[linux-audio-user] emu10k1 and jack

[Antonio]

Hi to all,
I'm tryng to tune my machine to get the lower latency I can get with my
hardware and linux of course.
I have an audigy player with a debian sarge with the audio apps take
from the unstable branch. I've recompiled the 2.4.22 kernel with
capabilities, low latency, preempted patches. I've compiled the source
packages of alsa 1.0.1 and jack 0.94.

I can obtain a clean sound playing timidity thru my midi keyboard using
3 fragments each of 256 (but only if I'm root, otherwise I get "can't
set sched_setscheduler" and the sound became dirty, maybe I have to
recompile it?) which means a pretty low latency for me.

On the other side I can run jack (jackstart works fine) with a period
not less than 512, and I can't change the number of periods (neither
increase) that is 2 by default. For example:

$ jackstart -R -d alsa -d hw:0 -r 48000 -p 512 -n 1
[snip]
hw:0|hw:0|512|1|48000|0|0|nomon|swmeter|rt|32bit
control device hw:0
configuring for 48000Hz, period = 512 frames, buffer = 1 periods
Couldn't open hw:0 for 32bit samples trying 24bit instead
Couldn't open hw:0 for 24bit samples trying 16bit instead
ALSA: cannot set number of periods to 1 for capture
ALSA: cannot configure capture channel
cannot load driver module alsa
$

The same it is if I set number of periods higher than two (and that's 
strange, can be a configuration issue?)
- Is it an hardware/driver limit, can't I reach the same latency that I
have with timidity with jack?
- Is it normal having 16 bit samples with my card?

The last but not least, I have a general question about jack: if I a 
stream pass twice or more times into jack (for example alsa in -> jack 
rack -> ardour -> alsa out, 3 times) does the latency increases twice or 
more, proportionally, or it is only related to the various apps latency?

Ok, I stop to bother anymore you with my (maybe stupid) doubts...

Thanks for the attention, every answer will be greatly apprecciated.

Ciao, Antonio