SubbandController

Updates filter coefficients and returns output gain coefficients.

Syntax

IppStatus ippsSubbandController_EC_32f(const Ipp32fc* pSrcAdaptiveFilterErr, const Ipp32fc* pSrcFixedFilterErr, Ipp32fc** ppDstAdaptiveCoefs, Ipp32fc** ppDstFixedCoefs, Ipp32f* pDstSGain, IppsSubbandControllerState_EC_32f* pState);

IppStatus ippsSubbandController_EC_16s(const Ipp32sc* pSrcAdaptiveFilterErr, const Ipp32sc* pSrcFixedFilterErr, Ipp32sc** pDstpAdaptiveCoefs, Ipp32sc** ppFixedCoefs, Ipp32s* pDstSGain, IppsSubbandControllerState_EC_16s* pState);

Parameters

pState	Pointer to the subband state structure.
pSrcAdaptiveFilterErr	Pointer to the adaptive filter error vector. Vector length is equal to numSubbands, specified in the function ippsSubbandControllerInit_EC.
pSrcFixedFilterErr	Pointer to the fixed filter error vector. Vector length is equal to numSubbands.
ppDstAdaptiveCoefs	Pointer to an array of pointers to the adaptive filter coefficients vectors. Size of the array is equal to numSegments specified in the function ippsSubbandControllerInit_EC.
ppDstFixedCoefs	Pointer to an array of pointers to the fixed filter coefficients vectors. Size of the array is equal to numSegments specified in the function ippsSubbandControllerInit_EC.
pDstSGain	Pointer to the send gain coefficient.

Description

The functions ippsSubbandController_EC are declared in the ippsc.h file.

These functions compare powers of adaptive filter error and fixed filter error and track changes of adaptive filter coefficients power.

If the adaptive filter has a significantly smaller error and is stable (which is indicated by coefficients power changing slowly), its coefficients are copied to the fixed filter. This case corresponds to “no double-talk” mode.

If the fixed filter has a significantly smaller error, its coefficients are copied to the adaptive filter. This case corresponds to the double-talk mode.

Send gain coefficient calculation (non-linear processor technology) is based on presence of the double-talk mode and changes of receive-in and send-in signal powers.

The subband controller state structure pState must be initialized by the function ippsSubbandControllerInit_EC beforehand.

Return Values

ippStsNoErr	Indicates no error.
ippStsNullPtrErr	Indicates an error when one of the specified pointers is NULL.