QuantTCX_AMRWBE

Quantizes the pre-shaped spectrum in TCX mode.

Syntax

IppStatus ippsQuantTCX_AMRWBE_16s(const Ipp16s* pSrc, Ipp16s* pDst, int nSubvectors, int nBits, Ipp16s* pDstNoiseFactor);

Parameters

pSrc	Pointer to the source signal [nSubvectors*8].
pDst	Pointer to the quantized normalized vector[nSubvectors*8 + nSubvectors].
nSubvectors	Number of subvectors.
nBits	Number of bits to use.
pDstNoiseFactor	Pointer to the comfort noise gain factor.

Description

The function ippsQuantTCX_AMRWBE is declared in ippsc.h file. This function quantizes the pre-shaped spectrum in TCX mode.This function quantizes the pre-shaped spectrum in TCX mode using lattice quantizers method. The spectrum is quantized in 8-dimensional blocks using vector codebooks composed of subsets of the Gosset lattice. In lattice quantization, the procedure of finding the nearest neighbour of an input vector among all codebook points is reduced to a several simple operations - rounding the components of the vector and verifying a few constraints with no exhaustive search. The binary indexes are computed only if a given TCX mode is retained as the best mode for a frame. It allows to reduce computation complexity.

See also 3GPP TS 26.290: “Extended AMR Wideband Speech Codec; Transcoding functions", clause 5.3.5.7 [AMRWB+].

Return Values

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