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authorLinus Torvalds <torvalds@linux-foundation.org>2016-07-27 21:58:31 (GMT)
committerLinus Torvalds <torvalds@linux-foundation.org>2016-07-27 21:58:31 (GMT)
commitff9a082fda424257976f08fce942609f358015e0 (patch)
tree478e6b449b19baaf842369a13923499ce83ef895 /Documentation/media/uapi/v4l/pixfmt-nv12mt.rst
parent6a492b0f23d28e1f946cdf08e54617484400dafb (diff)
parent85538b1ad145c67198cb55d02de14ba269cc323d (diff)
downloadlinux-ff9a082fda424257976f08fce942609f358015e0.tar.xz
Merge tag 'media/v4.8-4' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media
Pull media documentation updates from Mauro Carvalho Chehab: "This patch series does the conversion of all media documentation stuff to Restrutured Text markup format and add them to the Documentation/index.rst file. The media documentation was grouped into 4 books: - media uAPI - media kAPI - V4L driver-specific documentation - DVB driver-specific documentation It also contains several documentation improvements and one fixup patch for a core issue with cropcap. PS. After this patch series, the media DocBook is deprecated and should be removed. I'll add such patch on a future pull request" * tag 'media/v4.8-4' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (322 commits) [media] cx23885-cardlist.rst: add a new card [media] doc-rst: add some needed escape codes [media] doc-rst: kapi: use :c:func: instead of :cpp:func doc-rst: kernel-doc: fix a change introduced by mistake [media] v4l2-ioctl.h add debug info for struct v4l2_ioctl_ops [media] dvb_ringbuffer.h: some documentation improvements [media] v4l2-ctrls.h: fully document the header file [media] doc-rst: Fix some typedef ugly warnings [media] doc-rst: reorganize the kAPI v4l2 chapters [media] rename v4l2-framework.rst to v4l2-intro.rst [media] move V4L2 clocks to a separate .rst file [media] v4l2-fh.rst: add cross references and markups [media] v4l2-fh.rst: add fh contents from v4l2-framework.rst [media] v4l2-fh.h: add documentation for it [media] v4l2-event.rst: add cross-references and markups [media] v4l2-event.h: document all functions [media] v4l2-event.rst: add text from v4l2-framework.rst [media] v4l2-framework.rst: remove videobuf quick chapter [media] v4l2-dev: add cross-references and improve markup [media] doc-rst: move v4l2-dev doc to a separate file ...
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+.. -*- 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.