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Based on kernel version 3.0.4. Page generated on 2011-10-03 22:07 EST.

1	    <refentry id="V4L2-PIX-FMT-NV12M">
2	      <refmeta>
3		<refentrytitle>V4L2_PIX_FMT_NV12M ('NV12M')</refentrytitle>
4		&manvol;
5	      </refmeta>
6	      <refnamediv>
7		<refname> <constant>V4L2_PIX_FMT_NV12M</constant></refname>
8		<refpurpose>Variation of <constant>V4L2_PIX_FMT_NV12</constant> with planes
9		  non contiguous in memory. </refpurpose>
10	      </refnamediv>
11	      <refsect1>
12		<title>Description</title>
13	
14		<para>This is a multi-planar, two-plane version of the YUV 4:2:0 format.
15	The three components are separated into two sub-images or planes.
16	<constant>V4L2_PIX_FMT_NV12M</constant> differs from <constant>V4L2_PIX_FMT_NV12
17	</constant> in that the two planes are non-contiguous in memory, i.e. the chroma
18	plane do not necessarily immediately follows the luma plane.
19	The luminance data occupies the first plane. The Y plane has one byte per pixel.
20	In the second plane there is a chrominance data with alternating chroma samples.
21	The CbCr plane is the same width, in bytes, as the Y plane (and of the image),
22	but is half as tall in pixels. Each CbCr pair belongs to four pixels. For example,
23	Cb<subscript>0</subscript>/Cr<subscript>0</subscript> belongs to
24	Y'<subscript>00</subscript>, Y'<subscript>01</subscript>,
25	Y'<subscript>10</subscript>, Y'<subscript>11</subscript>. </para>
26	
27		<para><constant>V4L2_PIX_FMT_NV12M</constant> is intended to be
28	used only in drivers and applications that support the multi-planar API,
29	described in <xref linkend="planar-apis"/>. </para>
30	
31		<para>If the Y plane has pad bytes after each row, then the
32	CbCr plane has as many pad bytes after its rows.</para>
33	
34		<example>
35		  <title><constant>V4L2_PIX_FMT_NV12M</constant> 4 &times; 4 pixel image</title>
36	
37		  <formalpara>
38		    <title>Byte Order.</title>
39		    <para>Each cell is one byte.
40			<informaltable frame="none">
41			<tgroup cols="5" align="center">
42			  <colspec align="left" colwidth="2*" />
43			  <tbody valign="top">
44			    <row>
45			      <entry>start0&nbsp;+&nbsp;0:</entry>
46			      <entry>Y'<subscript>00</subscript></entry>
47			      <entry>Y'<subscript>01</subscript></entry>
48			      <entry>Y'<subscript>02</subscript></entry>
49			      <entry>Y'<subscript>03</subscript></entry>
50			    </row>
51			    <row>
52			      <entry>start0&nbsp;+&nbsp;4:</entry>
53			      <entry>Y'<subscript>10</subscript></entry>
54			      <entry>Y'<subscript>11</subscript></entry>
55			      <entry>Y'<subscript>12</subscript></entry>
56			      <entry>Y'<subscript>13</subscript></entry>
57			    </row>
58			    <row>
59			      <entry>start0&nbsp;+&nbsp;8:</entry>
60			      <entry>Y'<subscript>20</subscript></entry>
61			      <entry>Y'<subscript>21</subscript></entry>
62			      <entry>Y'<subscript>22</subscript></entry>
63			      <entry>Y'<subscript>23</subscript></entry>
64			    </row>
65			    <row>
66			      <entry>start0&nbsp;+&nbsp;12:</entry>
67			      <entry>Y'<subscript>30</subscript></entry>
68			      <entry>Y'<subscript>31</subscript></entry>
69			      <entry>Y'<subscript>32</subscript></entry>
70			      <entry>Y'<subscript>33</subscript></entry>
71			    </row>
72			    <row>
73			      <entry></entry>
74			    </row>
75			    <row>
76			      <entry>start1&nbsp;+&nbsp;0:</entry>
77			      <entry>Cb<subscript>00</subscript></entry>
78			      <entry>Cr<subscript>00</subscript></entry>
79			      <entry>Cb<subscript>01</subscript></entry>
80			      <entry>Cr<subscript>01</subscript></entry>
81			    </row>
82			    <row>
83			      <entry>start1&nbsp;+&nbsp;4:</entry>
84			      <entry>Cb<subscript>10</subscript></entry>
85			      <entry>Cr<subscript>10</subscript></entry>
86			      <entry>Cb<subscript>11</subscript></entry>
87			      <entry>Cr<subscript>11</subscript></entry>
88			    </row>
89			  </tbody>
90			</tgroup>
91			</informaltable>
92		      </para>
93		  </formalpara>
94	
95		  <formalpara>
96		    <title>Color Sample Location.</title>
97		    <para>
98			<informaltable frame="none">
99			<tgroup cols="7" align="center">
100			  <tbody valign="top">
101			    <row>
102			      <entry></entry>
103			      <entry>0</entry><entry></entry><entry>1</entry><entry></entry>
104			      <entry>2</entry><entry></entry><entry>3</entry>
105			    </row>
106			    <row>
107			      <entry>0</entry>
108			      <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
109			      <entry>Y</entry><entry></entry><entry>Y</entry>
110			    </row>
111			    <row>
112			      <entry></entry>
113			      <entry></entry><entry>C</entry><entry></entry><entry></entry>
114			      <entry></entry><entry>C</entry><entry></entry>
115			    </row>
116			    <row>
117			      <entry>1</entry>
118			      <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
119			      <entry>Y</entry><entry></entry><entry>Y</entry>
120			    </row>
121			    <row>
122			      <entry></entry>
123			    </row>
124			    <row>
125			      <entry>2</entry>
126			      <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
127			      <entry>Y</entry><entry></entry><entry>Y</entry>
128			    </row>
129			    <row>
130			      <entry></entry>
131			      <entry></entry><entry>C</entry><entry></entry><entry></entry>
132			      <entry></entry><entry>C</entry><entry></entry>
133			    </row>
134			    <row>
135			      <entry>3</entry>
136			      <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
137			      <entry>Y</entry><entry></entry><entry>Y</entry>
138			    </row>
139			  </tbody>
140			</tgroup>
141			</informaltable>
142		      </para>
143		  </formalpara>
144		</example>
145	      </refsect1>
146	    </refentry>
147	
148	  <!--
149	Local Variables:
150	mode: sgml
151	sgml-parent-document: "pixfmt.sgml"
152	indent-tabs-mode: nil
153	End:
154	  -->
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