Video for Linux Two API Specification: Revision 0.24
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# V4L2_PIX_FMT_NV12 ('NV12'), V4L2_PIX_FMT_NV21 ('NV21')

## Name

`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_YVU420`

## Description

These 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.

Example 2-1. `V4L2_PIX_FMT_NV12` 4 × 4 pixel image

Byte Order. Each cell is one byte.

start + 0: | Y'00 | Y'01 | Y'02 | Y'03
start + 4: | Y'10 | Y'11 | Y'12 | Y'13
start + 8: | Y'20 | Y'21 | Y'22 | Y'23
start + 12: | Y'30 | Y'31 | Y'32 | Y'33
start + 16: | Cb00 | Cr00 | Cb01 | Cr01
start + 20: | Cb10 | Cr10 | Cb11 | Cr11

Color Sample Location.

| 0 |  | 1 |  | 2 |  | 3
0 | Y |  | Y |  | Y |  | Y
|  | C |  |  |  | C |
1 | Y |  | Y |  | Y |  | Y
2 | Y |  | Y |  | Y |  | Y
|  | C |  |  |  | C |
3 | Y |  | Y |  | Y |  | Y

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