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authorMauro Carvalho Chehab <mchehab@redhat.com>2011-05-31 15:27:44 -0400
committerMauro Carvalho Chehab <mchehab@redhat.com>2011-07-27 16:52:05 -0400
commit4266129964b8238526936d723de65b419d8069c6 (patch)
tree38c6b5cd3dc99b8599391ffad3b87e399bef56a2 /Documentation/DocBook/media/v4l/controls.xml
parent04893043ae9ea8aa82b712491ed25ba6c4ffbca3 (diff)
[media] DocBook: Move all media docbook stuff into its own directory
This patch addresses several issues pointed by Randy Dunlap <rdunlap@xenotime.net> at changeset ece722c: - In the generated index.html file, "media" is listed first, but it should be listed in alphabetical order, not first. - The generated files are (hidden) in .tmpmedia/ - The link from the top-level index.html file to "media" is to media/index.html, but the file is actually in .tmpmedia/media/index.html - Please build docs with and without using "O=builddir" and test that. - Would it be possible for media to have its own Makefile instead of merging into this one? Due to the way cleandocs target works, I had to rename the media DocBook to media_api, otherwise cleandocs would remove the /media directory. Thanks-to: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
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1 <section id="control">
2 <title>User Controls</title>
3
4 <para>Devices typically have a number of user-settable controls
5such as brightness, saturation and so on, which would be presented to
6the user on a graphical user interface. But, different devices
7will have different controls available, and furthermore, the range of
8possible values, and the default value will vary from device to
9device. The control ioctls provide the information and a mechanism to
10create a nice user interface for these controls that will work
11correctly with any device.</para>
12
13 <para>All controls are accessed using an ID value. V4L2 defines
14several IDs for specific purposes. Drivers can also implement their
15own custom controls using <constant>V4L2_CID_PRIVATE_BASE</constant>
16and higher values. The pre-defined control IDs have the prefix
17<constant>V4L2_CID_</constant>, and are listed in <xref
18linkend="control-id" />. The ID is used when querying the attributes of
19a control, and when getting or setting the current value.</para>
20
21 <para>Generally applications should present controls to the user
22without assumptions about their purpose. Each control comes with a
23name string the user is supposed to understand. When the purpose is
24non-intuitive the driver writer should provide a user manual, a user
25interface plug-in or a driver specific panel application. Predefined
26IDs were introduced to change a few controls programmatically, for
27example to mute a device during a channel switch.</para>
28
29 <para>Drivers may enumerate different controls after switching
30the current video input or output, tuner or modulator, or audio input
31or output. Different in the sense of other bounds, another default and
32current value, step size or other menu items. A control with a certain
33<emphasis>custom</emphasis> ID can also change name and
34type.<footnote>
35 <para>It will be more convenient for applications if drivers
36make use of the <constant>V4L2_CTRL_FLAG_DISABLED</constant> flag, but
37that was never required.</para>
38 </footnote> Control values are stored globally, they do not
39change when switching except to stay within the reported bounds. They
40also do not change &eg; when the device is opened or closed, when the
41tuner radio frequency is changed or generally never without
42application request. Since V4L2 specifies no event mechanism, panel
43applications intended to cooperate with other panel applications (be
44they built into a larger application, as a TV viewer) may need to
45regularly poll control values to update their user
46interface.<footnote>
47 <para>Applications could call an ioctl to request events.
48After another process called &VIDIOC-S-CTRL; or another ioctl changing
49shared properties the &func-select; function would indicate
50readability until any ioctl (querying the properties) is
51called.</para>
52 </footnote></para>
53
54 <table pgwide="1" frame="none" id="control-id">
55 <title>Control IDs</title>
56 <tgroup cols="3">
57 &cs-def;
58 <thead>
59 <row>
60 <entry>ID</entry>
61 <entry>Type</entry>
62 <entry>Description</entry>
63 </row>
64 </thead>
65 <tbody valign="top">
66 <row>
67 <entry><constant>V4L2_CID_BASE</constant></entry>
68 <entry></entry>
69 <entry>First predefined ID, equal to
70<constant>V4L2_CID_BRIGHTNESS</constant>.</entry>
71 </row>
72 <row>
73 <entry><constant>V4L2_CID_USER_BASE</constant></entry>
74 <entry></entry>
75 <entry>Synonym of <constant>V4L2_CID_BASE</constant>.</entry>
76 </row>
77 <row>
78 <entry><constant>V4L2_CID_BRIGHTNESS</constant></entry>
79 <entry>integer</entry>
80 <entry>Picture brightness, or more precisely, the black
81level.</entry>
82 </row>
83 <row>
84 <entry><constant>V4L2_CID_CONTRAST</constant></entry>
85 <entry>integer</entry>
86 <entry>Picture contrast or luma gain.</entry>
87 </row>
88 <row>
89 <entry><constant>V4L2_CID_SATURATION</constant></entry>
90 <entry>integer</entry>
91 <entry>Picture color saturation or chroma gain.</entry>
92 </row>
93 <row>
94 <entry><constant>V4L2_CID_HUE</constant></entry>
95 <entry>integer</entry>
96 <entry>Hue or color balance.</entry>
97 </row>
98 <row>
99 <entry><constant>V4L2_CID_AUDIO_VOLUME</constant></entry>
100 <entry>integer</entry>
101 <entry>Overall audio volume. Note some drivers also
102provide an OSS or ALSA mixer interface.</entry>
103 </row>
104 <row>
105 <entry><constant>V4L2_CID_AUDIO_BALANCE</constant></entry>
106 <entry>integer</entry>
107 <entry>Audio stereo balance. Minimum corresponds to all
108the way left, maximum to right.</entry>
109 </row>
110 <row>
111 <entry><constant>V4L2_CID_AUDIO_BASS</constant></entry>
112 <entry>integer</entry>
113 <entry>Audio bass adjustment.</entry>
114 </row>
115 <row>
116 <entry><constant>V4L2_CID_AUDIO_TREBLE</constant></entry>
117 <entry>integer</entry>
118 <entry>Audio treble adjustment.</entry>
119 </row>
120 <row>
121 <entry><constant>V4L2_CID_AUDIO_MUTE</constant></entry>
122 <entry>boolean</entry>
123 <entry>Mute audio, &ie; set the volume to zero, however
124without affecting <constant>V4L2_CID_AUDIO_VOLUME</constant>. Like
125ALSA drivers, V4L2 drivers must mute at load time to avoid excessive
126noise. Actually the entire device should be reset to a low power
127consumption state.</entry>
128 </row>
129 <row>
130 <entry><constant>V4L2_CID_AUDIO_LOUDNESS</constant></entry>
131 <entry>boolean</entry>
132 <entry>Loudness mode (bass boost).</entry>
133 </row>
134 <row>
135 <entry><constant>V4L2_CID_BLACK_LEVEL</constant></entry>
136 <entry>integer</entry>
137 <entry>Another name for brightness (not a synonym of
138<constant>V4L2_CID_BRIGHTNESS</constant>). This control is deprecated
139and should not be used in new drivers and applications.</entry>
140 </row>
141 <row>
142 <entry><constant>V4L2_CID_AUTO_WHITE_BALANCE</constant></entry>
143 <entry>boolean</entry>
144 <entry>Automatic white balance (cameras).</entry>
145 </row>
146 <row>
147 <entry><constant>V4L2_CID_DO_WHITE_BALANCE</constant></entry>
148 <entry>button</entry>
149 <entry>This is an action control. When set (the value is
150ignored), the device will do a white balance and then hold the current
151setting. Contrast this with the boolean
152<constant>V4L2_CID_AUTO_WHITE_BALANCE</constant>, which, when
153activated, keeps adjusting the white balance.</entry>
154 </row>
155 <row>
156 <entry><constant>V4L2_CID_RED_BALANCE</constant></entry>
157 <entry>integer</entry>
158 <entry>Red chroma balance.</entry>
159 </row>
160 <row>
161 <entry><constant>V4L2_CID_BLUE_BALANCE</constant></entry>
162 <entry>integer</entry>
163 <entry>Blue chroma balance.</entry>
164 </row>
165 <row>
166 <entry><constant>V4L2_CID_GAMMA</constant></entry>
167 <entry>integer</entry>
168 <entry>Gamma adjust.</entry>
169 </row>
170 <row>
171 <entry><constant>V4L2_CID_WHITENESS</constant></entry>
172 <entry>integer</entry>
173 <entry>Whiteness for grey-scale devices. This is a synonym
174for <constant>V4L2_CID_GAMMA</constant>. This control is deprecated
175and should not be used in new drivers and applications.</entry>
176 </row>
177 <row>
178 <entry><constant>V4L2_CID_EXPOSURE</constant></entry>
179 <entry>integer</entry>
180 <entry>Exposure (cameras). [Unit?]</entry>
181 </row>
182 <row>
183 <entry><constant>V4L2_CID_AUTOGAIN</constant></entry>
184 <entry>boolean</entry>
185 <entry>Automatic gain/exposure control.</entry>
186 </row>
187 <row>
188 <entry><constant>V4L2_CID_GAIN</constant></entry>
189 <entry>integer</entry>
190 <entry>Gain control.</entry>
191 </row>
192 <row>
193 <entry><constant>V4L2_CID_HFLIP</constant></entry>
194 <entry>boolean</entry>
195 <entry>Mirror the picture horizontally.</entry>
196 </row>
197 <row>
198 <entry><constant>V4L2_CID_VFLIP</constant></entry>
199 <entry>boolean</entry>
200 <entry>Mirror the picture vertically.</entry>
201 </row>
202 <row>
203 <entry><constant>V4L2_CID_HCENTER_DEPRECATED</constant> (formerly <constant>V4L2_CID_HCENTER</constant>)</entry>
204 <entry>integer</entry>
205 <entry>Horizontal image centering. This control is
206deprecated. New drivers and applications should use the <link
207linkend="camera-controls">Camera class controls</link>
208<constant>V4L2_CID_PAN_ABSOLUTE</constant>,
209<constant>V4L2_CID_PAN_RELATIVE</constant> and
210<constant>V4L2_CID_PAN_RESET</constant> instead.</entry>
211 </row>
212 <row>
213 <entry><constant>V4L2_CID_VCENTER_DEPRECATED</constant>
214 (formerly <constant>V4L2_CID_VCENTER</constant>)</entry>
215 <entry>integer</entry>
216 <entry>Vertical image centering. Centering is intended to
217<emphasis>physically</emphasis> adjust cameras. For image cropping see
218<xref linkend="crop" />, for clipping <xref linkend="overlay" />. This
219control is deprecated. New drivers and applications should use the
220<link linkend="camera-controls">Camera class controls</link>
221<constant>V4L2_CID_TILT_ABSOLUTE</constant>,
222<constant>V4L2_CID_TILT_RELATIVE</constant> and
223<constant>V4L2_CID_TILT_RESET</constant> instead.</entry>
224 </row>
225 <row id="v4l2-power-line-frequency">
226 <entry><constant>V4L2_CID_POWER_LINE_FREQUENCY</constant></entry>
227 <entry>enum</entry>
228 <entry>Enables a power line frequency filter to avoid
229flicker. Possible values for <constant>enum v4l2_power_line_frequency</constant> are:
230<constant>V4L2_CID_POWER_LINE_FREQUENCY_DISABLED</constant> (0),
231<constant>V4L2_CID_POWER_LINE_FREQUENCY_50HZ</constant> (1) and
232<constant>V4L2_CID_POWER_LINE_FREQUENCY_60HZ</constant> (2).</entry>
233 </row>
234 <row>
235 <entry><constant>V4L2_CID_HUE_AUTO</constant></entry>
236 <entry>boolean</entry>
237 <entry>Enables automatic hue control by the device. The
238effect of setting <constant>V4L2_CID_HUE</constant> while automatic
239hue control is enabled is undefined, drivers should ignore such
240request.</entry>
241 </row>
242 <row>
243 <entry><constant>V4L2_CID_WHITE_BALANCE_TEMPERATURE</constant></entry>
244 <entry>integer</entry>
245 <entry>This control specifies the white balance settings
246as a color temperature in Kelvin. A driver should have a minimum of
2472800 (incandescent) to 6500 (daylight). For more information about
248color temperature see <ulink
249url="http://en.wikipedia.org/wiki/Color_temperature">Wikipedia</ulink>.</entry>
250 </row>
251 <row>
252 <entry><constant>V4L2_CID_SHARPNESS</constant></entry>
253 <entry>integer</entry>
254 <entry>Adjusts the sharpness filters in a camera. The
255minimum value disables the filters, higher values give a sharper
256picture.</entry>
257 </row>
258 <row>
259 <entry><constant>V4L2_CID_BACKLIGHT_COMPENSATION</constant></entry>
260 <entry>integer</entry>
261 <entry>Adjusts the backlight compensation in a camera. The
262minimum value disables backlight compensation.</entry>
263 </row>
264 <row>
265 <entry><constant>V4L2_CID_CHROMA_AGC</constant></entry>
266 <entry>boolean</entry>
267 <entry>Chroma automatic gain control.</entry>
268 </row>
269 <row>
270 <entry><constant>V4L2_CID_CHROMA_GAIN</constant></entry>
271 <entry>integer</entry>
272 <entry>Adjusts the Chroma gain control (for use when chroma AGC
273 is disabled).</entry>
274 </row>
275 <row>
276 <entry><constant>V4L2_CID_COLOR_KILLER</constant></entry>
277 <entry>boolean</entry>
278 <entry>Enable the color killer (&ie; force a black &amp; white image in case of a weak video signal).</entry>
279 </row>
280 <row id="v4l2-colorfx">
281 <entry><constant>V4L2_CID_COLORFX</constant></entry>
282 <entry>enum</entry>
283 <entry>Selects a color effect. Possible values for
284<constant>enum v4l2_colorfx</constant> are:
285<constant>V4L2_COLORFX_NONE</constant> (0),
286<constant>V4L2_COLORFX_BW</constant> (1),
287<constant>V4L2_COLORFX_SEPIA</constant> (2),
288<constant>V4L2_COLORFX_NEGATIVE</constant> (3),
289<constant>V4L2_COLORFX_EMBOSS</constant> (4),
290<constant>V4L2_COLORFX_SKETCH</constant> (5),
291<constant>V4L2_COLORFX_SKY_BLUE</constant> (6),
292<constant>V4L2_COLORFX_GRASS_GREEN</constant> (7),
293<constant>V4L2_COLORFX_SKIN_WHITEN</constant> (8) and
294<constant>V4L2_COLORFX_VIVID</constant> (9).</entry>
295 </row>
296 <row>
297 <entry><constant>V4L2_CID_ROTATE</constant></entry>
298 <entry>integer</entry>
299 <entry>Rotates the image by specified angle. Common angles are 90,
300 270 and 180. Rotating the image to 90 and 270 will reverse the height
301 and width of the display window. It is necessary to set the new height and
302 width of the picture using the &VIDIOC-S-FMT; ioctl according to
303 the rotation angle selected.</entry>
304 </row>
305 <row>
306 <entry><constant>V4L2_CID_BG_COLOR</constant></entry>
307 <entry>integer</entry>
308 <entry>Sets the background color on the current output device.
309 Background color needs to be specified in the RGB24 format. The
310 supplied 32 bit value is interpreted as bits 0-7 Red color information,
311 bits 8-15 Green color information, bits 16-23 Blue color
312 information and bits 24-31 must be zero.</entry>
313 </row>
314 <row>
315 <entry><constant>V4L2_CID_ILLUMINATORS_1</constant>
316 <constant>V4L2_CID_ILLUMINATORS_2</constant></entry>
317 <entry>boolean</entry>
318 <entry>Switch on or off the illuminator 1 or 2 of the device
319 (usually a microscope).</entry>
320 </row>
321 <row>
322 <entry><constant>V4L2_CID_LASTP1</constant></entry>
323 <entry></entry>
324 <entry>End of the predefined control IDs (currently
325<constant>V4L2_CID_ILLUMINATORS_2</constant> + 1).</entry>
326 </row>
327 <row>
328 <entry><constant>V4L2_CID_PRIVATE_BASE</constant></entry>
329 <entry></entry>
330 <entry>ID of the first custom (driver specific) control.
331Applications depending on particular custom controls should check the
332driver name and version, see <xref linkend="querycap" />.</entry>
333 </row>
334 </tbody>
335 </tgroup>
336 </table>
337
338 <para>Applications can enumerate the available controls with the
339&VIDIOC-QUERYCTRL; and &VIDIOC-QUERYMENU; ioctls, get and set a
340control value with the &VIDIOC-G-CTRL; and &VIDIOC-S-CTRL; ioctls.
341Drivers must implement <constant>VIDIOC_QUERYCTRL</constant>,
342<constant>VIDIOC_G_CTRL</constant> and
343<constant>VIDIOC_S_CTRL</constant> when the device has one or more
344controls, <constant>VIDIOC_QUERYMENU</constant> when it has one or
345more menu type controls.</para>
346
347 <example>
348 <title>Enumerating all controls</title>
349
350 <programlisting>
351&v4l2-queryctrl; queryctrl;
352&v4l2-querymenu; querymenu;
353
354static void
355enumerate_menu (void)
356{
357 printf (" Menu items:\n");
358
359 memset (&amp;querymenu, 0, sizeof (querymenu));
360 querymenu.id = queryctrl.id;
361
362 for (querymenu.index = queryctrl.minimum;
363 querymenu.index &lt;= queryctrl.maximum;
364 querymenu.index++) {
365 if (0 == ioctl (fd, &VIDIOC-QUERYMENU;, &amp;querymenu)) {
366 printf (" %s\n", querymenu.name);
367 }
368 }
369}
370
371memset (&amp;queryctrl, 0, sizeof (queryctrl));
372
373for (queryctrl.id = V4L2_CID_BASE;
374 queryctrl.id &lt; V4L2_CID_LASTP1;
375 queryctrl.id++) {
376 if (0 == ioctl (fd, &VIDIOC-QUERYCTRL;, &amp;queryctrl)) {
377 if (queryctrl.flags &amp; V4L2_CTRL_FLAG_DISABLED)
378 continue;
379
380 printf ("Control %s\n", queryctrl.name);
381
382 if (queryctrl.type == V4L2_CTRL_TYPE_MENU)
383 enumerate_menu ();
384 } else {
385 if (errno == EINVAL)
386 continue;
387
388 perror ("VIDIOC_QUERYCTRL");
389 exit (EXIT_FAILURE);
390 }
391}
392
393for (queryctrl.id = V4L2_CID_PRIVATE_BASE;;
394 queryctrl.id++) {
395 if (0 == ioctl (fd, &VIDIOC-QUERYCTRL;, &amp;queryctrl)) {
396 if (queryctrl.flags &amp; V4L2_CTRL_FLAG_DISABLED)
397 continue;
398
399 printf ("Control %s\n", queryctrl.name);
400
401 if (queryctrl.type == V4L2_CTRL_TYPE_MENU)
402 enumerate_menu ();
403 } else {
404 if (errno == EINVAL)
405 break;
406
407 perror ("VIDIOC_QUERYCTRL");
408 exit (EXIT_FAILURE);
409 }
410}
411</programlisting>
412 </example>
413
414 <example>
415 <title>Changing controls</title>
416
417 <programlisting>
418&v4l2-queryctrl; queryctrl;
419&v4l2-control; control;
420
421memset (&amp;queryctrl, 0, sizeof (queryctrl));
422queryctrl.id = V4L2_CID_BRIGHTNESS;
423
424if (-1 == ioctl (fd, &VIDIOC-QUERYCTRL;, &amp;queryctrl)) {
425 if (errno != EINVAL) {
426 perror ("VIDIOC_QUERYCTRL");
427 exit (EXIT_FAILURE);
428 } else {
429 printf ("V4L2_CID_BRIGHTNESS is not supported\n");
430 }
431} else if (queryctrl.flags &amp; V4L2_CTRL_FLAG_DISABLED) {
432 printf ("V4L2_CID_BRIGHTNESS is not supported\n");
433} else {
434 memset (&amp;control, 0, sizeof (control));
435 control.id = V4L2_CID_BRIGHTNESS;
436 control.value = queryctrl.default_value;
437
438 if (-1 == ioctl (fd, &VIDIOC-S-CTRL;, &amp;control)) {
439 perror ("VIDIOC_S_CTRL");
440 exit (EXIT_FAILURE);
441 }
442}
443
444memset (&amp;control, 0, sizeof (control));
445control.id = V4L2_CID_CONTRAST;
446
447if (0 == ioctl (fd, &VIDIOC-G-CTRL;, &amp;control)) {
448 control.value += 1;
449
450 /* The driver may clamp the value or return ERANGE, ignored here */
451
452 if (-1 == ioctl (fd, &VIDIOC-S-CTRL;, &amp;control)
453 &amp;&amp; errno != ERANGE) {
454 perror ("VIDIOC_S_CTRL");
455 exit (EXIT_FAILURE);
456 }
457/* Ignore if V4L2_CID_CONTRAST is unsupported */
458} else if (errno != EINVAL) {
459 perror ("VIDIOC_G_CTRL");
460 exit (EXIT_FAILURE);
461}
462
463control.id = V4L2_CID_AUDIO_MUTE;
464control.value = TRUE; /* silence */
465
466/* Errors ignored */
467ioctl (fd, VIDIOC_S_CTRL, &amp;control);
468</programlisting>
469 </example>
470 </section>
471
472 <section id="extended-controls">
473 <title>Extended Controls</title>
474
475 <section>
476 <title>Introduction</title>
477
478 <para>The control mechanism as originally designed was meant
479to be used for user settings (brightness, saturation, etc). However,
480it turned out to be a very useful model for implementing more
481complicated driver APIs where each driver implements only a subset of
482a larger API.</para>
483
484 <para>The MPEG encoding API was the driving force behind
485designing and implementing this extended control mechanism: the MPEG
486standard is quite large and the currently supported hardware MPEG
487encoders each only implement a subset of this standard. Further more,
488many parameters relating to how the video is encoded into an MPEG
489stream are specific to the MPEG encoding chip since the MPEG standard
490only defines the format of the resulting MPEG stream, not how the
491video is actually encoded into that format.</para>
492
493 <para>Unfortunately, the original control API lacked some
494features needed for these new uses and so it was extended into the
495(not terribly originally named) extended control API.</para>
496
497 <para>Even though the MPEG encoding API was the first effort
498to use the Extended Control API, nowadays there are also other classes
499of Extended Controls, such as Camera Controls and FM Transmitter Controls.
500The Extended Controls API as well as all Extended Controls classes are
501described in the following text.</para>
502 </section>
503
504 <section>
505 <title>The Extended Control API</title>
506
507 <para>Three new ioctls are available: &VIDIOC-G-EXT-CTRLS;,
508&VIDIOC-S-EXT-CTRLS; and &VIDIOC-TRY-EXT-CTRLS;. These ioctls act on
509arrays of controls (as opposed to the &VIDIOC-G-CTRL; and
510&VIDIOC-S-CTRL; ioctls that act on a single control). This is needed
511since it is often required to atomically change several controls at
512once.</para>
513
514 <para>Each of the new ioctls expects a pointer to a
515&v4l2-ext-controls;. This structure contains a pointer to the control
516array, a count of the number of controls in that array and a control
517class. Control classes are used to group similar controls into a
518single class. For example, control class
519<constant>V4L2_CTRL_CLASS_USER</constant> contains all user controls
520(&ie; all controls that can also be set using the old
521<constant>VIDIOC_S_CTRL</constant> ioctl). Control class
522<constant>V4L2_CTRL_CLASS_MPEG</constant> contains all controls
523relating to MPEG encoding, etc.</para>
524
525 <para>All controls in the control array must belong to the
526specified control class. An error is returned if this is not the
527case.</para>
528
529 <para>It is also possible to use an empty control array (count
530== 0) to check whether the specified control class is
531supported.</para>
532
533 <para>The control array is a &v4l2-ext-control; array. The
534<structname>v4l2_ext_control</structname> structure is very similar to
535&v4l2-control;, except for the fact that it also allows for 64-bit
536values and pointers to be passed.</para>
537
538 <para>It is important to realize that due to the flexibility of
539controls it is necessary to check whether the control you want to set
540actually is supported in the driver and what the valid range of values
541is. So use the &VIDIOC-QUERYCTRL; and &VIDIOC-QUERYMENU; ioctls to
542check this. Also note that it is possible that some of the menu
543indices in a control of type <constant>V4L2_CTRL_TYPE_MENU</constant>
544may not be supported (<constant>VIDIOC_QUERYMENU</constant> will
545return an error). A good example is the list of supported MPEG audio
546bitrates. Some drivers only support one or two bitrates, others
547support a wider range.</para>
548 </section>
549
550 <section>
551 <title>Enumerating Extended Controls</title>
552
553 <para>The recommended way to enumerate over the extended
554controls is by using &VIDIOC-QUERYCTRL; in combination with the
555<constant>V4L2_CTRL_FLAG_NEXT_CTRL</constant> flag:</para>
556
557 <informalexample>
558 <programlisting>
559&v4l2-queryctrl; qctrl;
560
561qctrl.id = V4L2_CTRL_FLAG_NEXT_CTRL;
562while (0 == ioctl (fd, &VIDIOC-QUERYCTRL;, &amp;qctrl)) {
563 /* ... */
564 qctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL;
565}
566</programlisting>
567 </informalexample>
568
569 <para>The initial control ID is set to 0 ORed with the
570<constant>V4L2_CTRL_FLAG_NEXT_CTRL</constant> flag. The
571<constant>VIDIOC_QUERYCTRL</constant> ioctl will return the first
572control with a higher ID than the specified one. When no such controls
573are found an error is returned.</para>
574
575 <para>If you want to get all controls within a specific control
576class, then you can set the initial
577<structfield>qctrl.id</structfield> value to the control class and add
578an extra check to break out of the loop when a control of another
579control class is found:</para>
580
581 <informalexample>
582 <programlisting>
583qctrl.id = V4L2_CTRL_CLASS_MPEG | V4L2_CTRL_FLAG_NEXT_CTRL;
584while (0 == ioctl (fd, &VIDIOC-QUERYCTRL;, &amp;qctrl)) {
585 if (V4L2_CTRL_ID2CLASS (qctrl.id) != V4L2_CTRL_CLASS_MPEG)
586 break;
587 /* ... */
588 qctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL;
589 }
590</programlisting>
591 </informalexample>
592
593 <para>The 32-bit <structfield>qctrl.id</structfield> value is
594subdivided into three bit ranges: the top 4 bits are reserved for
595flags (&eg; <constant>V4L2_CTRL_FLAG_NEXT_CTRL</constant>) and are not
596actually part of the ID. The remaining 28 bits form the control ID, of
597which the most significant 12 bits define the control class and the
598least significant 16 bits identify the control within the control
599class. It is guaranteed that these last 16 bits are always non-zero
600for controls. The range of 0x1000 and up are reserved for
601driver-specific controls. The macro
602<constant>V4L2_CTRL_ID2CLASS(id)</constant> returns the control class
603ID based on a control ID.</para>
604
605 <para>If the driver does not support extended controls, then
606<constant>VIDIOC_QUERYCTRL</constant> will fail when used in
607combination with <constant>V4L2_CTRL_FLAG_NEXT_CTRL</constant>. In
608that case the old method of enumerating control should be used (see
6091.8). But if it is supported, then it is guaranteed to enumerate over
610all controls, including driver-private controls.</para>
611 </section>
612
613 <section>
614 <title>Creating Control Panels</title>
615
616 <para>It is possible to create control panels for a graphical
617user interface where the user can select the various controls.
618Basically you will have to iterate over all controls using the method
619described above. Each control class starts with a control of type
620<constant>V4L2_CTRL_TYPE_CTRL_CLASS</constant>.
621<constant>VIDIOC_QUERYCTRL</constant> will return the name of this
622control class which can be used as the title of a tab page within a
623control panel.</para>
624
625 <para>The flags field of &v4l2-queryctrl; also contains hints on
626the behavior of the control. See the &VIDIOC-QUERYCTRL; documentation
627for more details.</para>
628 </section>
629
630 <section id="mpeg-controls">
631 <title>MPEG Control Reference</title>
632
633 <para>Below all controls within the MPEG control class are
634described. First the generic controls, then controls specific for
635certain hardware.</para>
636
637 <section>
638 <title>Generic MPEG Controls</title>
639
640 <table pgwide="1" frame="none" id="mpeg-control-id">
641 <title>MPEG Control IDs</title>
642 <tgroup cols="4">
643 <colspec colname="c1" colwidth="1*" />
644 <colspec colname="c2" colwidth="6*" />
645 <colspec colname="c3" colwidth="2*" />
646 <colspec colname="c4" colwidth="6*" />
647 <spanspec namest="c1" nameend="c2" spanname="id" />
648 <spanspec namest="c2" nameend="c4" spanname="descr" />
649 <thead>
650 <row>
651 <entry spanname="id" align="left">ID</entry>
652 <entry align="left">Type</entry>
653 </row><row rowsep="1"><entry spanname="descr" align="left">Description</entry>
654 </row>
655 </thead>
656 <tbody valign="top">
657 <row><entry></entry></row>
658 <row>
659 <entry spanname="id"><constant>V4L2_CID_MPEG_CLASS</constant>&nbsp;</entry>
660 <entry>class</entry>
661 </row><row><entry spanname="descr">The MPEG class
662descriptor. Calling &VIDIOC-QUERYCTRL; for this control will return a
663description of this control class. This description can be used as the
664caption of a Tab page in a GUI, for example.</entry>
665 </row>
666 <row><entry></entry></row>
667 <row id="v4l2-mpeg-stream-type">
668 <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_TYPE</constant>&nbsp;</entry>
669 <entry>enum&nbsp;v4l2_mpeg_stream_type</entry>
670 </row><row><entry spanname="descr">The MPEG-1, -2 or -4
671output stream type. One cannot assume anything here. Each hardware
672MPEG encoder tends to support different subsets of the available MPEG
673stream types. The currently defined stream types are:</entry>
674 </row>
675 <row>
676 <entrytbl spanname="descr" cols="2">
677 <tbody valign="top">
678 <row>
679 <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG2_PS</constant>&nbsp;</entry>
680 <entry>MPEG-2 program stream</entry>
681 </row>
682 <row>
683 <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG2_TS</constant>&nbsp;</entry>
684 <entry>MPEG-2 transport stream</entry>
685 </row>
686 <row>
687 <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG1_SS</constant>&nbsp;</entry>
688 <entry>MPEG-1 system stream</entry>
689 </row>
690 <row>
691 <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG2_DVD</constant>&nbsp;</entry>
692 <entry>MPEG-2 DVD-compatible stream</entry>
693 </row>
694 <row>
695 <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG1_VCD</constant>&nbsp;</entry>
696 <entry>MPEG-1 VCD-compatible stream</entry>
697 </row>
698 <row>
699 <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG2_SVCD</constant>&nbsp;</entry>
700 <entry>MPEG-2 SVCD-compatible stream</entry>
701 </row>
702 </tbody>
703 </entrytbl>
704 </row>
705 <row><entry></entry></row>
706 <row>
707 <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PID_PMT</constant>&nbsp;</entry>
708 <entry>integer</entry>
709 </row><row><entry spanname="descr">Program Map Table
710Packet ID for the MPEG transport stream (default 16)</entry>
711 </row>
712 <row><entry></entry></row>
713 <row>
714 <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PID_AUDIO</constant>&nbsp;</entry>
715 <entry>integer</entry>
716 </row><row><entry spanname="descr">Audio Packet ID for
717the MPEG transport stream (default 256)</entry>
718 </row>
719 <row><entry></entry></row>
720 <row>
721 <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PID_VIDEO</constant>&nbsp;</entry>
722 <entry>integer</entry>
723 </row><row><entry spanname="descr">Video Packet ID for
724the MPEG transport stream (default 260)</entry>
725 </row>
726 <row><entry></entry></row>
727 <row>
728 <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PID_PCR</constant>&nbsp;</entry>
729 <entry>integer</entry>
730 </row><row><entry spanname="descr">Packet ID for the
731MPEG transport stream carrying PCR fields (default 259)</entry>
732 </row>
733 <row><entry></entry></row>
734 <row>
735 <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PES_ID_AUDIO</constant>&nbsp;</entry>
736 <entry>integer</entry>
737 </row><row><entry spanname="descr">Audio ID for MPEG
738PES</entry>
739 </row>
740 <row><entry></entry></row>
741 <row>
742 <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PES_ID_VIDEO</constant>&nbsp;</entry>
743 <entry>integer</entry>
744 </row><row><entry spanname="descr">Video ID for MPEG
745PES</entry>
746 </row>
747 <row><entry></entry></row>
748 <row id="v4l2-mpeg-stream-vbi-fmt">
749 <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_VBI_FMT</constant>&nbsp;</entry>
750 <entry>enum&nbsp;v4l2_mpeg_stream_vbi_fmt</entry>
751 </row><row><entry spanname="descr">Some cards can embed
752VBI data (&eg; Closed Caption, Teletext) into the MPEG stream. This
753control selects whether VBI data should be embedded, and if so, what
754embedding method should be used. The list of possible VBI formats
755depends on the driver. The currently defined VBI format types
756are:</entry>
757 </row>
758 <row>
759 <entrytbl spanname="descr" cols="2">
760 <tbody valign="top">
761 <row>
762 <entry><constant>V4L2_MPEG_STREAM_VBI_FMT_NONE</constant>&nbsp;</entry>
763 <entry>No VBI in the MPEG stream</entry>
764 </row>
765 <row>
766 <entry><constant>V4L2_MPEG_STREAM_VBI_FMT_IVTV</constant>&nbsp;</entry>
767 <entry>VBI in private packets, IVTV format (documented
768in the kernel sources in the file <filename>Documentation/video4linux/cx2341x/README.vbi</filename>)</entry>
769 </row>
770 </tbody>
771 </entrytbl>
772 </row>
773 <row><entry></entry></row>
774 <row id="v4l2-mpeg-audio-sampling-freq">
775 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_SAMPLING_FREQ</constant>&nbsp;</entry>
776 <entry>enum&nbsp;v4l2_mpeg_audio_sampling_freq</entry>
777 </row><row><entry spanname="descr">MPEG Audio sampling
778frequency. Possible values are:</entry>
779 </row>
780 <row>
781 <entrytbl spanname="descr" cols="2">
782 <tbody valign="top">
783 <row>
784 <entry><constant>V4L2_MPEG_AUDIO_SAMPLING_FREQ_44100</constant>&nbsp;</entry>
785 <entry>44.1 kHz</entry>
786 </row>
787 <row>
788 <entry><constant>V4L2_MPEG_AUDIO_SAMPLING_FREQ_48000</constant>&nbsp;</entry>
789 <entry>48 kHz</entry>
790 </row>
791 <row>
792 <entry><constant>V4L2_MPEG_AUDIO_SAMPLING_FREQ_32000</constant>&nbsp;</entry>
793 <entry>32 kHz</entry>
794 </row>
795 </tbody>
796 </entrytbl>
797 </row>
798 <row><entry></entry></row>
799 <row id="v4l2-mpeg-audio-encoding">
800 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_ENCODING</constant>&nbsp;</entry>
801 <entry>enum&nbsp;v4l2_mpeg_audio_encoding</entry>
802 </row><row><entry spanname="descr">MPEG Audio encoding.
803Possible values are:</entry>
804 </row>
805 <row>
806 <entrytbl spanname="descr" cols="2">
807 <tbody valign="top">
808 <row>
809 <entry><constant>V4L2_MPEG_AUDIO_ENCODING_LAYER_1</constant>&nbsp;</entry>
810 <entry>MPEG-1/2 Layer I encoding</entry>
811 </row>
812 <row>
813 <entry><constant>V4L2_MPEG_AUDIO_ENCODING_LAYER_2</constant>&nbsp;</entry>
814 <entry>MPEG-1/2 Layer II encoding</entry>
815 </row>
816 <row>
817 <entry><constant>V4L2_MPEG_AUDIO_ENCODING_LAYER_3</constant>&nbsp;</entry>
818 <entry>MPEG-1/2 Layer III encoding</entry>
819 </row>
820 <row>
821 <entry><constant>V4L2_MPEG_AUDIO_ENCODING_AAC</constant>&nbsp;</entry>
822 <entry>MPEG-2/4 AAC (Advanced Audio Coding)</entry>
823 </row>
824 <row>
825 <entry><constant>V4L2_MPEG_AUDIO_ENCODING_AC3</constant>&nbsp;</entry>
826 <entry>AC-3 aka ATSC A/52 encoding</entry>
827 </row>
828 </tbody>
829 </entrytbl>
830 </row>
831 <row><entry></entry></row>
832 <row id="v4l2-mpeg-audio-l1-bitrate">
833 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_L1_BITRATE</constant>&nbsp;</entry>
834 <entry>enum&nbsp;v4l2_mpeg_audio_l1_bitrate</entry>
835 </row><row><entry spanname="descr">MPEG-1/2 Layer I bitrate.
836Possible values are:</entry>
837 </row>
838 <row>
839 <entrytbl spanname="descr" cols="2">
840 <tbody valign="top">
841 <row>
842 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_32K</constant>&nbsp;</entry>
843 <entry>32 kbit/s</entry></row>
844 <row>
845 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_64K</constant>&nbsp;</entry>
846 <entry>64 kbit/s</entry>
847 </row>
848 <row>
849 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_96K</constant>&nbsp;</entry>
850 <entry>96 kbit/s</entry>
851 </row>
852 <row>
853 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_128K</constant>&nbsp;</entry>
854 <entry>128 kbit/s</entry>
855 </row>
856 <row>
857 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_160K</constant>&nbsp;</entry>
858 <entry>160 kbit/s</entry>
859 </row>
860 <row>
861 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_192K</constant>&nbsp;</entry>
862 <entry>192 kbit/s</entry>
863 </row>
864 <row>
865 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_224K</constant>&nbsp;</entry>
866 <entry>224 kbit/s</entry>
867 </row>
868 <row>
869 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_256K</constant>&nbsp;</entry>
870 <entry>256 kbit/s</entry>
871 </row>
872 <row>
873 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_288K</constant>&nbsp;</entry>
874 <entry>288 kbit/s</entry>
875 </row>
876 <row>
877 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_320K</constant>&nbsp;</entry>
878 <entry>320 kbit/s</entry>
879 </row>
880 <row>
881 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_352K</constant>&nbsp;</entry>
882 <entry>352 kbit/s</entry>
883 </row>
884 <row>
885 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_384K</constant>&nbsp;</entry>
886 <entry>384 kbit/s</entry>
887 </row>
888 <row>
889 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_416K</constant>&nbsp;</entry>
890 <entry>416 kbit/s</entry>
891 </row>
892 <row>
893 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_448K</constant>&nbsp;</entry>
894 <entry>448 kbit/s</entry>
895 </row>
896 </tbody>
897 </entrytbl>
898 </row>
899 <row><entry></entry></row>
900 <row id="v4l2-mpeg-audio-l2-bitrate">
901 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_L2_BITRATE</constant>&nbsp;</entry>
902 <entry>enum&nbsp;v4l2_mpeg_audio_l2_bitrate</entry>
903 </row><row><entry spanname="descr">MPEG-1/2 Layer II bitrate.
904Possible values are:</entry>
905 </row>
906 <row>
907 <entrytbl spanname="descr" cols="2">
908 <tbody valign="top">
909 <row>
910 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_32K</constant>&nbsp;</entry>
911 <entry>32 kbit/s</entry>
912 </row>
913 <row>
914 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_48K</constant>&nbsp;</entry>
915 <entry>48 kbit/s</entry>
916 </row>
917 <row>
918 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_56K</constant>&nbsp;</entry>
919 <entry>56 kbit/s</entry>
920 </row>
921 <row>
922 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_64K</constant>&nbsp;</entry>
923 <entry>64 kbit/s</entry>
924 </row>
925 <row>
926 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_80K</constant>&nbsp;</entry>
927 <entry>80 kbit/s</entry>
928 </row>
929 <row>
930 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_96K</constant>&nbsp;</entry>
931 <entry>96 kbit/s</entry>
932 </row>
933 <row>
934 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_112K</constant>&nbsp;</entry>
935 <entry>112 kbit/s</entry>
936 </row>
937 <row>
938 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_128K</constant>&nbsp;</entry>
939 <entry>128 kbit/s</entry>
940 </row>
941 <row>
942 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_160K</constant>&nbsp;</entry>
943 <entry>160 kbit/s</entry>
944 </row>
945 <row>
946 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_192K</constant>&nbsp;</entry>
947 <entry>192 kbit/s</entry>
948 </row>
949 <row>
950 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_224K</constant>&nbsp;</entry>
951 <entry>224 kbit/s</entry>
952 </row>
953 <row>
954 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_256K</constant>&nbsp;</entry>
955 <entry>256 kbit/s</entry>
956 </row>
957 <row>
958 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_320K</constant>&nbsp;</entry>
959 <entry>320 kbit/s</entry>
960 </row>
961 <row>
962 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_384K</constant>&nbsp;</entry>
963 <entry>384 kbit/s</entry>
964 </row>
965 </tbody>
966 </entrytbl>
967 </row>
968 <row><entry></entry></row>
969 <row id="v4l2-mpeg-audio-l3-bitrate">
970 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_L3_BITRATE</constant>&nbsp;</entry>
971 <entry>enum&nbsp;v4l2_mpeg_audio_l3_bitrate</entry>
972 </row><row><entry spanname="descr">MPEG-1/2 Layer III bitrate.
973Possible values are:</entry>
974 </row>
975 <row>
976 <entrytbl spanname="descr" cols="2">
977 <tbody valign="top">
978 <row>
979 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_32K</constant>&nbsp;</entry>
980 <entry>32 kbit/s</entry>
981 </row>
982 <row>
983 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_40K</constant>&nbsp;</entry>
984 <entry>40 kbit/s</entry>
985 </row>
986 <row>
987 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_48K</constant>&nbsp;</entry>
988 <entry>48 kbit/s</entry>
989 </row>
990 <row>
991 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_56K</constant>&nbsp;</entry>
992 <entry>56 kbit/s</entry>
993 </row>
994 <row>
995 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_64K</constant>&nbsp;</entry>
996 <entry>64 kbit/s</entry>
997 </row>
998 <row>
999 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_80K</constant>&nbsp;</entry>
1000 <entry>80 kbit/s</entry>
1001 </row>
1002 <row>
1003 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_96K</constant>&nbsp;</entry>
1004 <entry>96 kbit/s</entry>
1005 </row>
1006 <row>
1007 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_112K</constant>&nbsp;</entry>
1008 <entry>112 kbit/s</entry>
1009 </row>
1010 <row>
1011 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_128K</constant>&nbsp;</entry>
1012 <entry>128 kbit/s</entry>
1013 </row>
1014 <row>
1015 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_160K</constant>&nbsp;</entry>
1016 <entry>160 kbit/s</entry>
1017 </row>
1018 <row>
1019 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_192K</constant>&nbsp;</entry>
1020 <entry>192 kbit/s</entry>
1021 </row>
1022 <row>
1023 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_224K</constant>&nbsp;</entry>
1024 <entry>224 kbit/s</entry>
1025 </row>
1026 <row>
1027 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_256K</constant>&nbsp;</entry>
1028 <entry>256 kbit/s</entry>
1029 </row>
1030 <row>
1031 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_320K</constant>&nbsp;</entry>
1032 <entry>320 kbit/s</entry>
1033 </row>
1034 </tbody>
1035 </entrytbl>
1036 </row>
1037 <row><entry></entry></row>
1038 <row>
1039 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_AAC_BITRATE</constant>&nbsp;</entry>
1040 <entry>integer</entry>
1041 </row><row><entry spanname="descr">AAC bitrate in bits per second.</entry>
1042 </row>
1043 <row><entry></entry></row>
1044 <row id="v4l2-mpeg-audio-ac3-bitrate">
1045 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_AC3_BITRATE</constant>&nbsp;</entry>
1046 <entry>enum&nbsp;v4l2_mpeg_audio_ac3_bitrate</entry>
1047 </row><row><entry spanname="descr">AC-3 bitrate.
1048Possible values are:</entry>
1049 </row>
1050 <row>
1051 <entrytbl spanname="descr" cols="2">
1052 <tbody valign="top">
1053 <row>
1054 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_32K</constant>&nbsp;</entry>
1055 <entry>32 kbit/s</entry>
1056 </row>
1057 <row>
1058 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_40K</constant>&nbsp;</entry>
1059 <entry>40 kbit/s</entry>
1060 </row>
1061 <row>
1062 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_48K</constant>&nbsp;</entry>
1063 <entry>48 kbit/s</entry>
1064 </row>
1065 <row>
1066 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_56K</constant>&nbsp;</entry>
1067 <entry>56 kbit/s</entry>
1068 </row>
1069 <row>
1070 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_64K</constant>&nbsp;</entry>
1071 <entry>64 kbit/s</entry>
1072 </row>
1073 <row>
1074 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_80K</constant>&nbsp;</entry>
1075 <entry>80 kbit/s</entry>
1076 </row>
1077 <row>
1078 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_96K</constant>&nbsp;</entry>
1079 <entry>96 kbit/s</entry>
1080 </row>
1081 <row>
1082 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_112K</constant>&nbsp;</entry>
1083 <entry>112 kbit/s</entry>
1084 </row>
1085 <row>
1086 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_128K</constant>&nbsp;</entry>
1087 <entry>128 kbit/s</entry>
1088 </row>
1089 <row>
1090 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_160K</constant>&nbsp;</entry>
1091 <entry>160 kbit/s</entry>
1092 </row>
1093 <row>
1094 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_192K</constant>&nbsp;</entry>
1095 <entry>192 kbit/s</entry>
1096 </row>
1097 <row>
1098 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_224K</constant>&nbsp;</entry>
1099 <entry>224 kbit/s</entry>
1100 </row>
1101 <row>
1102 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_256K</constant>&nbsp;</entry>
1103 <entry>256 kbit/s</entry>
1104 </row>
1105 <row>
1106 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_320K</constant>&nbsp;</entry>
1107 <entry>320 kbit/s</entry>
1108 </row>
1109 <row>
1110 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_384K</constant>&nbsp;</entry>
1111 <entry>384 kbit/s</entry>
1112 </row>
1113 <row>
1114 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_448K</constant>&nbsp;</entry>
1115 <entry>448 kbit/s</entry>
1116 </row>
1117 <row>
1118 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_512K</constant>&nbsp;</entry>
1119 <entry>512 kbit/s</entry>
1120 </row>
1121 <row>
1122 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_576K</constant>&nbsp;</entry>
1123 <entry>576 kbit/s</entry>
1124 </row>
1125 <row>
1126 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_640K</constant>&nbsp;</entry>
1127 <entry>640 kbit/s</entry>
1128 </row>
1129 </tbody>
1130 </entrytbl>
1131 </row>
1132 <row><entry></entry></row>
1133 <row id="v4l2-mpeg-audio-mode">
1134 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_MODE</constant>&nbsp;</entry>
1135 <entry>enum&nbsp;v4l2_mpeg_audio_mode</entry>
1136 </row><row><entry spanname="descr">MPEG Audio mode.
1137Possible values are:</entry>
1138 </row>
1139 <row>
1140 <entrytbl spanname="descr" cols="2">
1141 <tbody valign="top">
1142 <row>
1143 <entry><constant>V4L2_MPEG_AUDIO_MODE_STEREO</constant>&nbsp;</entry>
1144 <entry>Stereo</entry>
1145 </row>
1146 <row>
1147 <entry><constant>V4L2_MPEG_AUDIO_MODE_JOINT_STEREO</constant>&nbsp;</entry>
1148 <entry>Joint Stereo</entry>
1149 </row>
1150 <row>
1151 <entry><constant>V4L2_MPEG_AUDIO_MODE_DUAL</constant>&nbsp;</entry>
1152 <entry>Bilingual</entry>
1153 </row>
1154 <row>
1155 <entry><constant>V4L2_MPEG_AUDIO_MODE_MONO</constant>&nbsp;</entry>
1156 <entry>Mono</entry>
1157 </row>
1158 </tbody>
1159 </entrytbl>
1160 </row>
1161 <row><entry></entry></row>
1162 <row id="v4l2-mpeg-audio-mode-extension">
1163 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_MODE_EXTENSION</constant>&nbsp;</entry>
1164 <entry>enum&nbsp;v4l2_mpeg_audio_mode_extension</entry>
1165 </row><row><entry spanname="descr">Joint Stereo
1166audio mode extension. In Layer I and II they indicate which subbands
1167are in intensity stereo. All other subbands are coded in stereo. Layer
1168III is not (yet) supported. Possible values
1169are:</entry>
1170 </row>
1171 <row>
1172 <entrytbl spanname="descr" cols="2">
1173 <tbody valign="top">
1174 <row>
1175 <entry><constant>V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_4</constant>&nbsp;</entry>
1176 <entry>Subbands 4-31 in intensity stereo</entry>
1177 </row>
1178 <row>
1179 <entry><constant>V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_8</constant>&nbsp;</entry>
1180 <entry>Subbands 8-31 in intensity stereo</entry>
1181 </row>
1182 <row>
1183 <entry><constant>V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_12</constant>&nbsp;</entry>
1184 <entry>Subbands 12-31 in intensity stereo</entry>
1185 </row>
1186 <row>
1187 <entry><constant>V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_16</constant>&nbsp;</entry>
1188 <entry>Subbands 16-31 in intensity stereo</entry>
1189 </row>
1190 </tbody>
1191 </entrytbl>
1192 </row>
1193 <row><entry></entry></row>
1194 <row id="v4l2-mpeg-audio-emphasis">
1195 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_EMPHASIS</constant>&nbsp;</entry>
1196 <entry>enum&nbsp;v4l2_mpeg_audio_emphasis</entry>
1197 </row><row><entry spanname="descr">Audio Emphasis.
1198Possible values are:</entry>
1199 </row>
1200 <row>
1201 <entrytbl spanname="descr" cols="2">
1202 <tbody valign="top">
1203 <row>
1204 <entry><constant>V4L2_MPEG_AUDIO_EMPHASIS_NONE</constant>&nbsp;</entry>
1205 <entry>None</entry>
1206 </row>
1207 <row>
1208 <entry><constant>V4L2_MPEG_AUDIO_EMPHASIS_50_DIV_15_uS</constant>&nbsp;</entry>
1209 <entry>50/15 microsecond emphasis</entry>
1210 </row>
1211 <row>
1212 <entry><constant>V4L2_MPEG_AUDIO_EMPHASIS_CCITT_J17</constant>&nbsp;</entry>
1213 <entry>CCITT J.17</entry>
1214 </row>
1215 </tbody>
1216 </entrytbl>
1217 </row>
1218 <row><entry></entry></row>
1219 <row id="v4l2-mpeg-audio-crc">
1220 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_CRC</constant>&nbsp;</entry>
1221 <entry>enum&nbsp;v4l2_mpeg_audio_crc</entry>
1222 </row><row><entry spanname="descr">CRC method. Possible
1223values are:</entry>
1224 </row>
1225 <row>
1226 <entrytbl spanname="descr" cols="2">
1227 <tbody valign="top">
1228 <row>
1229 <entry><constant>V4L2_MPEG_AUDIO_CRC_NONE</constant>&nbsp;</entry>
1230 <entry>None</entry>
1231 </row>
1232 <row>
1233 <entry><constant>V4L2_MPEG_AUDIO_CRC_CRC16</constant>&nbsp;</entry>
1234 <entry>16 bit parity check</entry>
1235 </row>
1236 </tbody>
1237 </entrytbl>
1238 </row>
1239 <row><entry></entry></row>
1240 <row>
1241 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_MUTE</constant>&nbsp;</entry>
1242 <entry>boolean</entry>
1243 </row><row><entry spanname="descr">Mutes the audio when
1244capturing. This is not done by muting audio hardware, which can still
1245produce a slight hiss, but in the encoder itself, guaranteeing a fixed
1246and reproducible audio bitstream. 0 = unmuted, 1 = muted.</entry>
1247 </row>
1248 <row><entry></entry></row>
1249 <row id="v4l2-mpeg-video-encoding">
1250 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_ENCODING</constant>&nbsp;</entry>
1251 <entry>enum&nbsp;v4l2_mpeg_video_encoding</entry>
1252 </row><row><entry spanname="descr">MPEG Video encoding
1253method. Possible values are:</entry>
1254 </row>
1255 <row>
1256 <entrytbl spanname="descr" cols="2">
1257 <tbody valign="top">
1258 <row>
1259 <entry><constant>V4L2_MPEG_VIDEO_ENCODING_MPEG_1</constant>&nbsp;</entry>
1260 <entry>MPEG-1 Video encoding</entry>
1261 </row>
1262 <row>
1263 <entry><constant>V4L2_MPEG_VIDEO_ENCODING_MPEG_2</constant>&nbsp;</entry>
1264 <entry>MPEG-2 Video encoding</entry>
1265 </row>
1266 <row>
1267 <entry><constant>V4L2_MPEG_VIDEO_ENCODING_MPEG_4_AVC</constant>&nbsp;</entry>
1268 <entry>MPEG-4 AVC (H.264) Video encoding</entry>
1269 </row>
1270 </tbody>
1271 </entrytbl>
1272 </row>
1273 <row><entry></entry></row>
1274 <row id="v4l2-mpeg-video-aspect">
1275 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_ASPECT</constant>&nbsp;</entry>
1276 <entry>enum&nbsp;v4l2_mpeg_video_aspect</entry>
1277 </row><row><entry spanname="descr">Video aspect.
1278Possible values are:</entry>
1279 </row>
1280 <row>
1281 <entrytbl spanname="descr" cols="2">
1282 <tbody valign="top">
1283 <row>
1284 <entry><constant>V4L2_MPEG_VIDEO_ASPECT_1x1</constant>&nbsp;</entry>
1285 </row>
1286 <row>
1287 <entry><constant>V4L2_MPEG_VIDEO_ASPECT_4x3</constant>&nbsp;</entry>
1288 </row>
1289 <row>
1290 <entry><constant>V4L2_MPEG_VIDEO_ASPECT_16x9</constant>&nbsp;</entry>
1291 </row>
1292 <row>
1293 <entry><constant>V4L2_MPEG_VIDEO_ASPECT_221x100</constant>&nbsp;</entry>
1294 </row>
1295 </tbody>
1296 </entrytbl>
1297 </row>
1298 <row><entry></entry></row>
1299 <row>
1300 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_B_FRAMES</constant>&nbsp;</entry>
1301 <entry>integer</entry>
1302 </row><row><entry spanname="descr">Number of B-Frames
1303(default 2)</entry>
1304 </row>
1305 <row><entry></entry></row>
1306 <row>
1307 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_GOP_SIZE</constant>&nbsp;</entry>
1308 <entry>integer</entry>
1309 </row><row><entry spanname="descr">GOP size (default
131012)</entry>
1311 </row>
1312 <row><entry></entry></row>
1313 <row>
1314 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_GOP_CLOSURE</constant>&nbsp;</entry>
1315 <entry>boolean</entry>
1316 </row><row><entry spanname="descr">GOP closure (default
13171)</entry>
1318 </row>
1319 <row><entry></entry></row>
1320 <row>
1321 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_PULLDOWN</constant>&nbsp;</entry>
1322 <entry>boolean</entry>
1323 </row><row><entry spanname="descr">Enable 3:2 pulldown
1324(default 0)</entry>
1325 </row>
1326 <row><entry></entry></row>
1327 <row id="v4l2-mpeg-video-bitrate-mode">
1328 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_BITRATE_MODE</constant>&nbsp;</entry>
1329 <entry>enum&nbsp;v4l2_mpeg_video_bitrate_mode</entry>
1330 </row><row><entry spanname="descr">Video bitrate mode.
1331Possible values are:</entry>
1332 </row>
1333 <row>
1334 <entrytbl spanname="descr" cols="2">
1335 <tbody valign="top">
1336 <row>
1337 <entry><constant>V4L2_MPEG_VIDEO_BITRATE_MODE_VBR</constant>&nbsp;</entry>
1338 <entry>Variable bitrate</entry>
1339 </row>
1340 <row>
1341 <entry><constant>V4L2_MPEG_VIDEO_BITRATE_MODE_CBR</constant>&nbsp;</entry>
1342 <entry>Constant bitrate</entry>
1343 </row>
1344 </tbody>
1345 </entrytbl>
1346 </row>
1347 <row><entry></entry></row>
1348 <row>
1349 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_BITRATE</constant>&nbsp;</entry>
1350 <entry>integer</entry>
1351 </row><row><entry spanname="descr">Video bitrate in bits
1352per second.</entry>
1353 </row>
1354 <row><entry></entry></row>
1355 <row>
1356 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_BITRATE_PEAK</constant>&nbsp;</entry>
1357 <entry>integer</entry>
1358 </row><row><entry spanname="descr">Peak video bitrate in
1359bits per second. Must be larger or equal to the average video bitrate.
1360It is ignored if the video bitrate mode is set to constant
1361bitrate.</entry>
1362 </row>
1363 <row><entry></entry></row>
1364 <row>
1365 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_TEMPORAL_DECIMATION</constant>&nbsp;</entry>
1366 <entry>integer</entry>
1367 </row><row><entry spanname="descr">For every captured
1368frame, skip this many subsequent frames (default 0).</entry>
1369 </row>
1370 <row><entry></entry></row>
1371 <row>
1372 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_MUTE</constant>&nbsp;</entry>
1373 <entry>boolean</entry>
1374 </row>
1375 <row><entry spanname="descr">"Mutes" the video to a
1376fixed color when capturing. This is useful for testing, to produce a
1377fixed video bitstream. 0 = unmuted, 1 = muted.</entry>
1378 </row>
1379 <row><entry></entry></row>
1380 <row>
1381 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_MUTE_YUV</constant>&nbsp;</entry>
1382 <entry>integer</entry>
1383 </row><row><entry spanname="descr">Sets the "mute" color
1384of the video. The supplied 32-bit integer is interpreted as follows (bit
13850 = least significant bit):</entry>
1386 </row>
1387 <row>
1388 <entrytbl spanname="descr" cols="2">
1389 <tbody valign="top">
1390 <row>
1391 <entry>Bit 0:7</entry>
1392 <entry>V chrominance information</entry>
1393 </row>
1394 <row>
1395 <entry>Bit 8:15</entry>
1396 <entry>U chrominance information</entry>
1397 </row>
1398 <row>
1399 <entry>Bit 16:23</entry>
1400 <entry>Y luminance information</entry>
1401 </row>
1402 <row>
1403 <entry>Bit 24:31</entry>
1404 <entry>Must be zero.</entry>
1405 </row>
1406 </tbody>
1407 </entrytbl>
1408 </row>
1409 </tbody>
1410 </tgroup>
1411 </table>
1412 </section>
1413
1414 <section>
1415 <title>CX2341x MPEG Controls</title>
1416
1417 <para>The following MPEG class controls deal with MPEG
1418encoding settings that are specific to the Conexant CX23415 and
1419CX23416 MPEG encoding chips.</para>
1420
1421 <table pgwide="1" frame="none" id="cx2341x-control-id">
1422 <title>CX2341x Control IDs</title>
1423 <tgroup cols="4">
1424 <colspec colname="c1" colwidth="1*" />
1425 <colspec colname="c2" colwidth="6*" />
1426 <colspec colname="c3" colwidth="2*" />
1427 <colspec colname="c4" colwidth="6*" />
1428 <spanspec namest="c1" nameend="c2" spanname="id" />
1429 <spanspec namest="c2" nameend="c4" spanname="descr" />
1430 <thead>
1431 <row>
1432 <entry spanname="id" align="left">ID</entry>
1433 <entry align="left">Type</entry>
1434 </row><row><entry spanname="descr" align="left">Description</entry>
1435 </row>
1436 </thead>
1437 <tbody valign="top">
1438 <row><entry></entry></row>
1439 <row id="v4l2-mpeg-cx2341x-video-spatial-filter-mode">
1440 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE</constant>&nbsp;</entry>
1441 <entry>enum&nbsp;v4l2_mpeg_cx2341x_video_spatial_filter_mode</entry>
1442 </row><row><entry spanname="descr">Sets the Spatial
1443Filter mode (default <constant>MANUAL</constant>). Possible values
1444are:</entry>
1445 </row>
1446 <row>
1447 <entrytbl spanname="descr" cols="2">
1448 <tbody valign="top">
1449 <row>
1450 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE_MANUAL</constant>&nbsp;</entry>
1451 <entry>Choose the filter manually</entry>
1452 </row>
1453 <row>
1454 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE_AUTO</constant>&nbsp;</entry>
1455 <entry>Choose the filter automatically</entry>
1456 </row>
1457 </tbody>
1458 </entrytbl>
1459 </row>
1460 <row><entry></entry></row>
1461 <row>
1462 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER</constant>&nbsp;</entry>
1463 <entry>integer&nbsp;(0-15)</entry>
1464 </row><row><entry spanname="descr">The setting for the
1465Spatial Filter. 0 = off, 15 = maximum. (Default is 0.)</entry>
1466 </row>
1467 <row><entry></entry></row>
1468 <row id="luma-spatial-filter-type">
1469 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE</constant>&nbsp;</entry>
1470 <entry>enum&nbsp;v4l2_mpeg_cx2341x_video_luma_spatial_filter_type</entry>
1471 </row><row><entry spanname="descr">Select the algorithm
1472to use for the Luma Spatial Filter (default
1473<constant>1D_HOR</constant>). Possible values:</entry>
1474 </row>
1475 <row>
1476 <entrytbl spanname="descr" cols="2">
1477 <tbody valign="top">
1478 <row>
1479 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_OFF</constant>&nbsp;</entry>
1480 <entry>No filter</entry>
1481 </row>
1482 <row>
1483 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_1D_HOR</constant>&nbsp;</entry>
1484 <entry>One-dimensional horizontal</entry>
1485 </row>
1486 <row>
1487 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_1D_VERT</constant>&nbsp;</entry>
1488 <entry>One-dimensional vertical</entry>
1489 </row>
1490 <row>
1491 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_2D_HV_SEPARABLE</constant>&nbsp;</entry>
1492 <entry>Two-dimensional separable</entry>
1493 </row>
1494 <row>
1495 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_2D_SYM_NON_SEPARABLE</constant>&nbsp;</entry>
1496 <entry>Two-dimensional symmetrical
1497non-separable</entry>
1498 </row>
1499 </tbody>
1500 </entrytbl>
1501 </row>
1502 <row><entry></entry></row>
1503 <row id="chroma-spatial-filter-type">
1504 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE</constant>&nbsp;</entry>
1505 <entry>enum&nbsp;v4l2_mpeg_cx2341x_video_chroma_spatial_filter_type</entry>
1506 </row><row><entry spanname="descr">Select the algorithm
1507for the Chroma Spatial Filter (default <constant>1D_HOR</constant>).
1508Possible values are:</entry>
1509 </row>
1510 <row>
1511 <entrytbl spanname="descr" cols="2">
1512 <tbody valign="top">
1513 <row>
1514 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE_OFF</constant>&nbsp;</entry>
1515 <entry>No filter</entry>
1516 </row>
1517 <row>
1518 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE_1D_HOR</constant>&nbsp;</entry>
1519 <entry>One-dimensional horizontal</entry>
1520 </row>
1521 </tbody>
1522 </entrytbl>
1523 </row>
1524 <row><entry></entry></row>
1525 <row id="v4l2-mpeg-cx2341x-video-temporal-filter-mode">
1526 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE</constant>&nbsp;</entry>
1527 <entry>enum&nbsp;v4l2_mpeg_cx2341x_video_temporal_filter_mode</entry>
1528 </row><row><entry spanname="descr">Sets the Temporal
1529Filter mode (default <constant>MANUAL</constant>). Possible values
1530are:</entry>
1531 </row>
1532 <row>
1533 <entrytbl spanname="descr" cols="2">
1534 <tbody valign="top">
1535 <row>
1536 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE_MANUAL</constant>&nbsp;</entry>
1537 <entry>Choose the filter manually</entry>
1538 </row>
1539 <row>
1540 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE_AUTO</constant>&nbsp;</entry>
1541 <entry>Choose the filter automatically</entry>
1542 </row>
1543 </tbody>
1544 </entrytbl>
1545 </row>
1546 <row><entry></entry></row>
1547 <row>
1548 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER</constant>&nbsp;</entry>
1549 <entry>integer&nbsp;(0-31)</entry>
1550 </row><row><entry spanname="descr">The setting for the
1551Temporal Filter. 0 = off, 31 = maximum. (Default is 8 for full-scale
1552capturing and 0 for scaled capturing.)</entry>
1553 </row>
1554 <row><entry></entry></row>
1555 <row id="v4l2-mpeg-cx2341x-video-median-filter-type">
1556 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE</constant>&nbsp;</entry>
1557 <entry>enum&nbsp;v4l2_mpeg_cx2341x_video_median_filter_type</entry>
1558 </row><row><entry spanname="descr">Median Filter Type
1559(default <constant>OFF</constant>). Possible values are:</entry>
1560 </row>
1561 <row>
1562 <entrytbl spanname="descr" cols="2">
1563 <tbody valign="top">
1564 <row>
1565 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_OFF</constant>&nbsp;</entry>
1566 <entry>No filter</entry>
1567 </row>
1568 <row>
1569 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_HOR</constant>&nbsp;</entry>
1570 <entry>Horizontal filter</entry>
1571 </row>
1572 <row>
1573 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_VERT</constant>&nbsp;</entry>
1574 <entry>Vertical filter</entry>
1575 </row>
1576 <row>
1577 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_HOR_VERT</constant>&nbsp;</entry>
1578 <entry>Horizontal and vertical filter</entry>
1579 </row>
1580 <row>
1581 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_DIAG</constant>&nbsp;</entry>
1582 <entry>Diagonal filter</entry>
1583 </row>
1584 </tbody>
1585 </entrytbl>
1586 </row>
1587 <row><entry></entry></row>
1588 <row>
1589 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_MEDIAN_FILTER_BOTTOM</constant>&nbsp;</entry>
1590 <entry>integer&nbsp;(0-255)</entry>
1591 </row><row><entry spanname="descr">Threshold above which
1592the luminance median filter is enabled (default 0)</entry>
1593 </row>
1594 <row><entry></entry></row>
1595 <row>
1596 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_MEDIAN_FILTER_TOP</constant>&nbsp;</entry>
1597 <entry>integer&nbsp;(0-255)</entry>
1598 </row><row><entry spanname="descr">Threshold below which
1599the luminance median filter is enabled (default 255)</entry>
1600 </row>
1601 <row><entry></entry></row>
1602 <row>
1603 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_MEDIAN_FILTER_BOTTOM</constant>&nbsp;</entry>
1604 <entry>integer&nbsp;(0-255)</entry>
1605 </row><row><entry spanname="descr">Threshold above which
1606the chroma median filter is enabled (default 0)</entry>
1607 </row>
1608 <row><entry></entry></row>
1609 <row>
1610 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_MEDIAN_FILTER_TOP</constant>&nbsp;</entry>
1611 <entry>integer&nbsp;(0-255)</entry>
1612 </row><row><entry spanname="descr">Threshold below which
1613the chroma median filter is enabled (default 255)</entry>
1614 </row>
1615 <row><entry></entry></row>
1616 <row>
1617 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_STREAM_INSERT_NAV_PACKETS</constant>&nbsp;</entry>
1618 <entry>boolean</entry>
1619 </row>
1620 <row><entry spanname="descr">The CX2341X MPEG encoder
1621can insert one empty MPEG-2 PES packet into the stream between every
1622four video frames. The packet size is 2048 bytes, including the
1623packet_start_code_prefix and stream_id fields. The stream_id is 0xBF
1624(private stream 2). The payload consists of 0x00 bytes, to be filled
1625in by the application. 0 = do not insert, 1 = insert packets.</entry>
1626 </row>
1627 </tbody>
1628 </tgroup>
1629 </table>
1630 </section>
1631 </section>
1632
1633 <section id="camera-controls">
1634 <title>Camera Control Reference</title>
1635
1636 <para>The Camera class includes controls for mechanical (or
1637equivalent digital) features of a device such as controllable lenses
1638or sensors.</para>
1639
1640 <table pgwide="1" frame="none" id="camera-control-id">
1641 <title>Camera Control IDs</title>
1642 <tgroup cols="4">
1643 <colspec colname="c1" colwidth="1*" />
1644 <colspec colname="c2" colwidth="6*" />
1645 <colspec colname="c3" colwidth="2*" />
1646 <colspec colname="c4" colwidth="6*" />
1647 <spanspec namest="c1" nameend="c2" spanname="id" />
1648 <spanspec namest="c2" nameend="c4" spanname="descr" />
1649 <thead>
1650 <row>
1651 <entry spanname="id" align="left">ID</entry>
1652 <entry align="left">Type</entry>
1653 </row><row rowsep="1"><entry spanname="descr" align="left">Description</entry>
1654 </row>
1655 </thead>
1656 <tbody valign="top">
1657 <row><entry></entry></row>
1658 <row>
1659 <entry spanname="id"><constant>V4L2_CID_CAMERA_CLASS</constant>&nbsp;</entry>
1660 <entry>class</entry>
1661 </row><row><entry spanname="descr">The Camera class
1662descriptor. Calling &VIDIOC-QUERYCTRL; for this control will return a
1663description of this control class.</entry>
1664 </row>
1665 <row><entry></entry></row>
1666
1667 <row id="v4l2-exposure-auto-type">
1668 <entry spanname="id"><constant>V4L2_CID_EXPOSURE_AUTO</constant>&nbsp;</entry>
1669 <entry>enum&nbsp;v4l2_exposure_auto_type</entry>
1670 </row><row><entry spanname="descr">Enables automatic
1671adjustments of the exposure time and/or iris aperture. The effect of
1672manual changes of the exposure time or iris aperture while these
1673features are enabled is undefined, drivers should ignore such
1674requests. Possible values are:</entry>
1675 </row>
1676 <row>
1677 <entrytbl spanname="descr" cols="2">
1678 <tbody valign="top">
1679 <row>
1680 <entry><constant>V4L2_EXPOSURE_AUTO</constant>&nbsp;</entry>
1681 <entry>Automatic exposure time, automatic iris
1682aperture.</entry>
1683 </row>
1684 <row>
1685 <entry><constant>V4L2_EXPOSURE_MANUAL</constant>&nbsp;</entry>
1686 <entry>Manual exposure time, manual iris.</entry>
1687 </row>
1688 <row>
1689 <entry><constant>V4L2_EXPOSURE_SHUTTER_PRIORITY</constant>&nbsp;</entry>
1690 <entry>Manual exposure time, auto iris.</entry>
1691 </row>
1692 <row>
1693 <entry><constant>V4L2_EXPOSURE_APERTURE_PRIORITY</constant>&nbsp;</entry>
1694 <entry>Auto exposure time, manual iris.</entry>
1695 </row>
1696 </tbody>
1697 </entrytbl>
1698 </row>
1699 <row><entry></entry></row>
1700
1701 <row>
1702 <entry spanname="id"><constant>V4L2_CID_EXPOSURE_ABSOLUTE</constant>&nbsp;</entry>
1703 <entry>integer</entry>
1704 </row><row><entry spanname="descr">Determines the exposure
1705time of the camera sensor. The exposure time is limited by the frame
1706interval. Drivers should interpret the values as 100 &micro;s units,
1707where the value 1 stands for 1/10000th of a second, 10000 for 1 second
1708and 100000 for 10 seconds.</entry>
1709 </row>
1710 <row><entry></entry></row>
1711
1712 <row>
1713 <entry spanname="id"><constant>V4L2_CID_EXPOSURE_AUTO_PRIORITY</constant>&nbsp;</entry>
1714 <entry>boolean</entry>
1715 </row><row><entry spanname="descr">When
1716<constant>V4L2_CID_EXPOSURE_AUTO</constant> is set to
1717<constant>AUTO</constant> or <constant>APERTURE_PRIORITY</constant>,
1718this control determines if the device may dynamically vary the frame
1719rate. By default this feature is disabled (0) and the frame rate must
1720remain constant.</entry>
1721 </row>
1722 <row><entry></entry></row>
1723
1724 <row>
1725 <entry spanname="id"><constant>V4L2_CID_PAN_RELATIVE</constant>&nbsp;</entry>
1726 <entry>integer</entry>
1727 </row><row><entry spanname="descr">This control turns the
1728camera horizontally by the specified amount. The unit is undefined. A
1729positive value moves the camera to the right (clockwise when viewed
1730from above), a negative value to the left. A value of zero does not
1731cause motion. This is a write-only control.</entry>
1732 </row>
1733 <row><entry></entry></row>
1734
1735 <row>
1736 <entry spanname="id"><constant>V4L2_CID_TILT_RELATIVE</constant>&nbsp;</entry>
1737 <entry>integer</entry>
1738 </row><row><entry spanname="descr">This control turns the
1739camera vertically by the specified amount. The unit is undefined. A
1740positive value moves the camera up, a negative value down. A value of
1741zero does not cause motion. This is a write-only control.</entry>
1742 </row>
1743 <row><entry></entry></row>
1744
1745 <row>
1746 <entry spanname="id"><constant>V4L2_CID_PAN_RESET</constant>&nbsp;</entry>
1747 <entry>button</entry>
1748 </row><row><entry spanname="descr">When this control is set,
1749the camera moves horizontally to the default position.</entry>
1750 </row>
1751 <row><entry></entry></row>
1752
1753 <row>
1754 <entry spanname="id"><constant>V4L2_CID_TILT_RESET</constant>&nbsp;</entry>
1755 <entry>button</entry>
1756 </row><row><entry spanname="descr">When this control is set,
1757the camera moves vertically to the default position.</entry>
1758 </row>
1759 <row><entry></entry></row>
1760
1761 <row>
1762 <entry spanname="id"><constant>V4L2_CID_PAN_ABSOLUTE</constant>&nbsp;</entry>
1763 <entry>integer</entry>
1764 </row><row><entry spanname="descr">This control
1765turns the camera horizontally to the specified position. Positive
1766values move the camera to the right (clockwise when viewed from above),
1767negative values to the left. Drivers should interpret the values as arc
1768seconds, with valid values between -180 * 3600 and +180 * 3600
1769inclusive.</entry>
1770 </row>
1771 <row><entry></entry></row>
1772
1773 <row>
1774 <entry spanname="id"><constant>V4L2_CID_TILT_ABSOLUTE</constant>&nbsp;</entry>
1775 <entry>integer</entry>
1776 </row><row><entry spanname="descr">This control
1777turns the camera vertically to the specified position. Positive values
1778move the camera up, negative values down. Drivers should interpret the
1779values as arc seconds, with valid values between -180 * 3600 and +180
1780* 3600 inclusive.</entry>
1781 </row>
1782 <row><entry></entry></row>
1783
1784 <row>
1785 <entry spanname="id"><constant>V4L2_CID_FOCUS_ABSOLUTE</constant>&nbsp;</entry>
1786 <entry>integer</entry>
1787 </row><row><entry spanname="descr">This control sets the
1788focal point of the camera to the specified position. The unit is
1789undefined. Positive values set the focus closer to the camera,
1790negative values towards infinity.</entry>
1791 </row>
1792 <row><entry></entry></row>
1793
1794 <row>
1795 <entry spanname="id"><constant>V4L2_CID_FOCUS_RELATIVE</constant>&nbsp;</entry>
1796 <entry>integer</entry>
1797 </row><row><entry spanname="descr">This control moves the
1798focal point of the camera by the specified amount. The unit is
1799undefined. Positive values move the focus closer to the camera,
1800negative values towards infinity. This is a write-only control.</entry>
1801 </row>
1802 <row><entry></entry></row>
1803
1804 <row>
1805 <entry spanname="id"><constant>V4L2_CID_FOCUS_AUTO</constant>&nbsp;</entry>
1806 <entry>boolean</entry>
1807 </row><row><entry spanname="descr">Enables automatic focus
1808adjustments. The effect of manual focus adjustments while this feature
1809is enabled is undefined, drivers should ignore such requests.</entry>
1810 </row>
1811 <row><entry></entry></row>
1812
1813 <row>
1814 <entry spanname="id"><constant>V4L2_CID_ZOOM_ABSOLUTE</constant>&nbsp;</entry>
1815 <entry>integer</entry>
1816 </row><row><entry spanname="descr">Specify the objective lens
1817focal length as an absolute value. The zoom unit is driver-specific and its
1818value should be a positive integer.</entry>
1819 </row>
1820 <row><entry></entry></row>
1821
1822 <row>
1823 <entry spanname="id"><constant>V4L2_CID_ZOOM_RELATIVE</constant>&nbsp;</entry>
1824 <entry>integer</entry>
1825 </row><row><entry spanname="descr">Specify the objective lens
1826focal length relatively to the current value. Positive values move the zoom
1827lens group towards the telephoto direction, negative values towards the
1828wide-angle direction. The zoom unit is driver-specific. This is a write-only control.</entry>
1829 </row>
1830 <row><entry></entry></row>
1831
1832 <row>
1833 <entry spanname="id"><constant>V4L2_CID_ZOOM_CONTINUOUS</constant>&nbsp;</entry>
1834 <entry>integer</entry>
1835 </row><row><entry spanname="descr">Move the objective lens group
1836at the specified speed until it reaches physical device limits or until an
1837explicit request to stop the movement. A positive value moves the zoom lens
1838group towards the telephoto direction. A value of zero stops the zoom lens
1839group movement. A negative value moves the zoom lens group towards the
1840wide-angle direction. The zoom speed unit is driver-specific.</entry>
1841 </row>
1842 <row><entry></entry></row>
1843
1844 <row>
1845 <entry spanname="id"><constant>V4L2_CID_IRIS_ABSOLUTE</constant>&nbsp;</entry>
1846 <entry>integer</entry>
1847 </row><row><entry spanname="descr">This control sets the
1848camera's aperture to the specified value. The unit is undefined.
1849Larger values open the iris wider, smaller values close it.</entry>
1850 </row>
1851 <row><entry></entry></row>
1852
1853 <row>
1854 <entry spanname="id"><constant>V4L2_CID_IRIS_RELATIVE</constant>&nbsp;</entry>
1855 <entry>integer</entry>
1856 </row><row><entry spanname="descr">This control modifies the
1857camera's aperture by the specified amount. The unit is undefined.
1858Positive values open the iris one step further, negative values close
1859it one step further. This is a write-only control.</entry>
1860 </row>
1861 <row><entry></entry></row>
1862
1863 <row>
1864 <entry spanname="id"><constant>V4L2_CID_PRIVACY</constant>&nbsp;</entry>
1865 <entry>boolean</entry>
1866 </row><row><entry spanname="descr">Prevent video from being acquired
1867by the camera. When this control is set to <constant>TRUE</constant> (1), no
1868image can be captured by the camera. Common means to enforce privacy are
1869mechanical obturation of the sensor and firmware image processing, but the
1870device is not restricted to these methods. Devices that implement the privacy
1871control must support read access and may support write access.</entry>
1872 </row>
1873
1874 <row>
1875 <entry spanname="id"><constant>V4L2_CID_BAND_STOP_FILTER</constant>&nbsp;</entry>
1876 <entry>integer</entry>
1877 </row><row><entry spanname="descr">Switch the band-stop filter of a
1878camera sensor on or off, or specify its strength. Such band-stop filters can
1879be used, for example, to filter out the fluorescent light component.</entry>
1880 </row>
1881 <row><entry></entry></row>
1882 </tbody>
1883 </tgroup>
1884 </table>
1885 </section>
1886
1887 <section id="fm-tx-controls">
1888 <title>FM Transmitter Control Reference</title>
1889
1890 <para>The FM Transmitter (FM_TX) class includes controls for common features of
1891FM transmissions capable devices. Currently this class includes parameters for audio
1892compression, pilot tone generation, audio deviation limiter, RDS transmission and
1893tuning power features.</para>
1894
1895 <table pgwide="1" frame="none" id="fm-tx-control-id">
1896 <title>FM_TX Control IDs</title>
1897
1898 <tgroup cols="4">
1899 <colspec colname="c1" colwidth="1*" />
1900 <colspec colname="c2" colwidth="6*" />
1901 <colspec colname="c3" colwidth="2*" />
1902 <colspec colname="c4" colwidth="6*" />
1903 <spanspec namest="c1" nameend="c2" spanname="id" />
1904 <spanspec namest="c2" nameend="c4" spanname="descr" />
1905 <thead>
1906 <row>
1907 <entry spanname="id" align="left">ID</entry>
1908 <entry align="left">Type</entry>
1909 </row><row rowsep="1"><entry spanname="descr" align="left">Description</entry>
1910 </row>
1911 </thead>
1912 <tbody valign="top">
1913 <row><entry></entry></row>
1914 <row>
1915 <entry spanname="id"><constant>V4L2_CID_FM_TX_CLASS</constant>&nbsp;</entry>
1916 <entry>class</entry>
1917 </row><row><entry spanname="descr">The FM_TX class
1918descriptor. Calling &VIDIOC-QUERYCTRL; for this control will return a
1919description of this control class.</entry>
1920 </row>
1921 <row>
1922 <entry spanname="id"><constant>V4L2_CID_RDS_TX_DEVIATION</constant>&nbsp;</entry>
1923 <entry>integer</entry>
1924 </row>
1925 <row><entry spanname="descr">Configures RDS signal frequency deviation level in Hz.
1926The range and step are driver-specific.</entry>
1927 </row>
1928 <row>
1929 <entry spanname="id"><constant>V4L2_CID_RDS_TX_PI</constant>&nbsp;</entry>
1930 <entry>integer</entry>
1931 </row>
1932 <row><entry spanname="descr">Sets the RDS Programme Identification field
1933for transmission.</entry>
1934 </row>
1935 <row>
1936 <entry spanname="id"><constant>V4L2_CID_RDS_TX_PTY</constant>&nbsp;</entry>
1937 <entry>integer</entry>
1938 </row>
1939 <row><entry spanname="descr">Sets the RDS Programme Type field for transmission.
1940This encodes up to 31 pre-defined programme types.</entry>
1941 </row>
1942 <row>
1943 <entry spanname="id"><constant>V4L2_CID_RDS_TX_PS_NAME</constant>&nbsp;</entry>
1944 <entry>string</entry>
1945 </row>
1946 <row><entry spanname="descr">Sets the Programme Service name (PS_NAME) for transmission.
1947It is intended for static display on a receiver. It is the primary aid to listeners in programme service
1948identification and selection. In Annex E of <xref linkend="en50067" />, the RDS specification,
1949there is a full description of the correct character encoding for Programme Service name strings.
1950Also from RDS specification, PS is usually a single eight character text. However, it is also possible
1951to find receivers which can scroll strings sized as 8 x N characters. So, this control must be configured
1952with steps of 8 characters. The result is it must always contain a string with size multiple of 8.</entry>
1953 </row>
1954 <row>
1955 <entry spanname="id"><constant>V4L2_CID_RDS_TX_RADIO_TEXT</constant>&nbsp;</entry>
1956 <entry>string</entry>
1957 </row>
1958 <row><entry spanname="descr">Sets the Radio Text info for transmission. It is a textual description of
1959what is being broadcasted. RDS Radio Text can be applied when broadcaster wishes to transmit longer PS names,
1960programme-related information or any other text. In these cases, RadioText should be used in addition to
1961<constant>V4L2_CID_RDS_TX_PS_NAME</constant>. The encoding for Radio Text strings is also fully described
1962in Annex E of <xref linkend="en50067" />. The length of Radio Text strings depends on which RDS Block is being
1963used to transmit it, either 32 (2A block) or 64 (2B block). However, it is also possible
1964to find receivers which can scroll strings sized as 32 x N or 64 x N characters. So, this control must be configured
1965with steps of 32 or 64 characters. The result is it must always contain a string with size multiple of 32 or 64. </entry>
1966 </row>
1967 <row>
1968 <entry spanname="id"><constant>V4L2_CID_AUDIO_LIMITER_ENABLED</constant>&nbsp;</entry>
1969 <entry>boolean</entry>
1970 </row>
1971 <row><entry spanname="descr">Enables or disables the audio deviation limiter feature.
1972The limiter is useful when trying to maximize the audio volume, minimize receiver-generated
1973distortion and prevent overmodulation.
1974</entry>
1975 </row>
1976 <row>
1977 <entry spanname="id"><constant>V4L2_CID_AUDIO_LIMITER_RELEASE_TIME</constant>&nbsp;</entry>
1978 <entry>integer</entry>
1979 </row>
1980 <row><entry spanname="descr">Sets the audio deviation limiter feature release time.
1981Unit is in useconds. Step and range are driver-specific.</entry>
1982 </row>
1983 <row>
1984 <entry spanname="id"><constant>V4L2_CID_AUDIO_LIMITER_DEVIATION</constant>&nbsp;</entry>
1985 <entry>integer</entry>
1986 </row>
1987 <row><entry spanname="descr">Configures audio frequency deviation level in Hz.
1988The range and step are driver-specific.</entry>
1989 </row>
1990 <row>
1991 <entry spanname="id"><constant>V4L2_CID_AUDIO_COMPRESSION_ENABLED</constant>&nbsp;</entry>
1992 <entry>boolean</entry>
1993 </row>
1994 <row><entry spanname="descr">Enables or disables the audio compression feature.
1995This feature amplifies signals below the threshold by a fixed gain and compresses audio
1996signals above the threshold by the ratio of Threshold/(Gain + Threshold).</entry>
1997 </row>
1998 <row>
1999 <entry spanname="id"><constant>V4L2_CID_AUDIO_COMPRESSION_GAIN</constant>&nbsp;</entry>
2000 <entry>integer</entry>
2001 </row>
2002 <row><entry spanname="descr">Sets the gain for audio compression feature. It is
2003a dB value. The range and step are driver-specific.</entry>
2004 </row>
2005 <row>
2006 <entry spanname="id"><constant>V4L2_CID_AUDIO_COMPRESSION_THRESHOLD</constant>&nbsp;</entry>
2007 <entry>integer</entry>
2008 </row>
2009 <row><entry spanname="descr">Sets the threshold level for audio compression freature.
2010It is a dB value. The range and step are driver-specific.</entry>
2011 </row>
2012 <row>
2013 <entry spanname="id"><constant>V4L2_CID_AUDIO_COMPRESSION_ATTACK_TIME</constant>&nbsp;</entry>
2014 <entry>integer</entry>
2015 </row>
2016 <row><entry spanname="descr">Sets the attack time for audio compression feature.
2017It is a useconds value. The range and step are driver-specific.</entry>
2018 </row>
2019 <row>
2020 <entry spanname="id"><constant>V4L2_CID_AUDIO_COMPRESSION_RELEASE_TIME</constant>&nbsp;</entry>
2021 <entry>integer</entry>
2022 </row>
2023 <row><entry spanname="descr">Sets the release time for audio compression feature.
2024It is a useconds value. The range and step are driver-specific.</entry>
2025 </row>
2026 <row>
2027 <entry spanname="id"><constant>V4L2_CID_PILOT_TONE_ENABLED</constant>&nbsp;</entry>
2028 <entry>boolean</entry>
2029 </row>
2030 <row><entry spanname="descr">Enables or disables the pilot tone generation feature.</entry>
2031 </row>
2032 <row>
2033 <entry spanname="id"><constant>V4L2_CID_PILOT_TONE_DEVIATION</constant>&nbsp;</entry>
2034 <entry>integer</entry>
2035 </row>
2036 <row><entry spanname="descr">Configures pilot tone frequency deviation level. Unit is
2037in Hz. The range and step are driver-specific.</entry>
2038 </row>
2039 <row>
2040 <entry spanname="id"><constant>V4L2_CID_PILOT_TONE_FREQUENCY</constant>&nbsp;</entry>
2041 <entry>integer</entry>
2042 </row>
2043 <row><entry spanname="descr">Configures pilot tone frequency value. Unit is
2044in Hz. The range and step are driver-specific.</entry>
2045 </row>
2046 <row>
2047 <entry spanname="id"><constant>V4L2_CID_TUNE_PREEMPHASIS</constant>&nbsp;</entry>
2048 <entry>integer</entry>
2049 </row>
2050 <row id="v4l2-preemphasis"><entry spanname="descr">Configures the pre-emphasis value for broadcasting.
2051A pre-emphasis filter is applied to the broadcast to accentuate the high audio frequencies.
2052Depending on the region, a time constant of either 50 or 75 useconds is used. The enum&nbsp;v4l2_preemphasis
2053defines possible values for pre-emphasis. Here they are:</entry>
2054 </row><row>
2055 <entrytbl spanname="descr" cols="2">
2056 <tbody valign="top">
2057 <row>
2058 <entry><constant>V4L2_PREEMPHASIS_DISABLED</constant>&nbsp;</entry>
2059 <entry>No pre-emphasis is applied.</entry>
2060 </row>
2061 <row>
2062 <entry><constant>V4L2_PREEMPHASIS_50_uS</constant>&nbsp;</entry>
2063 <entry>A pre-emphasis of 50 uS is used.</entry>
2064 </row>
2065 <row>
2066 <entry><constant>V4L2_PREEMPHASIS_75_uS</constant>&nbsp;</entry>
2067 <entry>A pre-emphasis of 75 uS is used.</entry>
2068 </row>
2069 </tbody>
2070 </entrytbl>
2071
2072 </row>
2073 <row>
2074 <entry spanname="id"><constant>V4L2_CID_TUNE_POWER_LEVEL</constant>&nbsp;</entry>
2075 <entry>integer</entry>
2076 </row>
2077 <row><entry spanname="descr">Sets the output power level for signal transmission.
2078Unit is in dBuV. Range and step are driver-specific.</entry>
2079 </row>
2080 <row>
2081 <entry spanname="id"><constant>V4L2_CID_TUNE_ANTENNA_CAPACITOR</constant>&nbsp;</entry>
2082 <entry>integer</entry>
2083 </row>
2084 <row><entry spanname="descr">This selects the value of antenna tuning capacitor
2085manually or automatically if set to zero. Unit, range and step are driver-specific.</entry>
2086 </row>
2087 <row><entry></entry></row>
2088 </tbody>
2089 </tgroup>
2090 </table>
2091
2092<para>For more details about RDS specification, refer to
2093<xref linkend="en50067" /> document, from CENELEC.</para>
2094 </section>
2095</section>
2096
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