DecodeCoeffsIntraRVLCBack

Decodes DCT coefficients in backward direction for intra coded block using RVLC.

Syntax

IppStatus ippiDecodeCoeffsIntraRVLCBack_MPEG4_1u16s(Ipp8u** ppBitStream, int* pBitOffset, Ipp16s* pCoeffs, int* pIndxLastNonZero, int noDCFlag);

Parameters

ppBitStream	Pointer to the pointer to the current byte in the bitstream buffer. The pointer is updated by the function.
pBitOffset	Pointer to the bit position in the byte pointed by **ppBitStream. The pointer is updated by the function.
pCoeffs	Pointer to the output coefficients.
pIndxLastNonZero	Pointer to the index of the last non-zero coefficient. In case of error during decoding, the index of the previous successfully decoded coefficient is stored in it.
noDCFlag	Flag, when set to ‘0' indicates that pCoeffs is set starting with zero element, otherwise - with the first element.

Description

The function ippiDecodeCoeffsIntraRVLCBack_MPEG4_1u16s is declared in the ippvc.h header file. This function performs backward decoding of the DC coefficient (if noDCFlag is 0) and AC coefficients using variable length tables B.23, B.24, and B.25 [ISO14496] for one intra coded block. The backward RVLC decoding process is specified in [ISO14496], subclauses E.1.3 and E.1.4.

Return Values

ippStsNoErr	Indicates no error.
ippStsNullPtrErr	Indicates an error when at least one input pointer is NULL.
ippStsBitOffsetErr	Indicates an error condition if *pBitOffset is out of the range [0, 7].
ippStsVLCCodeErr	Indicates an error condition if an illegal code is detected through the decoding.