On Sunday 06 December 2009, Pieter Palmers wrote:
At the expense of a truly horrible latency built into the usb specs. In
another field (my interests are best described as eclectic), involving far
less data at a time than audio, machine control, aka cnc milling and similar
operations where the machine must be under the computers control at sub-
millisecond intervals for servo's and < 50 microsecond intervals for stepper
motors, those who have tried to go down the usb road have generally failed
rather miserably. So that road is both well traveled and has been found
wanting. 100 millisecond latency's just cannot be tolerated for that usage.
Ethernet is everywhere, and is one of the reasons my previous messages
favored it. Unforch, while I grant that firewire is hands down superior, and
I have a couple of ports here, it is apparently a totally daisy chain
topology from a single host port, and AIUI, cable lengths are very limited
in comparison to ethernet. However there is a 6 port 'hub' at
to expand the limited number (usually 1 or 2) of ports found on todays
motherboards, and the total cable length to 9 meters, and even the pluggin
cards available seem to be limited to 4 ports. I see that for 1394b, cables
up to 32 feet are available but at the price I'd have to assume there is a
booster hub in the middle. With pricy optical convertors, to 3/8's mile
using glass fiber. (actually it is probably plastic if it has that length
limitation, glass, good glass, checked out at .4 db loss over 39 kilometers
when we fed the local cable systems from our studios, several years ago now.
ATM out of 6 mobo USB ports and 6 hubs making branches as deep as 4 sub-hubs,
I have only 7 open sockets. And I don't believe my usb map is anywhere near
a record setter.
Were there a firewire audio gizmo on site, I might have it working too, so go
build one, I'm waiting. (and don't forget the daisy chain, most folks ignore
it) The first port here is for my movie camera, which kino generally runs
quite nicely, with very nearly realtime video and audio, only a slight echo
between the speaker on the camera and my speakers. :)
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
The NRA is offering FREE Associate memberships to anyone who wants them.
Kgnghtbrd: I wouldn't kow, I see no need for a spellchecker yet
you were saying?
Linux-audio-dev mailing list