Zylaphon's sequencer offers the usual tempo map. But it also offers a number of time related controller-like parameters. Below is a player for the first section of a composition by Zylaphon's orginating author performed from MIDI tracks using the first three parameters described below to control expressive elements of timing. Zylaphon's sequencer is just in the planning stage and so in this demo the parameter algorithms were implemented by the author in CAL. Fully quantized MIDI tracks were loaded from Sibelius into Sonar. Tempo variations were set and then the algorithms were applied. No other methods of time/duration manipulation were used. Note: This composition begins at pianississimo -- so up the volume!
Invariant Rubato.
An invariant rubato is a modulation of tempo applied over one or more voices that leaves the absolute time of the interval to which the rubato applies, unchanged. That is, within the rubato the tempo speeds up and slows down in such a way that the net change in the time covered is 0. Events that coincide across channels with the beginning and end of a rubato remain coincident while those inside the rubato generally lose coincidence This is why, unlike tempo changes, they can be applied to individual voices. Such rubatos are added by graphical means much as shown below, though usually in the visual context of the channels they affect. It should be noted that if one set of channels/voices remains closely tied to the base tempo the rubato applied to another set of voices will directly effect voice anticipation. In the plus section the tempos are faster--less time is covered by the same number of beats. In the negative section the tempos are slower--more time is covered by the same number of beats. A visual representation of a mapping between rubato and anticipation would be very desirable as the GUI for an expressive user input tool. At present Zylaphon does not have this mapping.
A rubato is invariant when the areas above and below the
base tempo are exactly equal. it cannot be assumed, however that the base tempo
will remain constant as it is in the drawings above.
Anticipation
Anticipation text and illustration here
Staccato
Staccato text and illustration here
