Documentation/DocBook/media/v4l/pixfmt-yuv422m.xml

   1     <refentry>
   2       <refmeta>
   3         <refentrytitle>V4L2_PIX_FMT_YUV422M ('YM16'), V4L2_PIX_FMT_YVU422M ('YM61')</refentrytitle>
   4         &manvol;
   5       </refmeta>
   6       <refnamediv>
   7         <refname id="V4L2-PIX-FMT-YUV422M"><constant>V4L2_PIX_FMT_YUV422M</constant></refname>
   8         <refname id="V4L2-PIX-FMT-YVU422M"><constant>V4L2_PIX_FMT_YVU422M</constant></refname>
   9         <refpurpose>Planar formats with &frac12; horizontal resolution, also
  10         known as YUV and YVU 4:2:2</refpurpose>
  11       </refnamediv>
  12
  13       <refsect1>
  14         <title>Description</title>
  15
  16         <para>This is a multi-planar format, as opposed to a packed format.
  17 The three components are separated into three sub-images or planes.</para>
  18
  19         <para>The Y plane is first. The Y plane has one byte per pixel.
  20 For <constant>V4L2_PIX_FMT_YUV422M</constant> the Cb data
  21 constitutes the second plane which is half the width of the Y plane (and of the
  22 image). Each Cb belongs to two pixels. For example,
  23 Cb<subscript>0</subscript> belongs to Y'<subscript>00</subscript>,
  24 Y'<subscript>01</subscript>. The Cr data, just like the Cb plane, is
  25 in the third plane. </para>
  26
  27         <para><constant>V4L2_PIX_FMT_YVU422M</constant> is the same except
  28 the Cr data is stored in the second plane and the Cb data in the third plane.
  29 </para>
  30
  31         <para>If the Y plane has pad bytes after each row, then the Cb
  32 and Cr planes have half as many pad bytes after their rows. In other
  33 words, two Cx rows (including padding) is exactly as long as one Y row
  34 (including padding).</para>
  35
  36         <para><constant>V4L2_PIX_FMT_YUV422M</constant> and
  37 <constant>V4L2_PIX_FMT_YVU422M</constant> are intended to be
  38 used only in drivers and applications that support the multi-planar API,
  39 described in <xref linkend="planar-apis"/>. </para>
  40
  41         <example>
  42           <title><constant>V4L2_PIX_FMT_YUV422M</constant> 4 &times; 4
  43 pixel image</title>
  44
  45           <formalpara>
  46             <title>Byte Order.</title>
  47             <para>Each cell is one byte.
  48                 <informaltable frame="none">
  49                 <tgroup cols="5" align="center">
  50                   <colspec align="left" colwidth="2*" />
  51                   <tbody valign="top">
  52                     <row>
  53                       <entry>start0&nbsp;+&nbsp;0:</entry>
  54                       <entry>Y'<subscript>00</subscript></entry>
  55                       <entry>Y'<subscript>01</subscript></entry>
  56                       <entry>Y'<subscript>02</subscript></entry>
  57                       <entry>Y'<subscript>03</subscript></entry>
  58                     </row>
  59                     <row>
  60                       <entry>start0&nbsp;+&nbsp;4:</entry>
  61                       <entry>Y'<subscript>10</subscript></entry>
  62                       <entry>Y'<subscript>11</subscript></entry>
  63                       <entry>Y'<subscript>12</subscript></entry>
  64                       <entry>Y'<subscript>13</subscript></entry>
  65                     </row>
  66                     <row>
  67                       <entry>start0&nbsp;+&nbsp;8:</entry>
  68                       <entry>Y'<subscript>20</subscript></entry>
  69                       <entry>Y'<subscript>21</subscript></entry>
  70                       <entry>Y'<subscript>22</subscript></entry>
  71                       <entry>Y'<subscript>23</subscript></entry>
  72                     </row>
  73                     <row>
  74                       <entry>start0&nbsp;+&nbsp;12:</entry>
  75                       <entry>Y'<subscript>30</subscript></entry>
  76                       <entry>Y'<subscript>31</subscript></entry>
  77                       <entry>Y'<subscript>32</subscript></entry>
  78                       <entry>Y'<subscript>33</subscript></entry>
  79                     </row>
  80                     <row><entry></entry></row>
  81                     <row>
  82                       <entry>start1&nbsp;+&nbsp;0:</entry>
  83                       <entry>Cb<subscript>00</subscript></entry>
  84                       <entry>Cb<subscript>01</subscript></entry>
  85                     </row>
  86                     <row>
  87                       <entry>start1&nbsp;+&nbsp;2:</entry>
  88                       <entry>Cb<subscript>10</subscript></entry>
  89                       <entry>Cb<subscript>11</subscript></entry>
  90                     </row>
  91                     <row>
  92                       <entry>start1&nbsp;+&nbsp;4:</entry>
  93                       <entry>Cb<subscript>20</subscript></entry>
  94                       <entry>Cb<subscript>21</subscript></entry>
  95                     </row>
  96                     <row>
  97                       <entry>start1&nbsp;+&nbsp;6:</entry>
  98                       <entry>Cb<subscript>30</subscript></entry>
  99                       <entry>Cb<subscript>31</subscript></entry>
 100                     </row>
 101                     <row><entry></entry></row>
 102                     <row>
 103                       <entry>start2&nbsp;+&nbsp;0:</entry>
 104                       <entry>Cr<subscript>00</subscript></entry>
 105                       <entry>Cr<subscript>01</subscript></entry>
 106                     </row>
 107                     <row>
 108                       <entry>start2&nbsp;+&nbsp;2:</entry>
 109                       <entry>Cr<subscript>10</subscript></entry>
 110                       <entry>Cr<subscript>11</subscript></entry>
 111                     </row>
 112                     <row>
 113                       <entry>start2&nbsp;+&nbsp;4:</entry>
 114                       <entry>Cr<subscript>20</subscript></entry>
 115                       <entry>Cr<subscript>21</subscript></entry>
 116                     </row>
 117                     <row>
 118                       <entry>start2&nbsp;+&nbsp;6:</entry>
 119                       <entry>Cr<subscript>30</subscript></entry>
 120                       <entry>Cr<subscript>31</subscript></entry>
 121                     </row>
 122                   </tbody>
 123                 </tgroup>
 124                 </informaltable>
 125               </para>
 126           </formalpara>
 127
 128           <formalpara>
 129             <title>Color Sample Location.</title>
 130             <para>
 131                 <informaltable frame="none">
 132                 <tgroup cols="7" align="center">
 133                   <tbody valign="top">
 134                     <row>
 135                       <entry></entry>
 136                       <entry>0</entry><entry></entry><entry>1</entry><entry></entry>
 137                       <entry>2</entry><entry></entry><entry>3</entry>
 138                     </row>
 139                     <row>
 140                       <entry>0</entry>
 141                       <entry>Y</entry><entry>C</entry><entry>Y</entry><entry></entry>
 142                       <entry>Y</entry><entry>C</entry><entry>Y</entry>
 143                     </row>
 144                     <row>
 145                       <entry>1</entry>
 146                       <entry>Y</entry><entry>C</entry><entry>Y</entry><entry></entry>
 147                       <entry>Y</entry><entry>C</entry><entry>Y</entry>
 148                     </row>
 149                     <row>
 150                       <entry>2</entry>
 151                       <entry>Y</entry><entry>C</entry><entry>Y</entry><entry></entry>
 152                       <entry>Y</entry><entry>C</entry><entry>Y</entry>
 153                     </row>
 154                     <row>
 155                       <entry>3</entry>
 156                       <entry>Y</entry><entry>C</entry><entry>Y</entry><entry></entry>
 157                       <entry>Y</entry><entry>C</entry><entry>Y</entry>
 158                     </row>
 159                   </tbody>
 160                 </tgroup>
 161                 </informaltable>
 162               </para>
 163           </formalpara>
 164         </example>
 165       </refsect1>
 166     </refentry>