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r: 242067
b: refs/heads/master
c: bd08a0c
h: refs/heads/master
i:
  242065: dfd47ff
  242063: b96163f
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Kamil Debski authored and Mauro Carvalho Chehab committed Mar 22, 2011
1 parent bcb1bed commit 3dfab4c
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2 changes: 1 addition & 1 deletion [refs]
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---
refs/heads/master: 91707b8b27a785c42949ba55b65f084027962afa
refs/heads/master: bd08a0cd5f546916a9454ae2c35756ed77957458
1 change: 1 addition & 0 deletions trunk/Documentation/DocBook/media-entities.tmpl
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<!ENTITY sub-grey SYSTEM "v4l/pixfmt-grey.xml">
<!ENTITY sub-nv12 SYSTEM "v4l/pixfmt-nv12.xml">
<!ENTITY sub-nv12m SYSTEM "v4l/pixfmt-nv12m.xml">
<!ENTITY sub-nv12mt SYSTEM "v4l/pixfmt-nv12mt.xml">
<!ENTITY sub-nv16 SYSTEM "v4l/pixfmt-nv16.xml">
<!ENTITY sub-packed-rgb SYSTEM "v4l/pixfmt-packed-rgb.xml">
<!ENTITY sub-packed-yuv SYSTEM "v4l/pixfmt-packed-yuv.xml">
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74 changes: 74 additions & 0 deletions trunk/Documentation/DocBook/v4l/pixfmt-nv12mt.xml
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<refentry>
<refmeta>
<refentrytitle>V4L2_PIX_FMT_NV12MT ('TM12')</refentrytitle>
&manvol;
</refmeta>
<refnamediv>
<refname id="V4L2-PIX-FMT-NV12MT"><constant>V4L2_PIX_FMT_NV12MT
</constant></refname>
<refpurpose>Formats with &frac12; horizontal and vertical
chroma resolution. This format has two planes - one for luminance and one for
chrominance. Chroma samples are interleaved. The difference to
<constant>V4L2_PIX_FMT_NV12</constant> is the memory layout. Pixels are
grouped in macroblocks of 64x32 size. The order of macroblocks in memory is
also not standard.
</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>

<para>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.</para>
<para>Width of the buffer has to be aligned to the multiple of 128, and
height alignment is 32. Every four adjactent buffers - two horizontally and two
vertically are grouped together and are located in memory in Z or flipped Z
order. </para>
<para>Layout of macroblocks in memory is presented in the following
figure.</para>
<para><figure id="nv12mt">
<title><constant>V4L2_PIX_FMT_NV12MT</constant> macroblock Z shape
memory layout</title>
<mediaobject>
<imageobject>
<imagedata fileref="nv12mt.gif" format="GIF" />
</imageobject>
</mediaobject>
</figure>
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. </para>
<para>In case of chroma the layout is identical. Cb and Cr samples are
interleaved. Height of the buffer is aligned to 32.
</para>
<example>
<title>Memory layout of macroblocks in <constant>V4L2_PIX_FMT_NV12
</constant> format pixel image - extreme case</title>
<para>
<figure id="nv12mt">
<title>Example <constant>V4L2_PIX_FMT_NV12MT</constant> memory
layout of macroblocks</title>
<mediaobject>
<imageobject>
<imagedata fileref="nv12mt_example.gif" format="GIF" />
</imageobject>
</mediaobject>
</figure>
Memory layout of macroblocks of <constant>V4L2_PIX_FMT_NV12MT
</constant> format in most extreme case.
</para>
</example>
</refsect1>
</refentry>

<!--
Local Variables:
mode: sgml
sgml-parent-document: "pixfmt.sgml"
indent-tabs-mode: nil
End:
-->
1 change: 1 addition & 0 deletions trunk/Documentation/DocBook/v4l/pixfmt.xml
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&sub-yuv411p;
&sub-nv12;
&sub-nv12m;
&sub-nv12mt;
&sub-nv16;
</section>

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