Subject: [linux-audio-dev] Re: [Alsa-devel] Re: more bad low latency results
From: Maarten de Boer (maarten.deboer_AT_iua.upf.es)
Date: Thu Nov 15 2001 - 20:17:19 EET
> Or, will you try AA patches? It's not a bad idea, since the current
> (vanilla) VM is based on Andrea's code. Linus still doesn't include
> all his patches.
Yes, I will try the AA patches, though I am not very sure which to use,
and on which kernel. The most recent one on a standard kernel (and not
on a pre-release) seems to be
http://kernel.org/pub/linux/kernel/people/andrea/patches/v2.4/2.4.12aa1.bz2
Or do you think it is better to jump into the deep, and try to apply
2.4.15pre1aa1.bz2 on 2.4.14 ?
> Maybe my 2.4.13 LL patches at
> ftp.suse.com/pub/people/tiwai/suse-patches can be applied without
> rejection.
> > It's a different problem. The alsa capture adds random values at
> > random places (not periodically as for a I can see) in a way that
> > it sounds like a dusty vinyl record. This doesn't happen when I
> > use arecord, it only happens with the alsa-lib/test/latency. I write
> > each captured buffer to disk, and the random values are clearly
> > visible (and hearable). It happens both in non-block and in poll mode.
>
> Hmm sounds like h/w problem, then..
> It's interesting to know where the data is contaminated, whether on
> the driver level or transfer between capture and playback on
> user-space, or what else..
I would say on driver level: I write the data to disk right after the
snd_pcm_readi call.
Maarten
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