mlib_SignalIFFTW_4(3mlib)

1mlib_SignalIFFTW_4(3MLIB) mediaLib Library Functions mlib_SignalIFFTW_4(3MLIB)
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NAME

6       mlib_SignalIFFTW_4,        mlib_SignalIFFTW_4_S16_S16,        mlib_Sig‐
7       nalIFFTW_4_S16C_S16C,      mlib_SignalIFFTW_4_S16_S16C,       mlib_Sig‐
8       nalIFFTW_4_S16,  mlib_SignalIFFTW_4_S16C  - signal Inverse Fast Fourier
9       Transform with windowing (IFFTW)
10

SYNOPSIS

12       cc [ flag... ] file... -lmlib [ library... ]
13       #include <mlib.h>
14
15       mlib_status mlib_SignalIFFTW_4_S16_S16(mlib_s16 *dstr, mlib_s16 *dsti,
16            const mlib_s16 *srcr, const mlib_s16 *srci, const mlib_s16 *window,
17            mlib_s32 order, mlib_s32 *scale);
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19
20       mlib_status mlib_SignalIFFTW_4_S16C_S16C(mlib_s16 *dstc,
21            const mlib_s16 *srcc,
22            const mlib_s16 *window, mlib_s32 order, mlib_s32 *scale);
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25       mlib_status mlib_SignalIFFTW_4_S16_S16C(mlib_s16 *dstr,
26            const mlib_s16 *srcc,
27            const mlib_s16 *window, mlib_s32 order, mlib_s32 *scale);
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30       mlib_status mlib_SignalIFFTW_4_S16(mlib_s16 *srcdstr,
31            mlib_s16 *srcdsti,
32            const mlib_s16 *window, mlib_s32 order, mlib_s32 *scale);
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35       mlib_status mlib_SignalIFFTW_4_S16C(mlib_s16 *srcdstc,
36            const mlib_s16 *window,
37            mlib_s32 order, mlib_s32 *scale);
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39

DESCRIPTION

41       Each of the functions in  this  group  performs  Inverse  Fast  Fourier
42       Transform with windowing (IFFTW).
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45       The FFTW functions use the following equation:
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47                   1   N-1
48         dst[k] = ---- SUM {src[n] * window[n] * exp(-j2*PI*n*k/N)}
49                   C1  n=0
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53       and the IFFTW functions use the following equation:
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55                   1   N-1
56         dst[n] = ---- SUM {src[k] * window[k] * exp(j2*PI*n*k/N)}
57                   C2  k=0
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61       where
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63         k = 0, 1, ..., (N - 1)
64         n = 0, 1, ..., (N - 1)
65         N = 2**order
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69       The  signal  FFTW/IFFTW  functions  can be categorized into four groups
70       according to the ScaleMode in the function names in the following form:
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72         mlib_Signal[FFTW|IFFTW]_ScaleMode_OutType_InType_OpMode()
73         mlib_Signal[FFTW|IFFTW]_ScaleMode_DataType_OpMode()
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77       The scaling factors C1 and C2 used in the equations are defined as fol‐
78       lows:
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80           o      For ScaleMode = 1, C1 = 1 and C2 = 2**order.
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82           o      For ScaleMode = 2, C1 = 2**order and C2 = 1.
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84           o      For  ScaleMode  =  3,  C1  = C2 = 2**(order/2) when order is
85                  even, or C1 = 2**((order+1)/2)  and  C2  =  2**((order-1)/2)
86                  when order is odd.
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88           o      For  ScaleMode  =  4, C1 = 2**P and C2 = 2**Q, where P and Q
89                  are adaptive scaling factors and are generated by the  func‐
90                  tions.
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93       For functions with only real parts for the source signal, the imaginary
94       parts are assumed to be all zero. For functions with  only  real  parts
95       for  the  destination  signal,  the  imaginary parts are discarded. The
96       functions with only one data type in their names perform the  operation
97       in place.
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PARAMETERS

100       Each function takes some of the following arguments:
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102       dstr       Destination signal array that contains the real parts.
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105       dsti       Destination signal array that contains the imaginary parts.
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108       srcr       Source signal array that contains the real parts.
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111       srci       Source signal array that contains the imaginary parts.
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114       dstc       Complex  destination  signal  array.  dstc[2*i] contains the
115                  real parts, and dstc[2*i+1] contains the imaginary parts.
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118       srcc       Complex source signal array.  srcc[2*i]  contains  the  real
119                  parts, and srcc[2*i+1] contains the imaginary parts.
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122       srcdstr    Source  and  destination signal array that contains the real
123                  parts.
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126       srcdsti    Source and destination signal array that contains the imagi‐
127                  nary parts.
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130       srcdstc    Complex  source  and  destination signal array. srcdstc[2*i]
131                  contains the real parts,  and  srcdstc[2*i+1]  contains  the
132                  imaginary parts.
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134
135       window     Window  coefficient  array  with 2**order real elements. The
136                  window coefficients are in Q15 format for the S16 data type,
137                  or in float format for the F32 data type.
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140       order      Order  of  the  transformation.  The base-2 logarithm of the
141                  number of data samples.
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144       scale      Adaptive scaling factor.
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RETURN VALUES

148       Each function returns MLIB_SUCCESS if successful. Otherwise it  returns
149       MLIB_FAILURE.
150

ATTRIBUTES

152       See attributes(5) for descriptions of the following attributes:
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157       ┌─────────────────────────────┬─────────────────────────────┐
158       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
159       ├─────────────────────────────┼─────────────────────────────┤
160       │Interface Stability          │Committed                    │
161       ├─────────────────────────────┼─────────────────────────────┤
162       │MT-Level                     │MT-Safe                      │
163       └─────────────────────────────┴─────────────────────────────┘
164

NAME

SYNOPSIS

DESCRIPTION

PARAMETERS

RETURN VALUES

ATTRIBUTES

SEE ALSO