24 Dec
2009
24 Dec
'09
6:02 a.m.
Hi,
On Thursday 24 December 2009 01:48:14 Patrick Shirkey wrote:
Comparing local wired network and local wifi...
Have fun,
Arnold
On 12/24/2009 11:31 AM, Arnold Krille wrote:
I was once taught that a good estimate for an error is better then a bad
calculation. This number is a guess from my understanding and experience of
networks and the osi layers...
On Wednesday 23 December 2009 23:52:46 Patrick
Shirkey wrote:
This is good analysis. Thanks for taking the time.
Is that number 100ms a real number or just an estimate? So the issue is with other streams being picked
up by the receiver which
affects latency by increasing collisions?
Would this still be a problem on a secured connection? Surely the
receiver would ignore all data that is not being transmitted over the
secured access point?
No, the problem is one or two layers deeper in the stack. We
are talking
wifi here. No matter if there is only two devices on that network or a
secure connection, its still wireless transmission over radio frequencies
in the 2GHz range. Which is per se much more affected by any disturbance
then a dedicated cable is. Every mobile phone, every blue-tooth device,
every neighbours network, every iron in your ceiling will influence this.
And not only with a constant background-noise in your frequency range,
but also with momentary scrambling and such stuff. So in the layers you
can not (easily) control by software there is already lots of resending
and rescheduling of packets. And all these introduce uncertainties and
latencies you don't want in your audio transmission. Unless you can do
with 100ms latency and more... But getting
the stream to be reliable is already complicated with things
like firewire (which has isochronous channels for exactly this purpose)
and its more complicated with usb (which has a master telling the clients
when to send bigger payloads to not disturb the other bus-members). Ask
the jack-over-udp guys how difficult it is to create such stream reliably
over tcp-ip network. And they take lost packets into account (which means
an xrun) and advise you to use it on dedicated networks if you want more
the the immediate experience...
In this case are we comparing a network located
over large distances
with internet nodes in between or a couple of computers sitting within a
couple of meters of each other?