Vso-Chmb - Lexicon PCM 81 - REV User Manual

The Algorithms and Their Parameters

VSO-Chmb

The VSO-Chmb algorithm provides the same high quality shifter as Stereo-
Chmb, designed for on the fly pitch correction of varispeed playback sources.
A varispeed parameter allows you to match the varispeed setting of the playback
source. The algorithm can match speeds ranging from +55.00% through
–35.48% with a resolution of .01%.
This algorithm is a utility program designed to provide pitch correction of
varispeed material. This is a true stereo algorithm which maintains the stereo
image of source material. It can be used in applications that require on the fly
compression/expansion. Simply match the value of the Varispeed parameter to
the varispeed setting of the playback source.
For example, to compress a 30 second spot to 24 seconds, the playback speed
must be increased by 20%. The spot now has the correct run length, but
increasing the speed created an upward pitch shift of 386 cents. Run the shifted
audio through the VSO-Chmb algorithm. Set the Varispeed parameter to +20%.
This shifts the pitch down 386 cents. The spot now has a run length of 24
seconds and is at its original pitch.
To expand a 28 second spot to 30 seconds, the playback speed must be
decreased by 7.14%. Set both the playback source and the VSO Shifter to
–7.14%. The spot will remain at its original pitch and have a run length of 30
seconds.
Like the Stereo-Chmb algorithm, VSO-Chmb is combined with a stereo chamber
reverb. This adds considerable flexibility. You can for example, add reverb to the
material as it is being pitch corrected (great for voiceovers, etc.).
Note that there is no direct synchronization of the pitch shift with the playback
source. The accuracy of the pitch correction is dependent upon the accuracy of
the playback source's varispeed mechanism and display.
3-49