143 lines
5.2 KiB
Common Lisp
143 lines
5.2 KiB
Common Lisp
$nyquist plug-in
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$version 3
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$type process
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$preview enabled
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$name (_ "Vocoder")
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$manpage "Vocoder"
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$action (_ "Processing Vocoder...")
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$author (_ "Edgar-RFT")
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$release 2.3.0
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$copyright (_ "Released under terms of the GNU General Public License version 2")
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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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;; Performance improvement, error message for mono, code cleanup
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;; by Paul Licameli and Steve Daulton October 2014
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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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;; https://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 (
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("BothChannels" (_ "Both Channels"))
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("RightOnly" (_ "Right Only"))
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) 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 artificial 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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(defun mix ()
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;; if track volume slider is less than 100 percent decrease track volume
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(if (< track-vl 100)
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(setf s
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(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)
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(setf s
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(vector (aref s 0)
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(sim (aref s 1)
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(scale radar-vol (osc (hz-to-step radar-f)
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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)
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(setf s
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(vector (aref s 0)
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(sim (aref s 1) (scale noise-vol (noise duration)))))))
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;;; The Vocoder
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(defun vocoder ()
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(do* ((i 0 (1+ i))
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mod-envelope ; local variable for filtered envelope of left channel.
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band ; local variable for band-passed audio.
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(result 0) ; result must be initialized because you cannot sum to NIL.
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(q (/ (sqrt 2.0) (/ octaves bands))) ; quick approximation of q
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; for given bandwidth.
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(p (+ (hz-to-step 20) (/ interval 2.0)) ; midi step of 20 Hz + offset.
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(+ p interval))
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(f (step-to-hz p) (step-to-hz p)))
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((= i bands) result) ; DO for each band then return 'result'.
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(setf band (bandpass2 s f q)) ; intermediate results (2 channels)
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(setf mod-envelope (lowpass8 (s-abs (aref band 0)) (/ f dst)))
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(setf result
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(sum result
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(bandpass2
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(mult mod-envelope (aref band 1))
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f q)))))
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;;; The Program
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(cond
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((arrayp s)
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(mix) ; changes s
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(let ((original (or (= mst 0) (aref s 0))))
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(setf s (vocoder))
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;; Now normalize s to 0 db peak
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(setf s (scale (/ (peak s ny:all)) s))
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(case mst
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(0 s) ; let Audacity coerce back to stereo
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(1 (vector original s)))))
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(t ; this effect isn't meant for mono
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(format nil (_ "Error.~%Stereo track required."))))
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