Lemur Synthesis Control Files

Time, frequency, and magnitude scaling and shifting may be varied continuously over the duration of a Lemur synthesis. Lemur can interpret ordinary samples files as control files for time scaling, frequency scaling, and frequency shifting. A base value is specified for scaling or shifting, and the control file samples are interpreted as floating point values between -1.0 and 1.0. Scale values are then computed as

scale = baseScale ^ controlFileSample

(where "^" denotes exponentiation) and shift values as

shift = baseShift * controlFileSample

Control files are resampled to match the duration of the Lemur file, so their sample rate and duration are arbitrary. Frequency scale modifications can be applied to all tracks in an analysis, or only to those tracks bearing a specified label. Track magnitude scaling may be applied in a similar fashion. The magnitude scale is a decibel value computed by multiplying the base magnitude scale by samples from the control file (as described for shift values). Lemur can also perform static time, frequency, and magnitude scaling and shifting, in which no control file is used and the base scale and shift values are used for all frames.

Control files for scaling and shifting in Lemur synthesis may be chosen in the Modification Parameters panel, accessed from Lemur's Parameters menu.

Examples

Cello analysis (see Track Editing examples) with a time-varying (ramp up) frequency shift applied to the tracks representing the even-numbered harmonics:

AIFF samples file (180K)

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