An Introduction to Hydrogen
You can save your instrument arrangement as a Hydrogen drumkit. The process is simple: after making your instrument choices, open the Window/Show Drumkit Manager dialog, click on the Save tab and do what must be done--name, comment, save.
If you'd like to share your drumkits with the world, use the Export tab to create a *.H2DRUMKIT file. Many kits already are available for import into Hydrogen, and more are welcome; see the Hydrogen Web site for details. Incidentally, you can load new drum kits or individual samples into Hydrogen in real time. Loading is smooth, with no delay or disturbance to the playback sound.
The mixer panel provides two functions in one panel. Its channels correspond to the instruments in your pattern, each channel strip providing a volume fader and level peak LED; four effects sends; controls for panning, mute and solo; and a sample trigger button. The master channel strip supplies a master volume control and three controls for humanizing swing, timing and velocities. These humanization controls add greater or lesser amounts of randomness to those factors and are effective at loosening up a too-rigid feel to your patterns.
The master channel also contains the FX toggle to summon the control strips for the four effects seen in each instrument channel. Double-click on the strip name (No plugin, by default) to call up the FX Properties dialog and then click on the Select FX button to see a list of the LADSPA plugins available on your system. If you've compiled Hydrogen with RDF (resource description framework) support, you should see the nicely organized display shown in Figure 7. Select a plugin, click on the OK button and the Properties dialog displays the parameter controls for the effect (Figure 8).
Now you can apply the plugin effect to any instrument channel, in whatever amount you choose, and you can adjust the effect parameters in real time from the FX Properties dialog. And don't forget, you still have three more plugins to select and apply.
A complete installation of Hydrogen includes documentation in the form of a UNIX-style man page (man hydrogen); a tutorial in English and Italian; and a manual in English, French, German, Italian and Spanish. Further documentation and elucidation can be found on the Hydrogen mail-list (see Resources).
Hydrogen also comes with some instructive and musical demos from developers Emiliano Grilli and Artemiy Pavlov. These demos are excellent lessons themselves, and you can learn a lot about the program simply by studying them.
Now I am going to show you how to create some patterns and put them together into a simple song form. We select Hydrogen's default General MIDI drum kit for our sounds. Open the File/Preferences to select either the JACK or OSS/Free (or ALSA's OSS emulation) audio driver. I suggest using the JACK driver: Hydrogen development keeps in close step with JACK development, and its implementation of JACK usually is up to date. Thanks to JACK, Hydrogen can direct each instrument to a separate audio output, a valuable feature for recordists who like to dedicate a channel to each drum in a drum kit. Hydrogen also adheres to the JACK transport interface and is equally happy acting as the master timekeeper or as a synchronizer for another master.
Begin by selecting File/New to initialize the pattern and song settings. Leave the tempo and time signature settings at their default values, then activate Pattern 1 by clicking on its name in the song editor window. Because you want to work in the pattern editor, click on the P button in the main window controls to start pattern playback. For the kick drum, in the pattern editor click on each of the four numbered beat divisions, then add a snare drum on beats two and four and add other instruments as you wish. Figure 9 demonstrates one possible result with beats added for open and closed high-hat. Now add more instances of Pattern 1 to its track in the song editor to create an eight-bar chain.
Left-click on Pattern 2 in the song editor and add a crash cymbal on the first beat. Add the pattern to the first position in its track in the song editor. Repeat this process with Pattern 3, but add a tom-tom fill on the fourth beat. Add this pattern to the fourth position in its track in the song editor. The song form now should look like the screenshot in Figure 9. Figure 9 also demonstrates the use of a LADSPA plugin, the Freeverb reverberation effect, which has been adjusted for and applied to the high-hat sounds. Notice the positions of the FX send knobs in the high-hat mixer channels.
Repeat these procedures to create more patterns and the song form you desire. Remember, you can edit your song form in real time just as you can with the pattern editor. Play with the mixer balances, the FX sends, the instrument panning and the humanization controls. Try controlling Hydrogen's transport status from an external JACK-aware application, such as Ardour or Rui Nuno Capela's QJackCtl utility. If you're recording to Ardour or ecasound, set up Hydrogen to send each instrument out on its own channel--see the Audio System tab in the File/Preferences dialog--and route each channel to a separate track in the recording software.
Similis sum folio de quo ludunt venti.