Applies the hybrid windowing.
Syntax
IppStatus ippsWinHybridBlock_G728_16s(Ipp16s bfi, const Ipp16s* pSrc, const Ipp16s* pSrcSfs, Ipp16s* pDst, IppsWinHybridState_G728_16s* pMem);
IppStatus ippsWinHybrid_G728_16s(Ipp16s bfi, const Ipp16s* pSrc, const Ipp16s* pSrcSfs, Ipp16s* pDst, IppsWinHybridState_G728_16s* pMem);
Parameters
bfi |
The input bad frame indicator: “1” signifies a bad frame, any other value signifies a good frame. |
pSrc |
Pointer to the input speech vector [20]. |
pSrcSfs |
Pointer to the input vector [5] of scale factors for elements of the input speech vector. Each element of the pSrcSfs vector may specify a separate scale factor for a block of input speech vector elements. Thus, pSrcSfs[0] is the scale factor of the elements pSrc[0],..pSrc[DIM-1]; pSrcSfs[1] is the scale factor for pSrc[ DIM],..pSrc[2*DIM-1], and so on, where DIM is a block length that must be defined by the function ippsWinHybridInit_G728. |
pDst |
Pointer to the output reflection coefficients vector [M+1], where M is the length of the LPC window defined in the function ippsWinHybridInit_G728. |
pMem |
Pointer to the post filter state structure. |
Description
The function ippsWinHybrid_G728 is declared in ippsc.h file. This function first applies the window to the input speech vector and then calculates the autocorrelation coefficients needed in LPC analysis by the formula:
where the recursive component of adaptation cycle is calculated as follows:
The recursive part is calculated using the data calculated in previous adaptation cycle and stored in module memory.
A white noise correction is applied to autocorrelation coefficients by increasing the energy as follows:
rm(0) = 257/256*rm(0)
The recursive component and previous speech samples are stored in the module memory and may be used in the next adaptation cycle.
If the bad frame indicator is on, then only 10 autocorrelation coefficients are calculated and output.
Return Values
ippStsNoErr |
Indicates no error. |
ippStsNullPtrErr |
Indicates an error when one of the specified pointer is NULL. |