DCT8x8Fwd

Performs a forward DCT on a 2D buffer of 8x8 size.

Syntax

Case 1: Not-in-place operation

IppStatus ippiDCT8x8Fwd_<mod>(const Ipp<datatype>* pSrc, Ipp<datatype>* pDst);

Supported values for mod:

16s_C1

32f_C1

Case 2: Not-in-place operation with ROI

IppStatus ippiDCT8x8Fwd_<mod>(const Ipp<srcDatatype>* pSrc, int srcStep, Ipp<dstDatatype>* pDst);

Supported values for mod:

16s_C1R

8u16s_C1R

Case 3: In-place operation

IppStatus ippiDCT8x8Fwd_<mod>(Ipp<datatype>* pSrcDst);

Supported values for mod:

16s_C1I

32f_C1I

Parameters

pSrc	Pointer to the source image buffer.
srcStep	Distance in bytes between starts of consecutive lines in the source image buffer for operations with ROI.
pDst	Pointer to the destination image buffer.
pSrcDst	Pointer to the source and destination image for in-place operations.

Description

The function ippiDCT8x8Fwd is declared in the ippi.h file. Some flavors operate with ROI (see Regions of Interest in Intel IPP).

This function computes the forward discrete cosine transform of short integer or floating-point data in a 2D buffer of 8x8 size. No prerequisites are needed to use this transform function.

The code Example “Forward DCT of 8x8 Size” illustrates the use of ippiDCT8x8Fwd function.

Forward DCT of 8x8 Size

IppStatus dct16s( void ) {

   Ipp16s x[64] = {0};

   IppiSize roi = {8,8};

   int i;

   for( i=0; i<8; ++i ) {

      ippiSet_16s_C1R( (Ipp16s)i, x+8*i+i, 8*sizeof(Ipp16s), roi );

      --roi.width;

      --roi.height;

   return ippiDCT8x8Fwd_16s_C1I( x );

The destination image x contains:

18 -9 -2 -1 -1  0  0  0

-9  7  0  0  0  0  0  0

-2  0  2  0  0  0  0  0

-1  0  0  1  0  0  0  0

 0  0  0  0  1  0  0  0

 0  0  0  0  0  0  0  0

 0  0  0  0  0  0  0  0

 0  0  0  0  0  0  0  0

Return Values

ippStsNoErr	Indicates no error. Any other value indicates an error or a warning.
ippStsNullPtrErr	Indicates an error condition if pSrc, pDst, or pSrcDst pointer is `NULL`.
ippStsStepErr	Indicates an error condition if srcStep value is zero or negative.