Manual Pages for UNIX Operating System command usage for man mlib_SignalFFTW_4_S16

mediaLib Library Functions               mlib_SignalFFTW_4(3MLIB)



NAME
     mlib_SignalFFTW_4,                mlib_SignalFFTW_4_S16_S16,
     mlib_SignalFFTW_4_S16C_S16C,     mlib_SignalFFTW_4_S16C_S16,
     mlib_SignalFFTW_4_S16, mlib_SignalFFTW_4_S16C - signal  Fast
     Fourier Transform with windowing (FFTW)

SYNOPSIS
     cc [ flag... ] file... -lmlib [ library... ]
     #include 

     mlib_status mlib_SignalFFTW_4_S16_S16(mlib_s16 *dstr, mlib_s16 *dsti,
          const mlib_s16 *srcr, const mlib_s16 *srci, const mlib_s16 *window,
          mlib_s32 order, mlib_s32 *scale);


     mlib_status mlib_SignalFFTW_4_S16C_S16C(mlib_s16 *dstc,
          const mlib_s16 *srcc,const mlib_s16 *window, mlib_s32 order,
          mlib_s32 *scale);


     mlib_status mlib_SignalFFTW_4_S16C_S16(mlib_s16 *dstc,
          const mlib_s16 *srcr,const mlib_s16 *window, mlib_s32 order,
          mlib_s32 *scale);


     mlib_status mlib_SignalFFTW_4_S16(mlib_s16 *srcdstr,
          mlib_s16 *srcdsti,const mlib_s16 *window, mlib_s32 order,
          mlib_s32 *scale);


     mlib_status mlib_SignalFFTW_4_S16C(mlib_s16 *srcdstc,
          const mlib_s16 *window,mlib_s32 order, mlib_s32 *scale);


DESCRIPTION
     Each of the functions in this group  performs  Fast  Fourier
     Transform with windowing (FFTW).


     The FFTW functions use the following equation:

                 1   N-1
       dst[k] = ---- SUM {src[n] * window[n] * exp(-j2*PI*n*k/N)}
                 C1  n=0



     and the IFFTW functions use the following equation:

                 1   N-1
       dst[n] = ---- SUM {src[k] * window[k] * exp(j2*PI*n*k/N)}
                 C2  k=0



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mediaLib Library Functions               mlib_SignalFFTW_4(3MLIB)



     where

       k = 0, 1, ..., (N - 1)
       n = 0, 1, ..., (N - 1)
       N = 2**order



     The signal FFTW/IFFTW functions can be categorized into four
     groups  according  to the ScaleMode in the function names in
     the following form:

       mlib_Signal[FFTW|IFFTW]_ScaleMode_OutType_InType_OpMode()
       mlib_Signal[FFTW|IFFTW]_ScaleMode_DataType_OpMode()



     The scaling factors C1 and C2  used  in  the  equations  are
     defined as follows:

         o    For ScaleMode = 1, C1 = 1 and C2 = 2**order.

         o    For ScaleMode = 2, C1 = 2**order and C2 = 1.

         o    For ScaleMode = 3, C1  =  C2  =  2**(order/2)  when
              order  is  even,  or C1 = 2**((order+1)/2) and C2 =
              2**((order-1)/2) when order is odd.

         o    For ScaleMode = 4, C1 = 2**P and C2 = 2**Q, where P
              and  Q  are  adaptive  scaling factors and are gen-
              erated by the functions.


     For functions with only real parts for  the  source  signal,
     the  imaginary  parts  are assumed to be all zero. For func-
     tions with only real parts for the destination  signal,  the
     imaginary  parts  are discarded. The functions with only one
     data type in their names perform the operation in place.

PARAMETERS
     Each function takes some of the following arguments:

     dstr       Destination signal array that contains  the  real
                parts.


     dsti       Destination signal array that contains  the  ima-
                ginary parts.


     srcr       Source signal array that contains the real parts.




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mediaLib Library Functions               mlib_SignalFFTW_4(3MLIB)



     srci       Source signal array that contains  the  imaginary
                parts.


     dstc       Complex destination signal array. dstc[2*i]  con-
                tains  the  real  parts, and dstc[2*i+1] contains
                the imaginary parts.


     srcc       Complex source signal array.  srcc[2*i]  contains
                the real parts, and srcc[2*i+1] contains the ima-
                ginary parts.


     srcdstr    Source and destination signal array that contains
                the real parts.


     srcdsti    Source and destination signal array that contains
                the imaginary parts.


     srcdstc    Complex  source  and  destination  signal  array.
                srcdstc[2*i]   contains   the   real  parts,  and
                srcdstc[2*i+1] contains the imaginary parts.


     window     Window coefficient array with 2**order real  ele-
                ments.  The window coefficients are in Q15 format
                for the S16 data type, or in float format for the
                F32 data type.


     order      Order of the transformation. The base-2 logarithm
                of the number of data samples.


     scale      Adaptive scaling factor.


RETURN VALUES
     Each function returns MLIB_SUCCESS if successful.  Otherwise
     it returns MLIB_FAILURE.

ATTRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:








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mediaLib Library Functions               mlib_SignalFFTW_4(3MLIB)



     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Interface Stability         | Committed                   |
    |_____________________________|_____________________________|
    | MT-Level                    | MT-Safe                     |
    |_____________________________|_____________________________|


SEE ALSO
     mlib_SignalFFTW_1(3MLIB),          mlib_SignalFFTW_2(3MLIB),
     mlib_SignalFFTW_3(3MLIB),         mlib_SignalIFFTW_1(3MLIB),
     mlib_SignalIFFTW_2(3MLIB),        mlib_SignalIFFTW_3(3MLIB),
     mlib_SignalIFFTW_4(3MLIB), attributes(5)









































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