AVAudioPlayer rate

audio-processing, avaudioplayer, avfoundation, avplayer, ios

Solution

here is some code that i know works, just re-tested in an app i've been working on. as you mention, using `setEnableRate:` and `setRate:` will only work with iOS 5.0 and above. so i use `respondsToSelector:` to test on the device whether or not the device will accept the request:

_noticeAudio = [[AVAudioPlayer alloc] initWithContentsOfURL:[NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"Rooster-mono" ofType:@"wav"]]
                                                      error:nil];;
if ([_noticeAudio respondsToSelector:@selector(setEnableRate:)])
    _noticeAudio.enableRate = YES;
if ([_noticeAudio respondsToSelector:@selector(setRate:)])
    _noticeAudio.rate = 2.0;

running on an iOS 5 device, it performs the double-rate successfully. running on iOS 4.3, it plays it at normal speed.

so, the only way you'll get the proper rate is if your device has iOS 5 on it.

Problem

So I'm trying to play a sound file at a different rate in iOS 5.1.1, and am having absolutely no luck. So far I have tried setting the rate of the AVAudioPlayer: ``` player = [[AVAudioPlayer alloc] initWithContentsOfURL:referenceURL error:&error]; player.enableRate = YES; player.rate = 1.5; player.numberOfLoops = 0; player.delegate = self; [player prepareToPlay]; [player play]; ``` with no luck at all, the sound plays but just ignores the rate I give it. I have also tried AVPlayer: ``` avPlayer = [[AVPlayer alloc] initWithURL:referenceURL]; avPlayer.rate = 0.5; [avPlayer play]; ``` Again, it plays but just ignores the rate I set. I have tried a number of different audio files but for the sake of this thread I selected Rooster-mono.wav from this catalogue: http://sig.sapp.org/sounds/wave/ Has anybody had any success with changing the playback rate on iOS 5.1.1? Or does anybody know what I am missing here? I am doing this to change the pitch slightly of some of my samples, I realise I could do this by using RemoteIO or something similar but that seems total overkill for what I am trying to achieve (a simple playback rate adjustment).

Original source