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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
66structure. Drivers fill the rest of the structure or return an
67&EINVAL; when the index is out of bounds. To enumerate all tuners
68applications shall begin at index zero, incrementing by one until the
69driver returns <errorcode>EINVAL</errorcode>.</para>
70
71 <para>Tuners have two writable properties, the audio mode and
72the radio frequency. To change the audio mode, applications initialize
73the <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
78by the current video input. Drivers may choose a different audio mode
79if the requested mode is invalid or unsupported. Since this is a
80<!-- FIXME -->write-only ioctl, it does not return the actually
81selected audio mode.</para>
82
83 <para>To change the radio frequency the &VIDIOC-S-FREQUENCY; ioctl
84is 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
99application.</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
105NUL-terminated ASCII string. This information is intended for the
106user.<!-- FIXME Video inputs already have a name, the purpose of this
107field 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
120to decode audio subprograms. They will <emphasis>not</emphasis>
121change, for example with the current video standard.</para><para>When
122the 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
131units of 62.5 kHz, or if the <structfield>capability</structfield>
132flag <constant>V4L2_TUNER_CAP_LOW</constant> is set, in units of 62.5
133Hz.</entry>
134 </row>
135 <row>
136 <entry>__u32</entry>
137 <entry><structfield>rangehigh</structfield></entry>
138 <entry spanname="hspan">The highest tunable frequency in
139units of 62.5 kHz, or if the <structfield>capability</structfield>
140flag <constant>V4L2_TUNER_CAP_LOW</constant> is set, in units of 62.5
141Hz.</entry>
142 </row>
143 <row>
144 <entry>__u32</entry>
145 <entry><structfield>rxsubchans</structfield></entry>
146 <entry spanname="hspan"><para>Some tuners or audio
147decoders can determine the received audio subprograms by analyzing
148audio carriers, pilot tones or other indicators. To pass this
149information drivers set flags defined in <xref
150 linkend="tuner-rxsubchans" /> in this field. For
151example:</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
164program</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
171distinguish</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
184audio</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
195here.</para><para>This field is valid only if this is the tuner of the
196current video input, or when the structure refers to a radio
197tuner.</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
204not affect audio subprogram detection, and like a <link
205linkend="control">control</link> it does not automatically change
206unless the requested mode is invalid or unsupported. See <xref
207 linkend="tuner-matrix" /> for possible results when
208the selected and received audio programs do not
209match.</para><para>Currently this is the only field of struct
210<structname>v4l2_tuner</structname> applications can
211change.</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
217from 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
224low, when positive too high.<!-- FIXME need example what to do when it never
225settles 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
231applications 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
26562.5&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
271can 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
287audio program is supported. Bilingual audio is a feature of
288two-channel systems, transmitting the primary language monaural on the
289main audio carrier and a secondary language monaural on a second
290carrier. 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
297audio 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
304supported. This is a feature of the BTSC system which accompanies the
305NTSC video standard. Two audio carriers are available for mono or
306stereo transmissions of a primary language, and an independent third
307carrier 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
312supports the <constant>V4L2_STD_NTSC_M</constant> video
313standard.</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
319radio 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
344bilingual audio signal. Drivers must clear this flag when the current
345video 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
351bilingual 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
360current 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
380signal this a down-mix of the left and right channel. When the tuner
381receives a bilingual or SAP signal this mode selects the primary
382language.</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
388bilingual audio it may play different languages on the left and right
389channel or the primary language is played on both channels.</para><para>Playing
390different languages in this mode is
391deprecated. New drivers should do this only in
392<constant>MODE_LANG1_LANG2</constant>.</para><para>When the tuner
393receives no stereo signal or does not support stereo reception the
394driver 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
401mode.</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
407receives no bilingual audio or SAP, or their reception is not
408supported the driver shall fall back to mono or stereo mode. Only
409<constant>V4L2_TUNER_ANALOG_TV</constant> tuners support this
410mode.</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
416receives no bilingual audio or SAP, or their reception is not
417supported the driver shall fall back to mono or stereo mode. Only
418<constant>V4L2_TUNER_ANALOG_TV</constant> tuners support this mode.
419Note 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
426secondary language on the right channel. When the tuner receives no
427bilingual audio or SAP, it shall fall back to
428<constant>MODE_LANG1</constant> or <constant>MODE_MONO</constant>.
429Only <constant>V4L2_TUNER_ANALOG_TV</constant> tuners support this
430mode.</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
458mode has been added in Linux 2.6.17 and may not be supported by older
459drivers.</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
499both languages in <constant>MODE_STEREO</constant> is deprecated. In
500the future drivers should produce only the primary language in this
501mode. Applications should request
502<constant>MODE_LANG1_LANG2</constant> to record both languages or a
503stereo signal.</para></footnote>) or
504Lang1/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
522out of bounds.</para>
523 </listitem>
524 </varlistentry>
525 </variablelist>
526 </refsect1>
527</refentry>
528
529<!--
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