[linux-audio-user] USB-Audio latency

Frank Barknecht fbar at footils.org
Wed Jul 28 11:07:55 EDT 2004


Hi,
Polashek, Matthew wrote:

> Anyone here know:
> 
> 1 - How I can measure the latency of a USB-audio device connected to PD via
> ALSA?

There is a patch in "doc/7.stuff/tools/" called latency.pd, which you
can use to measure roundtrip latencies with Pd. It comes with
instructions on use. Pd is *not* callback driven and uses various
buffers, so you will always get double or even triple latency in
Pd compared to something like Ardour.

> 2 - What the minimum latency of a USB-audio device is with Linux?

In my experiences with about 20 USB devices "jackstart -p 128" is the
lowest I ever could achieve more or less stable. How low a latency in
msecs that is depends on the samplerate.


Ciao
-- 
Frank Barknecht




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