Time Warp Processor
Warps time in the same way as Csound t-statement, but does not require "t" to be used. Statements are in alternating pairs of beat number and tempo.
From the Csound Manual:
Time and Tempo-for-that-time are given as ordered couples that define points on a "tempo vs. time" graph. (The time-axis here is in beats so is not necessarily linear.) The beat-rate of a Section can be thought of as a movement from point to point on that graph: motion between two points of equal height signifies constant tempo, while motion between two points of unequal height will cause an accelarando or ritardando accordingly. The graph can contain discontinuities: two points given equal times but different tempi will cause an immediate tempo change.
Motion between different tempos over non-zero time is inverse linear. That is, an accelerando between two tempos M1 and M2 proceeds by linear interpolation of the single-beat durations from 60/M1 to 60/M2.
The first tempo given must be for beat 0.
Notes on Usage
Beat values for beat/tempo pairs should related to the score *before* any time behavior is applied. For example, for the following score:
i1 0 1 2 3 4 i1 1 1 3 4 5 i1 2 1 3 4 5 i1 3 1 3 4 5
if it is in a GenericScore SoundObject of duration 20, if you want the tempo to decrease in half by the last note, you would enter a value for the processor as "0 60 3 30" and not "0 60 20 30"
If you're using a time behavior of "Repeat", remember that time behavior is applied *after* noteProcessors, and the resulting score will be a time warped score repeated x times and *NOT* a score repeated x time and then timewarped
Time Warping, when used with a time behavior of "Scale", be aware that estimating the final tempo of the object may be tricky, as the scaling will alter the duration of notes.