Author Topic: Why The Large Delay At KBOS ?  (Read 3769 times)

Offline B1900Mech

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Why The Large Delay At KBOS ?
« on: June 24, 2008, 06:33:27 PM »
Hi all :-D As the title states,Why do I get up to 60 seconds delay,Listening on my AT&T Tilt?



Offline KSYR-pjr

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Re: Why The Large Delay At KBOS ?
« Reply #1 on: June 24, 2008, 07:10:50 PM »
Hi all :-D As the title states,Why do I get up to 60 seconds delay,Listening on my AT&T Tilt?

Audio to digital coding, upload Internet congestion (path from feeder to LiveATC), streaming server load, download Internet congestion (path from LiveATC to your computer), and your local computer load to decode stream and convert to audio.  Is the AT&T Tilt wireless?  If so, there may be a small but noticeable delay inherent in wireless data transmission as well.

Regards, Peter
ATC Feed:  Syracuse (KSYR), NY

Offline dave

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Re: Why The Large Delay At KBOS ?
« Reply #2 on: June 25, 2008, 08:02:54 AM »
Everything Peter said...just curious, are you connected via WiFi, Edge, UMTS/HSDPA?  If you are connecting via one of the cellular networks, is there any difference in delay when you use WiFi instead of cellular?

We use a 16kbps bitrate to reach as many listeners as possible and to conserve bandwidth since we serve a lot of simultaneous listeners.  This has been a good decision, but using the lower bitrate means more delay since encoding is a little more expensive.  I don't know how good or fast the audio decoding is on Windows Mobile on a Tilt.  That is another factor.

Dave

Offline B1900Mech

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Re: Why The Large Delay At KBOS ?
« Reply #3 on: July 13, 2008, 06:32:13 PM »
Sorry for the delay in replying,I am using AT&T's 3G network,as that is all I have where I park. I guess I will have to go to the terminal,in order to try the WIFI.

Offline MathFox

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Re: Why The Large Delay At KBOS ?
« Reply #4 on: July 14, 2008, 03:59:06 AM »
I guess the delay is largely the cumulative effect of buffering at the various steps in the distribution network. It appears that my player (Xmms/Linux) uses a 24kbyte network buffer; that is 12 seconds of data. The servers in the distribution network have something like 8kbyte buffers, good for 4 seconds of delay.

Offline dave

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Re: Why The Large Delay At KBOS ?
« Reply #5 on: July 15, 2008, 02:21:10 PM »
I guess the delay is largely the cumulative effect of buffering at the various steps in the distribution network. It appears that my player (Xmms/Linux) uses a 24kbyte network buffer; that is 12 seconds of data. The servers in the distribution network have something like 8kbyte buffers, good for 4 seconds of delay.

The delay is mostly due to the encoding on the source end and the decoding at the client end.  But there is some additive delay as the stream goes from the origin server out to the slave (listener) servers.

If you absolutely must have minimal delay try the alt.liveatc.net server - it should be very low delay (just checked at 1-2 seconds):

http://alt.liveatc.net/kbos_twr

(note: do not use the .m3u extension on this server)

-dave