From alsa-devel-owner@alsa.jcu.cz  Wed Jan  6 17:52:42 1999
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Date: Wed, 6 Jan 1999 11:55:54 -0500 (EST)
From: Fred Floberg <emng@geocities.com>
To: alsa-devel@jcu.cz
Subject: ALSA lib documentation
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On Wed, 6 Jan 1999 perex@jcu.cz wrote:

> ALSA driver hides things like IRQ etc... We have new document for alsa-lib

I've searched your web/ftp sites and haven't been able to find any new
documentation for alsa-lib. Are you referring to the documentation provided
with older releases of alsa-lib?

> functions which explains more things about ALSA buffering, but seems that
> person which does corrections (English isn't my native language) is very
> busy.. Any volunteer?
> 

I can help out here. Just point me to the new documentation and allow me
an occasional question or two.

> I think that ALSA offers sufficient support for PCM recording/playback
> with enhanced buffer control (you can set both low and high wakeup
> watermarks) and overrun/underrun detection for application.

I've been working at trying to implement true quad+ audio output in Csound
using two or more soundcards lately with limited success (plain stereo works
fine and dandy). The problem has been that Csound relies on the delay inherent
in audio writes to establish it's timing (tempo). I've tried all sorts of tricks
using the info returned from snd_pcm_playback_status() in an attempt to generate
the delay that Csound is expecting with no luck. It seems that ALSA blocks until
data has been moved from user land to the sound card's buffer(? but I'm not
sure) and so returns much sooner than if it blocked until that data had actually 
been played. If the new document you mention above has an expanded explanation
of these timing/buffering issues that would be a big help, to me at least.

> 
> 							Jaroslav


Fred



