Monday, March 9, 2015

Cheaper Music Making - Part 4 You don't know Jack

In the first parts of this series, we covered how to get Linux installed on a Chromebook and how to get the KxStudio repository configured and merged into your installation. Part 3 covered installing some of the meta-packages which by default, give you a huge number of multimedia processors, plugins and tools.

The great thing about Linux is that most tools are open source and free to use. No torrenting, pirating or anything else the least bit illegal required. One downside, perhaps is that there are tons of similar packages all doing more or less the same thing and it can be difficult to get them all sorted out.

In the part, I'll help you get a few key packages installed and configured so that you will have a reasonably capable DAW configured and ready for use with your preferred MIDI controller. In my case I will set up a QuNexus keyboard to use with our Linux studio.

To start with, we are going to once again put in a little command that will add your userid to the hwaudio group in Linux - without going into too much detail, this will cause your audio tools to run with a much higher priority and will, in theory, keep latency low! Make sure you have started up your Linux desktop as described in the prior posts. Open up the Terminal emulator from the panel and type the following command:
sudo adduser (youruserid) hwaudio 

where (yourusername) is replaced with the linux id you created. In my case it would be

sudo adduser mike hwaudio

In order to make the various music applications and plugins on Linux see and talk to one another, we are going to need to use a utility that is similar to InterApp Audio on iPads or the Environment window on some DAWs such as Logic. This utility will manage the routing of audio and MIDI events between applications and is called Jack (as in the kind you plug in). 

Like most tools in Linux, Jack has a command line interface that can be used but we are going to use one of many GUI options for controlling Jack. I have found that the easiest one to use is QJackCtl which is available in your Applications Menu (upper left) in the Multimedia|Hardware Configuration section. 

Running that should show you this GUI screen:

Here we are going to press the Setup button and configure Jack for the Chromebook.

We are going to set the Interface to "cras" and the Frames/Period to "512". The Frames/Period controls the latency and 512 is a conservative value that seems to work well providing roughly 23.2 msec latency. You can experiment with smaller or larger values once you get things running.

Press OK to accept the values and then press the Start button on the Jack screen. You should see something like: 

If this lights up without errors, you are in business. If there are errors, you can press the Messages button to troubleshoot. In the next part, we will set up our DAW to use the Jack connections and we will hook up a MIDI keyboard to the Chromebook. I did say at one point that this is not for the faint of heart! 

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