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 :)
Wolfgang