我发现IPP函数存在:
这个函数很难找到,因为函数名称或描述中没有提到NV12。
该函数使用BT.601标准。
以下是在BT.601 标准下将RGB转换为NV12 的代码示例:
void Rgb2NV12(const unsigned char I[], int image_width, int image_height, unsigned char J[])
{
IppStatus ipp_status;
int srcStep = image_width*3;
int dstYStep = image_width;
int dstCbCrStep = image_width;
IppiSize roiSize = {image_width, image_height};
const Ipp8u* pSrc = (Ipp8u*)I;
Ipp8u *pDstY = (Ipp8u*)J; //Y color plane is the first image_width*image_height pixels of J.
Ipp8u *pDstCbCr = (Ipp8u*)&J[image_width*image_height]; //In NV12 format, UV plane starts below Y.
ipp_status = ippiRGBToYCbCr420_8u_C3P2R(pSrc, srcStep, pDstY, dstYStep, pDstCbCr, dstCbCrStep, roiSize);
//if (ipp_status != ippStsNoErr), Handle errors...
}
使用BT.709标准将RGB转换为NV12:
截至2019年,BT.709(高清电视)标准可能比BT.601(标准清晰度电视)更为相关。
IPP缺少直接将RGB转换为BT.709标准下的NV12的函数。
有一个函数可以将BGR转换为NV12。
解决方案包括两个阶段:
ippiSwapChannels_8u_C3R
进行RGB到BGR转换。ippiBGRToYCbCr420_709CSC_8u_C3P2R
进行BGR到NV12转换。示例函数需要一些额外的内存空间来存储中间的BGR图像。
指向草图内存的指针传递给函数(内存应在函数外分配)。
这是一个将RGB转换为BT.709标准下的NV12的代码示例:
//sketch_buff - Temporary buffer for storing image in BGR format.
// Size of sketch_buff must be at least image_width*image_height*3 bytes.
void Rgb2NV12_709(const unsigned char I[],
const int image_width,
const int image_height,
unsigned char sketch_buff[],
unsigned char J[])
{
IppStatus ipp_status;
int srcStep = image_width*3;
int dstBgrStep = image_width*3;
int dstYStep = image_width;
int dstCbCrStep = image_width;
IppiSize roiSize = {image_width, image_height};
const Ipp8u* pRGB = (Ipp8u*)I;
Ipp8u* pBGR = (Ipp8u*)sketch_buff; //BGR image is stored in sketch_buff
Ipp8u *pDstY = (Ipp8u*)J; //Y color plane is the first image_width*image_height pixels of J.
Ipp8u *pDstCbCr = (Ipp8u*)&J[image_width*image_height]; //In NV12 format, UV plane starts below Y.
const int bgrOrder[3] = {2, 1, 0};
//Swap Red and Blue color channels - convert from RGB to BGR
//Store the result into sketch_buff (sketch buffer is allocated outside the function)
ipp_status = ippiSwapChannels_8u_C3R(pRGB, srcStep, pBGR, dstBgrStep, roiSize, bgrOrder);
//if (ipp_status != ippStsNoErr), Handle errors...
//Convert BGR to NV12 in BT.709 standard
ipp_status = ippiBGRToYCbCr420_709CSC_8u_C3P2R(pBGR, srcStep, pDstY, dstYStep, pDstCbCr, dstCbCrStep, roiSize);
//if (ipp_status != ippStsNoErr), Handle errors...
}