Hello,

I'm trying to get consistant behavior out of the kAudioSessionProperty_OtherMixableAudioShouldDuck property on the iPhone to allow iPod music blending and I'm having trouble. At the start of my app I set an Ambient category like so:

-(void) initialize
{
 [[AVAudioSession sharedInstance] setCategory: AVAudioSessionCategoryAmbient error: nil];
}

Later on when I attempt to play audio I set the duck property using the following method:

//this will crossfade the audio with the ipod music
- (void) toggleCrossfadeOn:(UInt32)onOff
{
 //crossfade the ipod music
 AudioSessionSetProperty(kAudioSessionProperty_OtherMixableAudioShouldDuck,sizeof(onOff),&onOff);
 AudioSessionSetActive(onOff);
}

I call this passing a numeric "1" just before playing audio like so:

  [self toggleCrossfadeOn:1];
  [player play];

I then call the crossfade method again passing a zero when my app's audio completes using a playback is stopping callback like so:

-(void) playbackIsStoppingForPlayer:(MQAudioPlayer*)audioPlayer { NSLog(@"Releasing player"); [audioPlayer release]; [self toggleCrossfadeOn:0]; }

In my production app this exact code works as expected, causing the ipod to fade out just before playing my app's audio then fade back in when the audio finishes playing. In a new project I recently started, I get different behavior. The iPod audio fades down and never fades back in. In my production app I use the AVAudioPlayer where in my new app I've written a custom audio player that uses audio queues. Could somebody help me understand the differences and how to properly use this API?