[LAU] Until now Debian seems to be the right decision :), better performance than Ubuntu

[Ralf Mardorf]

On Tue, 2011-05-31 at 07:52 -0400, Paul Davis wrote:
> On Tue, May 31, 2011 at 7:40 AM, Ralf Mardorf
> <ralf.mardorf at alice-dsl.net> wrote:
> 
> > I only can use Jack2 from svn, if it shouldn't be available, than I'll
> > build it myself. This is regarding to hw MIDI jitter. Only Jack2 is hard
> > real-time capable regarding to this issue.
> 
> your claim is that jack1 has some issue with this? with what midi bridge?

No, my claim is hat older versions of Jack2 have issues. I can't test
Jack1 regarding to another issue. Jack2 from svn did solve this MIDI
issue for me.

First of all something about my work flow:

MIDI recordings done by Qtractor, needs to be recorded to Ardour2 audio
tracks. Because my old equipment only has got 2 analog stereo IOs, I
needed to record one instrument after the other. I couldn't record all
instruments at the same time. So even for the rhythm section I needed to
record the Kick, the Snare (*lol* yes, a snare), the HiHat, Bass etc.
one after the other, hence jitter is much more critical than if you
would record all instruments at the same time.

I didn't use Jack1, regarding to issues, on my machine Jack1 still
disconnect clients.
Current Jack2 version using ALSA hw MIDI out cause to much jitter for
this work flow. IIRC around more than 1ms for the PCI cards. USB MIDI is
for SysEx dump only and disconnected when making music.

When using Jack2 from svn I run

	sudo chgrp audio /dev/hpet
        sudo chmod g+rw /dev/hpet
	sudo modprobe snd-hrtimer

andenable his timer for Qtractor, resp. ALSA seq.

I run

jackd --sync -Xalsarawmidi -dalsa -r48000 -p256
a2jmidi_bridge

The hpet thingy still is a little bit trick on my machine, if I run jack
with hpet, there aren't enough devices available.

This -Xalsarawmidi cause 0ms jitter.

Hopefully a lot of things will become better now. The new RME card is
using PCI express, I dunno it this would be better for hw MIDI out.

After mounting my new card I can try Jack1 too!

-- Ralf