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SOUNDSHAPER: CDP REFERENCE

MORPHTUNE - morphed re-tuning of spectral peaks


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SUMMARY
MORPHTUNE (CDP: newmorph2, Modes 2-3) morphs the most prominent frequencies of the sound towards a different set of tuned spectral peaks.
The peak-frequency data can be derived from a second sound using PEAKFREQS
(CDP: newmorph2, Mode 1) .


MORPHTUNE

MODES

 1. (CDP Mode 2) Tuned field - linear: Interpolate linearly towards tuned peaks
 2. (CDP Mode 3) Tuned field - cosine: Interpolate cosinusoidally towards tuned peaks.
   Sound gradually tuned as in linear mode, but interpolation here is timewise-cosinusoidal.


PARAMETERS
  peaksfile: text file listing goal-peak frequencies, in order of prominence.
    Range: 10? to 22050? Hz 
    File is a list of frequencies, which may be extracted from another sound via PEAKFREQS, or may be any arbitary set, e.g.:
    220
    330
    440
    550 
    660 
  start: Start time of morph.
    Range: 0 to filelength-window_gap secs.
  end: End time of morph.
    Range: window-gap*2 to filelength secs.
  exponent of interpolation: >1 increasing slope; 1 linear; <1 decreasing slope
    Range: 0.02 to 50
  peaks: number of most-prominent source-peaks to interpolate.
    Range: 1-16
  [rand]: randomisation of the goal peak frequencies.
    Range 0 - 1
 
 
NOTES
The input spectral analysis file is gradually tuned to the frequencies specified in the peaksfile (and their octave transpositions), which may be any arbitrary set specified by the user.  Start is the start-time and end the end-time of the transition. If end is set to the minimum, there is no audible transition, just the retuned sound throughout.  Peaks, the number of most-prominent source-peaks to interpolate, should normally match the number of frequencies in peaksfile.

In Mode 2 the sound is gradually tuned as in linear mode, but the interpolation is timewise-cosinusoidal.


PEAKFREQS

PEAKFREQS finds the frequencies of the most prominent spectral peaks (in order of prominence) and outputs these to a textfile list, called "peaksfile.txt" by default.  Note that the output is simply a list of frequencies, time-averaged over the file: no times or amplitudes are given, as in the Info function PEAKFRQ.

MODES
 1. (CDP Mode 1): Extract average harmonic field of sound.

PARAMETERS
  peaks : number of most-prominent source-peaks to find.
    Range: 1-16

NOTES
The default output folder in Soundshaper is the root of <User-folder> (e.g. \CDP\TXT). You may prefer to choose a subfolder of this called \morphtune if this exists. You may save to any name, not necessarily "peaksfile.txt".   The complementary operation Morphtune looks in <User-folder>\morphtune\ for "peaksfile.txt", by default.

This function also has uses with ACCUMULATE, TUNE and VARIBANK, where sounds can be tuned to a pitch set derived from another sound, analysed by PEAKFREQS. As the last two of these functions are time-varying, it may be useful sometimes to split the sound to be analysed into two or more segments and derive a peaksfile for each segment, so that TUNE or VARIBANK can better follow the changing pitch content of the analysed sound.

© Ensemble Software and Composers Desktop Project 2014