160 lines
3.3 KiB
ReStructuredText
160 lines
3.3 KiB
ReStructuredText
.. Permission is granted to copy, distribute and/or modify this
|
|
.. document under the terms of the GNU Free Documentation License,
|
|
.. Version 1.1 or any later version published by the Free Software
|
|
.. Foundation, with no Invariant Sections, no Front-Cover Texts
|
|
.. and no Back-Cover Texts. A copy of the license is included at
|
|
.. Documentation/media/uapi/fdl-appendix.rst.
|
|
..
|
|
.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
|
|
|
|
.. _V4L2-PIX-FMT-YUV420M:
|
|
.. _v4l2-pix-fmt-yvu420m:
|
|
|
|
************************************************************
|
|
V4L2_PIX_FMT_YUV420M ('YM12'), V4L2_PIX_FMT_YVU420M ('YM21')
|
|
************************************************************
|
|
|
|
|
|
V4L2_PIX_FMT_YVU420M
|
|
Variation of ``V4L2_PIX_FMT_YUV420`` and ``V4L2_PIX_FMT_YVU420`` with
|
|
planes non contiguous in memory.
|
|
|
|
|
|
Description
|
|
===========
|
|
|
|
This is a multi-planar format, as opposed to a packed format. The three
|
|
components are separated into three sub-images or planes.
|
|
|
|
The Y plane is first. The Y plane has one byte per pixel. For
|
|
``V4L2_PIX_FMT_YUV420M`` the Cb data constitutes the second plane which
|
|
is half the width and half the height of the Y plane (and of the image).
|
|
Each Cb belongs to four pixels, a two-by-two square of the image. For
|
|
example, Cb\ :sub:`0` belongs to Y'\ :sub:`00`, Y'\ :sub:`01`,
|
|
Y'\ :sub:`10`, and Y'\ :sub:`11`. The Cr data, just like the Cb plane,
|
|
is in the third plane.
|
|
|
|
``V4L2_PIX_FMT_YVU420M`` is the same except the Cr data is stored in the
|
|
second plane and the Cb data in the third plane.
|
|
|
|
If the Y plane has pad bytes after each row, then the Cb and Cr planes
|
|
have half as many pad bytes after their rows. In other words, two Cx
|
|
rows (including padding) is exactly as long as one Y row (including
|
|
padding).
|
|
|
|
``V4L2_PIX_FMT_YUV420M`` and ``V4L2_PIX_FMT_YVU420M`` are intended to be
|
|
used only in drivers and applications that support the multi-planar API,
|
|
described in :ref:`planar-apis`.
|
|
|
|
**Byte Order.**
|
|
Each cell is one byte.
|
|
|
|
|
|
|
|
|
|
.. flat-table::
|
|
:header-rows: 0
|
|
:stub-columns: 0
|
|
|
|
* - start0 + 0:
|
|
- Y'\ :sub:`00`
|
|
- Y'\ :sub:`01`
|
|
- Y'\ :sub:`02`
|
|
- Y'\ :sub:`03`
|
|
* - start0 + 4:
|
|
- Y'\ :sub:`10`
|
|
- Y'\ :sub:`11`
|
|
- Y'\ :sub:`12`
|
|
- Y'\ :sub:`13`
|
|
* - start0 + 8:
|
|
- Y'\ :sub:`20`
|
|
- Y'\ :sub:`21`
|
|
- Y'\ :sub:`22`
|
|
- Y'\ :sub:`23`
|
|
* - start0 + 12:
|
|
- Y'\ :sub:`30`
|
|
- Y'\ :sub:`31`
|
|
- Y'\ :sub:`32`
|
|
- Y'\ :sub:`33`
|
|
* -
|
|
* - start1 + 0:
|
|
- Cb\ :sub:`00`
|
|
- Cb\ :sub:`01`
|
|
* - start1 + 2:
|
|
- Cb\ :sub:`10`
|
|
- Cb\ :sub:`11`
|
|
* -
|
|
* - start2 + 0:
|
|
- Cr\ :sub:`00`
|
|
- Cr\ :sub:`01`
|
|
* - start2 + 2:
|
|
- Cr\ :sub:`10`
|
|
- 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
|