UbuntuHelp:HowToJACKConfiguration
来自Ubuntu中文
In order to get the most out of JACK, you will want the lowest possible latency.
It can be a daunting task at first, because there are a lot of settings and if you change them a certain way, you can cause the server to not start up properly.
Firstly, you will want Real-Time capabilities. Check out the UbuntuHelp:UbuntuStudioPreparation page for help on getting your studio set up properly.
Now, open up Qjack``Ctl, and change the settings in here. Generally, to get the lowest latency, you're mostly concerned with the Frames/Period, Sample Rate, and Periods/Buffer settings.
For a Creative Audigy2 ZS PCI card, these settings seem to work well on my system (actual settings may vary for your card/system):
attachment:Audigy2ZSJACKSettings.png
As you can see, the latency is as low as just under 3ms. Not bad! You can even make it less if you lower the Frames/Period from 64 to 32, 1.33ms. A good, acceptable setting is 128, with a latency of 5.33ms.
You must save the settings and then try starting the JACK server before you will know if the settings work or not. Your ultimate goal is to reduce the number of Xruns you get to 0, while still having an acceptable latency. Many people have no issues with 10ms latencies, or even higher. Your ability to get low latencies while still avoiding Xruns will depend on several factors: your overall system speed, your particular sound card and its abilities, and your kernel configuration. If you aren't sure what Xruns are all about, re-read the Studio Preparation page.
Some sound cards have issues with sampling rates of 44.1KHz, and some sound cards have issues with 48KHz sampling rates. You probably will want to try using 48KHz first, and if you can't get settings that work, drop it down to 44.1KHz and try that.
Once you get the latency settings right how you want them, we recommend that you have Qjack``Ctl automatically start the JACK server when you launch it. Check off the boxes to make your config look like this:
attachment:QjackCtlMiscSettings.png
