Extracts an OLP lag estimate (VAD 2 scheme is enabled).
Syntax
IppStatus ippsOpenLoopPitchSearchDTXVAD2_GSMAMR_16s32s(const Ipp16s* pSrcWgtLpc1, const Ipp16s* pSrcWgtLpc2, const Ipp16s* pSrcSpch, Ipp16s* pValResultPrevMidPitchLag, Ipp16s* pValResultVvalue, Ipp16s* pSrcDstPrevPitchLag, Ipp16s* pSrcDstPrevWgtSpch, Ipp32s* pResultMaxCorr, Ipp32s pResultWgtEnergy, Ipp16s* pDstOpenLoopLag, Ipp16s* pDstOpenLoopGain, IppSpchBitRate mode);
Parameters
pSrcWgtLpc1 |
Pointer to the 44-element vector of weighted LP coefficients, represented using Q3.12. These LP coefficients comprise the numerator of the perceptual weighting filter. |
pSrcWgtLpc2 |
Pointer to the 44-element vector of weighted LP coefficients, represented using Q3.12. These LP coefficients comprise the denominator of the perceptual weighting filter. |
pSrcSpch |
Pointer to the 170-element input speech vector, represented using Q15.0. |
pValResultToneFlag |
Pointer to the tone flag for the VAD module. |
pValResultPrevMidPitchLag |
Pointer to a vector of median filtered pitch lags from the five previous voiced speech half-frames, represented using Q15.0. On output, points to the updated vector of median filtered pitch lags from the five previous voiced speech half-frames, represented using Q15.0. This argument is valid only for 10.2 kbps frames. |
pValResultVvalue |
Pointer to the adaptive parameter v, represented using Q0.15. On output, points to the updated adaptive parameter v, represented using Q0.15. This argument is valid only for 10.2 kbps frames. |
pSrcDstPrevPitchLag |
Pointer to a five-element vector of pitch lags associated with the five most recent voiced speech half-frames. On output, points to the updated five-element vector of pitch lags associated with the five most recent voiced speech half-frames. This argument is valid only for 10.2 kbps frames. |
pSrcDstPrevWgtSpch |
Pointer to a 143-element vector containing the perceptually weighted speech associated with the previous frame, represented using Q15.0. On output, points to the updated 143-element vector containing the perceptually weighted speech associated with the previous frame, represented using Q15.0. |
pResultMaxCorr |
Pointer to the correlation maximum. |
pResultWgtEnergy |
Pointer to the pitch delayed energy of the weighted speech signal, as described above. The output may be scaled, and the Q representation is not given. |
pDstOpenLoopLag |
Pointer to a two-element vector of OLP lags. For 5.15 and 4.75 kbps frames, only the first vector element contains a valid lag value, since only one lag is estimated. For all other bit rates, both vector elements contain valid pitch lag values. |
pDstOpenLoopGain |
Pointer to a two-element vector containing optimal OLP gains, represented using Q15.0. This argument is valid only for 10.2 kbps frames. |
mode |
Bit rate specifier. Values between IPP_SPCHBR_4750 and IPP_SPCHBR_12200 are valid. |
Description
The function ippsOpenLoopPitchSearchDTXVAD2_GSMAMR is declared in ippsc.h file. This function extracts an OLP lag estimate from the weighted input speech when the VAD 2 scheme is enabled, using a version of the pitch search algorithm described in Open-Loop Pitch Search (OLP) that is modified in the following way:
After finding the best OLP, extract from the weighted speech the maximum correlation MaxCorr and the delayed energy DelayEnergy. For both 4.75 and 5.15 kbps frames, the computation is carried for 160 samples. For all other bit rates, the computation is carried for only 80 samples using the relations
The MaxCorr and DelayEnergy values corresponding to the two half-frame OLP lag estimates are combined to obtain whole-frame estimates of MaxCorr and DelayEnergy (except during 4.75 and 5.15 kbps frames, when the OLP search is performed only once per frame).
Return Values
ippStsNoErr |
Indicates no error. |
ippStsNullPtrErr |
Indicates an error when one of the specified pointers is NULL. |
ippStsRangeErr |
Indicates an error when mode is not a valid element of the enumerated type IppSpchBitRate. |