Focused reference · Unreal Engine 5.8
Audio Modulation, mixing, and Quartz
Audio Modulation
Enable the Audio Modulation plugin when shared dynamic mix control is needed. Build:
- Modulation Parameters with defined unit/normalized mapping.
- Control Buses for categories such as master, music, SFX, dialogue, ambience, or accessibility.
- Control Bus Mixes for gameplay/menu/state profiles.
- Modulation Destinations on MetaSound Sources, Sound Classes, Components, Submixes, or effects.
- Blueprint/C++ activation/update/clear ownership and debugging.
Routing can Disable, Inherit, Override, or Union at supported destinations. Sound Class hierarchy is not automatically equivalent to modulation routing; assign required buses deliberately. When an API edits only the UObject representation, use the appropriate Update call to push it to the audio-thread proxy.
Use MetaSound Get Modulator Value/Mix Modulators when the graph must react to a bus. Modulation is
block-rate, not sample-rate. Use graph/audio-rate signals for true audio-rate modulation.
Mix hierarchy
Protect critical cues through class/submix routing, concurrency priority, headroom, ducking, and state mixes. Test the whole combat/ambience/music/dialogue mix, not soloed assets. Provide category volume controls and non-audio equivalents for critical signals.
Quartz
Use Quartz clocks for beat/bar/subdivision-aligned scheduling. Keep transport/clock ownership stable, schedule sufficiently ahead for the audio renderer, and define pause, tempo change, world transition, and late-event behavior. MetaSound produces/varies sound; Quartz owns musical-time scheduling.