Documentation/DocBook/v4l/vidioc-enuminput.xml

   1 <refentry id="vidioc-enuminput">
   2   <refmeta>
   3     <refentrytitle>ioctl VIDIOC_ENUMINPUT</refentrytitle>
   4     &manvol;
   5   </refmeta>
   6
   7   <refnamediv>
   8     <refname>VIDIOC_ENUMINPUT</refname>
   9     <refpurpose>Enumerate video inputs</refpurpose>
  10   </refnamediv>
  11
  12   <refsynopsisdiv>
  13     <funcsynopsis>
  14       <funcprototype>
  15         <funcdef>int <function>ioctl</function></funcdef>
  16         <paramdef>int <parameter>fd</parameter></paramdef>
  17         <paramdef>int <parameter>request</parameter></paramdef>
  18         <paramdef>struct v4l2_input
  19 *<parameter>argp</parameter></paramdef>
  20       </funcprototype>
  21     </funcsynopsis>
  22   </refsynopsisdiv>
  23
  24   <refsect1>
  25     <title>Arguments</title>
  26
  27     <variablelist>
  28       <varlistentry>
  29         <term><parameter>fd</parameter></term>
  30         <listitem>
  31           <para>&fd;</para>
  32         </listitem>
  33       </varlistentry>
  34       <varlistentry>
  35         <term><parameter>request</parameter></term>
  36         <listitem>
  37           <para>VIDIOC_ENUMINPUT</para>
  38         </listitem>
  39       </varlistentry>
  40       <varlistentry>
  41         <term><parameter>argp</parameter></term>
  42         <listitem>
  43           <para></para>
  44         </listitem>
  45       </varlistentry>
  46     </variablelist>
  47   </refsect1>
  48
  49   <refsect1>
  50     <title>Description</title>
  51
  52     <para>To query the attributes of a video input applications
  53 initialize the <structfield>index</structfield> field of &v4l2-input;
  54 and call the <constant>VIDIOC_ENUMINPUT</constant> ioctl with a
  55 pointer to this structure. Drivers fill the rest of the structure or
  56 return an &EINVAL; when the index is out of bounds. To enumerate all
  57 inputs applications shall begin at index zero, incrementing by one
  58 until the driver returns <errorcode>EINVAL</errorcode>.</para>
  59
  60     <table frame="none" pgwide="1" id="v4l2-input">
  61       <title>struct <structname>v4l2_input</structname></title>
  62       <tgroup cols="3">
  63         &cs-str;
  64         <tbody valign="top">
  65           <row>
  66             <entry>__u32</entry>
  67             <entry><structfield>index</structfield></entry>
  68             <entry>Identifies the input, set by the
  69 application.</entry>
  70           </row>
  71           <row>
  72             <entry>__u8</entry>
  73             <entry><structfield>name</structfield>[32]</entry>
  74             <entry>Name of the video input, a NUL-terminated ASCII
  75 string, for example: "Vin (Composite 2)". This information is intended
  76 for the user, preferably the connector label on the device itself.</entry>
  77           </row>
  78           <row>
  79             <entry>__u32</entry>
  80             <entry><structfield>type</structfield></entry>
  81             <entry>Type of the input, see <xref
  82                 linkend="input-type" />.</entry>
  83           </row>
  84           <row>
  85             <entry>__u32</entry>
  86             <entry><structfield>audioset</structfield></entry>
  87             <entry><para>Drivers can enumerate up to 32 video and
  88 audio inputs. This field shows which audio inputs were selectable as
  89 audio source if this was the currently selected video input. It is a
  90 bit mask. The LSB corresponds to audio input 0, the MSB to input 31.
  91 Any number of bits can be set, or none.</para><para>When the driver
  92 does not enumerate audio inputs no bits must be set. Applications
  93 shall not interpret this as lack of audio support. Some drivers
  94 automatically select audio sources and do not enumerate them since
  95 there is no choice anyway.</para><para>For details on audio inputs and
  96 how to select the current input see <xref
  97                   linkend="audio" />.</para></entry>
  98           </row>
  99           <row>
 100             <entry>__u32</entry>
 101             <entry><structfield>tuner</structfield></entry>
 102             <entry>Capture devices can have zero or more tuners (RF
 103 demodulators). When the <structfield>type</structfield> is set to
 104 <constant>V4L2_INPUT_TYPE_TUNER</constant> this is an RF connector and
 105 this field identifies the tuner. It corresponds to
 106 &v4l2-tuner; field <structfield>index</structfield>. For details on
 107 tuners see <xref linkend="tuner" />.</entry>
 108           </row>
 109           <row>
 110             <entry>&v4l2-std-id;</entry>
 111             <entry><structfield>std</structfield></entry>
 112             <entry>Every video input supports one or more different
 113 video standards. This field is a set of all supported standards. For
 114 details on video standards and how to switch see <xref
 115 linkend="standard" />.</entry>
 116           </row>
 117           <row>
 118             <entry>__u32</entry>
 119             <entry><structfield>status</structfield></entry>
 120             <entry>This field provides status information about the
 121 input. See <xref linkend="input-status" /> for flags.
 122 With the exception of the sensor orientation bits <structfield>status</structfield> is only valid when this is the
 123 current input.</entry>
 124           </row>
 125           <row>
 126             <entry>__u32</entry>
 127             <entry><structfield>capabilities</structfield></entry>
 128             <entry>This field provides capabilities for the
 129 input. See <xref linkend="input-capabilities" /> for flags.</entry>
 130           </row>
 131           <row>
 132             <entry>__u32</entry>
 133             <entry><structfield>reserved</structfield>[3]</entry>
 134             <entry>Reserved for future extensions. Drivers must set
 135 the array to zero.</entry>
 136           </row>
 137         </tbody>
 138       </tgroup>
 139     </table>
 140
 141     <table frame="none" pgwide="1" id="input-type">
 142       <title>Input Types</title>
 143       <tgroup cols="3">
 144         &cs-def;
 145         <tbody valign="top">
 146           <row>
 147             <entry><constant>V4L2_INPUT_TYPE_TUNER</constant></entry>
 148             <entry>1</entry>
 149             <entry>This input uses a tuner (RF demodulator).</entry>
 150           </row>
 151           <row>
 152             <entry><constant>V4L2_INPUT_TYPE_CAMERA</constant></entry>
 153             <entry>2</entry>
 154             <entry>Analog baseband input, for example CVBS /
 155 Composite Video, S-Video, RGB.</entry>
 156           </row>
 157         </tbody>
 158       </tgroup>
 159     </table>
 160
 161     <!-- Status flags based on proposal by Mark McClelland,
 162 video4linux-list@redhat.com on 18 Oct 2002, subject "Re: [V4L] Re:
 163 v4l2 api". "Why are some of them inverted? So that the driver doesn't
 164 have to lie about the status in cases where it can't tell one way or
 165 the other. Plus, a status of zero would generally mean that everything
 166 is OK." -->
 167
 168     <table frame="none" pgwide="1" id="input-status">
 169       <title>Input Status Flags</title>
 170       <tgroup cols="3">
 171         <colspec colname="c1" />
 172         <colspec colname="c2" align="center" />
 173         <colspec colname="c3" />
 174         <spanspec namest="c1" nameend="c3" spanname="hspan"
 175           align="left" />
 176         <tbody valign="top">
 177           <row>
 178             <entry spanname="hspan">General</entry>
 179           </row>
 180           <row>
 181             <entry><constant>V4L2_IN_ST_NO_POWER</constant></entry>
 182             <entry>0x00000001</entry>
 183             <entry>Attached device is off.</entry>
 184           </row>
 185           <row>
 186             <entry><constant>V4L2_IN_ST_NO_SIGNAL</constant></entry>
 187             <entry>0x00000002</entry>
 188             <entry></entry>
 189           </row>
 190           <row>
 191             <entry><constant>V4L2_IN_ST_NO_COLOR</constant></entry>
 192             <entry>0x00000004</entry>
 193             <entry>The hardware supports color decoding, but does not
 194 detect color modulation in the signal.</entry>
 195           </row>
 196           <row>
 197             <entry spanname="hspan">Sensor Orientation</entry>
 198           </row>
 199           <row>
 200             <entry><constant>V4L2_IN_ST_HFLIP</constant></entry>
 201             <entry>0x00000010</entry>
 202             <entry>The input is connected to a device that produces a signal
 203 that is flipped horizontally and does not correct this before passing the
 204 signal to userspace.</entry>
 205           </row>
 206           <row>
 207             <entry><constant>V4L2_IN_ST_VFLIP</constant></entry>
 208             <entry>0x00000020</entry>
 209             <entry>The input is connected to a device that produces a signal
 210 that is flipped vertically and does not correct this before passing the
 211 signal to userspace. Note that a 180 degree rotation is the same as HFLIP | VFLIP</entry>
 212           </row>
 213           <row>
 214             <entry spanname="hspan">Analog Video</entry>
 215           </row>
 216           <row>
 217             <entry><constant>V4L2_IN_ST_NO_H_LOCK</constant></entry>
 218             <entry>0x00000100</entry>
 219             <entry>No horizontal sync lock.</entry>
 220           </row>
 221           <row>
 222             <entry><constant>V4L2_IN_ST_COLOR_KILL</constant></entry>
 223             <entry>0x00000200</entry>
 224             <entry>A color killer circuit automatically disables color
 225 decoding when it detects no color modulation. When this flag is set
 226 the color killer is enabled <emphasis>and</emphasis> has shut off
 227 color decoding.</entry>
 228           </row>
 229           <row>
 230             <entry spanname="hspan">Digital Video</entry>
 231           </row>
 232           <row>
 233             <entry><constant>V4L2_IN_ST_NO_SYNC</constant></entry>
 234             <entry>0x00010000</entry>
 235             <entry>No synchronization lock.</entry>
 236           </row>
 237           <row>
 238             <entry><constant>V4L2_IN_ST_NO_EQU</constant></entry>
 239             <entry>0x00020000</entry>
 240             <entry>No equalizer lock.</entry>
 241           </row>
 242           <row>
 243             <entry><constant>V4L2_IN_ST_NO_CARRIER</constant></entry>
 244             <entry>0x00040000</entry>
 245             <entry>Carrier recovery failed.</entry>
 246           </row>
 247           <row>
 248             <entry spanname="hspan">VCR and Set-Top Box</entry>
 249           </row>
 250           <row>
 251             <entry><constant>V4L2_IN_ST_MACROVISION</constant></entry>
 252             <entry>0x01000000</entry>
 253             <entry>Macrovision is an analog copy prevention system
 254 mangling the video signal to confuse video recorders. When this
 255 flag is set Macrovision has been detected.</entry>
 256           </row>
 257           <row>
 258             <entry><constant>V4L2_IN_ST_NO_ACCESS</constant></entry>
 259             <entry>0x02000000</entry>
 260             <entry>Conditional access denied.</entry>
 261           </row>
 262           <row>
 263             <entry><constant>V4L2_IN_ST_VTR</constant></entry>
 264             <entry>0x04000000</entry>
 265             <entry>VTR time constant. [?]</entry>
 266           </row>
 267         </tbody>
 268       </tgroup>
 269     </table>
 270
 271     <!-- Capability flags based on video timings RFC by Muralidharan
 272 Karicheri, titled RFC (v1.2): V4L - Support for video timings at the
 273 input/output interface to linux-media@vger.kernel.org on 19 Oct 2009.
 274         -->
 275     <table frame="none" pgwide="1" id="input-capabilities">
 276       <title>Input capabilities</title>
 277       <tgroup cols="3">
 278         &cs-def;
 279         <tbody valign="top">
 280           <row>
 281             <entry><constant>V4L2_IN_CAP_PRESETS</constant></entry>
 282             <entry>0x00000001</entry>
 283             <entry>This input supports setting DV presets by using VIDIOC_S_DV_PRESET.</entry>
 284           </row>
 285           <row>
 286             <entry><constant>V4L2_OUT_CAP_CUSTOM_TIMINGS</constant></entry>
 287             <entry>0x00000002</entry>
 288             <entry>This input supports setting custom video timings by using VIDIOC_S_DV_TIMINGS.</entry>
 289           </row>
 290           <row>
 291             <entry><constant>V4L2_IN_CAP_STD</constant></entry>
 292             <entry>0x00000004</entry>
 293             <entry>This input supports setting the TV standard by using VIDIOC_S_STD.</entry>
 294           </row>
 295         </tbody>
 296       </tgroup>
 297     </table>
 298   </refsect1>
 299
 300   <refsect1>
 301     &return-value;
 302
 303     <variablelist>
 304       <varlistentry>
 305         <term><errorcode>EINVAL</errorcode></term>
 306         <listitem>
 307           <para>The &v4l2-input; <structfield>index</structfield> is
 308 out of bounds.</para>
 309         </listitem>
 310       </varlistentry>
 311     </variablelist>
 312   </refsect1>
 313 </refentry>
 314
 315 <!--
 316 Local Variables:
 317 mode: sgml
 318 sgml-parent-document: "v4l2.sgml"
 319 indent-tabs-mode: nil
 320 End:
 321 -->