Observing CurrentPlayTime in AUScheduledSoundPlayer
Observing CurrentPlayTime in AUScheduledSoundPlayer
- Subject: Observing CurrentPlayTime in AUScheduledSoundPlayer
- From: "Stephen F. Booth" <email@hidden>
- Date: Thu, 31 May 2007 12:50:08 -0700
Hello all,
I'm using an AUScheduledSoundPlayer to feed an AUGraph, and I would
like to have an UI indication of playback position. Is there a way
to observe changes in kAudioUnitProperty_CurrentPlayTime without
polling? I've tried using AUEvents, but my callback is never called
even when I know the property is changing (because audio is
playing). Here is how I register for the event:
AudioUnitEvent propertyEvent;
propertyEvent.mEventType = kAudioUnitEvent_PropertyChange;
propertyEvent.mArgument.mProperty.mAudioUnit = _generatorUnit;
propertyEvent.mArgument.mProperty.mPropertyID =
kAudioUnitProperty_CurrentPlayTime;
propertyEvent.mArgument.mProperty.mScope = kAudioUnitScope_Global;
propertyEvent.mArgument.mProperty.mElement = 0;
err = AUEventListenerAddEventType(_listener, NULL, &propertyEvent);
I was under the impression (after some googling and reading the list
archives) that anytime an AudioUnit property changes, a notification
should be generated, so I'm stumped. I also tried using
AudioUnitPropertyListeners directly, but couldn't get that to work
either.
Currently I'm using an NSTimer that fires every so often to query the
property and causes an UI update- which works- but I don't like it.
Stephen
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