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https://github.com/cookiengineer/audacity
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118 lines
4.4 KiB
Common Lisp
118 lines
4.4 KiB
Common Lisp
;nyquist plug-in
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;version 3
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;type process
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;categories "http://lv2plug.in/ns/lv2core#SpectralPlugin"
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;name "Vocoder..."
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;action "Processing Vocoder..."
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;; vocoder.ny by Edgar-RFT
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;; a bit of code added by David R. Sky
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;; GUI update by Steve Daulton July 2012.
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;; Released under terms of the GNU General Public License version 2:
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;; http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
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;;
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;; For information about writing and modifying Nyquist plug-ins:
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;; http://wiki.audacityteam.org/wiki/Nyquist_Plug-ins_Reference
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;control dst "Distance: (1 to 120, default = 20)" real "" 20 1 120
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;control mst "Output choice" choice "both channels, right only" 0
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;control bands "Number of vocoder bands" int "" 40 10 240
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;control track-vl "Amplitude of original audio (percent)" real "" 100 0 100
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;control noise-vl "Amplitude of white noise (percent)" real "" 0 0 100
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;control radar-vl "Amplitude of Radar Needles (percent)" real "" 0 0 100
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;control radar-f "Frequency of Radar Needles (Hz)" real "" 30 1 100
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; maybe the code once again has to be changed into _one_ local let-binding
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; if you have lots of nyquist "[gc:" messages try this:
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; (expand 100) ; gives Xlisp more memory but I have noticed no speed difference
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; number of octaves between 20hz and 20khz
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(setf octaves (/ (log 1000.0) (log 2.0)))
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; convert octaves to number of steps (semitones)
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(setf steps (* octaves 12.0))
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; interval - number of steps per vocoder band
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(setf interval (/ steps bands))
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; Some useful calculations but not used in this plugin
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; half tone distance in linear
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; (print (exp (/ (log 2.0) 12)))
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; octave distance in linear
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; (print (exp (/ (log 1000.0) 40)))
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; The Radar Wavetable
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; make *radar-table* a global variable.
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(setf contol-dummy *control-srate*) ; save old *control-srate*
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(set-control-srate *sound-srate*)
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(setf *radar-table* (pwl (/ 1.0 *control-srate*) 1.0 ; 1.0 after 1 sample
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(/ 2.0 *control-srate*) 0.0 ; 0.0 after 2 samples
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(/ 1.0 radar-f))) ; stay 0.0 until end of the period
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(set-control-srate contol-dummy) ; restore *control-srate*
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; make *radar-table* become a nyquist wavetable of frequency radar-f
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(setf *radar-table* (list *radar-table* (hz-to-step radar-f) T))
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; increase the volume of the audacity track in the middle of the slider
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; the sqrt trick is something like an artifical db scaling
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(setf track-vol (sqrt (/ track-vl 100.0)))
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; decrease the volume of the white noise in the middle of the slider
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; the expt trick is an inverse db scaling
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(setf noise-vol (expt (/ noise-vl 100.0) 2.0))
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; also increase the volume of the needles in the middle of the slider
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(setf radar-vol (sqrt (/ radar-vl 100.0)))
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; here you can switch the tracks on and off for bug tracking
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; (setf radar-vol 0)
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; (setf noise-vol 0)
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; (setf track-vol 0)
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; The Mixer
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; calculate duration of audacity selection
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(setf duration (/ len *sound-srate*))
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; if track volume slider is less than 100 percent decrease track volume
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(if (< track-vl 100) (setf s (vector (aref s 0) (scale track-vol (aref s 1)))))
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; if radar volume slider is more than 0 percent add some radar needles
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(if (> radar-vl 0) (setf s (vector (aref s 0) (sim (aref s 1)
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(scale radar-vol (osc (hz-to-step radar-f) duration *radar-table*))))))
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; if noise volume slider is more than 0 percent add some white noise
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(if (> noise-vl 0) (setf s (vector (aref s 0) (sim (aref s 1)
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(scale noise-vol (noise duration))))))
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; The Vocoder
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(defun vocoder ()
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(let ((p (+ (hz-to-step 20) (/ interval 2.0))) ; midi step of 20 Hz + offset
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f ; we can leave f initialized to NIL
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(q (/ (sqrt 2.0) (/ octaves bands))) ; explanation still missing
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(result 0)) ; must be initialized to 0 because you cannot sum to NIL
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(dotimes (i bands)
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(setf f (step-to-hz p))
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(setf result (sum result
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(bandpass2 (mult (lowpass8
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(s-max (bandpass2 (aref s 0) f q)
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(scale -1 (bandpass2 (aref s 0) f q))) (/ f dst))
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(bandpass2 (aref s 1) f q)) f q)))
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(setf p (+ p interval)))
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result))
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; The Program
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(if (arrayp s) (let ()
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(cond ((= mst 1) (vector (aref s 0) (setf (aref s 1) (vocoder))))
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((= mst 0) (setf s (vocoder))))
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(cond ((= mst 1) (setq peakamp (peak (aref s 1) ny:all)))
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((= mst 0) (setq peakamp (peak s ny:all))))
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(cond ((= mst 1) (vector (aref s 0) (setf (aref s 1)
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(scale (/ 1.0 peakamp) (aref s 1)))))
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((= mst 0) (setf s (scale (/ 1.0 peakamp) s))))
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s))
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