DecodeChanPairElt

Gets channel_pair_element from the input bitstream.

Syntax

IppStatus ippsDecodeChanPairElt_AAC(Ipp8u** ppBitStream, int* pOffset, IppAACIcsInfo* pIcsInfo, IppAACChanPairElt* pChanPairElt, int predSfbMax);

Parameters

ppBitStream	Double pointer to the current byte after decoding the channel pair element.
pOffset	Pointer to the bit position in the byte pointed to by ppBitStream. Valid within 0 to 7:
	0 stands for the most significant bit of the byte; 7 stands for the least significant bit of the byte.
pIcsInfo	Pointer to IppAACIcsInfo structure.
	If pIcsInfo->predDataPres = 0, set pIcsInfo->predReset = 0.
	Only the first pIcsInfo->numWinGrp elements in pIcsInfo->pWinGrpLen are meaningful. You must not change some members of the structure, as shown in table "Unchanged Members of pIcsInfo".
pChanPairElt	Pointer to IppAACChanPairElt structure. You must not change some members of the structure, as shown in table "Unchanged Members of pIcsInfo".
predSfbMax	Maximum prediction scale factor bands. For LC profile, set predSfbMax = 0.

Description

This function is declared in the ippac.h file. The function gets the channel pair element from the input bitstream. Individual channel stream is not included.

If common_window flag decoded from the input bitstream is 0, all members of pIcsInfo and pChanPairElt remain unchanged except for pChanPairElt->commonWin.

See clause 8.3 and Table 6.10, 6.11 of ISO/IEC 13818 - 7: 1997.

Unchanged Members of pIcsInfo
Unchanged Members	Conditions
sfGrouping	pIcsInfo-> winSequence != 2
predResetGroupNum	pIcsInfo-> predDataPres == 0 \|\| pIcsInfo ->predReset == 0
pPredUsed[sfb]	pIcsInfo-> predDataPres == 0
pMsUsed[sfb]	pChanPairElt->msMaskPres != 1

Return Values

ippStsNoErr	Indicates no error.
ippStsNullPtrErr	Indicates an error when at least one of the pointers ppBitStream, pOffset, ppBitStream, pIcsInfo, or pChanPairElt is NULL.
ippStsAacBitOffsetErr	Indicates an error when pOffset is out of the range of [0,7].
ippStsAacMaxSfbErr	Indicates an error when pIcsInfo->maxSfb decoded from bitstream is greater than IPP_AAC_MAX_SFB, the maximum scale factor band for all sampling frequencies.
ippStsAacPredSfbErr	Indicates an error when predSfbMax is out of the range of [0, IPP_AAC_PRED_SFB_MAX].