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Diffstat (limited to 'Documentation/DocBook/v4l/pixfmt-nv12m.xml')
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diff --git a/Documentation/DocBook/v4l/pixfmt-nv12m.xml b/Documentation/DocBook/v4l/pixfmt-nv12m.xml new file mode 100644 index 0000000..c9e166d --- /dev/null +++ b/Documentation/DocBook/v4l/pixfmt-nv12m.xml @@ -0,0 +1,154 @@ + <refentry id="V4L2-PIX-FMT-NV12M"> + <refmeta> + <refentrytitle>V4L2_PIX_FMT_NV12M ('NV12M')</refentrytitle> + &manvol; + </refmeta> + <refnamediv> + <refname> <constant>V4L2_PIX_FMT_NV12M</constant></refname> + <refpurpose>Variation of <constant>V4L2_PIX_FMT_NV12</constant> with planes + non contiguous in memory. </refpurpose> + </refnamediv> + <refsect1> + <title>Description</title> + + <para>This is a multi-planar, two-plane version of the YUV 4:2:0 format. +The three components are separated into two sub-images or planes. +<constant>V4L2_PIX_FMT_NV12M</constant> differs from <constant>V4L2_PIX_FMT_NV12 +</constant> in that the two planes are non-contiguous in memory, i.e. the chroma +plane do not necessarily immediately follows the luma plane. +The luminance data occupies the first plane. The Y plane has one byte per pixel. +In the second plane there is a chrominance data with alternating chroma samples. +The CbCr plane is the same width, in bytes, as the Y plane (and of the image), +but is half as tall in pixels. Each CbCr pair belongs to four pixels. For example, +Cb<subscript>0</subscript>/Cr<subscript>0</subscript> belongs to +Y'<subscript>00</subscript>, Y'<subscript>01</subscript>, +Y'<subscript>10</subscript>, Y'<subscript>11</subscript>. </para> + + <para><constant>V4L2_PIX_FMT_NV12M</constant> is intended to be +used only in drivers and applications that support the multi-planar API, +described in <xref linkend="planar-apis"/>. </para> + + <para>If the Y plane has pad bytes after each row, then the +CbCr plane has as many pad bytes after its rows.</para> + + <example> + <title><constant>V4L2_PIX_FMT_NV12M</constant> 4 × 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>start0 + 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>start0 + 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>start0 + 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>start0 + 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></entry> + </row> + <row> + <entry>start1 + 0:</entry> + <entry>Cb<subscript>00</subscript></entry> + <entry>Cr<subscript>00</subscript></entry> + <entry>Cb<subscript>01</subscript></entry> + <entry>Cr<subscript>01</subscript></entry> + </row> + <row> + <entry>start1 + 4:</entry> + <entry>Cb<subscript>10</subscript></entry> + <entry>Cr<subscript>10</subscript></entry> + <entry>Cb<subscript>11</subscript></entry> + <entry>Cr<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> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "pixfmt.sgml" +indent-tabs-mode: nil +End: + --> |