[Openal] Performance testing

[Chris Robinson]

On Tuesday 29 July 2008 06:59:20 am Stevens, Peter wrote:
> Any ideas on the approximate cost or extra expenses incurred for
> upgrading to multi-channel audio ?

For OpenAL Soft itself, not much. Just a couple more sqrtf calls per playing 
source, and a little more memory transfering (and extra memory from the sound 
card/audio system). The sensitive mixing loop is the same regardless of 
output channels, and the added source calculations are small next to the 
other calculations it must do (distance attenuation, directional cones, 
doppler shift, etc).

Comparing the SI's output to OpenAL Soft's output is just like night and day. 
The SI almost always has issues keeping the card updated so it doesn't skip, 
while I've yet to hear OpenAL Soft skip once from CPU usage issues.. and that 
seems to be the experience most often mentioned from people moving to OpenAL 
Soft from the SI. Since OpenAL Soft's sensitive loops are invariant WRT 
output mode, going between stereo and >2 multi-channel won't change much in 
CPU use.