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Time Warp Processor

Introduction

Time Warp

parameters: TimeWarpString

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. If you use Time Warping without scaled, it should act more of a local time change. If you are using it with scaled, you might find it easier to think of percentage and can use pairs like 0 1 5 2 10 1 where the second part of the pair is more like a multiple.

  • Time Warping is done over the objective duration of the Object, so the length of the Object as if Time Behavior would have been set to None.