PAIX

Vadim Antonov avg at exigengroup.com
Sat Nov 16 23:03:18 UTC 2002


On Sat, 16 Nov 2002, Petri Helenius wrote:
>
> >In any case, TV (of all things) does not have problems with latency or
> >jitter below 10s of seconds.  All TV content is pre-packaged.
> 
> Live events and interactive show's are not.

"Live" events are typically delayed by a minute or so to give time to 
editors to decide on course of action if something goes wrong with "live" 
feed.  In any case, nobody cares about another half-minute of delay.

The same pretty much goes for "interactive" shows - which all have 
interaction loops of minutes, not sub-second response which is hard to do 
over the regular Internet.

> In some cases you start to suffer if your latency goes to
> multiple-seconds range. That's quite rare anyway, >500ms network
> latency is quite rare and add few hundred codec and de-jitter latency
> and you'll find that excessive jitter is your enemy, not the latency
> itself.

Excessive jitter is easily converted into latency by having bigger buffers
at the receiving end.

So far, the only mass applications which have real need to have low
latency are telephony (including video kind) and on-line gaming.  Those 
are relatively low-bandwidth, and so don't contribute much to long-haul
traffic.

Of course, hauling bits over long-distance circuits costs more than doing 
the same over local exchanges - but the current routing technology makes 
having hundreds of local exchanges somewhat infeasible.

--vadim




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