Intel® Integrated Performance Primitives (Intel® IPP) Developer Guide and Reference
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YCbCr422To420_Interlace
Converts interlaced YCbCr image from 4:2:2 sampling format to 4:2:0 format.
Syntax
IppStatus ippiYCbCr422To420_Interlace_8u_P3R(const Ipp8u* pSrc[3], int srcStep[3], Ipp8u* pDst[3], int dstStep[3], IppiSize roiSize);
Include Files
ippcc.h
Domain Dependencies
Headers: ippcore.h, ippvm.h, ipps.h, ippi.h
Libraries: ippcore.lib, ippvm.lib, ipps.lib, ippi.lib
Parameters
| pSrc | Array of pointers to the ROI in each plane for source image. | 
| srcStep | Array of distances in bytes between starts of consecutive lines in each plane for the source image. | 
| pDst | Array of pointers to the ROI in each plane for destination image. | 
| dstStep | Array of distances in bytes between starts of consecutive lines in each plane fore destination image. | 
| roiSize | Size of the source and destination ROI in pixels, its width must be multiple of 2, and height must be multiple of 4. | 
Description
This function operates with ROI (see Regions of Interest in Intel IPP).
This function converts the interlaced 4:2:2 image pSrc to the 4:2:0 image pDst (see Table “Planar Image Formats”).
The conversion is performed in accordance with the following formulas:
Y1dest = Y1src;
Cb0(Cr0)dest = (3*Cb0(Cr0)src + Cb2(Cr2)src + 2)/4;
Cb1(Cr1)dest = (Cb1(Cr1)src + 3*Cb3(Cr3)src + 2)/4;
Return Values
| ippStsNoErr | Indicates no error. Any other value indicates an error. | 
| ippStsNullPtrErr | Indicates an error condition if any of the specified pointers is NULL. | 
| ippStsSizeErr | Indicates an error condition if roiSize.width is less than 2, or roiSize.height is less than 4. | 
| ippStsDoubleSize | Indicates a warning if roiSize.width is not multiple of 2, or roiSize.height is not multiple of 4. |