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;---------------------------------------------------------------------
; LPANAL. Performs LPC analysis
;
; snd sound for analysis
; an-dur duration of analysis (= duration of sound)
; skiptime step frame to frame
; npoles number of poles
;
; RESULT: analysis data in list format.
; Every element of the list is a list of the form
;
; (RMS1 RMS2 ERR FILTER-COEFS)
;
; RMS1 Energy (not rms value) of input signal
; RMS2 Energy (not rms value) of residual signal
; ERR = sqrt(RMS2/RMS1) If it is small then VOICED sound,
; else UNVOICED
; FILTER-COEFS Array of filter coefs.
;
;
; The z transform of filter is H(z) = 1/A(z)
;
; where A(z) is a polynome of the form:
;
;
; A(z) = 1 + a1 z + a2 z^2 + a3 z^3 + ... + aP z^P
;
; FILTER-COEFS is the array
;
; #(-aP -aP-1 -aP-2 ... a3 a2 a1)
;
; (this format is suited for the filter ALLPOLES)
;
(defun lpanal (snd an-dur skiptime npoles)
(let* ((sr (snd-srate snd))
(skipsize (round (* sr skiptime)))
(numframes (round (- (/ (* sr an-dur) skipsize) 0.5)))
(sndcpy (snd-copy snd))
(result (make-array numframes)))
(dotimes (i numframes)
(setf (aref result i)
(snd-lpanal
(snd-fetch-array sndcpy (* 2 skipsize) skipsize)
npoles)))
(format t "LPANAL: duration: ~A frames: ~A framedur: ~A skip: ~A poles ~A\n"
an-dur numframes (* skiptime 2) skiptime npoles)
result))
;; this code is based on fft_demo.lsp -- the idea is that an object
;; will return a stream of LPC frames. Other objects can manipulate
;; these frames, creating a new stream, or turn the frames back into
;; sound.
(setf lpc-class (send class :new '(sound framesize skipsize npoles)))
(send lpc-class :answer :isnew '(snd framedur skiptime np) '(
(let ((sr (snd-srate snd)))
(setf sound snd)
(setf framesize (round (* sr framedur)))
(setf skiptime (round (* sr skiptime)))
(setf npoles np)))
(send lpc-class :next '() '(
(let ((samps (snd-fetch-array framesize skipsize)))
(cond ((null samps) nil)
(t
(snd-lpanal samps npoles)))))
(defun make-lpanal-iterator (sound framedur skiptime npoles)
(send lpc-class :new (snd-copy sound) framedur skiptime npoles))
;---------------------------------------------------------------------
; SHOW-LPC-DATA. Show values of LPC analysis frames
;
; lpc-data data generated by LPANAL
; iniframe first frame to show
; endframe last frame to show
; poles? T or NIL show or not filter coefs
(defun show-lpc-data (lpc-data iniframe endframe &optional (poles? NIL))
(if (> endframe (length lpc-data)) (setf endframe (length lpc-data)))
(dotimes (i (- endframe iniframe))
(if poles? (format t "FRM ~A : ~A\n" (+ i iniframe) (aref lpc-data (+ i iniframe)))
(format t "FRM ~A : ~A\n" (+ i iniframe) (reverse (cdr (reverse (aref lpc-data (+ i iniframe)))))))))
;----------------------------------------------------------------------
; LPC-FREQ. Show frequency response of ALLPOLES filter.
; NEEDS MATLAB or OCTAVE
;
;
; HELPER FUNS : GET-FILTER-COEFS from a LPC analysis data
; lpc-data: data generated by LPCANAL
; numframe: index of frame data
;
; LPC-COEFS-TO-MATLAB : transforms LPC coefs format to Matlab format
;
; LPC-FREQ.
;
; varname : the name of variable that holds coef array in MATLAB
; lpc-data : as above
; numframe : as above
;
(defun get-filter-coefs (lpc-data numframe)
(nth 3 (aref lpc-data numframe)))
(defun lpc-coefs-to-matlab (lpc-data numframe)
(let* ((lpc-coefs (get-filter-coefs lpc-data numframe))
(lencoefs (length lpc-coefs))
(result (make-array (1+ lencoefs))))
(setf (aref result 0) 1.0)
(dotimes (i lencoefs)
(setf (aref result (1+ i))
(- (aref lpc-coefs (- lencoefs i 1)))))
result))
(defun lpc-freq (varname lpc-data numframe)
(octave (list (list (lpc-coefs-to-matlab lpc-data numframe) varname 'ARR))))
;----------------------------------------------------------------------------
; ALLPOLES
;
(defun get-allpoles-gain (lpc-data numframe)
(nth 2 (aref lpc-data numframe))) ; se toma ERR para que la amplitud de
; la salida se aproxime a 1
(defun allpoles-from-lpc (snd lpc-data numframe)
(snd-allpoles snd (get-filter-coefs lpc-data numframe) (get-allpoles-gain lpc-data numframe)))
;-------------------------------------------------------------------------------
; LPRESON
(defun get-lpreson-gain (lpc-data numframe)
(sqrt (nth 1 (aref lpc-data numframe)))) ; se toma (sqrt RMS2) para que la amplitud se
; aproxime a la original
(defun get-lpreson-coefs (lpc-data numframe)
(nth 3 (aref lpc-data numframe)))
|
