[alsa-devel] position_fix issue / snd-hda-intel / alsa <-> jack

Wolfgang Woehl tito at rumford.de
Tue Feb 12 17:06:37 CET 2008

Dienstag, 12. Februar 2008 Takashi Iwai:

> JACK does nothing special but do a very basic full-duplex
> operation. The difference is that you use short period size and
> likely two periods.  So, the position calculation isn't accurate on
> your hardware.  Maybe the positions of playback and capture streams
> differe.  An often used workaround for this kind of problems is to
> use three periods instead.

Takashi, thanks for your explanation. The position_fix=0/jackd problem 
occurs with bigger period sizes too, -p[16..1024] -n2. But: With 
position_fix=0 and -p[16..512] _-n3_ jackd is fine.

Not that I'd understand why but I'm happy there is a workaround. If 
someone knows the how and why of this workaround I'd much appreciate 
to learn it.

> (BTW, this problem really depends on the hardware.  That's why
> there are such a strange module option.  So, don't argue this as if
> it's a general problem.)

Like I said, the jack-devel thread was about 2 specific devices and I 
promise we won't make a big fuss about it :)


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