Subject: Re: [linux-audio-dev] RFC: API for audio across network - inter-host audio routing
From: Joern Nettingsmeier (nettings_AT_folkwang-hochschule.de)
Date: Fri Jun 14 2002 - 14:31:25 EEST
Men Muheim wrote:
>
> > Thats true, but doesn't match my experience of trying to play with 512
> > sample buffers... although that probably doesn't equate to 512 samples
> of
> > latency, its probably more.
>
> It is more indeed!
>
> An ALSA audio interface normally uses two double-buffers. One for the
> input and one for the output. 512 samples is the size of one half of the
> double buffer. Therefore the minimum delay in your test was 2*512/48kHz
> = 21.3ms. Usually the ADC/DAC adds another 1-2ms.
now that i read this, i probably need to correct my "comfortable
latency" estimate by a few msec, but the basic point still stands.
btw, when i do P.A. jobs, i have taken to setting up delay lines by ear,
and only measure the distance afterwards to check. guess what ? i'm
always correct within 3 msec, a little worse if the room has a lot of
reverb.
it's not hard to hear. at more than 5-8 msec, you feel that beats become
fuzzy, and below that, you can judge by sound coloration (comb filter).
granted, it's a slightly different situation, since you have both a
delayed and an undelayed signal combined, but it goes to show you can
hear quite a bit. i know a drummer who claims to listen for the sound
color of snare and ride together to check if he's in sync...
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