90 lines
3.0 KiB
Common Lisp
90 lines
3.0 KiB
Common Lisp
$nyquist plug-in
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$version 4
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$type process
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$name (_ "Crossfade Tracks")
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$manpage "Crossfade_Tracks"
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$debugbutton disabled
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$action (_ "Crossfading...")
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$preview selection
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$author (_ "Steve Daulton")
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$release 2.3.0
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$copyright (_ "Released under terms of the GNU General Public License version 2")
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;; crossfadetracks.ny by Steve Daulton Nov 2014 / Sep 2015
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;; Released under terms of the GNU General Public License version 2:
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;; http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
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;;
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;; For information about writing and modifying Nyquist plug-ins:
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;; https://wiki.audacityteam.org/wiki/Nyquist_Plug-ins_Reference
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$control type (_ "Fade type") choice (
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("ConstantGain" (_ "Constant Gain"))
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("ConstantPower1" (_ "Constant Power 1"))
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("ConstantPower2" (_ "Constant Power 2"))
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("CustomCurve" (_ "Custom Curve"))
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) 0
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$control curve (_ "Custom curve") real "" 0 0 1
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$control direction (_ "Fade direction") choice (
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(_ "Automatic")
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("OutIn" (_ "Alternating Out / In"))
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("InOut" (_ "Alternating In / Out"))
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) 0
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(defun crossfade (type dir curve)
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(setf fade-out
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(case dir
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(0 (equal (guessdirection) 'OUT)) ; auto
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(1 (oddp (get '*track* 'index))) ; fade out odd
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(T (evenp (get '*track* 'index))))) ; fade out even
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; Set control rate to sound rate to ensure length is exact.
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(setf *control-srate* *sound-srate*)
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(mult *track*
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(cond
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(fade-out
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(case type
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(0 (pwlv 1 1 0))
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(1 (osc (hz-to-step (/ (get-duration 4))) 1 *sine-table* 90))
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(2 (s-sqrt (pwlv 1 1 0)))
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(T (custom curve 0))))
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(T ; else fade in.
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(case type
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(0 (pwlv 0 1 1))
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(1 (osc (hz-to-step (/ (get-duration 4))) 1))
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(2 (s-sqrt (pwlv 0 1 1)))
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(T (custom curve 1)))))))
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(defun custom (curve inout)
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;; 'epsilon' defines the curvature of a logarithmc curve.
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;; To avoid log 0 or /0 it must be > 0 and < 1.
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(let* ((curve (+ 0.99 (* -0.98 (min 1 (max 0 curve)))))
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; magic number 2.7 gives approx 'constant power' curve at 50% setting.
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(epsilon (power curve 2.7)))
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(if (= inout 0)
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(setf logcurve (pwev epsilon 1 1))
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(setf logcurve (pwev 1 1 epsilon)))
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; Scale and invert curve for 0 to unity gain.
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(sum 1
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(mult (/ -1 (- 1 epsilon))
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(diff logcurve epsilon)))))
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(defun guessdirection ()
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"If the selection is closer to the start of the
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audio clip, fade in, otherwise fade out."
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(let* ((start (get '*selection* 'start))
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(end (get '*selection* 'end))
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(clips (get '*track* 'clips))
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(in-dist end)
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(out-dist end))
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(if (arrayp clips)
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(setf clips (append (aref clips 0)(aref clips 1))))
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(dotimes (i (length clips))
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(setf in-dist (min in-dist (abs (- start (first (nth i clips))))))
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(setf out-dist (min out-dist (abs (- end (second (nth i clips)))))))
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(if (< in-dist out-dist) 'in 'out)))
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(if (< (length (get '*selection* 'tracks)) 2)
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(format nil (_ "Error.~%Select 2 (or more) tracks to crossfade."))
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(crossfade type direction curve))
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