Subject: Re: [linux-audio-user] ALSA PCM OSS layer -> high latencies?
From: dave willis (dubson_AT_dhammanet.net)
Date: Tue Sep 25 2001 - 12:51:20 EEST
On Sun, 23 Sep 2001, Andre Pang wrote:
> With some major help from some real kernel gurus, I finally
> tracked down why I was getting _huge_ latencies in (Benno
> Senoner's) latencytest.
>
> I was using ALSA's snd-card-ymfpci driver for my YMF744B chip and
> had latencytest running using ALSA's OSS PCM emulation.
>
> Of course, I can't be sure whether the source of latency is from
> the snd-card-ymfpci driver or from snd-pcm-oss, but I'd guess it's
> the latter.
it seems to be snd-card-ymfpci, as i just bought an m-audio audiophile
2496 (ice1712/envy24 chip), and i have wonderful results with alsa and
oss-emulation (actual oss has one overrun of 86 ms on the 2nd sample when
initialised). the problem when using snd-card-ymfpci is that the fragment
size is always 1024, and that's too high (256 is better) but is not
changable under oss-emulation. it is changable with snd-card-ice1712.
so, it's not alsa in general, but just certain chips.
fwiw,
dave
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