Subject: Re: [linux-audio-user] jack latency & MIDI latency
From: Robert Jonsson (robert.jonsson_AT_dataductus.se)
Date: Tue Sep 30 2003 - 21:07:38 EEST
Hi Antonio,
Tuesday 30 September 2003 19.53 skrev Antonio:
> 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).
>
> Does this latency affects the sound I hear when I play my MIDI keyboard
> with a synth (for example muse)?
Yes, the output buffers which are 2x512 frames need to be filled before you
hear anything.
> Does anyone knows if the Audigy (player) can go under 512 of the -p
> parametre in jack?
No, emu10k1/2 based cards are currently limited to this setting. I think this
is a limitation of the driver and not the hardware though.
There is an asio driver available for windows from some russian developers
that achieve massively lower latency. (I think 2x128, or even lower)
Someone should really check with them if there is something easy that can be
changed in the alsa driver to achieve this...
>
> 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)?
You can skip jack if you want, but there is no difference in latency.
>
> 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.
Some people argue it's a problem with the hardware of Audigy/SBLive, but I'm
quite confident that it's a driver problem.
Or, put another way, the problem is probably that Creative doesn't provide
good enough specs of the card.
/Robert
This archive was generated by hypermail 2b28 : Tue Sep 30 2003 - 21:31:31 EEST