2.6.24. V4L2_PIX_FMT_NV12 (‘NV12’), V4L2_PIX_FMT_NV21 (‘NV21’)¶
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
2.6.24.1. 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.
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 | ||