Pitch Shift

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Description

As the name implies, the pitch shift algorithm modulates the frequency of the input signal by a designated interval. Csound has built-in opcodes to raise and lower pitches by user-specified intervals. The pitch is scaled proportionally and the time is scaled inverse proportionally according to a frequency modulation factor. This factor designates how the original input signal samples will be arranged in the output signal. A factor of 2 will cause the frequency of the signal to be doubled and the number of samples to be cut in half (i.e. every other sample is discarded).

 

Graphical Depiction

 

Effect Formula

y[n] = f(x[n])

y[n] = output signal

x[n] = input signal

f() = frequency modulation function

 

Source Code

Pitch_Shift.txt

Pitch_Shift.csd

(.csd files can be viewed with Notepad or any text editor)

 

Example Audio Clips

Original Unprocessed Signal

Original

Raised half step

Up_half_step

Raised whole step

Up_whole_step

Raised minor third

Up_minor_third

Raised major third

Up_major_third

Raised perfect fourth

Up_perfect_fourth

Raised diminished fifth

Up_diminished_fifth

Raised perfect fifth

Up_perfect_fifth

Raised minor sixth

Up_minor_sixth

Raised major sixth

Up_major_sixth

Raised minor seventh

Up_minor_seventh

Raised major seventh

Up_major_seventh

Raised one octave

Up_one_octave

 

References

Lehman, Scott (1996). Effects Explained. Harmony Central. Retrieved 6/04 from

http://www.harmony-central.com/Effects/effects-explained.html

 

Mikelson, Hans (2000). Modeling a multieffects processor in Csound. In Boulanger, Richard (2000), The Csound book (pp 575-594). Cambridge, MA: MIT Press.

 

Schindler, Allan. (1998). Eastman Csound tutorial.  Eastman School of Music. Retrieved 6/04 from

http://www.esm.rochester.edu/onlinedocs/allan.cs/

 

Vercoe, Barry. (1992). The public Csound reference manual, version 4.16. MIT Press.  Retrieved 6/04 from http://www.lakewoodsound.com/csound/hypertext/manual.htm

 

Zolzer, Udo. (2002). Digital audio effects. West Sussex, England: Baffins Lane.