Documentation/DocBook/media/v4l/selections-common.xml

   1 <section id="v4l2-selections-common">
   2
   3   <title>Common selection definitions</title>
   4
   5   <para>While the <link linkend="selection-api">V4L2 selection
   6   API</link> and <link linkend="v4l2-subdev-selections">V4L2 subdev
   7   selection APIs</link> are very similar, there's one fundamental
   8   difference between the two. On sub-device API, the selection
   9   rectangle refers to the media bus format, and is bound to a
  10   sub-device's pad. On the V4L2 interface the selection rectangles
  11   refer to the in-memory pixel format.</para>
  12
  13   <para>This section defines the common definitions of the
  14   selection interfaces on the two APIs.</para>
  15
  16   <section id="v4l2-selection-targets">
  17
  18     <title>Selection targets</title>
  19
  20     <para>The precise meaning of the selection targets may be
  21     dependent on which of the two interfaces they are used.</para>
  22
  23     <table pgwide="1" frame="none" id="v4l2-selection-targets-table">
  24     <title>Selection target definitions</title>
  25       <tgroup cols="5">
  26         <colspec colname="c1" />
  27         <colspec colname="c2" />
  28         <colspec colname="c3" />
  29         <colspec colname="c4" />
  30         <colspec colname="c5" />
  31         &cs-def;
  32         <thead>
  33           <row rowsep="1">
  34             <entry align="left">Target name</entry>
  35             <entry align="left">id</entry>
  36             <entry align="left">Definition</entry>
  37             <entry align="left">Valid for V4L2</entry>
  38             <entry align="left">Valid for V4L2 subdev</entry>
  39           </row>
  40         </thead>
  41         <tbody valign="top">
  42           <row>
  43             <entry><constant>V4L2_SEL_TGT_CROP</constant></entry>
  44             <entry>0x0000</entry>
  45             <entry>Crop rectangle. Defines the cropped area.</entry>
  46             <entry>Yes</entry>
  47             <entry>Yes</entry>
  48           </row>
  49           <row>
  50             <entry><constant>V4L2_SEL_TGT_CROP_DEFAULT</constant></entry>
  51             <entry>0x0001</entry>
  52             <entry>Suggested cropping rectangle that covers the "whole picture".</entry>
  53             <entry>Yes</entry>
  54             <entry>No</entry>
  55           </row>
  56           <row>
  57             <entry><constant>V4L2_SEL_TGT_CROP_BOUNDS</constant></entry>
  58             <entry>0x0002</entry>
  59             <entry>Bounds of the crop rectangle. All valid crop
  60             rectangles fit inside the crop bounds rectangle.
  61             </entry>
  62             <entry>Yes</entry>
  63             <entry>Yes</entry>
  64           </row>
  65           <row>
  66             <entry><constant>V4L2_SEL_TGT_NATIVE_SIZE</constant></entry>
  67             <entry>0x0003</entry>
  68             <entry>The native size of the device, e.g. a sensor's
  69             pixel array. <structfield>left</structfield> and
  70             <structfield>top</structfield> fields are zero for this
  71             target. Setting the native size will generally only make
  72             sense for memory to memory devices where the software can
  73             create a canvas of a given size in which for example a
  74             video frame can be composed. In that case
  75             V4L2_SEL_TGT_NATIVE_SIZE can be used to configure the size
  76             of that canvas.
  77             </entry>
  78             <entry>Yes</entry>
  79             <entry>Yes</entry>
  80           </row>
  81           <row>
  82             <entry><constant>V4L2_SEL_TGT_COMPOSE</constant></entry>
  83             <entry>0x0100</entry>
  84             <entry>Compose rectangle. Used to configure scaling
  85             and composition.</entry>
  86             <entry>Yes</entry>
  87             <entry>Yes</entry>
  88           </row>
  89           <row>
  90             <entry><constant>V4L2_SEL_TGT_COMPOSE_DEFAULT</constant></entry>
  91             <entry>0x0101</entry>
  92             <entry>Suggested composition rectangle that covers the "whole picture".</entry>
  93             <entry>Yes</entry>
  94             <entry>No</entry>
  95           </row>
  96           <row>
  97             <entry><constant>V4L2_SEL_TGT_COMPOSE_BOUNDS</constant></entry>
  98             <entry>0x0102</entry>
  99             <entry>Bounds of the compose rectangle. All valid compose
 100             rectangles fit inside the compose bounds rectangle.</entry>
 101             <entry>Yes</entry>
 102             <entry>Yes</entry>
 103           </row>
 104           <row>
 105             <entry><constant>V4L2_SEL_TGT_COMPOSE_PADDED</constant></entry>
 106             <entry>0x0103</entry>
 107             <entry>The active area and all padding pixels that are inserted or
 108             modified by hardware.</entry>
 109             <entry>Yes</entry>
 110             <entry>No</entry>
 111           </row>
 112         </tbody>
 113       </tgroup>
 114     </table>
 115
 116   </section>
 117
 118   <section id="v4l2-selection-flags">
 119
 120     <title>Selection flags</title>
 121
 122     <table pgwide="1" frame="none" id="v4l2-selection-flags-table">
 123     <title>Selection flag definitions</title>
 124       <tgroup cols="5">
 125         <colspec colname="c1" />
 126         <colspec colname="c2" />
 127         <colspec colname="c3" />
 128         <colspec colname="c4" />
 129         <colspec colname="c5" />
 130         &cs-def;
 131         <thead>
 132         <row rowsep="1">
 133             <entry align="left">Flag name</entry>
 134             <entry align="left">id</entry>
 135             <entry align="left">Definition</entry>
 136             <entry align="left">Valid for V4L2</entry>
 137             <entry align="left">Valid for V4L2 subdev</entry>
 138         </row>
 139         </thead>
 140         <tbody valign="top">
 141           <row>
 142             <entry><constant>V4L2_SEL_FLAG_GE</constant></entry>
 143             <entry>(1 &lt;&lt; 0)</entry>
 144             <entry>Suggest the driver it should choose greater or
 145             equal rectangle (in size) than was requested. Albeit the
 146             driver may choose a lesser size, it will only do so due to
 147             hardware limitations. Without this flag (and
 148             <constant>V4L2_SEL_FLAG_LE</constant>) the
 149             behaviour is to choose the closest possible
 150             rectangle.</entry>
 151             <entry>Yes</entry>
 152             <entry>Yes</entry>
 153           </row>
 154           <row>
 155             <entry><constant>V4L2_SEL_FLAG_LE</constant></entry>
 156             <entry>(1 &lt;&lt; 1)</entry>
 157             <entry>Suggest the driver it
 158             should choose lesser or equal rectangle (in size) than was
 159             requested. Albeit the driver may choose a greater size, it
 160             will only do so due to hardware limitations.</entry>
 161             <entry>Yes</entry>
 162             <entry>Yes</entry>
 163           </row>
 164           <row>
 165             <entry><constant>V4L2_SEL_FLAG_KEEP_CONFIG</constant></entry>
 166             <entry>(1 &lt;&lt; 2)</entry>
 167             <entry>The configuration must not be propagated to any
 168             further processing steps. If this flag is not given, the
 169             configuration is propagated inside the subdevice to all
 170             further processing steps.</entry>
 171             <entry>No</entry>
 172             <entry>Yes</entry>
 173           </row>
 174         </tbody>
 175       </tgroup>
 176     </table>
 177
 178   </section>
 179
 180 </section>