From alsa-devel-owner@alsa.jcu.cz  Sat Jan  9 21:47:59 1999
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To: alsa-devel@alsa.jcu.cz
Cc: Benjamin GOLINVAUX <golinvaux@benjamin.net>
Subject: Re: Hi - need some help? 
In-reply-to: Your message of "Sat, 09 Jan 1999 16:55:13 GMT."
             <369789F1.9A0B0477@benjamin.net> 
Date: Sat, 09 Jan 1999 15:46:39 -0500
From: Paul Barton-Davis <pbd@op.net>
Reply-To: alsa-devel@alsa.jcu.cz
Sender: alsa-devel-owner@alsa.jcu.cz
Precedence: list

>_but_ I'm pretty sure Linux CAN be tailored for real time audio stuff...
>After all, a good PII 450Mhz with a fast PCI audio card can make
>real-time effects WITH REAL TIME OS.
>
>The key point here is : Is it possible to reduce the latency down to
>1-5ms by using real-time Linux extensions... If it is possible, then we 
>could imagine AT LEAST that a virtual studio is possible.

Its not latency that is the heart of the problem. The difficulty is
whether the scheduler gets in the way at a critical moment. Buffering
and the like can help reduce the possibility of this being an issue,
but it cannot be eliminated.

Also, the RT stuff for Linux are not "extensions". RT Linux is a
different bag of wax completely, and KURT, well I don't know enough
about KURT. The SCHED_FIFO stuff works well, but it still doesn't do
what you need for a fault-free audio environment.

>Do you see as possible a hot band on stage feeding streams of data in a
>hotter 4 cpu/xeon/2Mb L2 linux station with some cooool effects
>(whatever the audio card... just need some low latency circuitry for
>digital output) ???

Well, personally, I'm hoping like crazy that my dual PII-450 machine
is going to be up for replacing several racks-worth of analog and
digital FX and other audio processing modules. I think (and this is
just a guess) that it should be possible on this kind of h/w to 
do "RT" synthesis and "RT" FX simultaneously. If not, I've wasted my
dollars :)

--p

