DecodeHuffman8x8_DCFirst

Performs progressive decoding of the DC coefficient from an 8x8 block of the quantized DCT coefficients (first scan).

Syntax

IppStatus ippiDecodeHuffman8x8_DCFirst_JPEG_1u16s_C1(const Ipp8u* pSrc, int srcLenBytes, int* pSrcCurrPos, Ipp16s* pDst, Ipp16s* pLastDC, int* pMarker, int Al, IppiDecodeHuffmanSpec* pDcTable, IppiDecodeHuffmanState* pDecHuffState);

Parameters

pSrc	Pointer to the buffer with the JPEG bit stream.
srcLenBytes	Length in bytes of the buffer for the bit stream.
pSrcCurrPos	Shift in bytes of the current byte in the buffer.
pDst	Pointer to the 8x8 block of the quantized DCT coefficients.
pLastDC	Pointer to the DC coefficient of the previous 8x8 block.
pMarker	Pointer to a variable that will receive JPEG marker detected during decoding.
Al	Successive approximation bit positions low, it specifies the actual point transform.
pDcTable	Pointer to the Huffman table for the DC coefficients.
pDecHuffState	Pointer to the IppiDecodeHuffmanState structure.

Description

The function ippiDecodeHuffman8x8_DCFirst_JPEG is declared in the ippj.h file. This function decodes the DC coefficient from an 8x8 block of the quantized DCT coefficients, progressive mode, the first scan, using pDcTable table. The decoding procedure conforms to [ISO10918], Annex G.2, Progressive Decoding of the DCT. If a JPEG marker is detected during decoding, the function stops decoding and writes the marker to a location indicated by pMarker.

Return Values

ippStsNoErr	Indicates no error.
ippStsNullPtrErr	Indicates an error condition if one or all of the specified pointers are NULL.
ippStsJPEGDCTRangeErr	Indicates an error condition if the DCT coefficient is out of the allowed range (-1023..1023).
ippStsJPEGOutOfBufErr	Indicates an error condition if the buffer limits are exceeded.
ippStsJPEGMarkerWarn	Indicates a warning if a JPEG marker is detected.