Re: [LAU] recommendations for usb sound card?

Am Sonntag, 9. März 2008 schrieb Paul Winkler:
> On Sun, Mar 09, 2008 at 03:26:56PM +0100, Frank Barknecht wrote:
> > USB-audio-guru Clemens Ladisch on LAU in 2005:
> > "Due to how the USB protocol works, all USB audio devices have the
> > same latency."
> > http://lalists.stanford.edu/lau/2005/06/0200.html
> Does Firewire get lower latency, or just better throughput?

Probably the same latency. But higher throughput than usb1. Which leaves room
for more channels. :-)

> What about USB 2 if/when freebob supports it?

freebob will support usb2?

freebob won't even get any further release! The next generation is called
ffado and is (still) firewire only. And I don't think there are any plans on
extending it to usb2.

> And just to be clear - if I run jackd -r 48000 -p 64 -n3, is it
> correct that the one-way latency in seconds is 64 * 3 / 48000.0 =
> 0.004? So round-trip latency is twice that?
> (Plus any converter overhead of course.)

That value is the time inside the computer. Additional are the times of the
converters buffers and the transfer over cable (from the systems memory to
the output-buffer of the usb and back).

With ffado the latency reported by jack will be the full latency without the
converts latency. So its compensating the transports latency...

Arnold

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