V4L2_PIX_FMT_NV12, V4L2_PIX_FMT_NV21 -- Formats with ½ horizontal and vertical
chroma resolution, also known as YUV 4:2:0. One luminance and one
chrominance plane with alternating chroma samples as opposed to
V4L2_PIX_FMT_YVU420These are two-plane versions of the YUV 4:2:0 format.
The three components are separated into two sub-images or planes. The
Y plane is first. The Y plane has one byte per pixel. For
V4L2_PIX_FMT_NV12, a combined CbCr plane
immediately follows the Y plane in memory. The CbCr plane is the same
width, in bytes, as the Y plane (and of the image), but is half as
tall in pixels. Each CbCr pair belongs to four pixels. For example,
Cb0/Cr0 belongs to
Y'00, Y'01,
Y'10, Y'11.
V4L2_PIX_FMT_NV21 is the same except the Cb and
Cr bytes are swapped, the CrCb plane starts with a Cr byte.
If the Y plane has pad bytes after each row, then the CbCr plane has as many pad bytes after its rows.