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54f38fcae5
Since 2017, there is an space reserved for userspace API,
created by changeset 1d596dee38 ("docs: Create a user-space API guide").
As the media subsystem was one of the first subsystems to use
Sphinx, until this patch, we were keeping things on a separate
place.
Let's just use the new location, as having all uAPI altogether
will likely make things easier for developers.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
152 lines
3.5 KiB
ReStructuredText
152 lines
3.5 KiB
ReStructuredText
.. Permission is granted to copy, distribute and/or modify this
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.. document under the terms of the GNU Free Documentation License,
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.. Version 1.1 or any later version published by the Free Software
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.. Foundation, with no Invariant Sections, no Front-Cover Texts
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.. and no Back-Cover Texts. A copy of the license is included at
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.. Documentation/userspace-api/media/fdl-appendix.rst.
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..
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.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
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.. _V4L2-PIX-FMT-NV12M:
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.. _v4l2-pix-fmt-nv12mt-16x16:
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.. _V4L2-PIX-FMT-NV21M:
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***********************************************************************************
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V4L2_PIX_FMT_NV12M ('NM12'), V4L2_PIX_FMT_NV21M ('NM21'), V4L2_PIX_FMT_NV12MT_16X16
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***********************************************************************************
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V4L2_PIX_FMT_NV21M
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V4L2_PIX_FMT_NV12MT_16X16
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Variation of ``V4L2_PIX_FMT_NV12`` and ``V4L2_PIX_FMT_NV21`` with planes
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non contiguous in memory.
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Description
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===========
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This is a multi-planar, two-plane version of the YUV 4:2:0 format. The
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three components are separated into two sub-images or planes.
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``V4L2_PIX_FMT_NV12M`` differs from ``V4L2_PIX_FMT_NV12`` in that the
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two planes are non-contiguous in memory, i.e. the chroma plane do not
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necessarily immediately follows the luma plane. The luminance data
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occupies the first plane. The Y plane has one byte per pixel. In the
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second plane there is a chrominance data with alternating chroma
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samples. The CbCr plane is the same width, in bytes, as the Y plane (and
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of the image), but is half as tall in pixels. Each CbCr pair belongs to
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four pixels. For example, Cb\ :sub:`0`/Cr\ :sub:`0` belongs to
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Y'\ :sub:`00`, Y'\ :sub:`01`, Y'\ :sub:`10`, Y'\ :sub:`11`.
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``V4L2_PIX_FMT_NV12MT_16X16`` is the tiled version of
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``V4L2_PIX_FMT_NV12M`` with 16x16 macroblock tiles. Here pixels are
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arranged in 16x16 2D tiles and tiles are arranged in linear order in
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memory. ``V4L2_PIX_FMT_NV21M`` is the same as ``V4L2_PIX_FMT_NV12M``
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except the Cb and Cr bytes are swapped, the CrCb plane starts with a Cr
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byte.
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``V4L2_PIX_FMT_NV12M`` is intended to be used only in drivers and
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applications that support the multi-planar API, described in
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:ref:`planar-apis`.
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If the Y plane has pad bytes after each row, then the CbCr plane has as
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many pad bytes after its rows.
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**Byte Order.**
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Each cell is one byte.
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.. flat-table::
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:header-rows: 0
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:stub-columns: 0
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* - start0 + 0:
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- Y'\ :sub:`00`
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- Y'\ :sub:`01`
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- Y'\ :sub:`02`
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- Y'\ :sub:`03`
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* - start0 + 4:
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- Y'\ :sub:`10`
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- Y'\ :sub:`11`
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- Y'\ :sub:`12`
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- Y'\ :sub:`13`
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* - start0 + 8:
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- Y'\ :sub:`20`
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- Y'\ :sub:`21`
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- Y'\ :sub:`22`
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- Y'\ :sub:`23`
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* - start0 + 12:
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- Y'\ :sub:`30`
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- Y'\ :sub:`31`
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- Y'\ :sub:`32`
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- Y'\ :sub:`33`
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* -
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* - start1 + 0:
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- Cb\ :sub:`00`
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- Cr\ :sub:`00`
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- Cb\ :sub:`01`
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- Cr\ :sub:`01`
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* - start1 + 4:
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- Cb\ :sub:`10`
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- Cr\ :sub:`10`
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- Cb\ :sub:`11`
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- Cr\ :sub:`11`
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**Color Sample Location:**
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.. flat-table::
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:header-rows: 0
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:stub-columns: 0
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* -
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- 0
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-
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- 1
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- 2
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-
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- 3
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* - 0
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- Y
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-
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- Y
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- Y
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-
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- Y
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* -
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-
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- C
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-
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- C
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* - 1
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- Y
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-
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- Y
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- Y
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-
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- Y
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* -
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* - 2
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- Y
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-
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- Y
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- Y
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- Y
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* -
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- C
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-
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- C
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* - 3
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- Y
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-
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- Y
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- Y
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- Y
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