mlib_SignalCepstral_S16_Adp(3MLIB)			    mediaLib Library Functions				mlib_SignalCepstral_S16_Adp(3MLIB)

NAME

       mlib_SignalCepstral_S16_Adp - perform cepstral analysis

SYNOPSIS

       cc [ flag... ] file... -lmlib [ library... ]
       #include <mlib.h>

       mlib_status mlib_SignalCepstral_S16_Adp(mlib_s16 *cepst,
	    mlib_s32 *cscale, const mlib_s16 *signal, void *state);

DESCRIPTION

       The  mlib_SignalCepstral_S16_Adp()  function  performs cepstral analysis. The scaling factor of the output data will be calculated based on
       the actual data.

       The basic operations to compute the cepstrum is shown below.

	       +-----------+	  +--------+	   +-----------+
	       |  Fourier  |	  |	   |	   |  Inverse  |
	 ----->|	   |----->| log|*| |------>|  Fourier  |----->
	  x(n) | Transform | X(k) |	   | X'(k) | Transform | c(n)
	       +-----------+	  +--------+	   +-----------+

       where x(n) is the input signal and c(n) is its cepstrum. In mathematics, they are

		N-1		   2*PI*k*n
	 X(k) = SUM x(n) * exp(-j*----------)
		n=0		      N

	 X'(k) = log|X(k)|

		 1  N-1 	       2*PI*k*n
	 c(n) = --- SUM X'(k) * exp(j*----------)
		 N  n=0 		  N

       Since X'(k) is real and even (symmetric), i.e.

	 X'(k) = X'(N - k)

       the c(n) is real and the equation becomes Cosine transform.

		 1  N-1 	     2*PI*k*n
	 c(n) = --- SUM X'(k) * cos(----------)
		 N  n=0 		N

       The cepstral coefficients in LPC is a special case of the above.

       See Digital Signal Processing by Alan V. Oppenheim and Ronald W. Schafer, Prentice Hall, 1974.

       See Fundamentals of Speech Recognition by Lawrence Rabinerand Biing-Hwang Juang, Prentice Hall, 1993.

PARAMETERS

       The function takes the following arguments:

       cepst	 The cepstral coefficients.

       cscale	 The scaling factor of cepstral coefficients, where actual_data = output_data * 2**(-scaling_factor).

       signal	 The input signal vector, the signal samples are in Q15 format.

       state	 Pointer to the internal state structure.

RETURN VALUES

       The function returns MLIB_SUCCESS if successful. Otherwise it returns MLIB_FAILURE.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Committed 		   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       mlib_SignalCepstralInit_S16(3MLIB), mlib_SignalCepstral_S16(3MLIB), mlib_SignalCepstralFree_S16(3MLIB), attributes(5)

SunOS 5.11							    2 Mar 2007					mlib_SignalCepstral_S16_Adp(3MLIB)