mlib_signalcepstral_f32(3mlib) [sunos man page]

mlib_SignalCepstral_F32(3MLIB)				    mediaLib Library Functions				    mlib_SignalCepstral_F32(3MLIB)

NAME

       mlib_SignalCepstral_F32 - perform cepstral analysis

SYNOPSIS

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

       mlib_status mlib_SignalCepstral_F32(mlib_f32 *cepst, const mlib_f32 *signal, void *state);

DESCRIPTION

       The mlib_SignalCepstral_F32() function performs cepstral analysis.

       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.

       signal	       The input signal vector.

       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_F32(3MLIB), mlib_SignalCepstralFree_F32(3MLIB), attributes(5)

SunOS 5.10							    10 Nov 2004 				    mlib_SignalCepstral_F32(3MLIB)

mlib_SignalMelCepstral_F32(3MLIB)			    mediaLib Library Functions				 mlib_SignalMelCepstral_F32(3MLIB)

NAME

       mlib_SignalMelCepstral_F32 - perform cepstral analysis in mel frequency scale

SYNOPSIS

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

       mlib_status mlib_SignalMelCepstral_F32(mlib_f32 *cepst, const mlib_f32 *signal, void *state);

DESCRIPTION

       The mlib_SignalMelCepstral_F32() function performs cepstral analysis in mel frequency scale.

       The  first  two steps of mel scale cepstral analysis is the same as in general cepstral anaysis. After the logarithm of the spectrum magni-
       tude is obtained, it is converted into mel frequency scale before the inverse Fourier transform.

		  +-----------+        +-----------+
		  |  Linear   |        |  Inverse  |
       ... ------>|    to     |------->|  Fourier  |----->
	    X'(k) | Mel Scale | X''(m) | Transform | c(n)
		  +-----------+        +-----------+

       where X'(k) is defined in linear frequency scale and X''(m) is defined in mel frequency scale.

       The mel frequency scale is defined as following.

       freq_mel = melmul * LOG10(1 + freq_linear / meldiv)

       where freq_mel is the frequency in mel scale, freq_linear is the frequency in linear scale, melmul is the multiplying factor, muldiv is the
       dividing factor.

       Optionally,  a  bank of band pass filters in linear frequency scale can be used below the bank of band pass filters in mel frequency scale,
       as shown below in linear frequency scale.

       0   f1  f2  f3	 fp  fp+1 fp+2	fp+3  fp+q
       |---|---|---| ... |---|----|-----| ... | ... -> freq

       where fp = melbgn, fp+q = melend, p = nlinear, q = nmel; the filters number 1 to p are defined in linear frequency scale which  have  equal
       bandwidth  in  linear  frequency  scale; the filters number p+1 to p+q are defined in mel frequency scale which have equal bandwidth in mel
       frequency scale and increasing bandwidth in linear frequency scale.

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

       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.

       signal	       The input signal vector.

       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_SignalMelCepstralInit_F32(3MLIB), mlib_SignalMelCepstralFree_F32(3MLIB), attributes(5)

SunOS 5.10							    10 Nov 2004 				 mlib_SignalMelCepstral_F32(3MLIB)