[AG-TECH] query re: delay
sondheim at panix.com
Mon Oct 2 04:02:30 CDT 2006
I'm pretty much an amateur at this; when I went to the Test Room the main
thing I noticed was a much clearer audio signal - the delay seemed about
the same. I measured the delay back and forth from Brooklyn to WVU in a
couple of ways - by comparing video and audio signals (Jimmie at the other
end would speak and wave something - I could tell the delay between the
two), as well as using our cellphones. The difference was palpable.
On Sun, 1 Oct 2006, John I Quebedeaux Jr wrote:
> The ISP could be employing some type of packet shaping that is queuing your
> various data streams. At least, i've had this happen at my university in the
> past and it manifested itself with my outgoing video and audio streams
> arriving at various times (generally intact, but sometimes slowed down or
> sped up as things caught up after being queued). My first stream had
> priority, but the rest did not.
> You can see the ports associated with the audio and video when you pull down
> the properties command under... i think it's under the file menu on the venue
> client. That may help if you can then look at the traffic associated with
> that port/ip.
> I'm also assuming you were bridging (unicast) as well. In general, the audio
> and video seem to be in sync simply due to network speeds and bandwidth on
> I2/etc. I believe. Also, your uplink bandwidth on your DSL is probably much
> lower than your downlink bandwidth causing some congestion on your outgoing.
> Were you exceeding your available bandwidth? Which way were you seeing the
> delays? Changing the location "room" wouldn't change anything except the
> ports you're sending/receiving on so I'd actually be surprised if it changed
> then. If you changed venue servers (went to NCSA instead) and saw a
> difference (like it went away) then that would be interesting to note. If i
> use my ADSL connection I have to VPN to my campus first out of my ADSL in
> order to get the ports i need in/out and through the nat'ing etc. And then a
> session could easily blow away my available (even my 6Mb downlink) bandwidth
> on the incoming not to mention there is no QoS if i'm not VPN'd.
> Just some thoughts from what little i know... John Q.
> John I. Quebedeaux, Jr.; Louisiana State University
> Computer Manager LBRN; 131 Life Sciences Bldg.
> e-mail: johnq at lsu.edu; web: http://lbrn.lsu.edu
> phone: 225-578-0062 / fax: 225-578-2597
> On Sep 29, 2006, at 7:11 PM, Alan Sondheim wrote:
>> I've been working on a PIG in Brooklyn, New York, through DSL, connected
>> through Argonne to an AG at West Virginia University, Morgantown. We're
>> using 2.4. My question - the sound delays approximately 7.5 seconds (the
>> video is about .5 which is understandable). What could cause such a large
>> delay? I don't think it's congestion; we tried the Lobby as well as the
>> Test Room; the results were the same. One reason I'm curious - I work at
>> times in sound and it would help to understand the mechanism here.
>> Thanks, Alan, sondheim at panix.com
>> blog at http://nikuko.blogspot.com - for URLs, DVDs, CDs, books/etc. see
>> http://www.asondheim.org/advert.txt - contact sondheim at panix.com, -
>> general directory of work: http://www.asondheim.org
>> Trace at: http://tracearchive.ntu.ac.uk - search "Alan Sondheim"
blog at http://nikuko.blogspot.com - for URLs, DVDs, CDs, books/etc. see
http://www.asondheim.org/advert.txt - contact sondheim at panix.com, -
general directory of work: http://www.asondheim.org
Trace at: http://tracearchive.ntu.ac.uk - search "Alan Sondheim"
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