[LAD] Trying to understand Jack Midi, (Arpage, Dino)

james morris james at jwm-art.net
Mon Feb 15 16:18:03 UTC 2010


I recently was testing out Seq24 >> Arpage >> Yoshimi, and it sounded
terribly out of time. This is on a fairly new Gentoo install so I
wondered if something was misconfigured. I also tried the first release
of Arpage and same result.

Then I noticed the latency of the Jack settings in use was quite high and
reset it to give a much lower latency which completely fixed the timing
problems the above seq/arp/synth setup was having.

The next test involved the Dino sequencer, but before doing so I
attempted to change the Jack settings to give a really bad latency,
170ms+. Jack could not start with such high latencies - the Alsa driver
would not load IIRC.

I reset the Jack settings for the worst latency I could get with Jack
starting, but the timing in Dino although far from perfect, was nowhere
near as bad as Arpage.

1) Is there any way to improve Jack Midi timing when the audio driver has
a high latency?

2) What is the reason the Alsa driver/Jack would not start when the
settings give a big 170ms+ latency?

BTW, I'm doing this stuff so I can program with Jack Midi.


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