note.png)
Note Pitch should not be applied to busses through which music objects are routed. Music objects will not be affected by any changes made to pitch in an Audio Bus.
At some points in your game, certain audio signals need to be brought to prominence. Ducking allows you to do this by automatically lowering the volume of objects passing through one or more busses, depending on the signal of another bus. For example, while characters are speaking, background music is lowered. When the characters stop speaking, background music is restored.
In the timeline that follows, when the current bus plays a sound, other busses fade out, according to the Fade Out and Volume parameters. When the sound from the current bus ends, the Recovery time elapses, followed by the Fade In.
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| Note |
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An alternative to auto-ducking is side-chaining with the Meter Effect plug-in. This method changes the level of the target bus dynamically, according to the level of the source bus. This offers more control than auto-ducking, where the ducked bus is lowered by a predetermined amount anytime there is sound on the current bus, regardless of the level of that sound. For more information, see Using side-chaining and Meter. |
To duck a bus:
Load a bus into the Property Editor. This is the current bus. It causes other busses to have their volume lowered, or ducked. Ducking is not available for Auxiliary Busses.
In the Auto-ducking tab, click Insert.
In the Project Explorer - Browser that opens, select the bus to be ducked when the current bus receives a signal. A bus can't duck itself or its direct parent.
Click OK to add the selected bus to the pane.
Set the properties for the bus:
Volume: Amount by which the volume of the ducked bus is reduced when the current bus receives a signal.
Fade Out: Time to fade out from the original volume to the ducked volume.
Fade In: Time to fade back to the original volume.
Curve: Curve shape used to define the fade-out and fade-in.
Set the collective properties for all busses in the pane:
Recovery time: Amount of time you want to pass from the termination of the current bus signal to the beginning of the fade-in for the signals that were ducked.
Maximum ducking volume: Maximum amount by which the volume of the busses listed in the pane can be lowered by the current bus.
The Xbox One, Xbox Series X, PlayStation 4, PlayStation 5, iOS, and Android platforms allow their game players to replace the game music with their own. For all platforms, you must enable the Mute for Background Music option on all the busses you want to mute when the user's music starts. Multiple busses can be selected and this is not restricted to music busses.
To assign a bus to a platform's background music option:
Load an Audio Bus into the Property Editor.
Select the Mute for Background Music option.
This bus will now be muted when users start their music through the console's music player.
The behavior of Mute for Background Music is slightly different on each platform. Also, additional programming needs to be done at the initialization of the sound engine.
Android: The Mute/Unmute action will occur only when the user switches from the music player app to the game. This means that there is no "Unmute" if the user music finishes by itself.
iOS: If the AudioSession flag "MixOther" is set in the sound engine initialization settings, the Mute/Unmute action will occur only when the user switches from the music player app to the game. This means that there is no "Unmute" if the user music finishes by itself. On iOS 8 and later, if the AVAudioSessionCategoryAmbient category is used, muting and unmuting of the game music will occur for all application audio interruptions.
Xbox One, Xbox Series X, PlayStation 4, and PlayStation 5: Some platforms have a DVR function that allows the gamer to record their gameplay and publish it. This raises a few legal issues regarding copyrighted music that might be part of the game audio, or user-replaceable music. While the game studio has the rights to use the music in their game, the end-user may not have the rights to distribute it in any form. Thus, the platform requirements usually state that user background music should not be recorded. The cost-effective solution (CPU-wise) for this problem is to mix the music separately from the rest of the game. This is done using the Secondary Output feature.
Xbox One, Xbox Series X, PlayStation 4, and PlayStation 5 provide a virtual device to which to send the sounds that should not be recorded. You will need to create a new master bus to be able to define a different mix for this DVR-bypass Audio Device. Then change the Audio Device property on that new bus to point to the DVR-bypass device. Then the sounds can be routed normally to the new bus, or any child bus. See Understanding secondary outputs for more information.
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