NAME

Audio::Hydrogen::Song - description of a song

DESCRIPTION

The song file is a standalone file with the extension .h2song which contains the descriptions of the patterns and instruments that make up a "song" in Hydrogen. There can be any number of patterns and these can be arranged in groups as pattern sequences. The instruments can either be copied from a drumkit or can be created afresh as required.

For a song file to be usable in Hydrogen it needs only at least one pattern and any instruments that may be used, the application will supply its own defaults if needed.

METHODS

attribute version

This is Version object that represents the version of Hydrogen that created the song file. This defaults to "0.9.5" which is the version I tested with, but it may have some impact on the way some values are interpreted.

attribute bpm

This is the BPM as an integer, it defaults to 120.

attribute volume

This is the global volume as a Rat, it defaults to 1.0

attribute metronome-volume

This is the volume of the built in metronome, it defaults to 0.0

attribute name

This is the user visible name of the song, it can be left blank.

attribute author

This is some text describing the author of the song, it may be blank.

attribute notes

Some free text notes regarding the song, it may be blank.

attribute license

Some license text. It may be blank.

attribute loop-enabled

A Bool which is by default not set, it appears that Hydrogen itself defaults to True though.

attribute mode

This is a string which may be "pattern" or "song" to determine the playback mode of Hydrogen, the default is "pattern".

attribute humanize-time

This is a Rat in the range 0 .. 1.0 that determines the extent to which a small random change is applied to the timing of notes. By default it isn't set which means time isn't "humanized".

attribute humanize-velocity

This is a Rat in the range 0 .. 1.0 that determines the extent to which a small random change is applied to the velocity of notes. By default it isn't set which means velocity isn't "humanized".

attribute swing-factor

This is a factor that adjusts the probability that the timing of a note will be altered by some amount. I'm not quite sure of the algorithm used. By default it isn't set which means there is no "swing". A good description of the notion of "swing" in terms of electronic sequencers can be found in this interview with Roger Linn who largely invented the idea:

https://www.attackmagazine.com/features/interview/roger-linn-swing-groove-magic-mpc-timing/

attribute patterns

This is a list of Audio::Hydrogen::Pattern objects. There should be at least one and they should all have a unique name.

attribute instruments

This is a list of Audio::Hydrogen::Instrument objects. The id attributes of the instruments should be unique and should be those referenced by the patterns. The sample filenames (either single or those in layers,) should be absolute paths (unlike those in drumkits that may be relative to the drumkit directory.)

attribute pattern-sequence

This is an ordered list of PatternGroup objects, which in turn contains a on ordered list of pattern-id Strs which refer to the patterns in the group.

attribute plugins

This is a list of Plugin objects that describe the LADSPA plugins that are configured for the song, there may only be four plugins per song (at least in the UI.) The Plugin object has the attributes:

attribute name

The name of the Plugin as will be displayed (determined from the plugin when it is loaded.)

attribute filename

This is the filename (a .so file typically) that the plugin was loaded from, it appears to default to '-'.

attribute enabled

A Bool indicating whether the plugin is enabled.

attribute volume

The "volume" of the plugin.

I'm not sure how it stores the plugin specific parameters.