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Reference of LPC primitive functions 
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snd-lpanal  ARGS: snd-array  npoles

   snd-array:  array of samples from a sound to be analyzed
   npoles:     number of poles for LPC analysis

   returns:    a list (RMS1 RMS2 ERR VECTOR)
               where  RMS1:    energy of input data (not rms value!)
                      RMS2:    energy of residual
                      ERR:     sqrt(RMS2/RMS1)
                      VECTOR:  array of LPC filter coefficients

   Note: this analysis lacks pitch detection

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snd-allpoles  ARGS: snd  coefs  gain

   snd:        A sound
   coefs:      Array of coefficients of an allpoles filter.
               The format of this array is the same of the fourth
               element of the list returned by snd-lpcanal.
               (see details in lpc.lsp)
   gain:       gain of the LPC filter (a FLONUM)

   returns:    The sound filtered by the specified allpoles filter

   Note: This is a static filter. Coefficients do not change. 

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snd-lpreson   ARGS: snd  lpc-obj skiptime
 
    snd:      A sound
    lpc-obj   A Lisp object such as when a :next message is send to 
              this object it returns a list of two elements (GAIN COEFS)
              where:
                     GAIN:  gain of the filter
                     COEFS: coefficients of LPC filter
    skiptime: a FLONUM. This is the frame duration for resyntesis.

    returns: The sound snd filtered by a dinamic LPC filter.
             The coefficients and gain of LPC filter are changed every frame
             The data for every frame is obtained by sending a :next message to
             lpc-obj.
             The output sound finish when input sound finish or when lpc-obj
             returns NIL


 

