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diff --git a/Documentation/userspace-api/media/v4l/pixfmt-nv12.rst b/Documentation/userspace-api/media/v4l/pixfmt-nv12.rst new file mode 100644 index 000000000..dd2f38129 --- /dev/null +++ b/Documentation/userspace-api/media/v4l/pixfmt-nv12.rst @@ -0,0 +1,129 @@ +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later + +.. _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 |