1.1. Download

The latest stable version of hydrogen is available at http://hydrogen.sourceforge.net

It is possible to download the source files directly from CVS snapshots with:

bash$ cvs -z3 -d:pserver:anonymous@cvs.hydrogen.sourceforge.net:/cvsroot/hydrogen co hydrogen

1.2. Build

After having downloaded and decompressed the tar.gz files there's only to:

bash$ cd hydrogen-*
bash$ ./configure
bash$ make
bash$ su -c "make install"

Before compiling, check for additional options with:

bash$ ./configure --help

1.3. Audio driver configuration

It's very important to choose the proper audio driver for our system, since the choice may influence quite much general performances. The choice is between Oss audio driver and Jack audio driver.

2.1. The main toolbar

Before analyzing the two main frames of Hydrogen, let's take a quick look at the main toolbar:

• Start a song or a pattern [Hotkey = Spacebar]

• Stop a song or a pattern [Hotkey = Spacebar]

• Set Pattern Mode.

• Set Song Mode.

• Set speed of playing (range: 40-300 bpm) [Hotkey = Keypad +/-, also mouse wheel up/down works!]

• Shows CPU load.

• Shows MIDI events.

• Click to enable Jack transport: Hydrogen will work as 'slave' with another 'master' program (e.g. Ardour). This applet is only available if Jack Audio Driver is selected.

Other useful keybindings (not customizable for the moment):

• [CTRL + O] = Open File

• [CTRL + S] = Save File

• [Backspace] = Restart song or pattern from the beginning

2.2. Song Editor

The frame "Song Editor" (Fig. 1) shows the song we are creating; each 'X' appearing on this frame means a complete bar as shown in the Pattern Editor, which gathers the different parts of the song (e.g. intro, verse, bridge, chorus and so on). Every bar in the Song Editor must completely identical to be allowed to stay on the same line, therefore even a minor change should slip to a different line (e.g. charleston opened on the forth snare beat). We can add or remove those 'X' only sequencially and once they're created they can only be erased if there's nothing following and moved up or down strictly in the same column (for example if we want to choose another beat between those already created).

The Song Editor comes with 5 buttons:

Create a new pattern (asks for a name)

Move selected pattern down

Move selected pattern up

Call a menu to modify properties concerning the song (name, author, comments), to erase the pattern sequence or every pattern created.

Repeat the whole song

Under these buttons there is a list of patterns created and when they will played (each 'X' = 1 bar). Click on an empty squarebox to submit or cancel the pattern (indicated as an 'X'). Clicking on right mouse button over the name of a pattern will bring up a menu to change name of the pattern, to copy or delete it. Patterns with very same name are not allowed.

2.3. Pattern Editor

The "Pattern Editor" frame (Fig. 2) let us create or modify the pattern (bar) which is being played, add or remove notes and tune intensity. The combobox "Grid Resolution" will modify the resolution so to help adding notes: it's possible to set grid for 4,8, 16, 32, 64 beats per bar and their 'three beats' bars indicated as 4T, 8T, 16T and 32T. You can also set the number of bars actually played by the "pattern size" menu on the right (1 to 8). Selecting an instrument which already has at least one beat on screen will popup a few vertical bars on the lowest part of this frame to allow tuning 'hard' or 'soft' beat. The button (hear new notes) will play the sound as it's been added to the pattern.

Also, you can set new beats clicking on which enables direct input by MIDI events or by keyboard according to the following map (key/instrument):

Note that the name of the instrument depends on the drumkit loaded. This list refers to the GMKit loaded by default. The position of the instrument, however, is the same.

• Z = Kick

• X = Snare Jazz

• C = Snare Rock

• V = Tom Low

• B = Tom Mid

• N = Tom Hi

• M = Cowbell

• Q = Ride Jazz

• W = Ride Rock

• E = Instrument No. 17 (currently not assigned)

• R = Instrument No. 18 (currently not assigned)

• T = Instrument No. 20 (currently not assigned)

• Y = Instrument No. 22 (currently not assigned)

• U = Instrument No. 24 (currently not assigned)

• S = Stick

• D = Hand Clap

• G = Closed HH

• H = Pedal HH

• J = Open HH

• 2 = Crash

• 3 = Crash Jazz

• 5 = Instrument No. 19 (currently not assigned)

• 6 = Instrument No. 21 (currently not assigned)

• 7 = Instrument No. 23 (currently not assigned)

A useful "Quantize" feature is available activating . This way the beats inserted will automatically respect the grid resolution currently applied.

Here's a quick reference of the above bindings for you convenience.

2.4. Mixer

The Mixer frame (Fig. 3) is useful for tuning a global or single volume of the current drumkit. It shows the current peak (click on to disable, useful on old CPUs) and the maximum peak allowed (use the knob to change), lets you modify attributes like pan , play solo , mute , load a WAV/AU/AIFF sample for an instrument or play only that instrument . An instrument currently played blinks the latter. Selecting in the Pattern Editor an instrument causes a green border to appear around that instrument in the Mixer.

Double clicking over the name of an instrument in the Mixer frame will bring up a dialog to modify properties. Switch MIX/FX buttons to modify effects.

Those four round knobs for every Mixer line are levels for the LADSPA plugins. See the next section for a detailed overview.

2.5. LADSPA plugins

Hydrogen can also add effects to sounds using any LADSPA plugin library. You need to have installed the LADSPA sources (tarball/rpm/apt available from http://www.ladspa.org) and while this will give a rough idea of how it works you should really have a taste of the real thing installing one or more of these libraries, it's as simple as a "make && make install":

• SWH-Plugins available at http://plugin.org.uk. Note that before compiling these plugins you need the FFTW tarball from http://www.fftw.org.

• CMT available at http://www.ladspa.org.

• TAP available at http://tap-plugins.sf.net.

Once you have installed a few plugins open File -> Preferences -> General and check if the path is correct (installing from sources defaults to /usr/local/lib/ladspa, for example), then open a song you'd like add an effect to and select an instrument that has a few beats in the pattern. In the Mixer click on and select one of the four available effect line (Fig. 3a). Click on the Edit Button ( ), than on "Select the FX": this will bring up another window (Fig. 3b) that let's you choose an effect amongst those installed, they are alphabetically sorted and categorized. Once you're done remember to "Activate" the effect, adjust the level if you want and finally go back to the Mixer: start playing and have fun! Each round knob in the Mixer line controls the level of one effect from top to bottom: the first is Effect 0, the second is Effect 1 and so on. If you want to quickly enable/disable the effect click the button.

2.6. Menu

From the pull-down menus it's worth noticing: File-->'Save as' to save the current song in .h2song format, File-->Export to export it in WAV format, File--> Preferences, Window--> Audio Engine Info and Window--> Drumkit manager.

3.1. "Song" mode and "Pattern" mode

Hydrogen has 2 main modes: "Pattern" mode (selecting ) and "Song" mode (selecting ). When "Pattern" mode is activated the current pattern is continously repeated, so to help changing it until we dont like it, while "Song" mode repeats only once the current pattern: this is useful when putting together the patterns, to create the whole structure for the song.

3.2. A new pattern

We'll start from an empty song with an empty pattern, as created by default (Fig. 12): "pattern" mode should be selected now. It is also possible to change name of the pattern.

Let's click on and while the pattern is playing let's add notes in the grid of the Song Editor (Fig. 13) simply left_mouse_clicking on it: adjust grid resolution and BPM speed if needed. Default is 32 for grid resolution and 120 for speed (within a range of 40-300). Click on to stop pattern playing. To create new pattern just click on and proceed as explained for adding notes, be sure to select the correct pattern before adding notes! Also note that if - for instance - you have selected a grid resolution of 16, you fill the pattern and then switch to a lower resolution (say, 8) you can't delete the the notes outside the grid.

3.3. A new sequence

Once patterns are created, to copy/paste/delete or move them in the pattern grid (Fig. 14) we can use the buttons in the frame "Song Editor" , and the copy/delete command that pops up right mouse clicking on the pattern selected.

3.4. Adjust from the mixer

Of course we can always use the mixer window, either when creating or playing patterns.

The Mixer frame (Fig. 15) is made of 32 independent tracks, each of these is binded to an instrument, plus a "Master Output" line to adjust general output volume and a "FX" button to set effects. Every line features 4 buttons ( ), pan adjust ( ), current maximum peak, volume fader e name of the track. Clicking on will play the selected instrument, cutting the others. The "Mute" button , simply mute that instrument. The maximun peak indicates the maximun volume reached from the instrument; the peak must be in a range of 0.0 and 1.0, otherwise it will get distorted producing a weird sound (especially with OSS audio driver), in these cases it's better to lower volume down.

Finally there is the volume fader to adjust volume of that instrument and check the peak reached thanks to a vu-meter behind the knob.