[AG-TECH] Echo from US sites

Michael Miller mimiller at ncsa.uiuc.edu
Thu Oct 26 15:28:25 CDT 2006


Once RAT is started, the venue servers play no role in communicating 
audio data.  So you can remove them from consideration.  Look more 
closely at what's going on with each sites' sound card.  The AC97 chip 
that exists in most sound cards has a loopback that needs to be muted.  
Usually, this can be done by opening the (Windows)Volume Control panel 
and muting the Microphone channel listed in the playback items.(Why it's 
there I don't know...).  I've also had reason to bring the volume slider 
on that channel down to 0.  On Linux there's a loopback channel labeled 
more precisely and this should be treated the same.

Beyond that, the problem would lie in the network, though I've never 
seen the network -cause- echo.  It's usually in the sound card.

Let me know when you experience the problem and I can drop in and take a 
listen if I'm available.


Joseph Stone wrote:
> For the last couple of days, our UK partners are experiencing echo from US
> sites using either AGTK 2.4 or InSORs software.  Two US venue servers were
> tested.  I had the site start up Windows Media player and listen to the BBC
> news over an internet connection - no echo.  I had the site listen to a US
> radio program also streamed over an internet connection to Media Player -
> echo.
> All traffic was unicast.
> Anyone experience this before?  Anyone in the UK currently seeing (hearing)
> this phenom right now?
> Joe
> Joseph Stone 
> Senior Informatics Manager 
> Family Medicine Community Health, Medical School, Univ. of Minnesota 
> Suite 220 Dinnaken 
> 925 Delaware St. SE 
> Minneapolis, MN 55414 
> (612) 624-3192 
> stone004 at umn.edu


Michael Miller
System Engineer
Video Technology Services
Persistent Infrastructure Directorate
National Center for Supercomputing Applications
University of Illinois - UC

"If you're clear in your vision and trust the people in your team with clear objectives, they will invariably do their best to achieve everything desired, and usually deliver everything you could have hoped for and even more." -Paul Debevec

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