Question

I’m struggling with an AudioQueue audio player I implemented. I initially thought it was truncating the 1st 1/2 of audio that it played but upon loading larger files I notice gaps every other 1/2-1 second. I’ve run it in debug and I’ve confirmed that I’m loading the queue correctly with audio. (There are no big zero regions loaded in the queue.) It plays without issue (no gaps) on the simulator but on device I get gaps as if its missing every other chunk of audio. In my app I decompress then pull audio from a memory NSMutableData object. I feed this data into the audio queue. I have a corresponding implementation in the same app that plays wave audio and this example works without issue on long and short audio clips. I’m comparing the wave implementation to the other which does the decompression. the only difference between the two is how I discover the audio meta data and where I get the audio samples for enqueuing. In the wave implementation I use AudioFileGetProperty and AudioFileReadPackets to get this data. In the other case I derive the data before hand using cached ivars loaded during callbacks from my decompressor. The meta data matches for both compressed and wave implementations. I’ve run the code in instruments and I don’t see anything taking more than 1ms in my audio packet delivery/enqueuing logic during playback. I’m completely lost. Please speak up if you have any idea how to solve the situation.

Answer 1

I finally resolved this issue. I found that if I skipped the 1st 44 bytes (the exact size of a wave header) of audio then it plays correctly on the device. It pays correctly on the sim regardless of wether I skip 44 or not. Strange and I’m not sure why but that’s the way it works.