MP3 playback causing poor performance.

[Duncster2k4]

Hi all,

I have a game which is running using a timer quite happily at 30fps. I have just tried adding playback of a local ambient MP3 track, but the performance of my game takes quite a hit, and becomes noticeably slower.

My question is, how *should* I be going about playing back an MP3?

Cheers,

D.

[Bersaelor]

For all I know the iPhone only has hardware support to play one compressed-audio-file at a time. (i.e. mp3)

I use an AVAudioplayer to play mp3 music only when the iPod is currently not playing any other music. So for me, using AVAudioPlayer means no performance difference, as long as one makes sure only one mp3 is currently playing. Starting a second AVAudioPlayer means the second song gets decoded by the software, which is computation-intensive. (Remember the users iPod App may be playing in the background when your app is started).

For Effects I use "AudioServicesPlaySystemSound" which doesn't interfere with performance either, but the effects then need to be uncompressed and less then 5 secs. A nice file format for uncompressed audio files seems to be "caf" which can be made from a wav but is considerably smaller even without compression.

[Centurion Games]

Originally Posted by Duncster2k4

Hi all,

I have a game which is running using a timer quite happily at 30fps. I have just tried adding playback of a local ambient MP3 track, but the performance of my game takes quite a hit, and becomes noticeably slower.

My question is, how *should* I be going about playing back an MP3?

Cheers,

D.

Make sure your audio session is set up to Ambient Solo and that your only playing one track, this will utilize the hardware. Still though even with hardware use MP3 playback takes quite a bit of utilization. We've noticed playback generally causes a 5-8fps drop, so it really depends on how much headroom you have above 30fps. For instance if your game could run at 40-50fps but you have it capped at 30fps you probably won't see a problem. On the other hand if your barely making 30fps, your going to be dipping down into mid and low 20's most likely.