RE: Streaming WAVE audio

"Jon Watte" <[email protected]>
Newsgroups gmane.games.devel.windows
Message-ID <[email protected]>
> 2) On some system there appears to be a minimum required buffer size,
> e.g. at least 250ms. On systems like these I got silence at best, and
> lock up at worst. I didn't spend a lot of time investigating this
> because 250ms is pretty short buffer. I was shooting for 4/8/16k buffer
> sizes at that time. In the end I don't think it matters.

250 ms is a REALLY BIG buffer. 250 ms of latency means you pull the trigger
now, and hear the gunshot sound when the target's already dead. (When I say
"buffer" I really mean "WAVHDR chunk").

I've found that once I went above 40 ms buffers, and used at least 3
buffers, any hardware I tested on worked well. Less that that in either
variable caused problems. Note that the scheduler on Win98 is VERY
jittery -- 20 ms scheduling jitter is common, and it can jerk higher than
that, even on a quiescent system with a fast CPU.

> Furthermore I recommend not using the ACM to up/down sample as it
> appears to perform point sampling(!) which can produce terrible audio.

I always code my own re-sampler, which sits at the reader/input stage of the
mixer, which I also code on my own, for the WAVE output. I prefer to use
cubic Hermite interpolation, which runs fast and sounds good.

Cheers,

			/ h+



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