Getting notified when a sound is done playing in OpenAL

Question

I'm using OpenAL on iPhone to play multiple audio samples simultaneously.

Can I get OpenAL to notify me when a single sample is done playing?

I'd like to avoid hardcoding the sample length and setting a timer.

Answer 1

If you have the OpenAL source abstracted into a class, I guess you can simply call performSelector:afterDelay: when you start the sound:

- (void) play
{
    [delegate performSelector:@selector(soundHasFinishedPlaying)
        afterDelay:self.length];
    …
}

(If you stop the sound manually in the meantime, the callback can be cancelled, see the NSObject Class Reference.) Or you can poll the AL_SOURCE_STATE:

- (void) checkStatus
{
    ALint state;
    alGetSourcei(source, AL_SOURCE_STATE, &state);
    if (state == AL_PLAYING)
        return;
    [timer invalidate];
    [delegate soundHasFinishedPlaying];
}

I don’t know how to have OpenAL call you back. What exactly do you want the callback for? Some things can be solved better without a callback.