Simulating Rapid Gunfire

Wwise SDK 2021.1.14

If you are working on a project that includes a firearm with a rapid rate of fire, such as a machine gun, it can be difficult to accurately synchronize the bullet sounds with the firing action. Because Wwise events are processed asynchronously on the audio thread, there might be a slight delay between the break action and the termination of a gunshot sound if you implement the sound through a Sample Accurate transition on a looping container.

To achieve a sample-accurate trigger rate with rapid gunshots, we recommend that you use MIDI to trigger each bullet sound. PostMIDIOnEvent makes it possible to respect the exact offset (in samples) within a given audio frame, which allows for high accuracy.

A MIDI-based solution requires the following:

Use one of the following options to manage audio rendering:
- Use the Global callback to post bullet events within that callback. Register the Global callback with Ak::SoundEngine::RegisterGlobalCallback.
- Manage the call to AK::SoundEngine::RenderAudio() yourself to place Play and Stop actions on the desired frame. Refer to the Audio Rendering Thread section in Custom Scheduling of Audio Rendering for details.
The Integration Demo contains a sample MIDI implementation that uses a metronome sound. You can apply the same principles to rapid gunfire. The relevant file is available at <WwiseInstallationFolder>\SDK\samples\IntegrationDemo\DemoMIDIMetronome.cpp and the corresponding documentation is available at Integration Demo Sample (see the MIDI API section).
The relevant APIs are PostMIDIOnEvent() and StopMIDIOnEvent().

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