Documentation/DocBook/media/v4l/pixfmt-y12i.xml

   1 <refentry id="V4L2-PIX-FMT-Y12I">
   2   <refmeta>
   3     <refentrytitle>V4L2_PIX_FMT_Y12I ('Y12I')</refentrytitle>
   4     &manvol;
   5   </refmeta>
   6   <refnamediv>
   7     <refname><constant>V4L2_PIX_FMT_Y12I</constant></refname>
   8     <refpurpose>Interleaved grey-scale image, e.g. from a stereo-pair</refpurpose>
   9   </refnamediv>
  10   <refsect1>
  11     <title>Description</title>
  12
  13     <para>This is a grey-scale image with a depth of 12 bits per pixel, but with
  14 pixels from 2 sources interleaved and bit-packed. Each pixel is stored in a
  15 24-bit word in the little-endian order. On a little-endian machine these pixels
  16 can be deinterlaced using</para>
  17
  18 <para>
  19 <programlisting>
  20 __u8 *buf;
  21 left0 = 0xfff &amp; *(__u16 *)buf;
  22 right0 = *(__u16 *)(buf + 1) >> 4;
  23 </programlisting>
  24 </para>
  25
  26     <example>
  27       <title><constant>V4L2_PIX_FMT_Y12I</constant> 2 pixel data stream taking 3 bytes</title>
  28
  29       <formalpara>
  30         <title>Bit-packed representation</title>
  31         <para>pixels cross the byte boundary and have a ratio of 3 bytes for each
  32           interleaved pixel.
  33           <informaltable frame="all">
  34             <tgroup cols="3" align="center">
  35               <colspec align="left" colwidth="2*" />
  36               <tbody valign="top">
  37                 <row>
  38                   <entry>Y'<subscript>0left[7:0]</subscript></entry>
  39                   <entry>Y'<subscript>0right[3:0]</subscript>Y'<subscript>0left[11:8]</subscript></entry>
  40                   <entry>Y'<subscript>0right[11:4]</subscript></entry>
  41                 </row>
  42               </tbody>
  43             </tgroup>
  44           </informaltable>
  45         </para>
  46       </formalpara>
  47     </example>
  48   </refsect1>
  49 </refentry>