Documentation/DocBook/v4l/pixfmt-m420.xml

   1     <refentry id="V4L2-PIX-FMT-M420">
   2       <refmeta>
   3         <refentrytitle>V4L2_PIX_FMT_M420 ('M420')</refentrytitle>
   4         &manvol;
   5       </refmeta>
   6       <refnamediv>
   7         <refname><constant>V4L2_PIX_FMT_M420</constant></refname>
   8         <refpurpose>Format with &frac12; horizontal and vertical chroma
   9         resolution, also known as YUV 4:2:0. Hybrid plane line-interleaved
  10         layout.</refpurpose>
  11       </refnamediv>
  12       <refsect1>
  13         <title>Description</title>
  14
  15         <para>M420 is a YUV format with &frac12; horizontal and vertical chroma
  16         subsampling (YUV 4:2:0). Pixels are organized as interleaved luma and
  17         chroma planes. Two lines of luma data are followed by one line of chroma
  18         data.</para>
  19         <para>The luma plane has one byte per pixel. The chroma plane contains
  20         interleaved CbCr pixels subsampled by &frac12; in the horizontal and
  21         vertical directions. Each CbCr pair belongs to four pixels. For example,
  22 Cb<subscript>0</subscript>/Cr<subscript>0</subscript> belongs to
  23 Y'<subscript>00</subscript>, Y'<subscript>01</subscript>,
  24 Y'<subscript>10</subscript>, Y'<subscript>11</subscript>.</para>
  25
  26         <para>All line lengths are identical: if the Y lines include pad bytes
  27         so do the CbCr lines.</para>
  28
  29         <example>
  30           <title><constant>V4L2_PIX_FMT_M420</constant> 4 &times; 4
  31 pixel image</title>
  32
  33           <formalpara>
  34             <title>Byte Order.</title>
  35             <para>Each cell is one byte.
  36                 <informaltable frame="none">
  37                 <tgroup cols="5" align="center">
  38                   <colspec align="left" colwidth="2*" />
  39                   <tbody valign="top">
  40                     <row>
  41                       <entry>start&nbsp;+&nbsp;0:</entry>
  42                       <entry>Y'<subscript>00</subscript></entry>
  43                       <entry>Y'<subscript>01</subscript></entry>
  44                       <entry>Y'<subscript>02</subscript></entry>
  45                       <entry>Y'<subscript>03</subscript></entry>
  46                     </row>
  47                     <row>
  48                       <entry>start&nbsp;+&nbsp;4:</entry>
  49                       <entry>Y'<subscript>10</subscript></entry>
  50                       <entry>Y'<subscript>11</subscript></entry>
  51                       <entry>Y'<subscript>12</subscript></entry>
  52                       <entry>Y'<subscript>13</subscript></entry>
  53                     </row>
  54                     <row>
  55                       <entry>start&nbsp;+&nbsp;8:</entry>
  56                       <entry>Cb<subscript>00</subscript></entry>
  57                       <entry>Cr<subscript>00</subscript></entry>
  58                       <entry>Cb<subscript>01</subscript></entry>
  59                       <entry>Cr<subscript>01</subscript></entry>
  60                     </row>
  61                     <row>
  62                       <entry>start&nbsp;+&nbsp;16:</entry>
  63                       <entry>Y'<subscript>20</subscript></entry>
  64                       <entry>Y'<subscript>21</subscript></entry>
  65                       <entry>Y'<subscript>22</subscript></entry>
  66                       <entry>Y'<subscript>23</subscript></entry>
  67                     </row>
  68                     <row>
  69                       <entry>start&nbsp;+&nbsp;20:</entry>
  70                       <entry>Y'<subscript>30</subscript></entry>
  71                       <entry>Y'<subscript>31</subscript></entry>
  72                       <entry>Y'<subscript>32</subscript></entry>
  73                       <entry>Y'<subscript>33</subscript></entry>
  74                     </row>
  75                     <row>
  76                       <entry>start&nbsp;+&nbsp;24:</entry>
  77                       <entry>Cb<subscript>10</subscript></entry>
  78                       <entry>Cr<subscript>10</subscript></entry>
  79                       <entry>Cb<subscript>11</subscript></entry>
  80                       <entry>Cr<subscript>11</subscript></entry>
  81                     </row>
  82                   </tbody>
  83                 </tgroup>
  84                 </informaltable>
  85               </para>
  86           </formalpara>
  87
  88           <formalpara>
  89             <title>Color Sample Location.</title>
  90             <para>
  91                 <informaltable frame="none">
  92                 <tgroup cols="7" align="center">
  93                   <tbody valign="top">
  94                     <row>
  95                       <entry></entry>
  96                       <entry>0</entry><entry></entry><entry>1</entry><entry></entry>
  97                       <entry>2</entry><entry></entry><entry>3</entry>
  98                     </row>
  99                     <row>
 100                       <entry>0</entry>
 101                       <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
 102                       <entry>Y</entry><entry></entry><entry>Y</entry>
 103                     </row>
 104                     <row>
 105                       <entry></entry>
 106                       <entry></entry><entry>C</entry><entry></entry><entry></entry>
 107                       <entry></entry><entry>C</entry><entry></entry>
 108                     </row>
 109                     <row>
 110                       <entry>1</entry>
 111                       <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
 112                       <entry>Y</entry><entry></entry><entry>Y</entry>
 113                     </row>
 114                     <row>
 115                       <entry></entry>
 116                     </row>
 117                     <row>
 118                       <entry>2</entry>
 119                       <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
 120                       <entry>Y</entry><entry></entry><entry>Y</entry>
 121                     </row>
 122                     <row>
 123                       <entry></entry>
 124                       <entry></entry><entry>C</entry><entry></entry><entry></entry>
 125                       <entry></entry><entry>C</entry><entry></entry>
 126                     </row>
 127                     <row>
 128                       <entry>3</entry>
 129                       <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
 130                       <entry>Y</entry><entry></entry><entry>Y</entry>
 131                     </row>
 132                   </tbody>
 133                 </tgroup>
 134                 </informaltable>
 135               </para>
 136           </formalpara>
 137         </example>
 138       </refsect1>
 139     </refentry>
 140
 141   <!--
 142 Local Variables:
 143 mode: sgml
 144 sgml-parent-document: "pixfmt.sgml"
 145 indent-tabs-mode: nil
 146 End:
 147   -->