Re: [LAU] Latency and USB interfaces

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To: Tim Goetze <tim@...>
Cc: A list for linux audio users <Linux-audio-user@...>
Date: Friday, January 10, 2014 - 7:48 am

Tim Goetze wrote:

In the case of the current version of snd-usb-audio, the queue has the
same length as the buffer, but never more than 18 ms.

> And is it correct to assume that in a best-case scenario where the

Pro devices typically don't do this.

> and the period size coincides with the interval at which USB frames

This does not happen with Jack, where period sizes typically are a power
of two.

> the additional latency will be one period?

These two conditions have nothing to do with the queue length; they
ensure that USB interrupts happen exactly at period boundaries, i.e.,
that there is no jitter in the reported period interrupts.

Regards,
Clemens
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Messages in current thread:
[LAU] Latency and USB interfaces, James Stone, (Wed Jan 8, 4:54 pm)
Re: [LAU] Latency and USB interfaces, Robin Gareus, (Wed Jan 8, 5:35 pm)
Re: [LAU] Latency and USB interfaces, Tim Goetze, (Thu Jan 9, 11:31 am)
Re: [LAU] Latency and USB interfaces, Clemens Ladisch, (Thu Jan 9, 12:18 pm)
Re: [LAU] Latency and USB interfaces, Tim Goetze, (Thu Jan 9, 1:26 pm)
Re: [LAU] Latency and USB interfaces, Clemens Ladisch, (Fri Jan 10, 7:48 am)
Re: [LAU] Latency and USB interfaces, James Stone, (Fri Jan 10, 10:31 am)