1.. Permission is granted to copy, distribute and/or modify this 2.. document under the terms of the GNU Free Documentation License, 3.. Version 1.1 or any later version published by the Free Software 4.. Foundation, with no Invariant Sections, no Front-Cover Texts 5.. and no Back-Cover Texts. A copy of the license is included at 6.. Documentation/media/uapi/fdl-appendix.rst. 7.. 8.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections 9 10.. _V4L2-PIX-FMT-NV12MT: 11 12**************************** 13V4L2_PIX_FMT_NV12MT ('TM12') 14**************************** 15 16Formats with ½ horizontal and vertical chroma resolution. This format 17has two planes - one for luminance and one for chrominance. Chroma 18samples are interleaved. The difference to ``V4L2_PIX_FMT_NV12`` is the 19memory layout. Pixels are grouped in macroblocks of 64x32 size. The 20order of macroblocks in memory is also not standard. 21 22 23Description 24=========== 25 26This is the two-plane versions of the YUV 4:2:0 format where data is 27grouped into 64x32 macroblocks. The three components are separated into 28two sub-images or planes. The Y plane has one byte per pixel and pixels 29are grouped into 64x32 macroblocks. The CbCr plane has the same width, 30in bytes, as the Y plane (and the image), but is half as tall in pixels. 31The chroma plane is also grouped into 64x32 macroblocks. 32 33Width of the buffer has to be aligned to the multiple of 128, and height 34alignment is 32. Every four adjacent buffers - two horizontally and two 35vertically are grouped together and are located in memory in Z or 36flipped Z order. 37 38Layout of macroblocks in memory is presented in the following figure. 39 40 41.. _nv12mt: 42 43.. kernel-figure:: nv12mt.svg 44 :alt: nv12mt.svg 45 :align: center 46 47 V4L2_PIX_FMT_NV12MT macroblock Z shape memory layout 48 49The requirement that width is multiple of 128 is implemented because, 50the Z shape cannot be cut in half horizontally. In case the vertical 51resolution of macroblocks is odd then the last row of macroblocks is 52arranged in a linear order. 53 54In case of chroma the layout is identical. Cb and Cr samples are 55interleaved. Height of the buffer is aligned to 32. 56 57 58.. _nv12mt_ex: 59 60.. kernel-figure:: nv12mt_example.svg 61 :alt: nv12mt_example.svg 62 :align: center 63 64 Example V4L2_PIX_FMT_NV12MT memory layout of macroblocks 65 66Memory layout of macroblocks of ``V4L2_PIX_FMT_NV12MT`` format in most 67extreme case. 68
