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Hi Guys,
I am working on a music composition game where user can arrange sound pieces to make a song. However, currently I face a lot of delay when individual pieces are loaded/played when user plays back a song. Any ideas would be really appreciated.
NOTE: I am working in UIKit and I was thinking I could use a different sound engine then SystemSounds or AVAudioPlayer, so that's why posting question to cocosDenshion :-)
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M
Steve Oldmeadow
Administrator
How are you currently playing the sounds? It isn't clear from your question.
Steve Oldmeadow
Administrator
Well, you could give CocosDenshion a try. I see a few problems. Firstly, if you want low latency then you need to load the sounds into memory. This means you are likely to use a lot of memory for something like a song, it really depends how long the song is and how much repetition of the sub pieces there is.
Secondly, stringing the pieces together might be difficult. There is no method in CocosDenshion to trigger a sound as soon as another one finishes. You can poll to determine when a sound has stopped playing, however, that means there could be a delay up to the duration of your polling interval before the next sound starts. Polling is also very inefficient.
If you could afford it I would seriously look at fmod for something like this: http://www.fmod.org
Hi Steve,
thanks for the suggestion but 1) I can't afford fmod. 2) Polling seems like no way to go.
Song is not very long, about 1 minute of music at most, so I can load all the pieces in memory at once if somehow AVAudioPlayer had let me do that (which it doesn't). is there any other good sound engine (may be OpenAL based) which has callbacks for audio finished?
OR if CocosDenshion lets me extract the duration of a piece say 20 seconds, I could use performSelector:WithDelay: which might be a little better than polling?
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MI
Steve Oldmeadow
Administrator
@malik - OpenAL doesn't support call backs for audio completion, otherwise I would have added it to CocosDenshion.
You can extract the duration of an audio file using methods in the AudioToolbox framework - I can't tell you off the top of my head though. However, performSelector:WithDelay is not going to be adequate for a music application in my opinion. You need really tight timing for music.
Apple's Metronome example is a good starting point for looking at how to do accurate timing - basically you need another thread dedicated to timing. If your sub pieces are as long as 20 seconds then you could combine a delay plus polling at around about the time you expect the sound to finish and drive the whole thing from an accurate timing thread as per the Metronome example.
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