Lorenzo: > >> Recent discussion on LAU morphed into an idea for an Ethernet > >> driven sound card, and as this is now becoming a real > >> development > So I will plug this into my ethernet and have < 1ms latency? :) 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 Aspö Data karl@xxxxxxxxxxx Lilla Aspö 148 Networks S-742 94 Östhammar +46 173 140 57 Computers Sweden +46 70 511 97 84 Consulting -----------------------------------------------------------------------
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