[alsa-devel] Fast Track Ultra latency and new streaming logic.

Felix Homann linuxaudio at showlabor.de
Thu May 3 16:03:38 CEST 2012

Some more observations:

I've measured the latency on the same machine running Windows 7 using
Centrance's latency test utility (http://centrance.com/downloads/ltu/)
and got much better results than under Linux. That's a bit

I don't know if these latencies come xrun-free since I don't know how
to detect xruns on Windows. On the other hand, telling Jack not to
complain about xruns from Alsa (softmode) I can get down to 64
frames/period and 2 periods/buffer without any noticable glitches or
crackles (playing a sine test tone). Maybe the Windows driver just
doesn't complain either?

Nevertheless, I'm a bit surprised that just starting Jack without any
clients will result in a flood of xruns at small buffer sizes. Is
there anything we can do about it? Is this to be expected? Is this a
flaw in Alsa, Jack or the USB stack? Is there a way to debug these

Any suggestions?


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