From d0b2f91bede3bd5e3d24dd6803e56eee959c1797 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Thu, 20 Oct 2016 00:10:27 -0300 Subject: Linux-libre 4.8.2-gnu --- Documentation/media/uapi/v4l/pixfmt-nv12mt.rst | 62 ++++++++++++++++++++++++++ 1 file changed, 62 insertions(+) create mode 100644 Documentation/media/uapi/v4l/pixfmt-nv12mt.rst (limited to 'Documentation/media/uapi/v4l/pixfmt-nv12mt.rst') diff --git a/Documentation/media/uapi/v4l/pixfmt-nv12mt.rst b/Documentation/media/uapi/v4l/pixfmt-nv12mt.rst new file mode 100644 index 000000000..6198941bb --- /dev/null +++ b/Documentation/media/uapi/v4l/pixfmt-nv12mt.rst @@ -0,0 +1,62 @@ +.. -*- coding: utf-8; mode: rst -*- + +.. _V4L2-PIX-FMT-NV12MT: + +**************************** +V4L2_PIX_FMT_NV12MT ('TM12') +**************************** + +*man V4L2_PIX_FMT_NV12MT(2)* + +Formats with ½ horizontal and vertical chroma resolution. This format +has two planes - one for luminance and one for chrominance. Chroma +samples are interleaved. The difference to ``V4L2_PIX_FMT_NV12`` is the +memory layout. Pixels are grouped in macroblocks of 64x32 size. The +order of macroblocks in memory is also not standard. + + +Description +=========== + +This is the two-plane versions of the YUV 4:2:0 format where data is +grouped into 64x32 macroblocks. The three components are separated into +two sub-images or planes. The Y plane has one byte per pixel and pixels +are grouped into 64x32 macroblocks. The CbCr plane has the same width, +in bytes, as the Y plane (and the image), but is half as tall in pixels. +The chroma plane is also grouped into 64x32 macroblocks. + +Width of the buffer has to be aligned to the multiple of 128, and height +alignment is 32. Every four adjacent buffers - two horizontally and two +vertically are grouped together and are located in memory in Z or +flipped Z order. + +Layout of macroblocks in memory is presented in the following figure. + + +.. _nv12mt: + +.. figure:: pixfmt-nv12mt_files/nv12mt.* + :alt: nv12mt.gif + :align: center + + V4L2_PIX_FMT_NV12MT macroblock Z shape memory layout + +The requirement that width is multiple of 128 is implemented because, +the Z shape cannot be cut in half horizontally. In case the vertical +resolution of macroblocks is odd then the last row of macroblocks is +arranged in a linear order. + +In case of chroma the layout is identical. Cb and Cr samples are +interleaved. Height of the buffer is aligned to 32. + + +.. _nv12mt_ex: + +.. figure:: pixfmt-nv12mt_files/nv12mt_example.* + :alt: nv12mt_example.gif + :align: center + + Example V4L2_PIX_FMT_NV12MT memory layout of macroblocks + +Memory layout of macroblocks of ``V4L2_PIX_FMT_NV12MT`` format in most +extreme case. -- cgit v1.2.3-54-g00ecf