mirror of https://gitee.com/openkylin/linux.git
152 lines
5.1 KiB
XML
152 lines
5.1 KiB
XML
<refentry>
|
|
<refmeta>
|
|
<refentrytitle>V4L2_PIX_FMT_NV12 ('NV12'), V4L2_PIX_FMT_NV21 ('NV21')</refentrytitle>
|
|
&manvol;
|
|
</refmeta>
|
|
<refnamediv>
|
|
<refname id="V4L2-PIX-FMT-NV12"><constant>V4L2_PIX_FMT_NV12</constant></refname>
|
|
<refname id="V4L2-PIX-FMT-NV21"><constant>V4L2_PIX_FMT_NV21</constant></refname>
|
|
<refpurpose>Formats with ½ horizontal and vertical
|
|
chroma resolution, also known as YUV 4:2:0. One luminance and one
|
|
chrominance plane with alternating chroma samples as opposed to
|
|
<constant>V4L2_PIX_FMT_YVU420</constant></refpurpose>
|
|
</refnamediv>
|
|
<refsect1>
|
|
<title>Description</title>
|
|
|
|
<para>These are two-plane versions of the YUV 4:2:0 format.
|
|
The three components are separated into two sub-images or planes. The
|
|
Y plane is first. The Y plane has one byte per pixel. For
|
|
<constant>V4L2_PIX_FMT_NV12</constant>, a combined CbCr plane
|
|
immediately follows the Y plane in memory. 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>.
|
|
<constant>V4L2_PIX_FMT_NV21</constant> is the same except the Cb and
|
|
Cr bytes are swapped, the CrCb plane starts with a Cr byte.</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_NV12</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>start + 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 + 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 + 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 + 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 + 16:</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>start + 20:</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:
|
|
-->
|