Pileus Git - ~andy/linux/blob - Documentation/DocBook/media/v4l/vidioc-g-tuner.xml

   1 <refentry id="vidioc-g-tuner">
   2   <refmeta>
   3     <refentrytitle>ioctl VIDIOC_G_TUNER, VIDIOC_S_TUNER</refentrytitle>
   4     &manvol;
   5   </refmeta>
   6
   7   <refnamediv>
   8     <refname>VIDIOC_G_TUNER</refname>
   9     <refname>VIDIOC_S_TUNER</refname>
  10     <refpurpose>Get or set tuner attributes</refpurpose>
  11   </refnamediv>
  12
  13   <refsynopsisdiv>
  14     <funcsynopsis>
  15       <funcprototype>
  16         <funcdef>int <function>ioctl</function></funcdef>
  17         <paramdef>int <parameter>fd</parameter></paramdef>
  18         <paramdef>int <parameter>request</parameter></paramdef>
  19         <paramdef>struct v4l2_tuner
  20 *<parameter>argp</parameter></paramdef>
  21       </funcprototype>
  22     </funcsynopsis>
  23     <funcsynopsis>
  24       <funcprototype>
  25         <funcdef>int <function>ioctl</function></funcdef>
  26         <paramdef>int <parameter>fd</parameter></paramdef>
  27         <paramdef>int <parameter>request</parameter></paramdef>
  28         <paramdef>const struct v4l2_tuner
  29 *<parameter>argp</parameter></paramdef>
  30       </funcprototype>
  31     </funcsynopsis>
  32   </refsynopsisdiv>
  33
  34   <refsect1>
  35     <title>Arguments</title>
  36
  37     <variablelist>
  38       <varlistentry>
  39         <term><parameter>fd</parameter></term>
  40         <listitem>
  41           <para>&fd;</para>
  42         </listitem>
  43       </varlistentry>
  44       <varlistentry>
  45         <term><parameter>request</parameter></term>
  46         <listitem>
  47           <para>VIDIOC_G_TUNER, VIDIOC_S_TUNER</para>
  48         </listitem>
  49       </varlistentry>
  50       <varlistentry>
  51         <term><parameter>argp</parameter></term>
  52         <listitem>
  53           <para></para>
  54         </listitem>
  55       </varlistentry>
  56     </variablelist>
  57   </refsect1>
  58
  59   <refsect1>
  60     <title>Description</title>
  61
  62     <para>To query the attributes of a tuner applications initialize the
  63 <structfield>index</structfield> field and zero out the
  64 <structfield>reserved</structfield> array of a &v4l2-tuner; and call the
  65 <constant>VIDIOC_G_TUNER</constant> ioctl with a pointer to this
  66 structure. Drivers fill the rest of the structure or return an
  67 &EINVAL; when the index is out of bounds. To enumerate all tuners
  68 applications shall begin at index zero, incrementing by one until the
  69 driver returns <errorcode>EINVAL</errorcode>.</para>
  70
  71     <para>Tuners have two writable properties, the audio mode and
  72 the radio frequency. To change the audio mode, applications initialize
  73 the <structfield>index</structfield>,
  74 <structfield>audmode</structfield> and
  75 <structfield>reserved</structfield> fields and call the
  76 <constant>VIDIOC_S_TUNER</constant> ioctl. This will
  77 <emphasis>not</emphasis> change the current tuner, which is determined
  78 by the current video input. Drivers may choose a different audio mode
  79 if the requested mode is invalid or unsupported. Since this is a
  80 <!-- FIXME -->write-only ioctl, it does not return the actually
  81 selected audio mode.</para>
  82
  83     <para>To change the radio frequency the &VIDIOC-S-FREQUENCY; ioctl
  84 is available.</para>
  85
  86     <table pgwide="1" frame="none" id="v4l2-tuner">
  87       <title>struct <structname>v4l2_tuner</structname></title>
  88       <tgroup cols="3">
  89         <colspec colname="c1" colwidth="1*" />
  90         <colspec colname="c2" colwidth="1*" />
  91         <colspec colname="c3" colwidth="1*" />
  92         <colspec colname="c4" colwidth="1*" />
  93         <spanspec spanname="hspan" namest="c3" nameend="c4" />
  94         <tbody valign="top">
  95           <row>
  96             <entry>__u32</entry>
  97             <entry><structfield>index</structfield></entry>
  98             <entry spanname="hspan">Identifies the tuner, set by the
  99 application.</entry>
 100           </row>
 101           <row>
 102             <entry>__u8</entry>
 103             <entry><structfield>name</structfield>[32]</entry>
 104             <entry spanname="hspan"><para>Name of the tuner, a
 105 NUL-terminated ASCII string. This information is intended for the
 106 user.<!-- FIXME Video inputs already have a name, the purpose of this
 107 field is not quite clear.--></para></entry>
 108           </row>
 109           <row>
 110             <entry>__u32</entry>
 111             <entry><structfield>type</structfield></entry>
 112             <entry spanname="hspan">Type of the tuner, see <xref
 113                 linkend="v4l2-tuner-type" />.</entry>
 114           </row>
 115           <row>
 116             <entry>__u32</entry>
 117             <entry><structfield>capability</structfield></entry>
 118             <entry spanname="hspan"><para>Tuner capability flags, see
 119 <xref linkend="tuner-capability" />. Audio flags indicate the ability
 120 to decode audio subprograms. They will <emphasis>not</emphasis>
 121 change, for example with the current video standard.</para><para>When
 122 the structure refers to a radio tuner the
 123 <constant>V4L2_TUNER_CAP_LANG1</constant>,
 124 <constant>V4L2_TUNER_CAP_LANG2</constant> and
 125 <constant>V4L2_TUNER_CAP_NORM</constant> flags can't be used.</para>
 126 <para>If multiple frequency bands are supported, then
 127 <structfield>capability</structfield> is the union of all
 128 <structfield>capability</structfield> fields of each &v4l2-frequency-band;.
 129 </para></entry>
 130           </row>
 131           <row>
 132             <entry>__u32</entry>
 133             <entry><structfield>rangelow</structfield></entry>
 134             <entry spanname="hspan">The lowest tunable frequency in
 135 units of 62.5 kHz, or if the <structfield>capability</structfield>
 136 flag <constant>V4L2_TUNER_CAP_LOW</constant> is set, in units of 62.5
 137 Hz. If multiple frequency bands are supported, then
 138 <structfield>rangelow</structfield> is the lowest frequency
 139 of all the frequency bands.</entry>
 140           </row>
 141           <row>
 142             <entry>__u32</entry>
 143             <entry><structfield>rangehigh</structfield></entry>
 144             <entry spanname="hspan">The highest tunable frequency in
 145 units of 62.5 kHz, or if the <structfield>capability</structfield>
 146 flag <constant>V4L2_TUNER_CAP_LOW</constant> is set, in units of 62.5
 147 Hz. If multiple frequency bands are supported, then
 148 <structfield>rangehigh</structfield> is the highest frequency
 149 of all the frequency bands.</entry>
 150           </row>
 151           <row>
 152             <entry>__u32</entry>
 153             <entry><structfield>rxsubchans</structfield></entry>
 154             <entry spanname="hspan"><para>Some tuners or audio
 155 decoders can determine the received audio subprograms by analyzing
 156 audio carriers, pilot tones or other indicators. To pass this
 157 information drivers set flags defined in <xref
 158                   linkend="tuner-rxsubchans" /> in this field. For
 159 example:</para></entry>
 160           </row>
 161           <row>
 162             <entry></entry>
 163             <entry></entry>
 164             <entry><constant>V4L2_TUNER_SUB_MONO</constant></entry>
 165             <entry>receiving mono audio</entry>
 166           </row>
 167           <row>
 168             <entry></entry>
 169             <entry></entry>
 170             <entry><constant>STEREO | SAP</constant></entry>
 171             <entry>receiving stereo audio and a secondary audio
 172 program</entry>
 173           </row>
 174           <row>
 175             <entry></entry>
 176             <entry></entry>
 177             <entry><constant>MONO | STEREO</constant></entry>
 178             <entry>receiving mono or stereo audio, the hardware cannot
 179 distinguish</entry>
 180           </row>
 181           <row>
 182             <entry></entry>
 183             <entry></entry>
 184             <entry><constant>LANG1 | LANG2</constant></entry>
 185             <entry>receiving bilingual audio</entry>
 186           </row>
 187           <row>
 188             <entry></entry>
 189             <entry></entry>
 190             <entry><constant>MONO | STEREO | LANG1 | LANG2</constant></entry>
 191             <entry>receiving mono, stereo or bilingual
 192 audio</entry>
 193           </row>
 194           <row>
 195             <entry></entry>
 196             <entry></entry>
 197             <entry spanname="hspan"><para>When the
 198 <constant>V4L2_TUNER_CAP_STEREO</constant>,
 199 <constant>_LANG1</constant>, <constant>_LANG2</constant> or
 200 <constant>_SAP</constant> flag is cleared in the
 201 <structfield>capability</structfield> field, the corresponding
 202 <constant>V4L2_TUNER_SUB_</constant> flag must not be set
 203 here.</para><para>This field is valid only if this is the tuner of the
 204 current video input, or when the structure refers to a radio
 205 tuner.</para></entry>
 206           </row>
 207           <row>
 208             <entry>__u32</entry>
 209             <entry><structfield>audmode</structfield></entry>
 210             <entry spanname="hspan"><para>The selected audio mode, see
 211 <xref linkend="tuner-audmode" /> for valid values. The audio mode does
 212 not affect audio subprogram detection, and like a <link
 213 linkend="control">control</link> it does not automatically change
 214 unless the requested mode is invalid or unsupported. See <xref
 215                   linkend="tuner-matrix" /> for possible results when
 216 the selected and received audio programs do not
 217 match.</para><para>Currently this is the only field of struct
 218 <structname>v4l2_tuner</structname> applications can
 219 change.</para></entry>
 220           </row>
 221           <row>
 222             <entry>__u32</entry>
 223             <entry><structfield>signal</structfield></entry>
 224             <entry spanname="hspan">The signal strength if known, ranging
 225 from 0 to 65535. Higher values indicate a better signal.</entry>
 226           </row>
 227           <row>
 228             <entry>__s32</entry>
 229             <entry><structfield>afc</structfield></entry>
 230             <entry spanname="hspan">Automatic frequency control: When the
 231 <structfield>afc</structfield> value is negative, the frequency is too
 232 low, when positive too high.<!-- FIXME need example what to do when it never
 233 settles at zero, &ie; range is what? --></entry>
 234           </row>
 235           <row>
 236             <entry>__u32</entry>
 237             <entry><structfield>reserved</structfield>[4]</entry>
 238             <entry spanname="hspan">Reserved for future extensions. Drivers and
 239 applications must set the array to zero.</entry>
 240           </row>
 241         </tbody>
 242       </tgroup>
 243     </table>
 244
 245     <table pgwide="1" frame="none" id="v4l2-tuner-type">
 246       <title>enum v4l2_tuner_type</title>
 247       <tgroup cols="3">
 248         &cs-def;
 249         <tbody valign="top">
 250           <row>
 251             <entry><constant>V4L2_TUNER_RADIO</constant></entry>
 252             <entry>1</entry>
 253             <entry></entry>
 254           </row>
 255           <row>
 256             <entry><constant>V4L2_TUNER_ANALOG_TV</constant></entry>
 257             <entry>2</entry>
 258             <entry></entry>
 259           </row>
 260         </tbody>
 261       </tgroup>
 262     </table>
 263
 264     <table pgwide="1" frame="none" id="tuner-capability">
 265       <title>Tuner and Modulator Capability Flags</title>
 266       <tgroup cols="3">
 267         &cs-def;
 268         <tbody valign="top">
 269           <row>
 270             <entry><constant>V4L2_TUNER_CAP_LOW</constant></entry>
 271             <entry>0x0001</entry>
 272             <entry>When set, tuning frequencies are expressed in units of
 273 62.5&nbsp;Hz, otherwise in units of 62.5&nbsp;kHz.</entry>
 274           </row>
 275           <row>
 276             <entry><constant>V4L2_TUNER_CAP_NORM</constant></entry>
 277             <entry>0x0002</entry>
 278             <entry>This is a multi-standard tuner; the video standard
 279 can or must be switched. (B/G PAL tuners for example are typically not
 280       considered multi-standard because the video standard is automatically
 281       determined from the frequency band.) The set of supported video
 282       standards is available from the &v4l2-input; pointing to this tuner,
 283       see the description of ioctl &VIDIOC-ENUMINPUT; for details. Only
 284       <constant>V4L2_TUNER_ANALOG_TV</constant> tuners can have this capability.</entry>
 285           </row>
 286           <row>
 287             <entry><constant>V4L2_TUNER_CAP_HWSEEK_BOUNDED</constant></entry>
 288             <entry>0x0004</entry>
 289             <entry>If set, then this tuner supports the hardware seek functionality
 290             where the seek stops when it reaches the end of the frequency range.</entry>
 291           </row>
 292           <row>
 293             <entry><constant>V4L2_TUNER_CAP_HWSEEK_WRAP</constant></entry>
 294             <entry>0x0008</entry>
 295             <entry>If set, then this tuner supports the hardware seek functionality
 296             where the seek wraps around when it reaches the end of the frequency range.</entry>
 297           </row>
 298           <row>
 299         <entry><constant>V4L2_TUNER_CAP_STEREO</constant></entry>
 300         <entry>0x0010</entry>
 301         <entry>Stereo audio reception is supported.</entry>
 302           </row>
 303           <row>
 304             <entry><constant>V4L2_TUNER_CAP_LANG1</constant></entry>
 305             <entry>0x0040</entry>
 306             <entry>Reception of the primary language of a bilingual
 307 audio program is supported. Bilingual audio is a feature of
 308 two-channel systems, transmitting the primary language monaural on the
 309 main audio carrier and a secondary language monaural on a second
 310 carrier. Only
 311       <constant>V4L2_TUNER_ANALOG_TV</constant> tuners can have this capability.</entry>
 312           </row>
 313           <row>
 314             <entry><constant>V4L2_TUNER_CAP_LANG2</constant></entry>
 315             <entry>0x0020</entry>
 316             <entry>Reception of the secondary language of a bilingual
 317 audio program is supported. Only
 318       <constant>V4L2_TUNER_ANALOG_TV</constant> tuners can have this capability.</entry>
 319           </row>
 320           <row>
 321             <entry><constant>V4L2_TUNER_CAP_SAP</constant></entry>
 322             <entry>0x0020</entry>
 323             <entry><para>Reception of a secondary audio program is
 324 supported. This is a feature of the BTSC system which accompanies the
 325 NTSC video standard. Two audio carriers are available for mono or
 326 stereo transmissions of a primary language, and an independent third
 327 carrier for a monaural secondary language. Only
 328       <constant>V4L2_TUNER_ANALOG_TV</constant> tuners can have this capability.</para><para>Note the
 329 <constant>V4L2_TUNER_CAP_LANG2</constant> and
 330 <constant>V4L2_TUNER_CAP_SAP</constant> flags are synonyms.
 331 <constant>V4L2_TUNER_CAP_SAP</constant> applies when the tuner
 332 supports the <constant>V4L2_STD_NTSC_M</constant> video
 333 standard.</para><!-- FIXME what if PAL+NTSC and Bi but not SAP? --></entry>
 334           </row>
 335           <row>
 336         <entry><constant>V4L2_TUNER_CAP_RDS</constant></entry>
 337         <entry>0x0080</entry>
 338         <entry>RDS capture is supported. This capability is only valid for
 339 radio tuners.</entry>
 340           </row>
 341           <row>
 342         <entry><constant>V4L2_TUNER_CAP_RDS_BLOCK_IO</constant></entry>
 343         <entry>0x0100</entry>
 344         <entry>The RDS data is passed as unparsed RDS blocks.</entry>
 345           </row>
 346           <row>
 347         <entry><constant>V4L2_TUNER_CAP_RDS_CONTROLS</constant></entry>
 348         <entry>0x0200</entry>
 349         <entry>The RDS data is parsed by the hardware and set via controls.</entry>
 350           </row>
 351           <row>
 352         <entry><constant>V4L2_TUNER_CAP_FREQ_BANDS</constant></entry>
 353         <entry>0x0400</entry>
 354         <entry>The &VIDIOC-ENUM-FREQ-BANDS; ioctl can be used to enumerate
 355         the available frequency bands.</entry>
 356           </row>
 357         </tbody>
 358       </tgroup>
 359     </table>
 360
 361     <table pgwide="1" frame="none" id="tuner-rxsubchans">
 362       <title>Tuner Audio Reception Flags</title>
 363       <tgroup cols="3">
 364         &cs-def;
 365         <tbody valign="top">
 366           <row>
 367             <entry><constant>V4L2_TUNER_SUB_MONO</constant></entry>
 368             <entry>0x0001</entry>
 369             <entry>The tuner receives a mono audio signal.</entry>
 370           </row>
 371           <row>
 372             <entry><constant>V4L2_TUNER_SUB_STEREO</constant></entry>
 373             <entry>0x0002</entry>
 374             <entry>The tuner receives a stereo audio signal.</entry>
 375           </row>
 376           <row>
 377             <entry><constant>V4L2_TUNER_SUB_LANG1</constant></entry>
 378             <entry>0x0008</entry>
 379             <entry>The tuner receives the primary language of a
 380 bilingual audio signal. Drivers must clear this flag when the current
 381 video standard is <constant>V4L2_STD_NTSC_M</constant>.</entry>
 382           </row>
 383           <row>
 384             <entry><constant>V4L2_TUNER_SUB_LANG2</constant></entry>
 385             <entry>0x0004</entry>
 386             <entry>The tuner receives the secondary language of a
 387 bilingual audio signal (or a second audio program).</entry>
 388           </row>
 389           <row>
 390             <entry><constant>V4L2_TUNER_SUB_SAP</constant></entry>
 391             <entry>0x0004</entry>
 392             <entry>The tuner receives a Second Audio Program. Note the
 393 <constant>V4L2_TUNER_SUB_LANG2</constant> and
 394 <constant>V4L2_TUNER_SUB_SAP</constant> flags are synonyms. The
 395 <constant>V4L2_TUNER_SUB_SAP</constant> flag applies when the
 396 current video standard is <constant>V4L2_STD_NTSC_M</constant>.</entry>
 397           </row>
 398           <row>
 399             <entry><constant>V4L2_TUNER_SUB_RDS</constant></entry>
 400             <entry>0x0010</entry>
 401             <entry>The tuner receives an RDS channel.</entry>
 402           </row>
 403         </tbody>
 404       </tgroup>
 405     </table>
 406
 407     <table pgwide="1" frame="none" id="tuner-audmode">
 408       <title>Tuner Audio Modes</title>
 409       <tgroup cols="3">
 410         &cs-def;
 411         <tbody valign="top">
 412           <row>
 413             <entry><constant>V4L2_TUNER_MODE_MONO</constant></entry>
 414             <entry>0</entry>
 415             <entry>Play mono audio. When the tuner receives a stereo
 416 signal this a down-mix of the left and right channel. When the tuner
 417 receives a bilingual or SAP signal this mode selects the primary
 418 language.</entry>
 419           </row>
 420           <row>
 421             <entry><constant>V4L2_TUNER_MODE_STEREO</constant></entry>
 422             <entry>1</entry>
 423             <entry><para>Play stereo audio. When the tuner receives
 424 bilingual audio it may play different languages on the left and right
 425 channel or the primary language is played on both channels.</para><para>Playing
 426 different languages in this mode is
 427 deprecated. New drivers should do this only in
 428 <constant>MODE_LANG1_LANG2</constant>.</para><para>When the tuner
 429 receives no stereo signal or does not support stereo reception the
 430 driver shall fall back to <constant>MODE_MONO</constant>.</para></entry>
 431           </row>
 432           <row>
 433             <entry><constant>V4L2_TUNER_MODE_LANG1</constant></entry>
 434             <entry>3</entry>
 435             <entry>Play the primary language, mono or stereo. Only
 436 <constant>V4L2_TUNER_ANALOG_TV</constant> tuners support this
 437 mode.</entry>
 438           </row>
 439           <row>
 440             <entry><constant>V4L2_TUNER_MODE_LANG2</constant></entry>
 441             <entry>2</entry>
 442             <entry>Play the secondary language, mono. When the tuner
 443 receives no bilingual audio or SAP, or their reception is not
 444 supported the driver shall fall back to mono or stereo mode. Only
 445 <constant>V4L2_TUNER_ANALOG_TV</constant> tuners support this
 446 mode.</entry>
 447           </row>
 448           <row>
 449             <entry><constant>V4L2_TUNER_MODE_SAP</constant></entry>
 450             <entry>2</entry>
 451             <entry>Play the Second Audio Program. When the tuner
 452 receives no bilingual audio or SAP, or their reception is not
 453 supported the driver shall fall back to mono or stereo mode. Only
 454 <constant>V4L2_TUNER_ANALOG_TV</constant> tuners support this mode.
 455 Note the <constant>V4L2_TUNER_MODE_LANG2</constant> and
 456 <constant>V4L2_TUNER_MODE_SAP</constant> are synonyms.</entry>
 457           </row>
 458           <row>
 459             <entry><constant>V4L2_TUNER_MODE_LANG1_LANG2</constant></entry>
 460             <entry>4</entry>
 461             <entry>Play the primary language on the left channel, the
 462 secondary language on the right channel. When the tuner receives no
 463 bilingual audio or SAP, it shall fall back to
 464 <constant>MODE_LANG1</constant> or <constant>MODE_MONO</constant>.
 465 Only <constant>V4L2_TUNER_ANALOG_TV</constant> tuners support this
 466 mode.</entry>
 467           </row>
 468         </tbody>
 469       </tgroup>
 470     </table>
 471
 472     <table pgwide="1" frame="all" id="tuner-matrix">
 473       <title>Tuner Audio Matrix</title>
 474       <tgroup cols="6" align="center">
 475         <colspec align="left" />
 476         <colspec colname="c2" colwidth="1*" />
 477         <colspec colwidth="1*" />
 478         <colspec colwidth="1*" />
 479         <colspec colnum="6" colname="c6" colwidth="1*" />
 480         <spanspec namest="c2" nameend="c6" spanname="hspan" align="center" />
 481         <thead>
 482           <row>
 483             <entry></entry>
 484             <entry spanname="hspan">Selected
 485 <constant>V4L2_TUNER_MODE_</constant></entry>
 486           </row>
 487           <row>
 488             <entry>Received <constant>V4L2_TUNER_SUB_</constant></entry>
 489             <entry><constant>MONO</constant></entry>
 490             <entry><constant>STEREO</constant></entry>
 491             <entry><constant>LANG1</constant></entry>
 492             <entry><constant>LANG2 = SAP</constant></entry>
 493             <entry><constant>LANG1_LANG2</constant><footnote><para>This
 494 mode has been added in Linux 2.6.17 and may not be supported by older
 495 drivers.</para></footnote></entry>
 496           </row>
 497         </thead>
 498         <tbody valign="top">
 499           <row>
 500             <entry><constant>MONO</constant></entry>
 501             <entry>Mono</entry>
 502             <entry>Mono/Mono</entry>
 503             <entry>Mono</entry>
 504             <entry>Mono</entry>
 505             <entry>Mono/Mono</entry>
 506           </row>
 507           <row>
 508             <entry><constant>MONO | SAP</constant></entry>
 509             <entry>Mono</entry>
 510             <entry>Mono/Mono</entry>
 511             <entry>Mono</entry>
 512             <entry>SAP</entry>
 513             <entry>Mono/SAP (preferred) or Mono/Mono</entry>
 514           </row>
 515           <row>
 516             <entry><constant>STEREO</constant></entry>
 517             <entry>L+R</entry>
 518             <entry>L/R</entry>
 519             <entry>Stereo L/R (preferred) or Mono L+R</entry>
 520             <entry>Stereo L/R (preferred) or Mono L+R</entry>
 521             <entry>L/R (preferred) or L+R/L+R</entry>
 522           </row>
 523           <row>
 524             <entry><constant>STEREO | SAP</constant></entry>
 525             <entry>L+R</entry>
 526             <entry>L/R</entry>
 527             <entry>Stereo L/R (preferred) or Mono L+R</entry>
 528             <entry>SAP</entry>
 529             <entry>L+R/SAP (preferred) or L/R or L+R/L+R</entry>
 530           </row>
 531           <row>
 532             <entry><constant>LANG1 | LANG2</constant></entry>
 533             <entry>Language&nbsp;1</entry>
 534             <entry>Lang1/Lang2 (deprecated<footnote><para>Playback of
 535 both languages in <constant>MODE_STEREO</constant> is deprecated. In
 536 the future drivers should produce only the primary language in this
 537 mode. Applications should request
 538 <constant>MODE_LANG1_LANG2</constant> to record both languages or a
 539 stereo signal.</para></footnote>) or
 540 Lang1/Lang1</entry>
 541             <entry>Language&nbsp;1</entry>
 542             <entry>Language&nbsp;2</entry>
 543             <entry>Lang1/Lang2 (preferred) or Lang1/Lang1</entry>
 544           </row>
 545         </tbody>
 546       </tgroup>
 547     </table>
 548   </refsect1>
 549
 550   <refsect1>
 551     &return-value;
 552
 553     <variablelist>
 554       <varlistentry>
 555         <term><errorcode>EINVAL</errorcode></term>
 556         <listitem>
 557           <para>The &v4l2-tuner; <structfield>index</structfield> is
 558 out of bounds.</para>
 559         </listitem>
 560       </varlistentry>
 561     </variablelist>
 562   </refsect1>
 563 </refentry>