If you read the introduction to this series (part 1) you will be familliar with what we are trying to acheive here, if you did not then brieflly, we are going to use Ardour (a digital audio workstation) to record music. In order to keep it in time and therefore sounding good we are using Hydrogen (a drum sequencer) and we are going to send the output from this program directly to a track in Ardour. I am assuming you have a version of LINUX to do this with but other operating systems are usable but some of the software we talk about has not been made available for them yet, or if it has there may be limitations. LINUX is free so if you have not tried it then you should.
One very important prerequisite is that you must have a way to get your music into your computer. If you do not know how to do this then check out this article I wrote a while ago on the subjet. In that article we use another program called Audacity, but if your signal gets that far then it will be usable by Ardour too. Bear in mind that you are connecting to the "Line in" or the "Microphone" socket on your sound card. For the cleanest possible sound you can get a device called an "audio interface".
Now that you have a signal the first thing that you need to do is open QjackCtl, as I said in the introduction JACK is an audio routing app that allows you to direct audio to and from sources and software very efficiently. I breifly explained usage of jack in part 4 of the previous series on recording, but here we are going to go into more detail. Once you have QjackCtl open start the JACK server by pressing the "start" button. Make sure that there are no errors (you will be made aware of this via a popup window) and if there are none you are ready to continue. One important thing that you need to be aware of is that JACK will take control of your computers sound, and some programs are not compatible with it, namely the Flash plugin that your web browser uses is not. There are ways of making flash able to use JACK but that is beyond the scope of this article. Just be aware that you cannot watch youtube while jack is running without messing about a bit.
JACK is a good friend
So JACK is running but without any programs that use it running with it, it can be very boring. So the next thing you will want to start is Hydrogen. Hydrogen deserves its own article and indeed it will get one in future but for now we are merely using it as a dynamic click track generator (it is so much more capable than that, but later...walk before you run). In the bottom half of the screen you will see a kind of beige rectangle with lines and numbers in it. This is called the pattern editor. At the top of the screen you will see a bunch of lines running sideways from buttons marked pattern1, pattern 2 etc. This is the song editor.
Hydrogen User Interface
With pattern 1 selected in the song editor click somewhere in the pattern editor and you will hear a sound and see a spot appear. In the image above I have placed four such markers in the "kick" row (make sure that your volume is set at a sensible level). If you do not hear anything make sure that Hydrogen's output is connected to your system's "playback" input in JACK. This is acheived by switching to your QjackCtl window and clicking the "connect" button. This opens the connections window, click the "expand all" button at the bottom on the left of this window. You should see something similar to the view in the next image. It is useful to press play in Hydrogen at this point so that you can hear what you are doing. Leave it playing for the next part.
Hydrogen Connected to Sound Card Playback
Practice This New Skill
The JACK connections window is very important and you should take a minute to familiarise yourself with using it, as we will be using it extensively during the course of this series, especially when we come to adding effects to tracks. So to practice, click on "out_L" in the "Readable Clients/ Output Port" pane under the Hydrogen tab so that it is highlighted, then click the "playback_1" in the "writable Clients/Input Ports" pane under the System tab. The "disconnect" button should become clickable now because these things shold already be connected (if they are not "connect" will become clickable) so click it and the line that joins them will disappear. If you play your song or pattern in hydrogen you will notice that your sound is now only coming from your right speaker. Reconnect "out_L" to "playback_1" for now, you may wish to change this later as you become more comfortable with JACK connections. You can think of the joining lines as patch leads in traditional equipment. Incidently there is a "patchbay" in QjackCtl, we wont worry about that for now though.
From Patterns to Songs
Now when you press the play button in Hydrogen your pattern will play through. You will notice that above the play button there is a litte light with "pattern" written next to it, if you look to the right of that there is a similar light with "song" written next to it which should be dimmed as it is not active. If you click the "song" light the "pattern" light will extinguish. Now when you click the play button Hydrogen will play through the song editor rather than the pattern editor.
Songs are constructed through the addition of patterns, which when arranged using the song editor will enable you to make complex arrangements of sounds, the difficult part is being creative enough to make a beat that sounds good. The other essential control is the BPM (beats per minute) control, which by default is set to 120.00, which is also the default BPM. This control is located next to the main controls at the top. BPM is changed using the small "+, -" buttons and can be changed during playback. To add patterns to a song simply click the little squares in the correct row and they will turn blue, which means the pattern they represent will play in the order that the play head encounters a blue square in the song editor. Experiment and soon you will have something that you can use. Once you are satisfied with your beat you can move on to the next part of this series, Recording in ardour.