From alsa-devel-owner@alsa.jcu.cz  Fri Nov 27 21:23:19 1998
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	Fri, 27 Nov 1998 21:21:43 +0100
Date: Fri, 27 Nov 1998 21:21:43 +0100 (CET)
From: Jaroslav Kysela <perex@jcu.cz>
To: Andrew Clausen <clausen@alphalink.com.au>
cc: alsa-devel@jcu.cz
Subject: Re: Linux sound cards latency
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On Sat, 28 Nov 1998, Andrew Clausen wrote:

> > Yes, all things are true. Maybe I forgot add notice that my test program
> > measures only OS latency, not hardware latency. I don't know how to
> > measure complete latency without some analog device which will be
> > connected to soundcard's line-in and line-out.
> 
> Could you just measure the time between a peak on a feedback loop?  ie,
> program the sound card in full-duplex mode, send a beep, and wait for it to
> come back.  Ask the user to place the microphone as close to the speaker as
> possible.  This should give some kind of indication...

Direct connection between line-out and line-in should be better for this
purpose. I'm moving to solve another things, thus I probably don't write
this code (I hope that I show some way with alsa-lib/utils/latency.c), but
maybe someone on this list can do it...

							Jaroslav

-----
Jaroslav Kysela <perex@jcu.cz>
Academic Computer Centre, University of South Bohemia
Branisovska 31, C. Budejovice, CZ-370 05 Czech Republic


