Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / Documentation / DocBook / media / v4l / pixfmt-yuv420.xml

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+    <refentry>
+      <refmeta>
+       <refentrytitle>V4L2_PIX_FMT_YVU420 ('YV12'), V4L2_PIX_FMT_YUV420 ('YU12')</refentrytitle>
+       &manvol;
+     </refmeta>
+      <refnamediv>
+       <refname id="V4L2-PIX-FMT-YVU420"><constant>V4L2_PIX_FMT_YVU420</constant></refname>
+       <refname id="V4L2-PIX-FMT-YUV420"><constant>V4L2_PIX_FMT_YUV420</constant></refname>
+       <refpurpose>Planar formats with &frac12; horizontal and
+vertical chroma resolution, also known as YUV 4:2:0</refpurpose>
+      </refnamediv>
+      <refsect1>
+       <title>Description</title>
+
+       <para>These are planar formats, as opposed to a packed format.
+The three components are separated into three sub- images or planes.
+The Y plane is first. The Y plane has one byte per pixel. For
+<constant>V4L2_PIX_FMT_YVU420</constant>, the Cr plane immediately
+follows the Y plane in memory. The Cr plane is half the width and half
+the height of the Y plane (and of the image). Each Cr belongs to four
+pixels, a two-by-two square of the image. For example,
+Cr<subscript>0</subscript> belongs to Y'<subscript>00</subscript>,
+Y'<subscript>01</subscript>, Y'<subscript>10</subscript>, and
+Y'<subscript>11</subscript>. Following the Cr plane is the Cb plane,
+just like the Cr plane. <constant>V4L2_PIX_FMT_YUV420</constant> is
+the same except the Cb plane comes first, then the Cr plane.</para>
+
+       <para>If the Y plane has pad bytes after each row, then the Cr
+and Cb planes have half as many pad bytes after their rows. In other
+words, two Cx rows (including padding) is exactly as long as one Y row
+(including padding).</para>
+
+       <example>
+         <title><constant>V4L2_PIX_FMT_YVU420</constant> 4 &times; 4
+pixel image</title>
+
+         <formalpara>
+           <title>Byte Order.</title>
+           <para>Each cell is one byte.
+               <informaltable frame="none">
+               <tgroup cols="5" align="center">
+                 <colspec align="left" colwidth="2*" />
+                 <tbody valign="top">
+                   <row>
+                     <entry>start&nbsp;+&nbsp;0:</entry>
+                     <entry>Y'<subscript>00</subscript></entry>
+                     <entry>Y'<subscript>01</subscript></entry>
+                     <entry>Y'<subscript>02</subscript></entry>
+                     <entry>Y'<subscript>03</subscript></entry>
+                   </row>
+                   <row>
+                     <entry>start&nbsp;+&nbsp;4:</entry>
+                     <entry>Y'<subscript>10</subscript></entry>
+                     <entry>Y'<subscript>11</subscript></entry>
+                     <entry>Y'<subscript>12</subscript></entry>
+                     <entry>Y'<subscript>13</subscript></entry>
+                   </row>
+                   <row>
+                     <entry>start&nbsp;+&nbsp;8:</entry>
+                     <entry>Y'<subscript>20</subscript></entry>
+                     <entry>Y'<subscript>21</subscript></entry>
+                     <entry>Y'<subscript>22</subscript></entry>
+                     <entry>Y'<subscript>23</subscript></entry>
+                   </row>
+                   <row>
+                     <entry>start&nbsp;+&nbsp;12:</entry>
+                     <entry>Y'<subscript>30</subscript></entry>
+                     <entry>Y'<subscript>31</subscript></entry>
+                     <entry>Y'<subscript>32</subscript></entry>
+                     <entry>Y'<subscript>33</subscript></entry>
+                   </row>
+                   <row>
+                     <entry>start&nbsp;+&nbsp;16:</entry>
+                     <entry>Cr<subscript>00</subscript></entry>
+                     <entry>Cr<subscript>01</subscript></entry>
+                   </row>
+                   <row>
+                     <entry>start&nbsp;+&nbsp;18:</entry>
+                     <entry>Cr<subscript>10</subscript></entry>
+                     <entry>Cr<subscript>11</subscript></entry>
+                   </row>
+                   <row>
+                     <entry>start&nbsp;+&nbsp;20:</entry>
+                     <entry>Cb<subscript>00</subscript></entry>
+                     <entry>Cb<subscript>01</subscript></entry>
+                   </row>
+                   <row>
+                     <entry>start&nbsp;+&nbsp;22:</entry>
+                     <entry>Cb<subscript>10</subscript></entry>
+                     <entry>Cb<subscript>11</subscript></entry>
+                   </row>
+                 </tbody>
+               </tgroup>
+               </informaltable>
+             </para>
+         </formalpara>
+
+         <formalpara>
+           <title>Color Sample Location.</title>
+           <para>
+               <informaltable frame="none">
+               <tgroup cols="7" align="center">
+                 <tbody valign="top">
+                   <row>
+                     <entry></entry>
+                     <entry>0</entry><entry></entry><entry>1</entry><entry></entry>
+                     <entry>2</entry><entry></entry><entry>3</entry>
+                   </row>
+                   <row>
+                     <entry>0</entry>
+                     <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
+                     <entry>Y</entry><entry></entry><entry>Y</entry>
+                   </row>
+                   <row>
+                     <entry></entry>
+                     <entry></entry><entry>C</entry><entry></entry><entry></entry>
+                     <entry></entry><entry>C</entry><entry></entry>
+                   </row>
+                   <row>
+                     <entry>1</entry>
+                     <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
+                     <entry>Y</entry><entry></entry><entry>Y</entry>
+                   </row>
+                   <row>
+                     <entry></entry>
+                   </row>
+                   <row>
+                     <entry>2</entry>
+                     <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
+                     <entry>Y</entry><entry></entry><entry>Y</entry>
+                   </row>
+                   <row>
+                     <entry></entry>
+                     <entry></entry><entry>C</entry><entry></entry><entry></entry>
+                     <entry></entry><entry>C</entry><entry></entry>
+                   </row>
+                   <row>
+                     <entry>3</entry>
+                     <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
+                     <entry>Y</entry><entry></entry><entry>Y</entry>
+                   </row>
+                 </tbody>
+               </tgroup>
+               </informaltable>
+             </para>
+         </formalpara>
+       </example>
+      </refsect1>
+    </refentry>