[linux-audio-user] jack latency & MIDI latency

Mark Knecht mknecht at controlnet.com
Tue Sep 30 14:42:00 EDT 2003

>  From a few days I'm trying to use my pc as a synth to improve the
> sounds of my keyboard.
> I've installed low-latency kernel, alsa, jack, muse, rosergarden... etc
> from planet ccrma.


> I can't start jack with the period (-p) under 512 frames (with my SB
> Audigy) and a number of periods (-n) under 2. That mean that I have a
> latency of at least 23.2 msec (from qjackctl).

this *may* be a limitation of the Audigy. I have one, but it's in a windows
box so I cannot check for you. I remember it was pretty high though compared
to my RME cards.

> Does this latency affects the sound I hear when I play my MIDI keyboard
> with a synth (for example muse)?
> Does anyone knows if the Audigy (player) can go under 512 of the -p
> parametre in jack?

Yep. MIDI in latency + soft synth latency + Jack output latency

> With windows & cubase VST I can get a latency of about 10 ms that it's
> good for my purpose, while 20 msec
> Can I play directly in to alsa to reduce the latency (jump the jack
> latency)?

With soft synths that support it. Timidity I think supports this. Maybe AMS,
but I'm not sure. Some of the older ones like Bristol, etc., before Jack
came along.

> I think that the only way to get the so claimed 2.9 msec latency is to
> reduce to 64 the numbers of frames, but I don't know if is it possible
> with my sound card and if my actual limit of 512 is due misconfiguration
> or is the real limit for the Audigy.

I do not remember being able to run this card that low. I can do this with
my RME cards.

Not a lot of info. All I have to give. Sorry.

Good luck,

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