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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_YVU420 ('YV12'), V4L2_PIX_FMT_YUV420 ('YU12')</refentrytitle>
4		&manvol;
5	     </refmeta>
6	      <refnamediv>
7		<refname id="V4L2-PIX-FMT-YVU420"><constant>V4L2_PIX_FMT_YVU420</constant></refname>
8		<refname id="V4L2-PIX-FMT-YUV420"><constant>V4L2_PIX_FMT_YUV420</constant></refname>
9		<refpurpose>Planar formats with &frac12; horizontal and
10	vertical chroma resolution, also known as YUV 4:2:0</refpurpose>
11	      </refnamediv>
12	      <refsect1>
13		<title>Description</title>
14	
15		<para>These are planar formats, as opposed to a packed format.
16	The three components are separated into three sub- images or planes.
17	The Y plane is first. The Y plane has one byte per pixel. For
18	<constant>V4L2_PIX_FMT_YVU420</constant>, the Cr plane immediately
19	follows the Y plane in memory. The Cr plane is half the width and half
20	the height of the Y plane (and of the image). Each Cr belongs to four
21	pixels, a two-by-two square of the image. For example,
22	Cr<subscript>0</subscript> belongs to Y'<subscript>00</subscript>,
23	Y'<subscript>01</subscript>, Y'<subscript>10</subscript>, and
24	Y'<subscript>11</subscript>. Following the Cr plane is the Cb plane,
25	just like the Cr plane. <constant>V4L2_PIX_FMT_YUV420</constant> is
26	the same except the Cb plane comes first, then the Cr plane.</para>
27	
28		<para>If the Y plane has pad bytes after each row, then the Cr
29	and Cb planes have half as many pad bytes after their rows. In other
30	words, two Cx rows (including padding) is exactly as long as one Y row
31	(including padding).</para>
32	
33		<example>
34		  <title><constant>V4L2_PIX_FMT_YVU420</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>Cr<subscript>00</subscript></entry>
75			      <entry>Cr<subscript>01</subscript></entry>
76			    </row>
77			    <row>
78			      <entry>start&nbsp;+&nbsp;18:</entry>
79			      <entry>Cr<subscript>10</subscript></entry>
80			      <entry>Cr<subscript>11</subscript></entry>
81			    </row>
82			    <row>
83			      <entry>start&nbsp;+&nbsp;20:</entry>
84			      <entry>Cb<subscript>00</subscript></entry>
85			      <entry>Cb<subscript>01</subscript></entry>
86			    </row>
87			    <row>
88			      <entry>start&nbsp;+&nbsp;22:</entry>
89			      <entry>Cb<subscript>10</subscript></entry>
90			      <entry>Cb<subscript>11</subscript></entry>
91			    </row>
92			  </tbody>
93			</tgroup>
94			</informaltable>
95		      </para>
96		  </formalpara>
97	
98		  <formalpara>
99		    <title>Color Sample Location.</title>
100		    <para>
101			<informaltable frame="none">
102			<tgroup cols="7" align="center">
103			  <tbody valign="top">
104			    <row>
105			      <entry></entry>
106			      <entry>0</entry><entry></entry><entry>1</entry><entry></entry>
107			      <entry>2</entry><entry></entry><entry>3</entry>
108			    </row>
109			    <row>
110			      <entry>0</entry>
111			      <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
112			      <entry>Y</entry><entry></entry><entry>Y</entry>
113			    </row>
114			    <row>
115			      <entry></entry>
116			      <entry></entry><entry>C</entry><entry></entry><entry></entry>
117			      <entry></entry><entry>C</entry><entry></entry>
118			    </row>
119			    <row>
120			      <entry>1</entry>
121			      <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
122			      <entry>Y</entry><entry></entry><entry>Y</entry>
123			    </row>
124			    <row>
125			      <entry></entry>
126			    </row>
127			    <row>
128			      <entry>2</entry>
129			      <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
130			      <entry>Y</entry><entry></entry><entry>Y</entry>
131			    </row>
132			    <row>
133			      <entry></entry>
134			      <entry></entry><entry>C</entry><entry></entry><entry></entry>
135			      <entry></entry><entry>C</entry><entry></entry>
136			    </row>
137			    <row>
138			      <entry>3</entry>
139			      <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
140			      <entry>Y</entry><entry></entry><entry>Y</entry>
141			    </row>
142			  </tbody>
143			</tgroup>
144			</informaltable>
145		      </para>
146		  </formalpara>
147		</example>
148	      </refsect1>
149	    </refentry>
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