An Introduction to Hydrogen
Hydrogen's user interface is made of a main parent window with a top-level menu bar and a set of play/record controls. This main window opens with its editor and mixer panels displayed. By default, Hydrogen displays the most recent work file upon opening, including any panels displayed when the file was last saved, but that action can be toggled from the File/Preferences dialog.
The main window's File menu supplies common operations such as new/open/save, export to MIDI and WAV and the program preferences settings. The Window menu is a list of show commands if you've hidden the song and instrument editors or the mixer. This menu also calls the drumkit manager and an audio engine status window, both hidden by default. The ? menu is Hydrogen's help menu for accessing the user manual and a tutorial.
The transport bar includes start/stop controls, pattern and song mode selectors, a tempo control scrollbox and status indicators for JACK, MIDI input and CPU load. That's all there is to describe for Hydrogen's main window functions, so now we move on to the various editor panels.
Pattern and song are related closely in Hydrogen's interface. Patterns are selected, named, copied, added and deleted using the Song editor, and clicking on the pattern name in the song editor window immediately activates the pattern editor for the selected pattern. By default, the song editor provides ten blank patterns, but you can add as many as you need. Right-clicking on the pattern name pops up a menu for copying, deleting and naming the selected pattern.
The pattern editor panel presents a grid whose horizontal axis is the timeline along which you place beats and whose vertical axis represents the instruments played. Entering beats into a pattern is as simple as clicking on the desired coordinates point, resulting in a display similar to Figure 2. Each beat can have its own velocity and pitch setting, available in the lower panel of the pattern editor (the VEL and keyboard buttons). This panel can be toggled between velocity and pitch grids; Figure 2 shows the panel in velocity mode.
The left side of the pattern editor shows the names of the instruments assigned to their particular timelines. Left-clicking on the instrument name triggers its sound; right-clicking pops up a menu for mute/solo status and a clear/fill notes function. The fill function is useful especially if you like to shape your pattern by removing beats from a filled line. At this time, there is no undo/redo function for either pattern or song edits.
The pattern editor's controls are located at the top of the editor panel, as seen in Figure 2. These controls include a toggle for sounding the sample when a beat is entered into your pattern. There also are two controls for recording and quantizing beats entered from either the computer keyboard or a MIDI device such as a keyboard, guitar, wind controller or external sequencer.
The pattern editor control strip also includes the grid resolution and pattern length value selectors. The grid resolution can be set to a maximum of 64, with triplet resolutions up to the 32nd-note triplet. The pattern length determines the number of beats per measure, like the numerator in a conventional time signature, thus allowing odd bar lengths such as five or seven beats per measure.
Hydrogen's song editor is its simplest panel. A song form is created by adding or deleting patterns in the linear track display; left-clicking on a box in a track enters or removes it from the form. Hydrogen allows the use of simultaneous patterns, a wonderful addition, especially for adding variations to an existing pattern. Of course, you can copy a pattern to an empty pattern slot and then edit it as you wish, but using a simultaneous pattern can be a more flexible approach to adding variations to an existing pattern.
The song editor's controls include buttons for adding a new pattern, shifting pattern positions, performing some song operations and toggling loop play on/off status. The song operations button calls a menu with an item for setting song properties (song name, composer's name and comments) and two controls for clearing a pattern sequence and deleting all patterns from the song form.
Up to 32 instruments can be used within a pattern. Each instrument can be a single sampled sound, or it may consist of up to 16 samples layered together for more complex sounds. Of course, your selected sounds need not be restricted to drum and percussion samples; they can be any sounds you like. Remember, a drum machine is essentially an audio sequencer, and Hydrogen can play any sound you tell it to play.
Hydrogen's instrument editor provides some nice controls for shaping your sounds, with parameter settings for layer properties and an ADSR (attack/sustain/decay/release) envelope designer. The editor also includes a neat control for random pitch fluctuation when the instrument is played, thus creating more realistic sounds. Yes, even percussion sounds have a pitch element. By the way, in Figure 4 you can see the scrollbox controls for the envelope values, but plans have been made for adding a graphic envelope editor.
An instrument's corresponding mixer strip also is shown in the instrument editor, a nice convenience when designing your sounds. By default, Hydrogen mutes unused channels, so be sure to un-mute your new instrument channel.
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Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
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