Based on kernel version 3.0.4. Page generated on 2011-10-03 22:07 EST.
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 Hz, otherwise in units of 62.5 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 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 1</entry> 506 <entry>Language 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 <!-- 530 Local Variables: 531 mode: sgml 532 sgml-parent-document: "v4l2.sgml" 533 indent-tabs-mode: nil 534 End: 535 -->
