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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)
;
(setfn lpc-frame-rms1 car)
(setfn lpc-frame-rms2 cadr)
(setfn lpc-frame-err caddr)
(setfn lpc-frame-filter-coefs cadddr)
;; LPANAL-CLASS -- does lpc analysis. Frames are returned
;; from an iterator object
(setf lpanal-class (send class :new '(sound framesize skipsize npoles)))
(send lpanal-class :answer :isnew '(snd framedur skiptime np) '(
(let ((sr (snd-srate snd)))
(setf sound snd)
(setf framesize (round (* sr framedur)))
(setf skipsize (round (* sr skiptime)))
(setf npoles np))))
(send lpanal-class :answer :next '() '(
(let ((samps (snd-fetch-array sound framesize skipsize)))
(cond ((null samps) nil)
(t
(snd-lpanal samps npoles))))))
(defun make-lpanal-iterator (sound framedur skiptime npoles)
(send lpanal-class :new (snd-copy sound) framedur skiptime npoles))
;; LPC-FILE-CLASS -- iterator returns frames from file
;;
(setf lpc-file-class (send class :new '(file)))
(send lpc-file-class :answer :isnew '(filename) '(
(setf file (open filename))))
(send lpc-file-class :answer :next '() '(
(read file)))
(defun make-lpc-file-iterator (filename)
(send lpc-file-class :new filename))
;; SAVE-LPC-FILE -- create a file from an iterator. This file can
;; be turned back into an iterator using make-lpc-file-iterator.
;;
(defun save-lpc-file (lpc-iterator filename)
(let ((fp (open filename :direction :output))
(frame t))
(while frame
(setf frame (send lpc-iterator :next))
(if frame (format fp "~A~%" frame)))
(close fp)))
;; SHOW-LPC-DATA. Show values of LPC analysis frames from interator.
;;
(defun show-lpc-data (lpc-iterator iniframe endframe &optional (poles? NIL))
(dotimes (i iniframe) (send lpc-iterator :next))
(dotimes (i (- endframe iniframe))
(let ((frame (send lpc-iterator :next)))
(cond ((null frame) (return))
(poles?
(format t "FRM ~A : ~A\n" (+ i iniframe) frame))
(t
(format t "FRM ~A : ~A\n" (+ i iniframe)
(reverse (cdr (reverse frame)))))))))
;----------------------------------------------------------------------
; 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
;
; THIS CODE TO GET FREQUENCY ASSUMES AN ARRAY OF LPC FRAMES AND REQUIRES
; MATLAB OR OCTAVE. I HAVE NOT ADAPTED THIS TO USE THE STREAM OF FRAMES
; APPROACH. -RBD
;
;(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
;
; THIS VERSION IS FOR ARRAY OF FRAMES
;
;(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)))
; ALLPOLES USES A SINGLE FRAME TO CREATE A FILTER
;
; We introduce two functions:
; NTH-FRAME runs the interator to get the nth frame;
; ALLPOLES-FROM-LPC filters a sound given a frame from an iterator
;; NTH-FRAME - get the nth frame from lpc iterator,
;; first frame is numbered zero
(defun nth-frame (lpc-iterator numframe)
(dotimes (i numframe) (send lpc-iterator :next))
(send lpc-iterator :next))
;; ALLPOLES-FROM-LPC -- filter a sound using an LPC frame
;;
(defun allpoles-from-lpc (snd lpc-frame)
(snd-allpoles snd (lpc-frame-filter-coefs lpc-frame)
(lpc-frame-err lpc-frame))) ;; use ERR for gain
;-------------------------------------------------------------------------------
; LPRESON
(setfn lpreson snd-lpreson)
|
