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c++yuv

Unpacking a single BYTE* of a YUV into 3 BYTE* pointers for each plane

I am not familiar with YUV and how the data is packed. Given that I have the following code...

int width = 1920;
int height = 1080;
BYTE* yuvData = GetFrame();

...how would I unpack yuvData into a method that has the following signature...

Display(BYTE* pYplane, BYTE* pVplane, BYTE* pUplane)

The YUV buffer is in planar format.

Solution

  • It depends on the YUV format type which you haven't specified in the question. The following links have a good explanation and illustrations regarding the various YUV types:

    https://msdn.microsoft.com/en-us/library/windows/desktop/dd206750%28v=vs.85%29.aspx

    http://www.fourcc.org/yuv.php

    For example, one commonly used YUV type is YUV420 planar. In this format the chroma components are down-sampled 2:1 horizontally, and 2:1 vertically. This means that for every 4 luma (Y) values, you have one chroma (1U + 1V) component (see the illustration in the links for a visual). The planar tells you that you first have all the luminance components, followed by all U components, followed by all V components. Therefore

    int iSizeY = width * height;
int iSizeUV = (width * height)/4;
BYTE* pY = yuvData;
BYTE* pU = yuvData + iSizeY // there are width * height Y components
BYTE* pV = pU + iSizeUV;    // skip the U components