Locate and position the current Audacity source code, and clear a variety of old junk out of the way into junk-branches

plug-ins/vocoder.ny

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