[coco-devel] Re: Copter-Commander AL query

[David M. <dm-...@bo...>]

Garin Hiebert <ga...@tu...> wrote:
> David:
> 
> I took a look at Copter-Commander today, and have a few comments regarding 
> your request for help on problems with the OpenAL code.
> 
> The audio seems to be running better on my machine than on some that you 
> mention -- it's a 550MHz Athlon with a Geforce 2 for video and an SB Live for 
> audio.  I get 10-12 fps continuously when running the game.  Running either 
> esd or OpenAL audio, the game sounds pretty much the same, although it 
> appears that you're playing around with the audio positioning differently 
> with AL -- I didn't do enough testing to make sure on that.
> 
> When it comes to performance of the AL audio, one thing comes to mind which 
> may help out.  I note that whenever any audio is played, an un-used source is 
> being found, then the buffer for that effect is attached, then the source 
> played.  For instance, when the machine gun on a copter is being shot, a new 
> source is being used for each shot from the gun, which is requiring a lot of 
> searching through the available sources, attaching of buffers, and "play" 
> calls.
> 
> A couple of ways come to mind for reducing the number of AL calls.  The 
> simplest -- for this game -- would be to allocate one source for each sound 
> effect you might want to play.  It seems that you probably have few enough 
> effects that this would work.  Then there wouldn't be any searching for 
> sources or buffer attachment required when you want to play an effect.
> 
> If there aren't enough sources available or if you just want a more flexible 
> audio engine, then you probably want to at least re-work the engine so that 
> it will use single sources for as long as possible rather than continuously 
> churning through new sources while repeating a single effect.  Along these 
> lines, I'd be tempted to reserve some sources for popular effects such as the 
> weapons, and then do more sophisticated management of sources for 
> intermittent effects such as people yelling.

I tried your suggestion.  It works very well!  

I keep a couple of dedicated "bullet", "rocket hit", and "bomb hit"
sources, eliminating the alSourcei(AL_BUFFER) for these frequent sounds.
That completely eliminates the problem.

I added a "project thank you" for you here:
http://www.speakeasy.org/~morse/copter-commander/thanks.html