18. Numbers that move
▶ Open in Aratu to hear and change the examples
Parameters that move. bass.lowpass.cutoff = 300 Hz -> 4000 Hz over 4 bars takes the cutoff from 300 to 4000 Hz over four bars and leaves it
there, like a crescendo of the sound.
| Write | What it does |
|---|---|
A -> B over 4 bars |
from A to B, once, and stays at B |
A <-> B over 4 bars |
there and back, 4 bars each way, again and again |
A -> B over 4 bars, back over 2 beats |
up, then back over another length, once |
A <-> B over 4 bars, back over 1 bar |
the same, again and again |
A -> B over 1 bar, loop |
up, then from A again, as a ramp |
The length is in bars, beats, eighths or sixteenths; in a
compound meter such as 6/8, a beat is the dotted quarter, three eighths. The
way follows the parameter's scale: frequencies and times move by equal
ratios, as the knob turns, and mix, volume and pan in a straight line. Aratu
marks a point every sixteenth of a beat and the sound glides between them.
With no time written, the line starts moving where it is written: at the
start of the piece, or at the next bar if the music is playing. at bar 9:
makes it start at bar 9; every 8 bars: makes it end at the end of every
eight bars, like a fill, and every 8 bars, first: start at the first. A
later change of the same parameter (at bar 17: bass.lowpass.cutoff = 800 Hz) takes over. Changing the numbers while the music plays does not
start the motion over: it goes on from where it is, along the new way. Both
numbers get a knob, and while it plays a second needle shows where the
parameter is; a new version of the text does not send it back to the
written value.