410 lines
8.5 KiB
ReStructuredText
410 lines
8.5 KiB
ReStructuredText
.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
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.. _packed-yuv:
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******************
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Packed YUV formats
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******************
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Similarly to the packed RGB formats, the packed YUV formats store the Y, Cb and
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Cr components consecutively in memory. They may apply subsampling to the chroma
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components and thus differ in how they interlave the three components.
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.. note::
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- In all the tables that follow, bit 7 is the most significant bit in a byte.
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- 'Y', 'Cb' and 'Cr' denote bits of the luma, blue chroma (also known as
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'U') and red chroma (also known as 'V') components respectively. 'A'
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denotes bits of the alpha component (if supported by the format), and 'X'
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denotes padding bits.
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4:4:4 Subsampling
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=================
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These formats do not subsample the chroma components and store each pixels as a
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full triplet of Y, Cb and Cr values.
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The next table lists the packed YUV 4:4:4 formats with less than 8 bits per
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component. They are named based on the order of the Y, Cb and Cr components as
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seen in a 16-bit word, which is then stored in memory in little endian byte
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order, and on the number of bits for each component. For instance the YUV565
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format stores a pixel in a 16-bit word [15:0] laid out at as [Y'\ :sub:`4-0`
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Cb\ :sub:`5-0` Cr\ :sub:`4-0`], and stored in memory in two bytes,
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[Cb\ :sub:`2-0` Cr\ :sub:`4-0`] followed by [Y'\ :sub:`4-0` Cb\ :sub:`5-3`].
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.. raw:: latex
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\begingroup
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\scriptsize
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\setlength{\tabcolsep}{2pt}
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.. tabularcolumns:: |p{3.5cm}|p{0.96cm}|p{0.52cm}|p{0.52cm}|p{0.52cm}|p{0.52cm}|p{0.52cm}|p{0.52cm}|p{0.52cm}|p{0.52cm}|p{0.52cm}|p{0.52cm}|p{0.52cm}|p{0.52cm}|p{0.52cm}|p{0.52cm}|p{0.52cm}|p{0.52cm}|
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.. flat-table:: Packed YUV 4:4:4 Image Formats (less than 8bpc)
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:header-rows: 2
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:stub-columns: 0
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* - Identifier
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- Code
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- :cspan:`7` Byte 0 in memory
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- :cspan:`7` Byte 1
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* -
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-
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- 7
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- 6
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- 5
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- 4
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- 3
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- 2
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- 1
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- 0
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- 7
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- 6
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- 5
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- 4
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- 3
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- 2
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- 1
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- 0
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* .. _V4L2-PIX-FMT-YUV444:
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- ``V4L2_PIX_FMT_YUV444``
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- 'Y444'
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- Cb\ :sub:`3`
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- Cb\ :sub:`2`
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- Cb\ :sub:`1`
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- Cb\ :sub:`0`
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- Cr\ :sub:`3`
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- Cr\ :sub:`2`
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- Cr\ :sub:`1`
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- Cr\ :sub:`0`
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- a\ :sub:`3`
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- a\ :sub:`2`
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- a\ :sub:`1`
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- a\ :sub:`0`
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- Y'\ :sub:`3`
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- Y'\ :sub:`2`
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- Y'\ :sub:`1`
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- Y'\ :sub:`0`
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* .. _V4L2-PIX-FMT-YUV555:
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- ``V4L2_PIX_FMT_YUV555``
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- 'YUVO'
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- Cb\ :sub:`2`
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- Cb\ :sub:`1`
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- Cb\ :sub:`0`
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- Cr\ :sub:`4`
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- Cr\ :sub:`3`
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- Cr\ :sub:`2`
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- Cr\ :sub:`1`
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- Cr\ :sub:`0`
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- a
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- Y'\ :sub:`4`
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- Y'\ :sub:`3`
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- Y'\ :sub:`2`
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- Y'\ :sub:`1`
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- Y'\ :sub:`0`
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- Cb\ :sub:`4`
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- Cb\ :sub:`3`
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* .. _V4L2-PIX-FMT-YUV565:
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- ``V4L2_PIX_FMT_YUV565``
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- 'YUVP'
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- Cb\ :sub:`2`
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- Cb\ :sub:`1`
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- Cb\ :sub:`0`
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- Cr\ :sub:`4`
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- Cr\ :sub:`3`
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- Cr\ :sub:`2`
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- Cr\ :sub:`1`
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- Cr\ :sub:`0`
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- Y'\ :sub:`4`
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- Y'\ :sub:`3`
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- Y'\ :sub:`2`
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- Y'\ :sub:`1`
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- Y'\ :sub:`0`
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- Cb\ :sub:`5`
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- Cb\ :sub:`4`
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- Cb\ :sub:`3`
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.. raw:: latex
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\endgroup
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.. note::
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For the YUV444 and YUV555 formats, the value of alpha bits is undefined
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when reading from the driver, ignored when writing to the driver, except
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when alpha blending has been negotiated for a :ref:`Video Overlay
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<overlay>` or :ref:`Video Output Overlay <osd>`.
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The next table lists the packed YUV 4:4:4 formats with 8 bits per component.
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They are named based on the order of the Y, Cb and Cr components as stored in
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memory, and on the total number of bits per pixel. For instance, the VUYX32
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format stores a pixel with Cr\ :sub:`7-0` in the first byte, Cb\ :sub:`7-0` in
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the second byte and Y'\ :sub:`7-0` in the third byte.
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.. flat-table:: Packed YUV Image Formats (8bpc)
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:header-rows: 1
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:stub-columns: 0
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* - Identifier
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- Code
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- Byte 0
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- Byte 1
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- Byte 2
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- Byte 3
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* .. _V4L2-PIX-FMT-YUV32:
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- ``V4L2_PIX_FMT_YUV32``
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- 'YUV4'
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- A\ :sub:`7-0`
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- Y'\ :sub:`7-0`
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- Cb\ :sub:`7-0`
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- Cr\ :sub:`7-0`
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* .. _V4L2-PIX-FMT-AYUV32:
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- ``V4L2_PIX_FMT_AYUV32``
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- 'AYUV'
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- A\ :sub:`7-0`
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- Y'\ :sub:`7-0`
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- Cb\ :sub:`7-0`
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- Cr\ :sub:`7-0`
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* .. _V4L2-PIX-FMT-XYUV32:
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- ``V4L2_PIX_FMT_XYUV32``
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- 'XYUV'
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- X\ :sub:`7-0`
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- Y'\ :sub:`7-0`
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- Cb\ :sub:`7-0`
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- Cr\ :sub:`7-0`
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* .. _V4L2-PIX-FMT-VUYA32:
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- ``V4L2_PIX_FMT_VUYA32``
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- 'VUYA'
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- Cr\ :sub:`7-0`
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- Cb\ :sub:`7-0`
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- Y'\ :sub:`7-0`
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- A\ :sub:`7-0`
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* .. _V4L2-PIX-FMT-VUYX32:
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- ``V4L2_PIX_FMT_VUYX32``
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- 'VUYX'
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- Cr\ :sub:`7-0`
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- Cb\ :sub:`7-0`
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- Y'\ :sub:`7-0`
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- X\ :sub:`7-0`
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* .. _V4L2-PIX-FMT-YUVA32:
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- ``V4L2_PIX_FMT_YUVA32``
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- 'YUVA'
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- Y'\ :sub:`7-0`
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- Cb\ :sub:`7-0`
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- Cr\ :sub:`7-0`
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- A\ :sub:`7-0`
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* .. _V4L2-PIX-FMT-YUVX32:
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- ``V4L2_PIX_FMT_YUVX32``
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- 'YUVX'
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- Y'\ :sub:`7-0`
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- Cb\ :sub:`7-0`
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- Cr\ :sub:`7-0`
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- X\ :sub:`7-0`
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* .. _V4L2-PIX-FMT-YUV24:
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- ``V4L2_PIX_FMT_YUV24``
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- 'YUV3'
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- Y'\ :sub:`7-0`
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- Cb\ :sub:`7-0`
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- Cr\ :sub:`7-0`
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- -\
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.. note::
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- The alpha component is expected to contain a meaningful value that can be
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used by drivers and applications.
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- The padding bits contain undefined values that must be ignored by all
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applications and drivers.
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4:2:2 Subsampling
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=================
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These formats, commonly referred to as YUYV or YUY2, subsample the chroma
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components horizontally by 2, storing 2 pixels in 4 bytes.
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.. raw:: latex
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\footnotesize
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.. tabularcolumns:: |p{3.4cm}|p{1.2cm}|p{0.8cm}|p{0.8cm}|p{0.8cm}|p{0.8cm}|p{0.8cm}|p{0.8cm}|p{0.8cm}|p{0.8cm}|
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.. flat-table:: Packed YUV 4:2:2 Formats
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:header-rows: 1
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:stub-columns: 0
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* - Identifier
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- Code
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- Byte 0
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- Byte 1
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- Byte 2
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- Byte 3
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- Byte 4
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- Byte 5
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- Byte 6
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- Byte 7
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* .. _V4L2-PIX-FMT-UYVY:
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- ``V4L2_PIX_FMT_UYVY``
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- 'UYVY'
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- Cb\ :sub:`0`
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- Y'\ :sub:`0`
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- Cr\ :sub:`0`
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- Y'\ :sub:`1`
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- Cb\ :sub:`2`
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- Y'\ :sub:`2`
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- Cr\ :sub:`2`
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- Y'\ :sub:`3`
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* .. _V4L2-PIX-FMT-VYUY:
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- ``V4L2_PIX_FMT_VYUY``
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- 'VYUY'
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- Cr\ :sub:`0`
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- Y'\ :sub:`0`
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- Cb\ :sub:`0`
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- Y'\ :sub:`1`
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- Cr\ :sub:`2`
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- Y'\ :sub:`2`
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- Cb\ :sub:`2`
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- Y'\ :sub:`3`
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* .. _V4L2-PIX-FMT-YUYV:
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- ``V4L2_PIX_FMT_YUYV``
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- 'YUYV'
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- Y'\ :sub:`0`
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- Cb\ :sub:`0`
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- Y'\ :sub:`1`
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- Cr\ :sub:`0`
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- Y'\ :sub:`2`
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- Cb\ :sub:`2`
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- Y'\ :sub:`3`
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- Cr\ :sub:`2`
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* .. _V4L2-PIX-FMT-YVYU:
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- ``V4L2_PIX_FMT_YVYU``
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- 'YVYU'
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- Y'\ :sub:`0`
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- Cr\ :sub:`0`
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- Y'\ :sub:`1`
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- Cb\ :sub:`0`
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- Y'\ :sub:`2`
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- Cr\ :sub:`2`
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- Y'\ :sub:`3`
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- Cb\ :sub:`2`
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.. raw:: latex
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\normalsize
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**Color Sample Location:**
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Chroma samples are :ref:`interstitially sited<yuv-chroma-centered>`
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horizontally.
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4:1:1 Subsampling
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=================
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This format subsamples the chroma components horizontally by 4, storing 8
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pixels in 12 bytes.
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.. raw:: latex
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\scriptsize
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.. tabularcolumns:: |p{2.9cm}|p{0.8cm}|p{0.5cm}|p{0.5cm}|p{0.5cm}|p{0.5cm}|p{0.5cm}|p{0.5cm}|p{0.5cm}|p{0.5cm}|p{0.5cm}|p{0.5cm}|p{0.5cm}|p{0.5cm}|
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.. flat-table:: Packed YUV 4:1:1 Formats
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:header-rows: 1
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:stub-columns: 0
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* - Identifier
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- Code
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- Byte 0
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- Byte 1
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- Byte 2
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- Byte 3
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- Byte 4
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- Byte 5
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- Byte 6
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- Byte 7
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- Byte 8
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- Byte 9
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- Byte 10
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- Byte 11
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* .. _V4L2-PIX-FMT-Y41P:
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- ``V4L2_PIX_FMT_Y41P``
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- 'Y41P'
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- Cb\ :sub:`0`
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- Y'\ :sub:`0`
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- Cr\ :sub:`0`
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- Y'\ :sub:`1`
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- Cb\ :sub:`4`
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- Y'\ :sub:`2`
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- Cr\ :sub:`4`
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- Y'\ :sub:`3`
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- Y'\ :sub:`4`
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- Y'\ :sub:`5`
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- Y'\ :sub:`6`
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- Y'\ :sub:`7`
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.. raw:: latex
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\normalsize
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.. note::
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Do not confuse ``V4L2_PIX_FMT_Y41P`` with
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:ref:`V4L2_PIX_FMT_YUV411P <V4L2-PIX-FMT-YUV411P>`. Y41P is derived from
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"YUV 4:1:1 **packed**", while YUV411P stands for "YUV 4:1:1 **planar**".
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**Color Sample Location:**
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Chroma samples are :ref:`interstitially sited<yuv-chroma-centered>`
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horizontally.
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