Searches for an optimal pitch value.
Syntax
IppStatus ippsOpenLoopPitchSearch_G723_16s(const Ipp16s* pSrcWgtSpch, Ipp16s* pResultOpenDelay);
Parameters
pSrcWgtSpch |
Pointer to the perceptually weighted speech signal. The signal length is 265, and the pointer pSrcWgtSpch points to its 146th element, in Q12. |
pResultOpenDelay |
Pointer to the OLP search result. |
Description
The function ippsOpenLoopPitchSearch_G723 is declared in the ippsc.h file. This function extracts the open loop pitch from the weighted speech signal. It is applied in half-frames as follows:
1. The open loop pitch is chosen such that the cross-correlation is maximized:
j = 18,...,142
2. During the search, preference is given to smaller pitch periods to avoid choosing pitch multiples. Every found pitch value is compared with the previous best. If the difference is less than 18 and col(j) > col(j') , the process is over. Otherwise, the pitch is chosen only if col(j) is greater than col(j') by 1.25db.
Return Values
ippStsNoErr |
Indicates no error. |
ippStsNullPtrErr |
Indicates an error when one of the specified pointers is NULL. |