Editing Lemur Tracks
Frequency, phase, and magnitude can be modified for individual tracks in a Lemur file. Selected tracks can be scaled or shifted in any of these three parameters. The Scale Tracks... option (on the Edit menu) applies a multiplicative modification to the track parameter. The Shift Tacks... option (on the Edit menu) applies an additive modification in hertz, radians, or decibels to the track frequency, phase, or magnitude. Track frequency scaling and shifting allow selected components (the sustaining harmonic components, for example) of an analysis to be modified in frequency without affecting the frequency scale of the other components. Track magnitude and phase scaling and shifting provide selective filtering capabilities that would be difficult or impossible to achieve using ordinary digital filtering methods. These techniques can be used to create subtle timbre modifications as well. For instance, de-emphasizing (negative magnitude scaling) the odd-numbered harmonic components of a bowed cello analysis produced the sound of a bowed artificial harmonic on the cello.
Examples
Unmodified cello analysis, tracks representing odd-numbered harmonics labeled 1, tracks representing even-numbered harmonics labeled 2:
Cello analysis with odd-numbered harmonic magnitudes scaled by -30dB:
These parametric modifications are applied uniformly to all the peaks that make up a track. They cannot be time-varying. Time-varying track modifications are currently available only during Lemur synthesis (see Synthesis Control Files).
Track Labeling
Selected tracks in a Lemur file can be assigned a label using the Label Selected Tracks... option on the Edit menu. A track label is a positive integer between zero (the default label) and 32000. Track labels can be used for track selection, as described in Track Selection, or for selective track modification during Lemur synthesis, as described in Synthesis with Modifications. In this manner, time-variant frequency and magnitude scaling and shifting to be applied to a select group of tracks (e.g. the harmonic components, the long, sustaining components, the loud components, etc.) while the other tracks are synthesized without modification.
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