Re: [LAU] FOSS Ethernet Soundcard

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To: <linux-audio-user@...>
Date: Tuesday, November 24, 2009 - 10:08 am

Lorenzo:

The "this" part is currently only in our minds for the moment, but if
you solve the issue of connecting our "minds" to your ethernet port,
I'll solve the 1ms latency part :)

A simple ping:

$ ping granat
PING granat.lcl.aspodata.se (192.168.93.37) 56(84) bytes of data.
64 bytes from granat.lcl.aspodata.se (192.168.93.37): icmp_seq=1 ttl=15 time=0.758 ms

gives me a round trip of < 1ms, so it should be possible.

So the time from analog, pushing out samples from the sender port,
till it is received the receiver port would be lower bounded by:

sample conversion time
lcl transport time to cpu
cpu processing
cpu to ethernet tranceiver
ethernet preamble (assume quiet net)
cable delay
packet bit speed * packet length

Add to this any processing on the receiving side.

To help achieve low (network) latency one can:

. set up fixed arp entries (see arp(8))
. use fixed ip-addresses, no dhcp, no mDNS, no autoconfiguration or
other talky protocols
. don't mix other hosts on the lan, make it as quiet as possible
. no DNS, use /ets/hosts files
. if possible use a crossover cable [1]

What kind of latency do you think would be a goal to strive to ?

Regards,
/Karl

[1] http://en.wikipedia.org/wiki/Ethernet_crossover_cable

-----------------------------------------------------------------------
Karl Hammar Asp

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Messages in current thread:
[LAU] FOSS Ethernet Soundcard, Folderol, (Mon Nov 23, 8:28 pm)
Re: [LAU] FOSS Ethernet Soundcard, Peter Plessas, (Tue Nov 24, 1:04 pm)
Re: [LAU] FOSS Ethernet Soundcard, Thomas Vecchione, (Tue Nov 24, 3:06 pm)
Re: [LAU] FOSS Ethernet Soundcard, Atte André Jensen, (Tue Nov 24, 10:18 am)
Re: [LAU] FOSS Ethernet Soundcard, david, (Tue Nov 24, 11:07 am)
Re: [LAU] FOSS Ethernet Soundcard, Florian Faber, (Tue Nov 24, 10:26 am)
Re: [LAU] FOSS Ethernet Soundcard, Kevin Cosgrove, (Tue Nov 24, 7:12 pm)
Re: [LAU] FOSS Ethernet Soundcard, Hans Wilmers, (Tue Nov 24, 10:37 am)
Re: [LAU] FOSS Ethernet Soundcard, Kevin Cosgrove, (Tue Nov 24, 7:15 pm)
Re: [LAU] FOSS Ethernet Soundcard, Kevin Cosgrove, (Tue Nov 24, 7:14 pm)
Re: [LAU] FOSS Ethernet Soundcard, Florian Faber, (Tue Nov 24, 7:25 pm)
Re: [LAU] FOSS Ethernet Soundcard, Kevin Cosgrove, (Mon Nov 23, 9:25 pm)
Re: [LAU] FOSS Ethernet Soundcard, Folderol, (Tue Nov 24, 8:27 pm)
Re: [LAU] FOSS Ethernet Soundcard, Karl Hammar, (Tue Nov 24, 9:25 am)
Re: [LAU] FOSS Ethernet Soundcard, Ken Restivo, (Sun Nov 29, 4:25 am)
Re: [LAU] FOSS Ethernet Soundcard, Lorenzo, (Tue Nov 24, 8:44 am)
Re: [LAU] FOSS Ethernet Soundcard, Karl Hammar, (Tue Nov 24, 10:08 am)
Re: [LAU] FOSS Ethernet Soundcard, Lorenzo, (Tue Nov 24, 10:16 am)
Re: [LAU] FOSS Ethernet Soundcard, Arnold Krille, (Tue Nov 24, 9:10 am)
Re: [LAU] FOSS Ethernet Soundcard, Florian Faber, (Tue Nov 24, 9:15 am)
Re: [LAU] FOSS Ethernet Soundcard, , (Tue Nov 24, 10:23 am)