[AG-TECH] query re: delay

[Alan Sondheim]

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.

- Alan


On Sun, 1 Oct 2006, John I Quebedeaux Jr wrote:

> Alan,
>
> 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"
>> http://clc.as.wvu.edu:8080/clc/Members/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"
http://clc.as.wvu.edu:8080/clc/Members/sondheim