Documentation/DocBook/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>&v4l2-tuner-type;</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 only the
 123 <constant>V4L2_TUNER_CAP_LOW</constant>,
 124 <constant>V4L2_TUNER_CAP_STEREO</constant> and
 125 <constant>V4L2_TUNER_CAP_RDS</constant> flags can be set.</para></entry>
 126           </row>
 127           <row>
 128             <entry>__u32</entry>
 129             <entry><structfield>rangelow</structfield></entry>
 130             <entry spanname="hspan">The lowest tunable frequency in
 131 units of 62.5 kHz, or if the <structfield>capability</structfield>
 132 flag <constant>V4L2_TUNER_CAP_LOW</constant> is set, in units of 62.5
 133 Hz.</entry>
 134           </row>
 135           <row>
 136             <entry>__u32</entry>
 137             <entry><structfield>rangehigh</structfield></entry>
 138             <entry spanname="hspan">The highest tunable frequency in
 139 units of 62.5 kHz, or if the <structfield>capability</structfield>
 140 flag <constant>V4L2_TUNER_CAP_LOW</constant> is set, in units of 62.5
 141 Hz.</entry>
 142           </row>
 143           <row>
 144             <entry>__u32</entry>
 145             <entry><structfield>rxsubchans</structfield></entry>
 146             <entry spanname="hspan"><para>Some tuners or audio
 147 decoders can determine the received audio subprograms by analyzing
 148 audio carriers, pilot tones or other indicators. To pass this
 149 information drivers set flags defined in <xref
 150                   linkend="tuner-rxsubchans" /> in this field. For
 151 example:</para></entry>
 152           </row>
 153           <row>
 154             <entry></entry>
 155             <entry></entry>
 156             <entry><constant>V4L2_TUNER_SUB_MONO</constant></entry>
 157             <entry>receiving mono audio</entry>
 158           </row>
 159           <row>
 160             <entry></entry>
 161             <entry></entry>
 162             <entry><constant>STEREO | SAP</constant></entry>
 163             <entry>receiving stereo audio and a secondary audio
 164 program</entry>
 165           </row>
 166           <row>
 167             <entry></entry>
 168             <entry></entry>
 169             <entry><constant>MONO | STEREO</constant></entry>
 170             <entry>receiving mono or stereo audio, the hardware cannot
 171 distinguish</entry>
 172           </row>
 173           <row>
 174             <entry></entry>
 175             <entry></entry>
 176             <entry><constant>LANG1 | LANG2</constant></entry>
 177             <entry>receiving bilingual audio</entry>
 178           </row>
 179           <row>
 180             <entry></entry>
 181             <entry></entry>
 182             <entry><constant>MONO | STEREO | LANG1 | LANG2</constant></entry>
 183             <entry>receiving mono, stereo or bilingual
 184 audio</entry>
 185           </row>
 186           <row>
 187             <entry></entry>
 188             <entry></entry>
 189             <entry spanname="hspan"><para>When the
 190 <constant>V4L2_TUNER_CAP_STEREO</constant>,
 191 <constant>_LANG1</constant>, <constant>_LANG2</constant> or
 192 <constant>_SAP</constant> flag is cleared in the
 193 <structfield>capability</structfield> field, the corresponding
 194 <constant>V4L2_TUNER_SUB_</constant> flag must not be set
 195 here.</para><para>This field is valid only if this is the tuner of the
 196 current video input, or when the structure refers to a radio
 197 tuner.</para></entry>
 198           </row>
 199           <row>
 200             <entry>__u32</entry>
 201             <entry><structfield>audmode</structfield></entry>
 202             <entry spanname="hspan"><para>The selected audio mode, see
 203 <xref linkend="tuner-audmode" /> for valid values. The audio mode does
 204 not affect audio subprogram detection, and like a <link
 205 linkend="control">control</link> it does not automatically change
 206 unless the requested mode is invalid or unsupported. See <xref
 207                   linkend="tuner-matrix" /> for possible results when
 208 the selected and received audio programs do not
 209 match.</para><para>Currently this is the only field of struct
 210 <structname>v4l2_tuner</structname> applications can
 211 change.</para></entry>
 212           </row>
 213           <row>
 214             <entry>__u32</entry>
 215             <entry><structfield>signal</structfield></entry>
 216             <entry spanname="hspan">The signal strength if known, ranging
 217 from 0 to 65535. Higher values indicate a better signal.</entry>
 218           </row>
 219           <row>
 220             <entry>__s32</entry>
 221             <entry><structfield>afc</structfield></entry>
 222             <entry spanname="hspan">Automatic frequency control: When the
 223 <structfield>afc</structfield> value is negative, the frequency is too
 224 low, when positive too high.<!-- FIXME need example what to do when it never
 225 settles at zero, &ie; range is what? --></entry>
 226           </row>
 227           <row>
 228             <entry>__u32</entry>
 229             <entry><structfield>reserved</structfield>[4]</entry>
 230             <entry spanname="hspan">Reserved for future extensions. Drivers and
 231 applications must set the array to zero.</entry>
 232           </row>
 233         </tbody>
 234       </tgroup>
 235     </table>
 236
 237     <table pgwide="1" frame="none" id="v4l2-tuner-type">
 238       <title>enum v4l2_tuner_type</title>
 239       <tgroup cols="3">
 240         &cs-def;
 241         <tbody valign="top">
 242           <row>
 243             <entry><constant>V4L2_TUNER_RADIO</constant></entry>
 244             <entry>1</entry>
 245             <entry></entry>
 246           </row>
 247           <row>
 248             <entry><constant>V4L2_TUNER_ANALOG_TV</constant></entry>
 249             <entry>2</entry>
 250             <entry></entry>
 251           </row>
 252         </tbody>
 253       </tgroup>
 254     </table>
 255
 256     <table pgwide="1" frame="none" id="tuner-capability">
 257       <title>Tuner and Modulator Capability Flags</title>
 258       <tgroup cols="3">
 259         &cs-def;
 260         <tbody valign="top">
 261           <row>
 262             <entry><constant>V4L2_TUNER_CAP_LOW</constant></entry>
 263             <entry>0x0001</entry>
 264             <entry>When set, tuning frequencies are expressed in units of
 265 62.5&nbsp;Hz, otherwise in units of 62.5&nbsp;kHz.</entry>
 266           </row>
 267           <row>
 268             <entry><constant>V4L2_TUNER_CAP_NORM</constant></entry>
 269             <entry>0x0002</entry>
 270             <entry>This is a multi-standard tuner; the video standard
 271 can or must be switched. (B/G PAL tuners for example are typically not
 272       considered multi-standard because the video standard is automatically
 273       determined from the frequency band.) The set of supported video
 274       standards is available from the &v4l2-input; pointing to this tuner,
 275       see the description of ioctl &VIDIOC-ENUMINPUT; for details. Only
 276       <constant>V4L2_TUNER_ANALOG_TV</constant> tuners can have this capability.</entry>
 277           </row>
 278           <row>
 279         <entry><constant>V4L2_TUNER_CAP_STEREO</constant></entry>
 280         <entry>0x0010</entry>
 281         <entry>Stereo audio reception is supported.</entry>
 282           </row>
 283           <row>
 284             <entry><constant>V4L2_TUNER_CAP_LANG1</constant></entry>
 285             <entry>0x0040</entry>
 286             <entry>Reception of the primary language of a bilingual
 287 audio program is supported. Bilingual audio is a feature of
 288 two-channel systems, transmitting the primary language monaural on the
 289 main audio carrier and a secondary language monaural on a second
 290 carrier. Only
 291       <constant>V4L2_TUNER_ANALOG_TV</constant> tuners can have this capability.</entry>
 292           </row>
 293           <row>
 294             <entry><constant>V4L2_TUNER_CAP_LANG2</constant></entry>
 295             <entry>0x0020</entry>
 296             <entry>Reception of the secondary language of a bilingual
 297 audio program is supported. Only
 298       <constant>V4L2_TUNER_ANALOG_TV</constant> tuners can have this capability.</entry>
 299           </row>
 300           <row>
 301             <entry><constant>V4L2_TUNER_CAP_SAP</constant></entry>
 302             <entry>0x0020</entry>
 303             <entry><para>Reception of a secondary audio program is
 304 supported. This is a feature of the BTSC system which accompanies the
 305 NTSC video standard. Two audio carriers are available for mono or
 306 stereo transmissions of a primary language, and an independent third
 307 carrier for a monaural secondary language. Only
 308       <constant>V4L2_TUNER_ANALOG_TV</constant> tuners can have this capability.</para><para>Note the
 309 <constant>V4L2_TUNER_CAP_LANG2</constant> and
 310 <constant>V4L2_TUNER_CAP_SAP</constant> flags are synonyms.
 311 <constant>V4L2_TUNER_CAP_SAP</constant> applies when the tuner
 312 supports the <constant>V4L2_STD_NTSC_M</constant> video
 313 standard.</para><!-- FIXME what if PAL+NTSC and Bi but not SAP? --></entry>
 314           </row>
 315           <row>
 316         <entry><constant>V4L2_TUNER_CAP_RDS</constant></entry>
 317         <entry>0x0080</entry>
 318         <entry>RDS capture is supported. This capability is only valid for
 319 radio tuners.</entry>
 320           </row>
 321         </tbody>
 322       </tgroup>
 323     </table>
 324
 325     <table pgwide="1" frame="none" id="tuner-rxsubchans">
 326       <title>Tuner Audio Reception Flags</title>
 327       <tgroup cols="3">
 328         &cs-def;
 329         <tbody valign="top">
 330           <row>
 331             <entry><constant>V4L2_TUNER_SUB_MONO</constant></entry>
 332             <entry>0x0001</entry>
 333             <entry>The tuner receives a mono audio signal.</entry>
 334           </row>
 335           <row>
 336             <entry><constant>V4L2_TUNER_SUB_STEREO</constant></entry>
 337             <entry>0x0002</entry>
 338             <entry>The tuner receives a stereo audio signal.</entry>
 339           </row>
 340           <row>
 341             <entry><constant>V4L2_TUNER_SUB_LANG1</constant></entry>
 342             <entry>0x0008</entry>
 343             <entry>The tuner receives the primary language of a
 344 bilingual audio signal. Drivers must clear this flag when the current
 345 video standard is <constant>V4L2_STD_NTSC_M</constant>.</entry>
 346           </row>
 347           <row>
 348             <entry><constant>V4L2_TUNER_SUB_LANG2</constant></entry>
 349             <entry>0x0004</entry>
 350             <entry>The tuner receives the secondary language of a
 351 bilingual audio signal (or a second audio program).</entry>
 352           </row>
 353           <row>
 354             <entry><constant>V4L2_TUNER_SUB_SAP</constant></entry>
 355             <entry>0x0004</entry>
 356             <entry>The tuner receives a Second Audio Program. Note the
 357 <constant>V4L2_TUNER_SUB_LANG2</constant> and
 358 <constant>V4L2_TUNER_SUB_SAP</constant> flags are synonyms. The
 359 <constant>V4L2_TUNER_SUB_SAP</constant> flag applies when the
 360 current video standard is <constant>V4L2_STD_NTSC_M</constant>.</entry>
 361           </row>
 362           <row>
 363             <entry><constant>V4L2_TUNER_SUB_RDS</constant></entry>
 364             <entry>0x0010</entry>
 365             <entry>The tuner receives an RDS channel.</entry>
 366           </row>
 367         </tbody>
 368       </tgroup>
 369     </table>
 370
 371     <table pgwide="1" frame="none" id="tuner-audmode">
 372       <title>Tuner Audio Modes</title>
 373       <tgroup cols="3">
 374         &cs-def;
 375         <tbody valign="top">
 376           <row>
 377             <entry><constant>V4L2_TUNER_MODE_MONO</constant></entry>
 378             <entry>0</entry>
 379             <entry>Play mono audio. When the tuner receives a stereo
 380 signal this a down-mix of the left and right channel. When the tuner
 381 receives a bilingual or SAP signal this mode selects the primary
 382 language.</entry>
 383           </row>
 384           <row>
 385             <entry><constant>V4L2_TUNER_MODE_STEREO</constant></entry>
 386             <entry>1</entry>
 387             <entry><para>Play stereo audio. When the tuner receives
 388 bilingual audio it may play different languages on the left and right
 389 channel or the primary language is played on both channels.</para><para>Playing
 390 different languages in this mode is
 391 deprecated. New drivers should do this only in
 392 <constant>MODE_LANG1_LANG2</constant>.</para><para>When the tuner
 393 receives no stereo signal or does not support stereo reception the
 394 driver shall fall back to <constant>MODE_MONO</constant>.</para></entry>
 395           </row>
 396           <row>
 397             <entry><constant>V4L2_TUNER_MODE_LANG1</constant></entry>
 398             <entry>3</entry>
 399             <entry>Play the primary language, mono or stereo. Only
 400 <constant>V4L2_TUNER_ANALOG_TV</constant> tuners support this
 401 mode.</entry>
 402           </row>
 403           <row>
 404             <entry><constant>V4L2_TUNER_MODE_LANG2</constant></entry>
 405             <entry>2</entry>
 406             <entry>Play the secondary language, mono. When the tuner
 407 receives no bilingual audio or SAP, or their reception is not
 408 supported the driver shall fall back to mono or stereo mode. Only
 409 <constant>V4L2_TUNER_ANALOG_TV</constant> tuners support this
 410 mode.</entry>
 411           </row>
 412           <row>
 413             <entry><constant>V4L2_TUNER_MODE_SAP</constant></entry>
 414             <entry>2</entry>
 415             <entry>Play the Second Audio Program. When the tuner
 416 receives no bilingual audio or SAP, or their reception is not
 417 supported the driver shall fall back to mono or stereo mode. Only
 418 <constant>V4L2_TUNER_ANALOG_TV</constant> tuners support this mode.
 419 Note the <constant>V4L2_TUNER_MODE_LANG2</constant> and
 420 <constant>V4L2_TUNER_MODE_SAP</constant> are synonyms.</entry>
 421           </row>
 422           <row>
 423             <entry><constant>V4L2_TUNER_MODE_LANG1_LANG2</constant></entry>
 424             <entry>4</entry>
 425             <entry>Play the primary language on the left channel, the
 426 secondary language on the right channel. When the tuner receives no
 427 bilingual audio or SAP, it shall fall back to
 428 <constant>MODE_LANG1</constant> or <constant>MODE_MONO</constant>.
 429 Only <constant>V4L2_TUNER_ANALOG_TV</constant> tuners support this
 430 mode.</entry>
 431           </row>
 432         </tbody>
 433       </tgroup>
 434     </table>
 435
 436     <table pgwide="1" frame="all" id="tuner-matrix">
 437       <title>Tuner Audio Matrix</title>
 438       <tgroup cols="6" align="center">
 439         <colspec align="left" />
 440         <colspec colname="c2" colwidth="1*" />
 441         <colspec colwidth="1*" />
 442         <colspec colwidth="1*" />
 443         <colspec colnum="6" colname="c6" colwidth="1*" />
 444         <spanspec namest="c2" nameend="c6" spanname="hspan" align="center" />
 445         <thead>
 446           <row>
 447             <entry></entry>
 448             <entry spanname="hspan">Selected
 449 <constant>V4L2_TUNER_MODE_</constant></entry>
 450           </row>
 451           <row>
 452             <entry>Received <constant>V4L2_TUNER_SUB_</constant></entry>
 453             <entry><constant>MONO</constant></entry>
 454             <entry><constant>STEREO</constant></entry>
 455             <entry><constant>LANG1</constant></entry>
 456             <entry><constant>LANG2 = SAP</constant></entry>
 457             <entry><constant>LANG1_LANG2</constant><footnote><para>This
 458 mode has been added in Linux 2.6.17 and may not be supported by older
 459 drivers.</para></footnote></entry>
 460           </row>
 461         </thead>
 462         <tbody valign="top">
 463           <row>
 464             <entry><constant>MONO</constant></entry>
 465             <entry>Mono</entry>
 466             <entry>Mono/Mono</entry>
 467             <entry>Mono</entry>
 468             <entry>Mono</entry>
 469             <entry>Mono/Mono</entry>
 470           </row>
 471           <row>
 472             <entry><constant>MONO | SAP</constant></entry>
 473             <entry>Mono</entry>
 474             <entry>Mono/Mono</entry>
 475             <entry>Mono</entry>
 476             <entry>SAP</entry>
 477             <entry>Mono/SAP (preferred) or Mono/Mono</entry>
 478           </row>
 479           <row>
 480             <entry><constant>STEREO</constant></entry>
 481             <entry>L+R</entry>
 482             <entry>L/R</entry>
 483             <entry>Stereo L/R (preferred) or Mono L+R</entry>
 484             <entry>Stereo L/R (preferred) or Mono L+R</entry>
 485             <entry>L/R (preferred) or L+R/L+R</entry>
 486           </row>
 487           <row>
 488             <entry><constant>STEREO | SAP</constant></entry>
 489             <entry>L+R</entry>
 490             <entry>L/R</entry>
 491             <entry>Stereo L/R (preferred) or Mono L+R</entry>
 492             <entry>SAP</entry>
 493             <entry>L+R/SAP (preferred) or L/R or L+R/L+R</entry>
 494           </row>
 495           <row>
 496             <entry><constant>LANG1 | LANG2</constant></entry>
 497             <entry>Language&nbsp;1</entry>
 498             <entry>Lang1/Lang2 (deprecated<footnote><para>Playback of
 499 both languages in <constant>MODE_STEREO</constant> is deprecated. In
 500 the future drivers should produce only the primary language in this
 501 mode. Applications should request
 502 <constant>MODE_LANG1_LANG2</constant> to record both languages or a
 503 stereo signal.</para></footnote>) or
 504 Lang1/Lang1</entry>
 505             <entry>Language&nbsp;1</entry>
 506             <entry>Language&nbsp;2</entry>
 507             <entry>Lang1/Lang2 (preferred) or Lang1/Lang1</entry>
 508           </row>
 509         </tbody>
 510       </tgroup>
 511     </table>
 512   </refsect1>
 513
 514   <refsect1>
 515     &return-value;
 516
 517     <variablelist>
 518       <varlistentry>
 519         <term><errorcode>EINVAL</errorcode></term>
 520         <listitem>
 521           <para>The &v4l2-tuner; <structfield>index</structfield> is
 522 out of bounds.</para>
 523         </listitem>
 524       </varlistentry>
 525     </variablelist>
 526   </refsect1>
 527 </refentry>
 528
 529 <!--
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 532 sgml-parent-document: "v4l2.sgml"
 533 indent-tabs-mode: nil
 534 End:
 535 -->