YUV

Planar

I420

In I420, you have luma "luminance" planes Y and chroma planes U, V.

In I420, chroma planes (blue and red) are subsampled in both the horizontal and vertical dimensions by a factor of 2.

For a 2x2 group of pixels, you have 4 Y samples and 1 U and 1 V sample.

YV12

YV12 is exactly like I420, but with U and V order reversed.

NV12

In NV12, you have one luma "luminance" planes Y and one plane with U and V data interleaved. NV12 is considered as semiplanar.

In NV12, chroma planes (blue and red) are subsampled in both the horizontal and vertical dimensions by a factor of 2.

For a 2x2 group of pixels, you have 4 Y samples and 1 U and 1 V sample.

NV21

NV21 is like NV12, but with U and V order reversed.