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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_NV12 ('NV12'), V4L2_PIX_FMT_NV21 ('NV21')</refentrytitle>
4		&manvol;
5	      </refmeta>
6	      <refnamediv>
7		<refname id="V4L2-PIX-FMT-NV12"><constant>V4L2_PIX_FMT_NV12</constant></refname>
8		<refname id="V4L2-PIX-FMT-NV21"><constant>V4L2_PIX_FMT_NV21</constant></refname>
9		<refpurpose>Formats with &frac12; horizontal and vertical
10	chroma resolution, also known as YUV 4:2:0. One luminance and one
11	chrominance plane with alternating chroma samples as opposed to
12	<constant>V4L2_PIX_FMT_YVU420</constant></refpurpose>
13	      </refnamediv>
14	      <refsect1>
15		<title>Description</title>
16	
17		<para>These are two-plane versions of the YUV 4:2:0 format.
18	The three components are separated into two sub-images or planes. The
19	Y plane is first. The Y plane has one byte per pixel. For
20	<constant>V4L2_PIX_FMT_NV12</constant>, a combined CbCr plane
21	immediately follows the Y plane in memory.  The CbCr plane is the same
22	width, in bytes, as the Y plane (and of the image), but is half as
23	tall in pixels. Each CbCr pair belongs to four pixels. For example,
24	Cb<subscript>0</subscript>/Cr<subscript>0</subscript> belongs to
25	Y'<subscript>00</subscript>, Y'<subscript>01</subscript>,
26	Y'<subscript>10</subscript>, Y'<subscript>11</subscript>.
27	<constant>V4L2_PIX_FMT_NV21</constant> is the same except the Cb and
28	Cr bytes are swapped, the CrCb plane starts with a Cr byte.</para>
29	
30		<para>If the Y plane has pad bytes after each row, then the
31	CbCr plane has as many pad bytes after its rows.</para>
32	
33		<example>
34		  <title><constant>V4L2_PIX_FMT_NV12</constant> 4 &times; 4
35	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>start&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>start&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>start&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>start&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>start&nbsp;+&nbsp;16:</entry>
74			      <entry>Cb<subscript>00</subscript></entry>
75			      <entry>Cr<subscript>00</subscript></entry>
76			      <entry>Cb<subscript>01</subscript></entry>
77			      <entry>Cr<subscript>01</subscript></entry>
78			    </row>
79			    <row>
80			      <entry>start&nbsp;+&nbsp;20:</entry>
81			      <entry>Cb<subscript>10</subscript></entry>
82			      <entry>Cr<subscript>10</subscript></entry>
83			      <entry>Cb<subscript>11</subscript></entry>
84			      <entry>Cr<subscript>11</subscript></entry>
85			    </row>
86			  </tbody>
87			</tgroup>
88			</informaltable>
89		      </para>
90		  </formalpara>
91	
92		  <formalpara>
93		    <title>Color Sample Location.</title>
94		    <para>
95			<informaltable frame="none">
96			<tgroup cols="7" align="center">
97			  <tbody valign="top">
98			    <row>
99			      <entry></entry>
100			      <entry>0</entry><entry></entry><entry>1</entry><entry></entry>
101			      <entry>2</entry><entry></entry><entry>3</entry>
102			    </row>
103			    <row>
104			      <entry>0</entry>
105			      <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
106			      <entry>Y</entry><entry></entry><entry>Y</entry>
107			    </row>
108			    <row>
109			      <entry></entry>
110			      <entry></entry><entry>C</entry><entry></entry><entry></entry>
111			      <entry></entry><entry>C</entry><entry></entry>
112			    </row>
113			    <row>
114			      <entry>1</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			    </row>
121			    <row>
122			      <entry>2</entry>
123			      <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
124			      <entry>Y</entry><entry></entry><entry>Y</entry>
125			    </row>
126			    <row>
127			      <entry></entry>
128			      <entry></entry><entry>C</entry><entry></entry><entry></entry>
129			      <entry></entry><entry>C</entry><entry></entry>
130			    </row>
131			    <row>
132			      <entry>3</entry>
133			      <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
134			      <entry>Y</entry><entry></entry><entry>Y</entry>
135			    </row>
136			  </tbody>
137			</tgroup>
138			</informaltable>
139		      </para>
140		  </formalpara>
141		</example>
142	      </refsect1>
143	    </refentry>
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