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Based on kernel version 3.13. Page generated on 2014-01-20 22:02 EST.

1	    <refentry>
2	      <refmeta>
3		<refentrytitle>V4L2_PIX_FMT_NV12M ('NM12'), V4L2_PIX_FMT_NV21M ('NM21'), V4L2_PIX_FMT_NV12MT_16X16</refentrytitle>
4		&manvol;
5	      </refmeta>
6	      <refnamediv>
7		<refname id="V4L2-PIX-FMT-NV12M"><constant>V4L2_PIX_FMT_NV12M</constant></refname>
8		<refname id="V4L2-PIX-FMT-NV21M"><constant>V4L2_PIX_FMT_NV21M</constant></refname>
9		<refname id="V4L2-PIX-FMT-NV12MT-16X16"><constant>V4L2_PIX_FMT_NV12MT_16X16</constant></refname>
10		<refpurpose>Variation of <constant>V4L2_PIX_FMT_NV12</constant> and <constant>V4L2_PIX_FMT_NV21</constant> with planes
11		  non contiguous in memory. </refpurpose>
12	      </refnamediv>
13	      <refsect1>
14		<title>Description</title>
15	
16		<para>This is a multi-planar, two-plane version of the YUV 4:2:0 format.
17	The three components are separated into two sub-images or planes.
18	<constant>V4L2_PIX_FMT_NV12M</constant> differs from <constant>V4L2_PIX_FMT_NV12
19	</constant> in that the two planes are non-contiguous in memory, i.e. the chroma
20	plane do not necessarily immediately follows the luma plane.
21	The luminance data occupies the first plane. The Y plane has one byte per pixel.
22	In the second plane there is a chrominance data with alternating chroma samples.
23	The CbCr plane is the same width, in bytes, as the Y plane (and of the image),
24	but is half as tall in pixels. Each CbCr pair belongs to four pixels. For example,
25	Cb<subscript>0</subscript>/Cr<subscript>0</subscript> belongs to
26	Y'<subscript>00</subscript>, Y'<subscript>01</subscript>,
27	Y'<subscript>10</subscript>, Y'<subscript>11</subscript>.
28	<constant>V4L2_PIX_FMT_NV12MT_16X16</constant> is the tiled version of
29	<constant>V4L2_PIX_FMT_NV12M</constant> with 16x16 macroblock tiles. Here pixels
30	are arranged in 16x16 2D tiles and tiles are arranged in linear order in memory.
31	<constant>V4L2_PIX_FMT_NV21M</constant> is the same as <constant>V4L2_PIX_FMT_NV12M</constant>
32	except the Cb and Cr bytes are swapped, the CrCb plane starts with a Cr byte.</para>
33	
34		<para><constant>V4L2_PIX_FMT_NV12M</constant> is intended to be
35	used only in drivers and applications that support the multi-planar API,
36	described in <xref linkend="planar-apis"/>. </para>
37	
38		<para>If the Y plane has pad bytes after each row, then the
39	CbCr plane has as many pad bytes after its rows.</para>
40	
41		<example>
42		  <title><constant>V4L2_PIX_FMT_NV12M</constant> 4 &times; 4 pixel image</title>
43	
44		  <formalpara>
45		    <title>Byte Order.</title>
46		    <para>Each cell is one byte.
47			<informaltable frame="none">
48			<tgroup cols="5" align="center">
49			  <colspec align="left" colwidth="2*" />
50			  <tbody valign="top">
51			    <row>
52			      <entry>start0&nbsp;+&nbsp;0:</entry>
53			      <entry>Y'<subscript>00</subscript></entry>
54			      <entry>Y'<subscript>01</subscript></entry>
55			      <entry>Y'<subscript>02</subscript></entry>
56			      <entry>Y'<subscript>03</subscript></entry>
57			    </row>
58			    <row>
59			      <entry>start0&nbsp;+&nbsp;4:</entry>
60			      <entry>Y'<subscript>10</subscript></entry>
61			      <entry>Y'<subscript>11</subscript></entry>
62			      <entry>Y'<subscript>12</subscript></entry>
63			      <entry>Y'<subscript>13</subscript></entry>
64			    </row>
65			    <row>
66			      <entry>start0&nbsp;+&nbsp;8:</entry>
67			      <entry>Y'<subscript>20</subscript></entry>
68			      <entry>Y'<subscript>21</subscript></entry>
69			      <entry>Y'<subscript>22</subscript></entry>
70			      <entry>Y'<subscript>23</subscript></entry>
71			    </row>
72			    <row>
73			      <entry>start0&nbsp;+&nbsp;12:</entry>
74			      <entry>Y'<subscript>30</subscript></entry>
75			      <entry>Y'<subscript>31</subscript></entry>
76			      <entry>Y'<subscript>32</subscript></entry>
77			      <entry>Y'<subscript>33</subscript></entry>
78			    </row>
79			    <row>
80			      <entry></entry>
81			    </row>
82			    <row>
83			      <entry>start1&nbsp;+&nbsp;0:</entry>
84			      <entry>Cb<subscript>00</subscript></entry>
85			      <entry>Cr<subscript>00</subscript></entry>
86			      <entry>Cb<subscript>01</subscript></entry>
87			      <entry>Cr<subscript>01</subscript></entry>
88			    </row>
89			    <row>
90			      <entry>start1&nbsp;+&nbsp;4:</entry>
91			      <entry>Cb<subscript>10</subscript></entry>
92			      <entry>Cr<subscript>10</subscript></entry>
93			      <entry>Cb<subscript>11</subscript></entry>
94			      <entry>Cr<subscript>11</subscript></entry>
95			    </row>
96			  </tbody>
97			</tgroup>
98			</informaltable>
99		      </para>
100		  </formalpara>
101	
102		  <formalpara>
103		    <title>Color Sample Location.</title>
104		    <para>
105			<informaltable frame="none">
106			<tgroup cols="7" align="center">
107			  <tbody valign="top">
108			    <row>
109			      <entry></entry>
110			      <entry>0</entry><entry></entry><entry>1</entry><entry></entry>
111			      <entry>2</entry><entry></entry><entry>3</entry>
112			    </row>
113			    <row>
114			      <entry>0</entry>
115			      <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
116			      <entry>Y</entry><entry></entry><entry>Y</entry>
117			    </row>
118			    <row>
119			      <entry></entry>
120			      <entry></entry><entry>C</entry><entry></entry><entry></entry>
121			      <entry></entry><entry>C</entry><entry></entry>
122			    </row>
123			    <row>
124			      <entry>1</entry>
125			      <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
126			      <entry>Y</entry><entry></entry><entry>Y</entry>
127			    </row>
128			    <row>
129			      <entry></entry>
130			    </row>
131			    <row>
132			      <entry>2</entry>
133			      <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
134			      <entry>Y</entry><entry></entry><entry>Y</entry>
135			    </row>
136			    <row>
137			      <entry></entry>
138			      <entry></entry><entry>C</entry><entry></entry><entry></entry>
139			      <entry></entry><entry>C</entry><entry></entry>
140			    </row>
141			    <row>
142			      <entry>3</entry>
143			      <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
144			      <entry>Y</entry><entry></entry><entry>Y</entry>
145			    </row>
146			  </tbody>
147			</tgroup>
148			</informaltable>
149		      </para>
150		  </formalpara>
151		</example>
152	      </refsect1>
153	    </refentry>
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