QuantIntra

Performs quantization on an intra coded block.

Syntax

IppStatus ippiQuantIntra_H263_16s_C1I(Ipp16s* pSrcDst, int QP, int* pCountNonZero, int advIntraFlag, int modQuantFlag);

Parameters

pSrcDst	Pointer to the coefficient buffer of the block.
QP	Quantization parameter.
pCountNonZero	Pointer to the number of non-zero coefficients after quantization.
advIntraFlag	Flag equal to a non-zero value when Advanced Intra Coding mode is in use, equal to 0 otherwise.
modQuantFlag	Flag equal to a non-zero value when Modified Quantization mode is in use, equal to 0 otherwise.

Description

The function ippiQuantIntra_H263_16s_C1I is declared in the ippvc.h header file. This function performs quantization on an intra coded block according to H.263 standard. The standard specifies dequantization process, while quantization decision levels are not defined. When not in Advanced Intra Coding mode, the intra DC coefficient is dequantized using uniformly placed reconstruction levels with a step size of 8, and the other DCT coefficients are reconstructed using equally spaced levels with a central dead-zone around zero and with a step size of 2*QP ([ITUH263], subclauses 4.2.4, 6.2). When in Advanced Intra Coding mode, all the block coefficients are dequantized using a reconstruction spacing without a dead-zone and with a step size of 2*QP ([ITUH263] Annex I, clause I.3). When not in Modified Quantization mode, the quantized intra DC coefficient (when not in Advanced Intra Coding mode) is clipped to the range [1, 254], and the other quantized coefficients (all coefficients, if in Advanced Intra Coding mode) are clipped to the range [-127, 127].

This function is used in the H.261, H.263, and MPEG-4 encoders included into Intel IPP Samples. See introduction to H.263.

Return Values

ippStsNoErr	Indicates no error.
ippStsNullPtrErr	Indicates an error condition if at least one of the specified pointers is NULL.
ippStsQPErr	Indicates an error condition if QP is out of the range [1, 31].