Hi folks, I’m writing a plugin that lets you execute gameplay using your microphone.
Full source code available on GitHub.
I’m using delegates, my idea was to bind gameplay code to a delegate and execute it from the audio thread.
Here’s my audio input subsystem
// ...
void UAudioInputSubsystem::Initialize(FSubsystemCollectionBase& Collection)
{
Audio::FAudioCaptureDeviceParams Params;
Params.DeviceIndex = 0;
EnvelopeFollowerInitParams.AttackTimeMsec = 0.5f;
EnvelopeFollowerInitParams.ReleaseTimeMsec = 1.0f;
EnvelopeFollowerInitParams.AnalysisWindowMsec = 2.0f;
EnvelopeFollower = Audio::FEnvelopeFollower(EnvelopeFollowerInitParams);
const FOnSoundDelegate& Delegate = OnSoundDelegate;
Audio::FOnCaptureFunction OnCapture = [this, Delegate](const float* AudioData, int32 NumFrames, int32 NumChannels, int32 SampleRate, double StreamTime, bool bOverFlow)
{
EnvelopeFollower.ProcessAudio(AudioData, NumFrames);
const TArray<float>& EnvelopeValues = EnvelopeFollower.GetEnvelopeValues();
for (const float Value : EnvelopeValues)
{
const float Amplitude = FMath::Abs(Value);
if (Amplitude > FilterThreshold)
{
FAudioThread::RunCommandOnGameThread([Delegate, Amplitude]()
{
Delegate.Broadcast(Amplitude);
});
}
}
};
bool IsOpen = AudioCapture.OpenCaptureStream(Params, MoveTemp(OnCapture), AudioBufferSize);
if (IsOpen)
{
AudioCapture.StartStream();
}
}
And here’s how I bind the gameplay code to the delegate in a game mode
void AVoicerinoGameModeBase::BeginPlay()
{
const auto GameInstance = UGameplayStatics::GetGameInstance(GetWorld());
UAudioInputSubsystem* AudioInput = GameInstance->GetSubsystem<UAudioInputSubsystem>();
AudioInput->OnSoundDelegate.AddDynamic(this, &AVoicerinoGameModeBase::InputReceived);
}
void AVoicerinoGameModeBase::InputReceived(float Amplitude)
{
DrawDebugPoint(GetWorld(), FVector(0,0, 50.f), 30.f, FColor::White);
UNiagaraFunctionLibrary::SpawnSystemAtLocation(GetWorld(), NiagaraSystemToSpawnOnAudioInputReceived, FVector());
}
It works if I log to the console, but crashes if I try to spawn a particle system (e.g. anything gameplay thread related). How can I call gameplay code without getting this crash?
