fmpiano.lsp
 Version 1.00 	16 May 2005
 Author Steven Jones

 Contact jones57@swbell.net include the word "nyquist" in subject line

 The contents of this file are released under the terms of the GNU General
 Public License. See the file LICENSE.txt

 A vain attempt at piano like instrument using FM. 

  [2]--->|
  [3]--->|--->[1]---> out
  [4]--->|

 The instrument uses three modulators and a carrier. Modulator [2] has a
 fixed frequency and provides in initial burst of non-harmonic
 partials. Modulator [3] uses a filtered square wave and provides the body
 of the tone. Modulator [4] provides the upper harmonics.

function

 (fmpiano:voice step gate [:vel][:dt])
 A piano like instrument using FM.
 
 step   - MIDI step number.
 gate   - Flonum. The "key down" time. The maximum tones duration is a 
          function of the step number. Higher notes have shorter decays. 
          The gate parameter is used to truncated the "natural" decay.
 :vel   - MIDI velocity. Default 64
 :dt    - Flonum. Detune ratio, default 1.00
 return - Sound.

wrapper

 (fmpiano  plist gate [:vel][:pos][:arpeg][:comp][:dt])
 An FM piano instrument.

 plist  - List | MIDI step. List of note(s) to be played.
 gate   - Flonum. The "key down" time. The maximum tones duration is a 
          function of the step number. Higher notes have shorter decays. 
          The gate parameter is used to truncated the "natural" decay.
 :vel   - MIDI velocity. Default 64
 :pos   - Flonum | sound. Pan position 0 <= pos <=1, default 0.5
 :arpeg - Flonum. Arpeggio interval, default 0 seconds.
 :comp  - Flonum | Bool. Amplitude compensation. See definst.lsp
 :dt    - Flonum. Detune ratio, default 1.00
 return - Sound vector.

;; fmpiano.lsp
;; Version 1.00 	16 May 2005
;; Author Steven Jones
;;
;; Contact jones57@swbell.net include the word "nyquist" in subject line
;;
;; The contents of this file are released under the terms of the GNU General
;; Public License. See the file LICENSE.txt
;;
;; A vain attempt at piano like instrument using FM. 
;;
;;  [2]--->|
;;  [3]--->|--->[1]---> out
;;  [4]--->|
;;
;; The instrument uses three modulators and a carrier. Modulator [2] has a
;; fixed frequency and provides in initial burst of non-harmonic
;; partials. Modulator [3] uses a filtered square wave and provides the body
;; of the tone. Modulator [4] provides the upper harmonics.
;;

(require 'square-08)
(require 'map)
(require 'map-vel3)
(require 'map-vel6)
(require 'definst)
(provide 'fmpiano)
(current-file "fmpiano")


;; Map decay time as function of MIDI step number.
;;
(setf fmpiano:*map-decay-time*
      (map:split :y0 20 :y1 10 :y2 0.01
		 :x0 00 :x1 64 :x2 128
		 :c1 1  :c2 .1))


;; @doc function fmpiano:voice 
;; (fmpiano:voice step gate [:vel][:dt])
;; A piano like instrument using FM.
;; 
;; step   - MIDI step number.
;; gate   - Flonum. The "key down" time. The maximum tones duration is a 
;;          function of the step number. Higher notes have shorter decays. 
;;          The gate parameter is used to truncated the "natural" decay.
;; :vel   - MIDI velocity. Default 64
;; :dt    - Flonum. Detune ratio, default 1.00
;; return - Sound.
;;

(defun fmpiano:voice (step gate &key vel (dt 1))
  (let (
	hz1  hz2  hz3  hz4		;Frequencies
	a1   a2   a3   a4		;Amplitudes
	ev1  ev2  ev3  ev4 decay pinch  ;Envelopes
	     sig2 sig3 sig4         	;Intermediate signals
	vhigh vlow                      ;velocity scale factors (linear)
	)
    
    (setf vel (or vel 64))
    (setf vhigh (db-to-linear (send map:*vel6* :get vel)))
    (setf vlow  (db-to-linear (send map:*vel3* :get vel)))

    (setf hz1 (* dt (step-to-hz step))
	  hz2 74.13			;Fixed
	  hz3 (* hz1 0.995)
	  hz4 (* hz1 20.03)
	  )

    (setf a1 vhigh
	  a2 (* 0.050 vhigh)
	  a3 (* 4.000 vhigh)
	  a4 (* 1.260 vlow)
	  )
    
    (setf decay (send fmpiano:*map-decay-time* :get step))
    (setf pinch 0.25)
    (setf ev1 (mult (cond ((> step 64)
			   (mult (percussion decay)(percussion decay)))
			  (t (percussion decay)))
		    (asd 0 gate pinch)))

    (setf ev2 (percussion 0.50))
    
    (setf ev3 ev1)
    (setf ev4 ev1)

    (setf sig2 
	  (mult (osc (hz-to-step hz2) decay) ev2))

    (setf sig3 
	  (lowpass2 
	   (mult (osc (hz-to-step hz3) decay *square-08*) ev3)
	   1000))

    (setf sig4 
	  (lowpass2
	   (mult (osc (hz-to-step hz4) decay) ev4)
	   1000))


    (mult (fmosc (hz-to-step hz1)
		 (sum (scale (* hz1 a2) sig2)
		      (scale (* hz1 a3) sig3)
		      (scale (* hz1 a4) sig4)
		      ))
	  (scale a1 ev1))
    ))


;; @doc wrapper fmpiano
;; (fmpiano  plist gate [:vel][:pos][:arpeg][:comp][:dt])
;; An FM piano instrument.
;;
;; plist  - List | MIDI step. List of note(s) to be played.
;; gate   - Flonum. The "key down" time. The maximum tones duration is a 
;;          function of the step number. Higher notes have shorter decays. 
;;          The gate parameter is used to truncated the "natural" decay.
;; :vel   - MIDI velocity. Default 64
;; :pos   - Flonum | sound. Pan position 0 <= pos <=1, default 0.5
;; :arpeg - Flonum. Arpeggio interval, default 0 seconds.
;; :comp  - Flonum | Bool. Amplitude compensation. See definst.lsp
;; :dt    - Flonum. Detune ratio, default 1.00
;; return - Sound vector.
;;

(defwrapper fmpiano #'fmpiano:voice)