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.. -*- coding: utf-8; mode: rst -*-
.. _V4L2-PIX-FMT-NV12:
.. _V4L2-PIX-FMT-NV21:
******************************************************
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``
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, Cb\ :sub:`0`/Cr\ :sub:`0` belongs to Y'\ :sub:`00`,
Y'\ :sub:`01`, Y'\ :sub:`10`, Y'\ :sub:`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.
.. flat-table::
:header-rows: 0
:stub-columns: 0
* - start + 0:
- Y'\ :sub:`00`
- Y'\ :sub:`01`
- Y'\ :sub:`02`
- Y'\ :sub:`03`
* - start + 4:
- Y'\ :sub:`10`
- Y'\ :sub:`11`
- Y'\ :sub:`12`
- Y'\ :sub:`13`
* - start + 8:
- Y'\ :sub:`20`
- Y'\ :sub:`21`
- Y'\ :sub:`22`
- Y'\ :sub:`23`
* - start + 12:
- Y'\ :sub:`30`
- Y'\ :sub:`31`
- Y'\ :sub:`32`
- Y'\ :sub:`33`
* - start + 16:
- Cb\ :sub:`00`
- Cr\ :sub:`00`
- Cb\ :sub:`01`
- Cr\ :sub:`01`
* - start + 20:
- Cb\ :sub:`10`
- Cr\ :sub:`10`
- Cb\ :sub:`11`
- Cr\ :sub:`11`
**Color Sample Location:**
.. flat-table::
:header-rows: 0
:stub-columns: 0
* -
- 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
|
