Selects candidates for the nearest code vector of codebooks.
Syntax
IppStatus ippsVQPreliminarySelect_32f(const Ipp32f* pSrc, const Ipp32f* pWeights, int nDiv, const Ipp32s* pLengths, Ipp32s* pIndx, Ipps32s* pSign, int nCand, int* pPolbits, IppsVQCodeBookState_32f* pCodeBook);
Parameters
pSrc |
Pointer to the source vector. |
pWeights |
Pointer to the vector of weights. |
nDiv |
Number of fragmentations of the pSrc and pWeights vectors. |
pLengths |
Pointer to an array of lengths of fragmentations. |
pIndx |
Pointer to the output vector of indexes of the nCand minimum candidates. |
pSign |
Pointer to the output vector of signs of nCand minimum candidates. The value of 1 indicates that the minimal distortion appears when the norm is negative. The value of 0 indicates that the minimal distortion appears when the norm is positive. |
nCand |
Number of output candidates. |
pPolbits |
Pointer to the flag vector. |
pCodeBook |
Pointer to the initialized codebook state structure. |
Description
The function ippsVQPreliminarySelect is declared in the ippac.h header file. This function computes indexes and finds nCand vectors with the closest values from the codebook.
If the polbits[idiv ] is greater than MAXBIT_SHAPE, the following distortion are also calculated
for idiv = 0 to nDiv - 1, icb is the number of the codebook line.
In these formulas
- pSrcDiv is a pointer
to the beginning of idiv fragmentation in the
stream computed by the following formula:
- pWeightDiv is a pointer to the weight array
for a given fragmentation.
- ppTable is a pointer to the table with a set of vectors for quantization, where icb is the vector number, ismp is the number of element in the given vector. This table is part of the structure pCodeBook initialized in the function ippsVQCodeBookInitAlloc.
The function then selects nCand candidates of dist and dist n with the minimum distortion measure.
Return Values
ippStsNoErr |
Indicates no error. |
ippStsNullPtrErr |
Indicates an error when pCodeBook or pSrc pointer is NULL. |