AVAssetReader and Audio Queue streaming problem

Question

I have a problem with the AVAssetReader here to get samples from the iPod library and stream it via Audio Queue. I have not been able to find any such example so I try to im

Answer 1

I was getting this same mystifying error. Sure enough, "setting up" an audio session made the error go away. This is how I set up my audio session.

- (void)setupAudio {
    [[AVAudioSession sharedInstance] setDelegate:self];
    [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryAmbient error:nil];
    NSError *activationError = nil;
    [[AVAudioSession sharedInstance] setActive: YES error:&activationError];

    NSLog(@"setupAudio ACTIVATION ERROR IS %@", activationError);
    [[AVAudioSession sharedInstance] setPreferredIOBufferDuration:0.1 error:&activationError];
    NSLog(@"setupAudio BUFFER DURATION ERROR IS %@", activationError);
}

Answer 2

Ok I have somehow solved this weird error... Apparently it is because of the audio session not properly set. Talk about lack of documentation on this one...

Answer 3

From the Audio Session Programming Guide, under AVAudioSessionCategoryAmbient:

This category allows audio from the iPod, Safari, and other built-in applications to play while your application is playing audio.

Using an AVAssetReader probably uses iOS' hardware decoder, which blocks the use of the AudioQueue. Setting AVAudioSessionCategoryAmbient means the audio is rendered in software, allowing both to work at the same time - however, this would have an impact on performance/battery life. (See Audio Session Programming Guide under "How Categories Affect Encoding and Decoding").