WatchOutput works correctly on the initial play, but after calling SetSound and Play again, the output callback never fires.

Development Programming & Scripting C++
,
1

Hi,

I’m having an issue with UMetaSoundOutputSubsystem::WatchOutput() when changing a MetaSound dynamically on an UAudioComponent.

Issue

WatchOutput() works correctly on the initial play, but after calling SetSound() and Play() again, the output callback never fires.

Repro Code

C++


void UMyAudioComponent::SetMetaSound(USoundBase* NewSound)
{
    Stop();
    SetSound(NewSound);
    Play();

    GetWorld()->GetTimerManager().SetTimerForNextTick(
        this,
        &UMyAudioComponent::RegisterWatcher
    );
}

void UMyAudioComponent::RegisterWatcher()
{
    if (!IsPlaying())
    {
        return;
    }

    if (UMetaSoundOutputSubsystem* Subsystem =
        GetWorld()->GetSubsystem<UMetaSoundOutputSubsystem>())
    {
        Delegate.Unbind();
        Delegate.BindDynamic(this, &UMyAudioComponent::OnOutput);

        bool bResult = Subsystem->WatchOutput(
            this,
            TEXT("LastState"),
            Delegate
        );

        UE_LOG(LogTemp, Warning, TEXT("WatchOutput result: %s"),
            bResult ? TEXT("Success") : TEXT("Fail"));
    }
}

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Observed Behavior

  • First Play → :white_check_mark: callback fires

  • After SetSound() → :cross_mark: callback never fires again

  • WatchOutput() still returns true

Question

Is WatchOutput() expected to work after calling SetSound() on an existing AudioComponent, or is it only valid for the initial MetaSound instance?

Thanks!