mirror of https://gitee.com/openkylin/linux.git
154 lines
5.8 KiB
XML
154 lines
5.8 KiB
XML
<refentry>
|
|
<refmeta>
|
|
<refentrytitle>V4L2_PIX_FMT_NV12M ('NM12'), V4L2_PIX_FMT_NV21M ('NM21'), V4L2_PIX_FMT_NV12MT_16X16</refentrytitle>
|
|
&manvol;
|
|
</refmeta>
|
|
<refnamediv>
|
|
<refname id="V4L2-PIX-FMT-NV12M"><constant>V4L2_PIX_FMT_NV12M</constant></refname>
|
|
<refname id="V4L2-PIX-FMT-NV21M"><constant>V4L2_PIX_FMT_NV21M</constant></refname>
|
|
<refname id="V4L2-PIX-FMT-NV12MT-16X16"><constant>V4L2_PIX_FMT_NV12MT_16X16</constant></refname>
|
|
<refpurpose>Variation of <constant>V4L2_PIX_FMT_NV12</constant> and <constant>V4L2_PIX_FMT_NV21</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>.
|
|
<constant>V4L2_PIX_FMT_NV12MT_16X16</constant> is the tiled version of
|
|
<constant>V4L2_PIX_FMT_NV12M</constant> with 16x16 macroblock tiles. Here pixels
|
|
are arranged in 16x16 2D tiles and tiles are arranged in linear order in memory.
|
|
<constant>V4L2_PIX_FMT_NV21M</constant> is the same as <constant>V4L2_PIX_FMT_NV12M</constant>
|
|
except the Cb and Cr bytes are swapped, the CrCb plane starts with a Cr byte.</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>
|