Slow start for AVAudioPlayer the first time a sound is played

user_337184 0
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I'm trying to eliminate startup lag when playing a (very short -- less than 2 seconds) audio file via AVAudioPlayer on the iPhone.

First, the code:

NSString *audioFile = [NSString stringWithFormat:@"%@/%@.caf", [[NSBundle mainBundle] resourcePath], @"audiofile"];
NSData *audioData = [NSData dataWithContentsOfMappedFile:audioFile];

NSError *err;
AVAudioPlayer *audioPlayer = [(AVAudioPlayer*)[AVAudioPlayer alloc] initWithData:audioData error:&err];

audioPlayer.delegate = self;
[audioPlayer play];

I also implement the audioPlayerDidFinishPlaying method to release the AVAudioPlayer once I'm done.

The first time I play the audio the lag is palpable -- at least 2 seconds. However, after that the sound plays immediately. I suspect that the culprit, then, is the [NSData dataWithContentsOfMappedFile] taking a long time reading from the flash initially, but then being fast on later reads. I'm not sure how to test that, though.

Is that the case? If so, should I just pre-cache the NSData objects and be aggressive about clearing them in low memory conditions?

avaudioplayer nsdata audio caching iphone
9 Answers

I don't know for sure, but I suspect the NSData object is being lazy and loading the contents of the file on demand. You can try "cheating" by calling [audioData getBytes:someBuffer length:1]; at some early point to get it to load that file before it's needed.

user_1039340
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