Lesson 8

Table of Contents

Creating a Bus Structure

You’ve spent the last seven lessons building the music structure for Cube. This structure was as much organizational as it was functional, with the primary function of the structure controlling the behavior of how the music plays during the game. What that structure has not really addressed is the audio signal structure. All audio signals in Wwise must eventually flow through one of the Master Busses found in the Master-Mixer Hierarchy in order for them to be heard at run time.


Refer to the Wwise-101 Lesson 5 - Understanding Audio Signal Flow to review how bussing and bus structure works in Wwise.

Currently, every object is sending its signal directly to the Master Audio Bus, where it’s combined with all of the other sounds being produced in the game. The Master Audio Bus can be seen by expanding the Default Work Unit in the Master-Mixer Hierarchy.

  1. Open the Lesson 8 project.

  2. In the Project Explorer, expand the Default Work Unit and then further expand the Master Audio Bus and the Environments bus and SFX bus contained within.

    If you look at the structure used for the sound effects already present in the project, you can see that there are different Audio Busses that control specific types of sounds, like sound effects or voice for spoken word. This provides a way to easily manipulate all of the sounds assigned to the bus, like offsetting volume of the sound effects from the dialogue. This same kind of control can be useful for the music. For example, it makes sense to have a separate music bus so that the music could easily be turned up or down in relationship to the other types of sounds. Furthermore, you have to consider that you may want to make global changes to the different segments of music, such as changing the relational volume of the Explore music compared to the Combat music. To accomplish this, you’ll create an Audio Bus structure within the Interactive-Music Hierarchy specifically for the music you’ve integrated.

    Unlike other hierarchies where you’ve created work units specifically for music related objects, only the Default Work Unit is available in the Master-Mixer Hierarchy. For this reason, you’ll place the Music Bus as a child within the Master Audio Bus.

  3. Collapse the Environmental Audio Bus, then select the Master Audio Bus and right-click to choose New Child > Audio Bus.

  4. Name the new Audio Bus Music.

    The new Music Audio Bus is created.

    Cube is a game that has various maps, where each map might have differing music. The map you’ve been working on is the Wwise 201 Music map designed specifically for this tutorial. You can imagine that music composed for various maps may not quite match each other in volume, so having an Audio Bus just for the Wwise 201 Music would make it very easy to make global adjustments to the Wwise 201 map music.

  5. Create a Wwise 201 Music Audio Bus within the Music Audio Bus you just created.

    In a similar way, it’s helpful to have Audio Busses for the various types of music used with the Wwise 201 map, such as Combat and Explore.

  6. Select the Wwise 201 Music Audio Bus, click the Create New Bus icon, and name the new bus Combat.

  7. Repeat this process for Explore, Boss, Story, Death, and Victory.


    As you create the Audio Busses, the order may not appear in the same order as displayed in the preceding image. While this has no effect on the functionality of the busses, you can force the objects into alphabetical order by collapsing and then expanding the parent object.

    While you’ve created a bus structure, all of the objects in the Interactive Music Hierarchy are still assigned directly to the Master Audio Bus. You’ll need to assign the Music Playlist Containers in the Interactive Music Hierarchy to their respective Audio Bus.

  8. In the Interactive Music Hierarchy, expand the Wwise 201 Music Music Switch Container and select the Boss Music Playlist Container.

    In the Property Editor, you see that the Output Bus assignment is grayed out and set to Master Audio Bus. This is because the property is being inherited from its parent, the Wwise 201 Music Music Switch Container. You’ll need to override the value to assign it to the Boss Audio Bus you created.

  9. In the Property Editor’s Output Bus group box, click the Override parent check box, then drag the Boss Audio Bus to the assignment field.

    Because of the inheritance system, all objects contained within the Boss Music Playlist Container are automatically assigned to the Boss Audio Bus.

  10. Reassign the Output Bus for the Explore, Combat, Story, Victory, and Combat Music Playlist Containers.

    The only remaining items in the Interactive Music Hierarchy are the Stingers. The Stingers could play over various types of music, so you’ll assign them directly to the Wwise 201 Music Audio Bus.

  11. Assign each of the objects in the Stingers folder to the Wwise 201 Music Audio Bus.

    While you’ve made all of the appropriate assignments in the Interactive Music Hierarchy, there’s one other set of sounds that still needs to be reassigned. The synth and sampler objects you built in the Actor-Mixer Hierarchy for the Boss music’s MIDI tracks need to also be assigned to the Boss Audio Bus.

  12. Assign the Boss-D Suling Samples to the Boss Audio Bus.

  13. Assign the Arpeggio Synth and Melody Synth objects to the Boss Audio Bus.