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+ <refentry id="V4L2-PIX-FMT-YUV420M">
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+ <refmeta>
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+ <refentrytitle>V4L2_PIX_FMT_YUV420M ('YU12M')</refentrytitle>
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+ &manvol;
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+ </refmeta>
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+ <refnamediv>
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+ <refname> <constant>V4L2_PIX_FMT_YUV420M</constant></refname>
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+ <refpurpose>Variation of <constant>V4L2_PIX_FMT_YUV420</constant>
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+ with planes non contiguous in memory. </refpurpose>
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+ </refnamediv>
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+
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+ <refsect1>
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+ <title>Description</title>
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+
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+ <para>This is a multi-planar format, as opposed to a packed format.
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+The three components are separated into three sub- images or planes.
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+
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+The Y plane is first. The Y plane has one byte per pixel. The Cb data
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+constitutes the second plane which is half the width and half
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+the height of the Y plane (and of the image). Each Cb belongs to four
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+pixels, a two-by-two square of the image. For example,
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+Cb<subscript>0</subscript> belongs to Y'<subscript>00</subscript>,
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+Y'<subscript>01</subscript>, Y'<subscript>10</subscript>, and
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+Y'<subscript>11</subscript>. The Cr data, just like the Cb plane, is
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+in the third plane. </para>
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+
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+ <para>If the Y plane has pad bytes after each row, then the Cb
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+and Cr planes have half as many pad bytes after their rows. In other
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+words, two Cx rows (including padding) is exactly as long as one Y row
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+(including padding).</para>
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+
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+ <para><constant>V4L2_PIX_FMT_NV12M</constant> is intended to be
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+used only in drivers and applications that support the multi-planar API,
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+described in <xref linkend="planar-apis"/>. </para>
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+
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+ <example>
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+ <title><constant>V4L2_PIX_FMT_YVU420M</constant> 4 × 4
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+pixel image</title>
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+
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+ <formalpara>
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+ <title>Byte Order.</title>
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+ <para>Each cell is one byte.
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+ <informaltable frame="none">
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+ <tgroup cols="5" align="center">
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+ <colspec align="left" colwidth="2*" />
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+ <tbody valign="top">
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+ <row>
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+ <entry>start0 + 0:</entry>
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+ <entry>Y'<subscript>00</subscript></entry>
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+ <entry>Y'<subscript>01</subscript></entry>
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+ <entry>Y'<subscript>02</subscript></entry>
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+ <entry>Y'<subscript>03</subscript></entry>
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+ </row>
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+ <row>
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+ <entry>start0 + 4:</entry>
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+ <entry>Y'<subscript>10</subscript></entry>
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+ <entry>Y'<subscript>11</subscript></entry>
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+ <entry>Y'<subscript>12</subscript></entry>
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+ <entry>Y'<subscript>13</subscript></entry>
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+ </row>
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+ <row>
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+ <entry>start0 + 8:</entry>
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+ <entry>Y'<subscript>20</subscript></entry>
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+ <entry>Y'<subscript>21</subscript></entry>
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+ <entry>Y'<subscript>22</subscript></entry>
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+ <entry>Y'<subscript>23</subscript></entry>
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+ </row>
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+ <row>
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+ <entry>start0 + 12:</entry>
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+ <entry>Y'<subscript>30</subscript></entry>
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+ <entry>Y'<subscript>31</subscript></entry>
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+ <entry>Y'<subscript>32</subscript></entry>
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+ <entry>Y'<subscript>33</subscript></entry>
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+ </row>
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+ <row><entry></entry></row>
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+ <row>
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+ <entry>start1 + 0:</entry>
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+ <entry>Cb<subscript>00</subscript></entry>
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+ <entry>Cb<subscript>01</subscript></entry>
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+ </row>
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+ <row>
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+ <entry>start1 + 2:</entry>
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+ <entry>Cb<subscript>10</subscript></entry>
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+ <entry>Cb<subscript>11</subscript></entry>
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+ </row>
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+ <row><entry></entry></row>
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+ <row>
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+ <entry>start2 + 0:</entry>
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+ <entry>Cr<subscript>00</subscript></entry>
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+ <entry>Cr<subscript>01</subscript></entry>
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+ </row>
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+ <row>
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+ <entry>start2 + 2:</entry>
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+ <entry>Cr<subscript>10</subscript></entry>
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+ <entry>Cr<subscript>11</subscript></entry>
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+ </row>
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+ </tbody>
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+ </tgroup>
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+ </informaltable>
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+ </para>
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+ </formalpara>
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+
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+ <formalpara>
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+ <title>Color Sample Location.</title>
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+ <para>
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+ <informaltable frame="none">
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+ <tgroup cols="7" align="center">
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+ <tbody valign="top">
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+ <row>
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+ <entry></entry>
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+ <entry>0</entry><entry></entry><entry>1</entry><entry></entry>
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+ <entry>2</entry><entry></entry><entry>3</entry>
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+ </row>
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+ <row>
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+ <entry>0</entry>
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+ <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
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+ <entry>Y</entry><entry></entry><entry>Y</entry>
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+ </row>
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+ <row>
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+ <entry></entry>
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+ <entry></entry><entry>C</entry><entry></entry><entry></entry>
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+ <entry></entry><entry>C</entry><entry></entry>
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+ </row>
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+ <row>
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+ <entry>1</entry>
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+ <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
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+ <entry>Y</entry><entry></entry><entry>Y</entry>
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+ </row>
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+ <row>
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+ <entry></entry>
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+ </row>
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+ <row>
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+ <entry>2</entry>
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+ <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
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+ <entry>Y</entry><entry></entry><entry>Y</entry>
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+ </row>
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+ <row>
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+ <entry></entry>
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+ <entry></entry><entry>C</entry><entry></entry><entry></entry>
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+ <entry></entry><entry>C</entry><entry></entry>
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+ </row>
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+ <row>
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+ <entry>3</entry>
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+ <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
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+ <entry>Y</entry><entry></entry><entry>Y</entry>
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+ </row>
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+ </tbody>
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+ </tgroup>
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+ </informaltable>
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+ </para>
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+ </formalpara>
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+ </example>
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+ </refsect1>
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+ </refentry>
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+
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+ <!--
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+Local Variables:
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+mode: sgml
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+sgml-parent-document: "pixfmt.sgml"
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+indent-tabs-mode: nil
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+End:
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+ -->
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