mlib_signallpc2cepstral_s16(3mlib) [sunos man page]

mlib_SignalLPC2Cepstral_S16(3MLIB)			    mediaLib Library Functions				mlib_SignalLPC2Cepstral_S16(3MLIB)

NAME

       mlib_SignalLPC2Cepstral_S16 - convert linear prediction coefficients to cepstral coefficients

SYNOPSIS

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

       mlib_status  mlib_SignalLPC2Cepstral_S16(mlib_s16  *cepst,  mlib_s32  cscale, const mlib_s16 *lpc, mlib_s32 lscale, mlib_s16 gain, mlib_s32
       gscale, mlib_s32 length, mlib_s32 order);

DESCRIPTION

       The mlib_SignalLPC2Cepstral_S16() function converts linear prediction coefficients to cepstral coefficients.   The  user  supplied  scaling
       factor, cscale, will be used and the output will be saturated if necessary.

       The cepstral coefficients are the coefficients of the Fourier transform representation of the log magnitude spectrum.

       The LPC cepstral coefficients can be derived recursively from the LPC coefficients as following.

       c(0) = log(G)

		     m-1  k
       c(m) = a(m) + SUM --- * c(k) * a(m-k), 1 <= m <= M
		     k=1  m

	      m-1  k
       c(m) = SUM --- * c(k) * a(m-k), m > M
	      k=1  m

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

PARAMETERS

       The function takes the following arguments:

       cepst	       The cepstral coefficients.

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

       lpc	       The linear prediction coefficients.

       lscale	       The scaling factor of the linear prediction coefficients, where actual_data = input_data * 2**(-scaling_factor).

       gain	       The gain of the LPC model.

       gscale	       The scaling factor of the gain of the LPC model, where actual_data = input_data * 2**(-scaling_factor).

       length	       The length of the cepstral coefficients.

       order	       The order of the linear prediction filter.

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	     |Evolving			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       mlib_SignalLPC2Cepstral_S16(3MLIB), mlib_SignalLPC2Cepstral_S16_Adp(3MLIB), mlib_SignalLPC2Cepstral_F32(3MLIB), attributes(5)

SunOS 5.10							    10 Nov 2004 				mlib_SignalLPC2Cepstral_S16(3MLIB)

mlib_SignalCepstral_S16(3MLIB)				    mediaLib Library Functions				    mlib_SignalCepstral_S16(3MLIB)

NAME

       mlib_SignalCepstral_S16 - perform cepstral analysis

SYNOPSIS

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

       mlib_status mlib_SignalCepstral_S16(mlib_s16 *cepst, mlib_s32 cscale, const mlib_s16 *signal, void *state);

DESCRIPTION

       The  mlib_SignalCepstral_S16()  function  performs cepstral analysis.  The user supplied scaling factor will be used and the output will be
       saturated if necessary.

       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	     |Evolving			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       mlib_SignalCepstralInit_S16(3MLIB), mlib_SignalCepstral_S16_Adp(3MLIB), mlib_SignalCepstralFree_S16(3MLIB), attributes(5)

SunOS 5.10							    10 Nov 2004 				    mlib_SignalCepstral_S16(3MLIB)