[Openal] Sound stuttering for small buffer sizes in hardware OpenAL implementation for Audigy SE

[Thilo Schulz]

Hello,

I have a user who uses the "Sound Blaster Audigy SE".. when he uses one of the 
two upper native devices:

Lautsprecher (SB Audigy)
Digitale Audioschnittstelle (SB Audigy)
Generic Software

the background music playing in the game stutters. Generic Software plays 
fine.

There are 4 buffers which are queued, unqueued, refilled with data and 
requeued, and always chunks of 4096bytes of 44khz sampled 16 bit pcm stereo 
data are fed to each buffer. The buffers should be refilled right on time, 
there is always enough data available, there is only one or two buffers 
consumed after each frame so all should be fine. Still, the sound stutters.
It seems to me as though the hardware OpenAL device would not be able to 
correctly switch in time to the next queued buffer if each buffer is only 
4096 bytes large (meaning 1024 samples). Doubling the buffer size to 8192 
gets rid of the problem.

Now I am left wondering: why does it work on Generic Software but not 
Hardware? What would be a good buffer size to use to make sure that it works 
on all hardware?

-- 
Thilo Schulz
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