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/Documentation/DocBook/v4l/controls.xml

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  1. <section id="control">
  2. <title>User Controls</title>
  3. <para>Devices typically have a number of user-settable controls
  4. such as brightness, saturation and so on, which would be presented to
  5. the user on a graphical user interface. But, different devices
  6. will have different controls available, and furthermore, the range of
  7. possible values, and the default value will vary from device to
  8. device. The control ioctls provide the information and a mechanism to
  9. create a nice user interface for these controls that will work
  10. correctly with any device.</para>
  11. <para>All controls are accessed using an ID value. V4L2 defines
  12. several IDs for specific purposes. Drivers can also implement their
  13. own custom controls using <constant>V4L2_CID_PRIVATE_BASE</constant>
  14. and higher values. The pre-defined control IDs have the prefix
  15. <constant>V4L2_CID_</constant>, and are listed in <xref
  16. linkend="control-id" />. The ID is used when querying the attributes of
  17. a control, and when getting or setting the current value.</para>
  18. <para>Generally applications should present controls to the user
  19. without assumptions about their purpose. Each control comes with a
  20. name string the user is supposed to understand. When the purpose is
  21. non-intuitive the driver writer should provide a user manual, a user
  22. interface plug-in or a driver specific panel application. Predefined
  23. IDs were introduced to change a few controls programmatically, for
  24. example to mute a device during a channel switch.</para>
  25. <para>Drivers may enumerate different controls after switching
  26. the current video input or output, tuner or modulator, or audio input
  27. or output. Different in the sense of other bounds, another default and
  28. current value, step size or other menu items. A control with a certain
  29. <emphasis>custom</emphasis> ID can also change name and
  30. type.<footnote>
  31. <para>It will be more convenient for applications if drivers
  32. make use of the <constant>V4L2_CTRL_FLAG_DISABLED</constant> flag, but
  33. that was never required.</para>
  34. </footnote> Control values are stored globally, they do not
  35. change when switching except to stay within the reported bounds. They
  36. also do not change &eg; when the device is opened or closed, when the
  37. tuner radio frequency is changed or generally never without
  38. application request. Since V4L2 specifies no event mechanism, panel
  39. applications intended to cooperate with other panel applications (be
  40. they built into a larger application, as a TV viewer) may need to
  41. regularly poll control values to update their user
  42. interface.<footnote>
  43. <para>Applications could call an ioctl to request events.
  44. After another process called &VIDIOC-S-CTRL; or another ioctl changing
  45. shared properties the &func-select; function would indicate
  46. readability until any ioctl (querying the properties) is
  47. called.</para>
  48. </footnote></para>
  49. <table pgwide="1" frame="none" id="control-id">
  50. <title>Control IDs</title>
  51. <tgroup cols="3">
  52. &cs-def;
  53. <thead>
  54. <row>
  55. <entry>ID</entry>
  56. <entry>Type</entry>
  57. <entry>Description</entry>
  58. </row>
  59. </thead>
  60. <tbody valign="top">
  61. <row>
  62. <entry><constant>V4L2_CID_BASE</constant></entry>
  63. <entry></entry>
  64. <entry>First predefined ID, equal to
  65. <constant>V4L2_CID_BRIGHTNESS</constant>.</entry>
  66. </row>
  67. <row>
  68. <entry><constant>V4L2_CID_USER_BASE</constant></entry>
  69. <entry></entry>
  70. <entry>Synonym of <constant>V4L2_CID_BASE</constant>.</entry>
  71. </row>
  72. <row>
  73. <entry><constant>V4L2_CID_BRIGHTNESS</constant></entry>
  74. <entry>integer</entry>
  75. <entry>Picture brightness, or more precisely, the black
  76. level.</entry>
  77. </row>
  78. <row>
  79. <entry><constant>V4L2_CID_CONTRAST</constant></entry>
  80. <entry>integer</entry>
  81. <entry>Picture contrast or luma gain.</entry>
  82. </row>
  83. <row>
  84. <entry><constant>V4L2_CID_SATURATION</constant></entry>
  85. <entry>integer</entry>
  86. <entry>Picture color saturation or chroma gain.</entry>
  87. </row>
  88. <row>
  89. <entry><constant>V4L2_CID_HUE</constant></entry>
  90. <entry>integer</entry>
  91. <entry>Hue or color balance.</entry>
  92. </row>
  93. <row>
  94. <entry><constant>V4L2_CID_AUDIO_VOLUME</constant></entry>
  95. <entry>integer</entry>
  96. <entry>Overall audio volume. Note some drivers also
  97. provide an OSS or ALSA mixer interface.</entry>
  98. </row>
  99. <row>
  100. <entry><constant>V4L2_CID_AUDIO_BALANCE</constant></entry>
  101. <entry>integer</entry>
  102. <entry>Audio stereo balance. Minimum corresponds to all
  103. the way left, maximum to right.</entry>
  104. </row>
  105. <row>
  106. <entry><constant>V4L2_CID_AUDIO_BASS</constant></entry>
  107. <entry>integer</entry>
  108. <entry>Audio bass adjustment.</entry>
  109. </row>
  110. <row>
  111. <entry><constant>V4L2_CID_AUDIO_TREBLE</constant></entry>
  112. <entry>integer</entry>
  113. <entry>Audio treble adjustment.</entry>
  114. </row>
  115. <row>
  116. <entry><constant>V4L2_CID_AUDIO_MUTE</constant></entry>
  117. <entry>boolean</entry>
  118. <entry>Mute audio, &ie; set the volume to zero, however
  119. without affecting <constant>V4L2_CID_AUDIO_VOLUME</constant>. Like
  120. ALSA drivers, V4L2 drivers must mute at load time to avoid excessive
  121. noise. Actually the entire device should be reset to a low power
  122. consumption state.</entry>
  123. </row>
  124. <row>
  125. <entry><constant>V4L2_CID_AUDIO_LOUDNESS</constant></entry>
  126. <entry>boolean</entry>
  127. <entry>Loudness mode (bass boost).</entry>
  128. </row>
  129. <row>
  130. <entry><constant>V4L2_CID_BLACK_LEVEL</constant></entry>
  131. <entry>integer</entry>
  132. <entry>Another name for brightness (not a synonym of
  133. <constant>V4L2_CID_BRIGHTNESS</constant>). This control is deprecated
  134. and should not be used in new drivers and applications.</entry>
  135. </row>
  136. <row>
  137. <entry><constant>V4L2_CID_AUTO_WHITE_BALANCE</constant></entry>
  138. <entry>boolean</entry>
  139. <entry>Automatic white balance (cameras).</entry>
  140. </row>
  141. <row>
  142. <entry><constant>V4L2_CID_DO_WHITE_BALANCE</constant></entry>
  143. <entry>button</entry>
  144. <entry>This is an action control. When set (the value is
  145. ignored), the device will do a white balance and then hold the current
  146. setting. Contrast this with the boolean
  147. <constant>V4L2_CID_AUTO_WHITE_BALANCE</constant>, which, when
  148. activated, keeps adjusting the white balance.</entry>
  149. </row>
  150. <row>
  151. <entry><constant>V4L2_CID_RED_BALANCE</constant></entry>
  152. <entry>integer</entry>
  153. <entry>Red chroma balance.</entry>
  154. </row>
  155. <row>
  156. <entry><constant>V4L2_CID_BLUE_BALANCE</constant></entry>
  157. <entry>integer</entry>
  158. <entry>Blue chroma balance.</entry>
  159. </row>
  160. <row>
  161. <entry><constant>V4L2_CID_GAMMA</constant></entry>
  162. <entry>integer</entry>
  163. <entry>Gamma adjust.</entry>
  164. </row>
  165. <row>
  166. <entry><constant>V4L2_CID_WHITENESS</constant></entry>
  167. <entry>integer</entry>
  168. <entry>Whiteness for grey-scale devices. This is a synonym
  169. for <constant>V4L2_CID_GAMMA</constant>. This control is deprecated
  170. and should not be used in new drivers and applications.</entry>
  171. </row>
  172. <row>
  173. <entry><constant>V4L2_CID_EXPOSURE</constant></entry>
  174. <entry>integer</entry>
  175. <entry>Exposure (cameras). [Unit?]</entry>
  176. </row>
  177. <row>
  178. <entry><constant>V4L2_CID_AUTOGAIN</constant></entry>
  179. <entry>boolean</entry>
  180. <entry>Automatic gain/exposure control.</entry>
  181. </row>
  182. <row>
  183. <entry><constant>V4L2_CID_GAIN</constant></entry>
  184. <entry>integer</entry>
  185. <entry>Gain control.</entry>
  186. </row>
  187. <row>
  188. <entry><constant>V4L2_CID_HFLIP</constant></entry>
  189. <entry>boolean</entry>
  190. <entry>Mirror the picture horizontally.</entry>
  191. </row>
  192. <row>
  193. <entry><constant>V4L2_CID_VFLIP</constant></entry>
  194. <entry>boolean</entry>
  195. <entry>Mirror the picture vertically.</entry>
  196. </row>
  197. <row>
  198. <entry><constant>V4L2_CID_HCENTER_DEPRECATED</constant> (formerly <constant>V4L2_CID_HCENTER</constant>)</entry>
  199. <entry>integer</entry>
  200. <entry>Horizontal image centering. This control is
  201. deprecated. New drivers and applications should use the <link
  202. linkend="camera-controls">Camera class controls</link>
  203. <constant>V4L2_CID_PAN_ABSOLUTE</constant>,
  204. <constant>V4L2_CID_PAN_RELATIVE</constant> and
  205. <constant>V4L2_CID_PAN_RESET</constant> instead.</entry>
  206. </row>
  207. <row>
  208. <entry><constant>V4L2_CID_VCENTER_DEPRECATED</constant>
  209. (formerly <constant>V4L2_CID_VCENTER</constant>)</entry>
  210. <entry>integer</entry>
  211. <entry>Vertical image centering. Centering is intended to
  212. <emphasis>physically</emphasis> adjust cameras. For image cropping see
  213. <xref linkend="crop" />, for clipping <xref linkend="overlay" />. This
  214. control is deprecated. New drivers and applications should use the
  215. <link linkend="camera-controls">Camera class controls</link>
  216. <constant>V4L2_CID_TILT_ABSOLUTE</constant>,
  217. <constant>V4L2_CID_TILT_RELATIVE</constant> and
  218. <constant>V4L2_CID_TILT_RESET</constant> instead.</entry>
  219. </row>
  220. <row id="v4l2-power-line-frequency">
  221. <entry><constant>V4L2_CID_POWER_LINE_FREQUENCY</constant></entry>
  222. <entry>enum</entry>
  223. <entry>Enables a power line frequency filter to avoid
  224. flicker. Possible values for <constant>enum v4l2_power_line_frequency</constant> are:
  225. <constant>V4L2_CID_POWER_LINE_FREQUENCY_DISABLED</constant> (0),
  226. <constant>V4L2_CID_POWER_LINE_FREQUENCY_50HZ</constant> (1) and
  227. <constant>V4L2_CID_POWER_LINE_FREQUENCY_60HZ</constant> (2).</entry>
  228. </row>
  229. <row>
  230. <entry><constant>V4L2_CID_HUE_AUTO</constant></entry>
  231. <entry>boolean</entry>
  232. <entry>Enables automatic hue control by the device. The
  233. effect of setting <constant>V4L2_CID_HUE</constant> while automatic
  234. hue control is enabled is undefined, drivers should ignore such
  235. request.</entry>
  236. </row>
  237. <row>
  238. <entry><constant>V4L2_CID_WHITE_BALANCE_TEMPERATURE</constant></entry>
  239. <entry>integer</entry>
  240. <entry>This control specifies the white balance settings
  241. as a color temperature in Kelvin. A driver should have a minimum of
  242. 2800 (incandescent) to 6500 (daylight). For more information about
  243. color temperature see <ulink
  244. url="http://en.wikipedia.org/wiki/Color_temperature">Wikipedia</ulink>.</entry>
  245. </row>
  246. <row>
  247. <entry><constant>V4L2_CID_SHARPNESS</constant></entry>
  248. <entry>integer</entry>
  249. <entry>Adjusts the sharpness filters in a camera. The
  250. minimum value disables the filters, higher values give a sharper
  251. picture.</entry>
  252. </row>
  253. <row>
  254. <entry><constant>V4L2_CID_BACKLIGHT_COMPENSATION</constant></entry>
  255. <entry>integer</entry>
  256. <entry>Adjusts the backlight compensation in a camera. The
  257. minimum value disables backlight compensation.</entry>
  258. </row>
  259. <row>
  260. <entry><constant>V4L2_CID_CHROMA_AGC</constant></entry>
  261. <entry>boolean</entry>
  262. <entry>Chroma automatic gain control.</entry>
  263. </row>
  264. <row>
  265. <entry><constant>V4L2_CID_CHROMA_GAIN</constant></entry>
  266. <entry>integer</entry>
  267. <entry>Adjusts the Chroma gain control (for use when chroma AGC
  268. is disabled).</entry>
  269. </row>
  270. <row>
  271. <entry><constant>V4L2_CID_COLOR_KILLER</constant></entry>
  272. <entry>boolean</entry>
  273. <entry>Enable the color killer (&ie; force a black &amp; white image in case of a weak video signal).</entry>
  274. </row>
  275. <row id="v4l2-colorfx">
  276. <entry><constant>V4L2_CID_COLORFX</constant></entry>
  277. <entry>enum</entry>
  278. <entry>Selects a color effect. Possible values for
  279. <constant>enum v4l2_colorfx</constant> are:
  280. <constant>V4L2_COLORFX_NONE</constant> (0),
  281. <constant>V4L2_COLORFX_BW</constant> (1),
  282. <constant>V4L2_COLORFX_SEPIA</constant> (2),
  283. <constant>V4L2_COLORFX_NEGATIVE</constant> (3),
  284. <constant>V4L2_COLORFX_EMBOSS</constant> (4),
  285. <constant>V4L2_COLORFX_SKETCH</constant> (5),
  286. <constant>V4L2_COLORFX_SKY_BLUE</constant> (6),
  287. <constant>V4L2_COLORFX_GRASS_GREEN</constant> (7),
  288. <constant>V4L2_COLORFX_SKIN_WHITEN</constant> (8) and
  289. <constant>V4L2_COLORFX_VIVID</constant> (9).</entry>
  290. </row>
  291. <row>
  292. <entry><constant>V4L2_CID_ROTATE</constant></entry>
  293. <entry>integer</entry>
  294. <entry>Rotates the image by specified angle. Common angles are 90,
  295. 270 and 180. Rotating the image to 90 and 270 will reverse the height
  296. and width of the display window. It is necessary to set the new height and
  297. width of the picture using the &VIDIOC-S-FMT; ioctl according to
  298. the rotation angle selected.</entry>
  299. </row>
  300. <row>
  301. <entry><constant>V4L2_CID_BG_COLOR</constant></entry>
  302. <entry>integer</entry>
  303. <entry>Sets the background color on the current output device.
  304. Background color needs to be specified in the RGB24 format. The
  305. supplied 32 bit value is interpreted as bits 0-7 Red color information,
  306. bits 8-15 Green color information, bits 16-23 Blue color
  307. information and bits 24-31 must be zero.</entry>
  308. </row>
  309. <row>
  310. <entry><constant>V4L2_CID_LASTP1</constant></entry>
  311. <entry></entry>
  312. <entry>End of the predefined control IDs (currently
  313. <constant>V4L2_CID_BG_COLOR</constant> + 1).</entry>
  314. </row>
  315. <row>
  316. <entry><constant>V4L2_CID_PRIVATE_BASE</constant></entry>
  317. <entry></entry>
  318. <entry>ID of the first custom (driver specific) control.
  319. Applications depending on particular custom controls should check the
  320. driver name and version, see <xref linkend="querycap" />.</entry>
  321. </row>
  322. </tbody>
  323. </tgroup>
  324. </table>
  325. <para>Applications can enumerate the available controls with the
  326. &VIDIOC-QUERYCTRL; and &VIDIOC-QUERYMENU; ioctls, get and set a
  327. control value with the &VIDIOC-G-CTRL; and &VIDIOC-S-CTRL; ioctls.
  328. Drivers must implement <constant>VIDIOC_QUERYCTRL</constant>,
  329. <constant>VIDIOC_G_CTRL</constant> and
  330. <constant>VIDIOC_S_CTRL</constant> when the device has one or more
  331. controls, <constant>VIDIOC_QUERYMENU</constant> when it has one or
  332. more menu type controls.</para>
  333. <example>
  334. <title>Enumerating all controls</title>
  335. <programlisting>
  336. &v4l2-queryctrl; queryctrl;
  337. &v4l2-querymenu; querymenu;
  338. static void
  339. enumerate_menu (void)
  340. {
  341. printf (" Menu items:\n");
  342. memset (&amp;querymenu, 0, sizeof (querymenu));
  343. querymenu.id = queryctrl.id;
  344. for (querymenu.index = queryctrl.minimum;
  345. querymenu.index &lt;= queryctrl.maximum;
  346. querymenu.index++) {
  347. if (0 == ioctl (fd, &VIDIOC-QUERYMENU;, &amp;querymenu)) {
  348. printf (" %s\n", querymenu.name);
  349. } else {
  350. perror ("VIDIOC_QUERYMENU");
  351. exit (EXIT_FAILURE);
  352. }
  353. }
  354. }
  355. memset (&amp;queryctrl, 0, sizeof (queryctrl));
  356. for (queryctrl.id = V4L2_CID_BASE;
  357. queryctrl.id &lt; V4L2_CID_LASTP1;
  358. queryctrl.id++) {
  359. if (0 == ioctl (fd, &VIDIOC-QUERYCTRL;, &amp;queryctrl)) {
  360. if (queryctrl.flags &amp; V4L2_CTRL_FLAG_DISABLED)
  361. continue;
  362. printf ("Control %s\n", queryctrl.name);
  363. if (queryctrl.type == V4L2_CTRL_TYPE_MENU)
  364. enumerate_menu ();
  365. } else {
  366. if (errno == EINVAL)
  367. continue;
  368. perror ("VIDIOC_QUERYCTRL");
  369. exit (EXIT_FAILURE);
  370. }
  371. }
  372. for (queryctrl.id = V4L2_CID_PRIVATE_BASE;;
  373. queryctrl.id++) {
  374. if (0 == ioctl (fd, &VIDIOC-QUERYCTRL;, &amp;queryctrl)) {
  375. if (queryctrl.flags &amp; V4L2_CTRL_FLAG_DISABLED)
  376. continue;
  377. printf ("Control %s\n", queryctrl.name);
  378. if (queryctrl.type == V4L2_CTRL_TYPE_MENU)
  379. enumerate_menu ();
  380. } else {
  381. if (errno == EINVAL)
  382. break;
  383. perror ("VIDIOC_QUERYCTRL");
  384. exit (EXIT_FAILURE);
  385. }
  386. }
  387. </programlisting>
  388. </example>
  389. <example>
  390. <title>Changing controls</title>
  391. <programlisting>
  392. &v4l2-queryctrl; queryctrl;
  393. &v4l2-control; control;
  394. memset (&amp;queryctrl, 0, sizeof (queryctrl));
  395. queryctrl.id = V4L2_CID_BRIGHTNESS;
  396. if (-1 == ioctl (fd, &VIDIOC-QUERYCTRL;, &amp;queryctrl)) {
  397. if (errno != EINVAL) {
  398. perror ("VIDIOC_QUERYCTRL");
  399. exit (EXIT_FAILURE);
  400. } else {
  401. printf ("V4L2_CID_BRIGHTNESS is not supported\n");
  402. }
  403. } else if (queryctrl.flags &amp; V4L2_CTRL_FLAG_DISABLED) {
  404. printf ("V4L2_CID_BRIGHTNESS is not supported\n");
  405. } else {
  406. memset (&amp;control, 0, sizeof (control));
  407. control.id = V4L2_CID_BRIGHTNESS;
  408. control.value = queryctrl.default_value;
  409. if (-1 == ioctl (fd, &VIDIOC-S-CTRL;, &amp;control)) {
  410. perror ("VIDIOC_S_CTRL");
  411. exit (EXIT_FAILURE);
  412. }
  413. }
  414. memset (&amp;control, 0, sizeof (control));
  415. control.id = V4L2_CID_CONTRAST;
  416. if (0 == ioctl (fd, &VIDIOC-G-CTRL;, &amp;control)) {
  417. control.value += 1;
  418. /* The driver may clamp the value or return ERANGE, ignored here */
  419. if (-1 == ioctl (fd, &VIDIOC-S-CTRL;, &amp;control)
  420. &amp;&amp; errno != ERANGE) {
  421. perror ("VIDIOC_S_CTRL");
  422. exit (EXIT_FAILURE);
  423. }
  424. /* Ignore if V4L2_CID_CONTRAST is unsupported */
  425. } else if (errno != EINVAL) {
  426. perror ("VIDIOC_G_CTRL");
  427. exit (EXIT_FAILURE);
  428. }
  429. control.id = V4L2_CID_AUDIO_MUTE;
  430. control.value = TRUE; /* silence */
  431. /* Errors ignored */
  432. ioctl (fd, VIDIOC_S_CTRL, &amp;control);
  433. </programlisting>
  434. </example>
  435. </section>
  436. <section id="extended-controls">
  437. <title>Extended Controls</title>
  438. <section>
  439. <title>Introduction</title>
  440. <para>The control mechanism as originally designed was meant
  441. to be used for user settings (brightness, saturation, etc). However,
  442. it turned out to be a very useful model for implementing more
  443. complicated driver APIs where each driver implements only a subset of
  444. a larger API.</para>
  445. <para>The MPEG encoding API was the driving force behind
  446. designing and implementing this extended control mechanism: the MPEG
  447. standard is quite large and the currently supported hardware MPEG
  448. encoders each only implement a subset of this standard. Further more,
  449. many parameters relating to how the video is encoded into an MPEG
  450. stream are specific to the MPEG encoding chip since the MPEG standard
  451. only defines the format of the resulting MPEG stream, not how the
  452. video is actually encoded into that format.</para>
  453. <para>Unfortunately, the original control API lacked some
  454. features needed for these new uses and so it was extended into the
  455. (not terribly originally named) extended control API.</para>
  456. <para>Even though the MPEG encoding API was the first effort
  457. to use the Extended Control API, nowadays there are also other classes
  458. of Extended Controls, such as Camera Controls and FM Transmitter Controls.
  459. The Extended Controls API as well as all Extended Controls classes are
  460. described in the following text.</para>
  461. </section>
  462. <section>
  463. <title>The Extended Control API</title>
  464. <para>Three new ioctls are available: &VIDIOC-G-EXT-CTRLS;,
  465. &VIDIOC-S-EXT-CTRLS; and &VIDIOC-TRY-EXT-CTRLS;. These ioctls act on
  466. arrays of controls (as opposed to the &VIDIOC-G-CTRL; and
  467. &VIDIOC-S-CTRL; ioctls that act on a single control). This is needed
  468. since it is often required to atomically change several controls at
  469. once.</para>
  470. <para>Each of the new ioctls expects a pointer to a
  471. &v4l2-ext-controls;. This structure contains a pointer to the control
  472. array, a count of the number of controls in that array and a control
  473. class. Control classes are used to group similar controls into a
  474. single class. For example, control class
  475. <constant>V4L2_CTRL_CLASS_USER</constant> contains all user controls
  476. (&ie; all controls that can also be set using the old
  477. <constant>VIDIOC_S_CTRL</constant> ioctl). Control class
  478. <constant>V4L2_CTRL_CLASS_MPEG</constant> contains all controls
  479. relating to MPEG encoding, etc.</para>
  480. <para>All controls in the control array must belong to the
  481. specified control class. An error is returned if this is not the
  482. case.</para>
  483. <para>It is also possible to use an empty control array (count
  484. == 0) to check whether the specified control class is
  485. supported.</para>
  486. <para>The control array is a &v4l2-ext-control; array. The
  487. <structname>v4l2_ext_control</structname> structure is very similar to
  488. &v4l2-control;, except for the fact that it also allows for 64-bit
  489. values and pointers to be passed.</para>
  490. <para>It is important to realize that due to the flexibility of
  491. controls it is necessary to check whether the control you want to set
  492. actually is supported in the driver and what the valid range of values
  493. is. So use the &VIDIOC-QUERYCTRL; and &VIDIOC-QUERYMENU; ioctls to
  494. check this. Also note that it is possible that some of the menu
  495. indices in a control of type <constant>V4L2_CTRL_TYPE_MENU</constant>
  496. may not be supported (<constant>VIDIOC_QUERYMENU</constant> will
  497. return an error). A good example is the list of supported MPEG audio
  498. bitrates. Some drivers only support one or two bitrates, others
  499. support a wider range.</para>
  500. </section>
  501. <section>
  502. <title>Enumerating Extended Controls</title>
  503. <para>The recommended way to enumerate over the extended
  504. controls is by using &VIDIOC-QUERYCTRL; in combination with the
  505. <constant>V4L2_CTRL_FLAG_NEXT_CTRL</constant> flag:</para>
  506. <informalexample>
  507. <programlisting>
  508. &v4l2-queryctrl; qctrl;
  509. qctrl.id = V4L2_CTRL_FLAG_NEXT_CTRL;
  510. while (0 == ioctl (fd, &VIDIOC-QUERYCTRL;, &amp;qctrl)) {
  511. /* ... */
  512. qctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL;
  513. }
  514. </programlisting>
  515. </informalexample>
  516. <para>The initial control ID is set to 0 ORed with the
  517. <constant>V4L2_CTRL_FLAG_NEXT_CTRL</constant> flag. The
  518. <constant>VIDIOC_QUERYCTRL</constant> ioctl will return the first
  519. control with a higher ID than the specified one. When no such controls
  520. are found an error is returned.</para>
  521. <para>If you want to get all controls within a specific control
  522. class, then you can set the initial
  523. <structfield>qctrl.id</structfield> value to the control class and add
  524. an extra check to break out of the loop when a control of another
  525. control class is found:</para>
  526. <informalexample>
  527. <programlisting>
  528. qctrl.id = V4L2_CTRL_CLASS_MPEG | V4L2_CTRL_FLAG_NEXT_CTRL;
  529. while (0 == ioctl (fd, &VIDIOC-QUERYCTRL;, &amp;qctrl)) {
  530. if (V4L2_CTRL_ID2CLASS (qctrl.id) != V4L2_CTRL_CLASS_MPEG)
  531. break;
  532. /* ... */
  533. qctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL;
  534. }
  535. </programlisting>
  536. </informalexample>
  537. <para>The 32-bit <structfield>qctrl.id</structfield> value is
  538. subdivided into three bit ranges: the top 4 bits are reserved for
  539. flags (&eg; <constant>V4L2_CTRL_FLAG_NEXT_CTRL</constant>) and are not
  540. actually part of the ID. The remaining 28 bits form the control ID, of
  541. which the most significant 12 bits define the control class and the
  542. least significant 16 bits identify the control within the control
  543. class. It is guaranteed that these last 16 bits are always non-zero
  544. for controls. The range of 0x1000 and up are reserved for
  545. driver-specific controls. The macro
  546. <constant>V4L2_CTRL_ID2CLASS(id)</constant> returns the control class
  547. ID based on a control ID.</para>
  548. <para>If the driver does not support extended controls, then
  549. <constant>VIDIOC_QUERYCTRL</constant> will fail when used in
  550. combination with <constant>V4L2_CTRL_FLAG_NEXT_CTRL</constant>. In
  551. that case the old method of enumerating control should be used (see
  552. 1.8). But if it is supported, then it is guaranteed to enumerate over
  553. all controls, including driver-private controls.</para>
  554. </section>
  555. <section>
  556. <title>Creating Control Panels</title>
  557. <para>It is possible to create control panels for a graphical
  558. user interface where the user can select the various controls.
  559. Basically you will have to iterate over all controls using the method
  560. described above. Each control class starts with a control of type
  561. <constant>V4L2_CTRL_TYPE_CTRL_CLASS</constant>.
  562. <constant>VIDIOC_QUERYCTRL</constant> will return the name of this
  563. control class which can be used as the title of a tab page within a
  564. control panel.</para>
  565. <para>The flags field of &v4l2-queryctrl; also contains hints on
  566. the behavior of the control. See the &VIDIOC-QUERYCTRL; documentation
  567. for more details.</para>
  568. </section>
  569. <section id="mpeg-controls">
  570. <title>MPEG Control Reference</title>
  571. <para>Below all controls within the MPEG control class are
  572. described. First the generic controls, then controls specific for
  573. certain hardware.</para>
  574. <section>
  575. <title>Generic MPEG Controls</title>
  576. <table pgwide="1" frame="none" id="mpeg-control-id">
  577. <title>MPEG Control IDs</title>
  578. <tgroup cols="4">
  579. <colspec colname="c1" colwidth="1*" />
  580. <colspec colname="c2" colwidth="6*" />
  581. <colspec colname="c3" colwidth="2*" />
  582. <colspec colname="c4" colwidth="6*" />
  583. <spanspec namest="c1" nameend="c2" spanname="id" />
  584. <spanspec namest="c2" nameend="c4" spanname="descr" />
  585. <thead>
  586. <row>
  587. <entry spanname="id" align="left">ID</entry>
  588. <entry align="left">Type</entry>
  589. </row><row rowsep="1"><entry spanname="descr" align="left">Description</entry>
  590. </row>
  591. </thead>
  592. <tbody valign="top">
  593. <row><entry></entry></row>
  594. <row>
  595. <entry spanname="id"><constant>V4L2_CID_MPEG_CLASS</constant>&nbsp;</entry>
  596. <entry>class</entry>
  597. </row><row><entry spanname="descr">The MPEG class
  598. descriptor. Calling &VIDIOC-QUERYCTRL; for this control will return a
  599. description of this control class. This description can be used as the
  600. caption of a Tab page in a GUI, for example.</entry>
  601. </row>
  602. <row><entry></entry></row>
  603. <row id="v4l2-mpeg-stream-type">
  604. <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_TYPE</constant>&nbsp;</entry>
  605. <entry>enum&nbsp;v4l2_mpeg_stream_type</entry>
  606. </row><row><entry spanname="descr">The MPEG-1, -2 or -4
  607. output stream type. One cannot assume anything here. Each hardware
  608. MPEG encoder tends to support different subsets of the available MPEG
  609. stream types. The currently defined stream types are:</entry>
  610. </row>
  611. <row>
  612. <entrytbl spanname="descr" cols="2">
  613. <tbody valign="top">
  614. <row>
  615. <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG2_PS</constant>&nbsp;</entry>
  616. <entry>MPEG-2 program stream</entry>
  617. </row>
  618. <row>
  619. <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG2_TS</constant>&nbsp;</entry>
  620. <entry>MPEG-2 transport stream</entry>
  621. </row>
  622. <row>
  623. <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG1_SS</constant>&nbsp;</entry>
  624. <entry>MPEG-1 system stream</entry>
  625. </row>
  626. <row>
  627. <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG2_DVD</constant>&nbsp;</entry>
  628. <entry>MPEG-2 DVD-compatible stream</entry>
  629. </row>
  630. <row>
  631. <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG1_VCD</constant>&nbsp;</entry>
  632. <entry>MPEG-1 VCD-compatible stream</entry>
  633. </row>
  634. <row>
  635. <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG2_SVCD</constant>&nbsp;</entry>
  636. <entry>MPEG-2 SVCD-compatible stream</entry>
  637. </row>
  638. </tbody>
  639. </entrytbl>
  640. </row>
  641. <row><entry></entry></row>
  642. <row>
  643. <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PID_PMT</constant>&nbsp;</entry>
  644. <entry>integer</entry>
  645. </row><row><entry spanname="descr">Program Map Table
  646. Packet ID for the MPEG transport stream (default 16)</entry>
  647. </row>
  648. <row><entry></entry></row>
  649. <row>
  650. <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PID_AUDIO</constant>&nbsp;</entry>
  651. <entry>integer</entry>
  652. </row><row><entry spanname="descr">Audio Packet ID for
  653. the MPEG transport stream (default 256)</entry>
  654. </row>
  655. <row><entry></entry></row>
  656. <row>
  657. <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PID_VIDEO</constant>&nbsp;</entry>
  658. <entry>integer</entry>
  659. </row><row><entry spanname="descr">Video Packet ID for
  660. the MPEG transport stream (default 260)</entry>
  661. </row>
  662. <row><entry></entry></row>
  663. <row>
  664. <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PID_PCR</constant>&nbsp;</entry>
  665. <entry>integer</entry>
  666. </row><row><entry spanname="descr">Packet ID for the
  667. MPEG transport stream carrying PCR fields (default 259)</entry>
  668. </row>
  669. <row><entry></entry></row>
  670. <row>
  671. <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PES_ID_AUDIO</constant>&nbsp;</entry>
  672. <entry>integer</entry>
  673. </row><row><entry spanname="descr">Audio ID for MPEG
  674. PES</entry>
  675. </row>
  676. <row><entry></entry></row>
  677. <row>
  678. <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PES_ID_VIDEO</constant>&nbsp;</entry>
  679. <entry>integer</entry>
  680. </row><row><entry spanname="descr">Video ID for MPEG
  681. PES</entry>
  682. </row>
  683. <row><entry></entry></row>
  684. <row id="v4l2-mpeg-stream-vbi-fmt">
  685. <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_VBI_FMT</constant>&nbsp;</entry>
  686. <entry>enum&nbsp;v4l2_mpeg_stream_vbi_fmt</entry>
  687. </row><row><entry spanname="descr">Some cards can embed
  688. VBI data (&eg; Closed Caption, Teletext) into the MPEG stream. This
  689. control selects whether VBI data should be embedded, and if so, what
  690. embedding method should be used. The list of possible VBI formats
  691. depends on the driver. The currently defined VBI format types
  692. are:</entry>
  693. </row>
  694. <row>
  695. <entrytbl spanname="descr" cols="2">
  696. <tbody valign="top">
  697. <row>
  698. <entry><constant>V4L2_MPEG_STREAM_VBI_FMT_NONE</constant>&nbsp;</entry>
  699. <entry>No VBI in the MPEG stream</entry>
  700. </row>
  701. <row>
  702. <entry><constant>V4L2_MPEG_STREAM_VBI_FMT_IVTV</constant>&nbsp;</entry>
  703. <entry>VBI in private packets, IVTV format (documented
  704. in the kernel sources in the file <filename>Documentation/video4linux/cx2341x/README.vbi</filename>)</entry>
  705. </row>
  706. </tbody>
  707. </entrytbl>
  708. </row>
  709. <row><entry></entry></row>
  710. <row id="v4l2-mpeg-audio-sampling-freq">
  711. <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_SAMPLING_FREQ</constant>&nbsp;</entry>
  712. <entry>enum&nbsp;v4l2_mpeg_audio_sampling_freq</entry>
  713. </row><row><entry spanname="descr">MPEG Audio sampling
  714. frequency. Possible values are:</entry>
  715. </row>
  716. <row>
  717. <entrytbl spanname="descr" cols="2">
  718. <tbody valign="top">
  719. <row>
  720. <entry><constant>V4L2_MPEG_AUDIO_SAMPLING_FREQ_44100</constant>&nbsp;</entry>
  721. <entry>44.1 kHz</entry>
  722. </row>
  723. <row>
  724. <entry><constant>V4L2_MPEG_AUDIO_SAMPLING_FREQ_48000</constant>&nbsp;</entry>
  725. <entry>48 kHz</entry>
  726. </row>
  727. <row>
  728. <entry><constant>V4L2_MPEG_AUDIO_SAMPLING_FREQ_32000</constant>&nbsp;</entry>
  729. <entry>32 kHz</entry>
  730. </row>
  731. </tbody>
  732. </entrytbl>
  733. </row>
  734. <row><entry></entry></row>
  735. <row id="v4l2-mpeg-audio-encoding">
  736. <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_ENCODING</constant>&nbsp;</entry>
  737. <entry>enum&nbsp;v4l2_mpeg_audio_encoding</entry>
  738. </row><row><entry spanname="descr">MPEG Audio encoding.
  739. Possible values are:</entry>
  740. </row>
  741. <row>
  742. <entrytbl spanname="descr" cols="2">
  743. <tbody valign="top">
  744. <row>
  745. <entry><constant>V4L2_MPEG_AUDIO_ENCODING_LAYER_1</constant>&nbsp;</entry>
  746. <entry>MPEG-1/2 Layer I encoding</entry>
  747. </row>
  748. <row>
  749. <entry><constant>V4L2_MPEG_AUDIO_ENCODING_LAYER_2</constant>&nbsp;</entry>
  750. <entry>MPEG-1/2 Layer II encoding</entry>
  751. </row>
  752. <row>
  753. <entry><constant>V4L2_MPEG_AUDIO_ENCODING_LAYER_3</constant>&nbsp;</entry>
  754. <entry>MPEG-1/2 Layer III encoding</entry>
  755. </row>
  756. <row>
  757. <entry><constant>V4L2_MPEG_AUDIO_ENCODING_AAC</constant>&nbsp;</entry>
  758. <entry>MPEG-2/4 AAC (Advanced Audio Coding)</entry>
  759. </row>
  760. <row>
  761. <entry><constant>V4L2_MPEG_AUDIO_ENCODING_AC3</constant>&nbsp;</entry>
  762. <entry>AC-3 aka ATSC A/52 encoding</entry>
  763. </row>
  764. </tbody>
  765. </entrytbl>
  766. </row>
  767. <row><entry></entry></row>
  768. <row id="v4l2-mpeg-audio-l1-bitrate">
  769. <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_L1_BITRATE</constant>&nbsp;</entry>
  770. <entry>enum&nbsp;v4l2_mpeg_audio_l1_bitrate</entry>
  771. </row><row><entry spanname="descr">MPEG-1/2 Layer I bitrate.
  772. Possible values are:</entry>
  773. </row>
  774. <row>
  775. <entrytbl spanname="descr" cols="2">
  776. <tbody valign="top">
  777. <row>
  778. <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_32K</constant>&nbsp;</entry>
  779. <entry>32 kbit/s</entry></row>
  780. <row>
  781. <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_64K</constant>&nbsp;</entry>
  782. <entry>64 kbit/s</entry>
  783. </row>
  784. <row>
  785. <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_96K</constant>&nbsp;</entry>
  786. <entry>96 kbit/s</entry>
  787. </row>
  788. <row>
  789. <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_128K</constant>&nbsp;</entry>
  790. <entry>128 kbit/s</entry>
  791. </row>
  792. <row>
  793. <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_160K</constant>&nbsp;</entry>
  794. <entry>160 kbit/s</entry>
  795. </row>
  796. <row>
  797. <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_192K</constant>&nbsp;</entry>
  798. <entry>192 kbit/s</entry>
  799. </row>
  800. <row>
  801. <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_224K</constant>&nbsp;</entry>
  802. <entry>224 kbit/s</entry>
  803. </row>
  804. <row>
  805. <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_256K</constant>&nbsp;</entry>
  806. <entry>256 kbit/s</entry>
  807. </row>
  808. <row>
  809. <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_288K</constant>&nbsp;</entry>
  810. <entry>288 kbit/s</entry>
  811. </row>
  812. <row>
  813. <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_320K</constant>&nbsp;</entry>
  814. <entry>320 kbit/s</entry>
  815. </row>
  816. <row>
  817. <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_352K</constant>&nbsp;</entry>
  818. <entry>352 kbit/s</entry>
  819. </row>
  820. <row>
  821. <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_384K</constant>&nbsp;</entry>
  822. <entry>384 kbit/s</entry>
  823. </row>
  824. <row>
  825. <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_416K</constant>&nbsp;</entry>
  826. <entry>416 kbit/s</entry>
  827. </row>
  828. <row>
  829. <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_448K</constant>&nbsp;</entry>
  830. <entry>448 kbit/s</entry>
  831. </row>
  832. </tbody>
  833. </entrytbl>
  834. </row>
  835. <row><entry></entry></row>
  836. <row id="v4l2-mpeg-audio-l2-bitrate">
  837. <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_L2_BITRATE</constant>&nbsp;</entry>
  838. <entry>enum&nbsp;v4l2_mpeg_audio_l2_bitrate</entry>
  839. </row><row><entry spanname="descr">MPEG-1/2 Layer II bitrate.
  840. Possible values are:</entry>
  841. </row>
  842. <row>
  843. <entrytbl spanname="descr" cols="2">
  844. <tbody valign="top">
  845. <row>
  846. <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_32K</constant>&nbsp;</entry>
  847. <entry>32 kbit/s</entry>
  848. </row>
  849. <row>
  850. <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_48K</constant>&nbsp;</entry>
  851. <entry>48 kbit/s</entry>
  852. </row>
  853. <row>
  854. <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_56K</constant>&nbsp;</entry>
  855. <entry>56 kbit/s</entry>
  856. </row>
  857. <row>
  858. <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_64K</constant>&nbsp;</entry>
  859. <entry>64 kbit/s</entry>
  860. </row>
  861. <row>
  862. <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_80K</constant>&nbsp;</entry>
  863. <entry>80 kbit/s</entry>
  864. </row>
  865. <row>
  866. <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_96K</constant>&nbsp;</entry>
  867. <entry>96 kbit/s</entry>
  868. </row>
  869. <row>
  870. <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_112K</constant>&nbsp;</entry>
  871. <entry>112 kbit/s</entry>
  872. </row>
  873. <row>
  874. <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_128K</constant>&nbsp;</entry>
  875. <entry>128 kbit/s</entry>
  876. </row>
  877. <row>
  878. <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_160K</constant>&nbsp;</entry>
  879. <entry>160 kbit/s</entry>
  880. </row>
  881. <row>
  882. <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_192K</constant>&nbsp;</entry>
  883. <entry>192 kbit/s</entry>
  884. </row>
  885. <row>
  886. <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_224K</constant>&nbsp;</entry>
  887. <entry>224 kbit/s</entry>
  888. </row>
  889. <row>
  890. <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_256K</constant>&nbsp;</entry>
  891. <entry>256 kbit/s</entry>
  892. </row>
  893. <row>
  894. <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_320K</constant>&nbsp;</entry>
  895. <entry>320 kbit/s</entry>
  896. </row>
  897. <row>
  898. <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_384K</constant>&nbsp;</entry>
  899. <entry>384 kbit/s</entry>
  900. </row>
  901. </tbody>
  902. </entrytbl>
  903. </row>
  904. <row><entry></entry></row>
  905. <row id="v4l2-mpeg-audio-l3-bitrate">
  906. <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_L3_BITRATE</constant>&nbsp;</entry>
  907. <entry>enum&nbsp;v4l2_mpeg_audio_l3_bitrate</entry>
  908. </row><row><entry spanname="descr">MPEG-1/2 Layer III bitrate.
  909. Possible values are:</entry>
  910. </row>
  911. <row>
  912. <entrytbl spanname="descr" cols="2">
  913. <tbody valign="top">
  914. <row>
  915. <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_32K</constant>&nbsp;</entry>
  916. <entry>32 kbit/s</entry>
  917. </row>
  918. <row>
  919. <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_40K</constant>&nbsp;</entry>
  920. <entry>40 kbit/s</entry>
  921. </row>
  922. <row>
  923. <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_48K</constant>&nbsp;</entry>
  924. <entry>48 kbit/s</entry>
  925. </row>
  926. <row>
  927. <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_56K</constant>&nbsp;</entry>
  928. <entry>56 kbit/s</entry>
  929. </row>
  930. <row>
  931. <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_64K</constant>&nbsp;</entry>
  932. <entry>64 kbit/s</entry>
  933. </row>
  934. <row>
  935. <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_80K</constant>&nbsp;</entry>
  936. <entry>80 kbit/s</entry>
  937. </row>
  938. <row>
  939. <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_96K</constant>&nbsp;</entry>
  940. <entry>96 kbit/s</entry>
  941. </row>
  942. <row>
  943. <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_112K</constant>&nbsp;</entry>
  944. <entry>112 kbit/s</entry>
  945. </row>
  946. <row>
  947. <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_128K</constant>&nbsp;</entry>
  948. <entry>128 kbit/s</entry>
  949. </row>
  950. <row>
  951. <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_160K</constant>&nbsp;</entry>
  952. <entry>160 kbit/s</entry>
  953. </row>
  954. <row>
  955. <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_192K</constant>&nbsp;</entry>
  956. <entry>192 kbit/s</entry>
  957. </row>
  958. <row>
  959. <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_224K</constant>&nbsp;</entry>
  960. <entry>224 kbit/s</entry>
  961. </row>
  962. <row>
  963. <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_256K</constant>&nbsp;</entry>
  964. <entry>256 kbit/s</entry>
  965. </row>
  966. <row>
  967. <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_320K</constant>&nbsp;</entry>
  968. <entry>320 kbit/s</entry>
  969. </row>
  970. </tbody>
  971. </entrytbl>
  972. </row>
  973. <row><entry></entry></row>
  974. <row>
  975. <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_AAC_BITRATE</constant>&nbsp;</entry>
  976. <entry>integer</entry>
  977. </row><row><entry spanname="descr">AAC bitrate in bits per second.</entry>
  978. </row>
  979. <row><entry></entry></row>
  980. <row id="v4l2-mpeg-audio-ac3-bitrate">
  981. <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_AC3_BITRATE</constant>&nbsp;</entry>
  982. <entry>enum&nbsp;v4l2_mpeg_audio_ac3_bitrate</entry>
  983. </row><row><entry spanname="descr">AC-3 bitrate.
  984. Possible values are:</entry>
  985. </row>
  986. <row>
  987. <entrytbl spanname="descr" cols="2">
  988. <tbody valign="top">
  989. <row>
  990. <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_32K</constant>&nbsp;</entry>
  991. <entry>32 kbit/s</entry>
  992. </row>
  993. <row>
  994. <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_40K</constant>&nbsp;</entry>
  995. <entry>40 kbit/s</entry>
  996. </row>
  997. <row>
  998. <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_48K</constant>&nbsp;</entry>
  999. <entry>48 kbit/s</entry>
  1000. </row>
  1001. <row>
  1002. <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_56K</constant>&nbsp;</entry>
  1003. <entry>56 kbit/s</entry>
  1004. </row>
  1005. <row>
  1006. <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_64K</constant>&nbsp;</entry>
  1007. <entry>64 kbit/s</entry>
  1008. </row>
  1009. <row>
  1010. <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_80K</constant>&nbsp;</entry>
  1011. <entry>80 kbit/s</entry>
  1012. </row>
  1013. <row>
  1014. <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_96K</constant>&nbsp;</entry>
  1015. <entry>96 kbit/s</entry>
  1016. </row>
  1017. <row>
  1018. <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_112K</constant>&nbsp;</entry>
  1019. <entry>112 kbit/s</entry>
  1020. </row>
  1021. <row>
  1022. <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_128K</constant>&nbsp;</entry>
  1023. <entry>128 kbit/s</entry>
  1024. </row>
  1025. <row>
  1026. <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_160K</constant>&nbsp;</entry>
  1027. <entry>160 kbit/s</entry>
  1028. </row>
  1029. <row>
  1030. <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_192K</constant>&nbsp;</entry>
  1031. <entry>192 kbit/s</entry>
  1032. </row>
  1033. <row>
  1034. <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_224K</constant>&nbsp;</entry>
  1035. <entry>224 kbit/s</entry>
  1036. </row>
  1037. <row>
  1038. <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_256K</constant>&nbsp;</entry>
  1039. <entry>256 kbit/s</entry>
  1040. </row>
  1041. <row>
  1042. <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_320K</constant>&nbsp;</entry>
  1043. <entry>320 kbit/s</entry>
  1044. </row>
  1045. <row>
  1046. <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_384K</constant>&nbsp;</entry>
  1047. <entry>384 kbit/s</entry>
  1048. </row>
  1049. <row>
  1050. <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_448K</constant>&nbsp;</entry>
  1051. <entry>448 kbit/s</entry>
  1052. </row>
  1053. <row>
  1054. <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_512K</constant>&nbsp;</entry>
  1055. <entry>512 kbit/s</entry>
  1056. </row>
  1057. <row>
  1058. <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_576K</constant>&nbsp;</entry>
  1059. <entry>576 kbit/s</entry>
  1060. </row>
  1061. <row>
  1062. <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_640K</constant>&nbsp;</entry>
  1063. <entry>640 kbit/s</entry>
  1064. </row>
  1065. </tbody>
  1066. </entrytbl>
  1067. </row>
  1068. <row><entry></entry></row>
  1069. <row id="v4l2-mpeg-audio-mode">
  1070. <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_MODE</constant>&nbsp;</entry>
  1071. <entry>enum&nbsp;v4l2_mpeg_audio_mode</entry>
  1072. </row><row><entry spanname="descr">MPEG Audio mode.
  1073. Possible values are:</entry>
  1074. </row>
  1075. <row>
  1076. <entrytbl spanname="descr" cols="2">
  1077. <tbody valign="top">
  1078. <row>
  1079. <entry><constant>V4L2_MPEG_AUDIO_MODE_STEREO</constant>&nbsp;</entry>
  1080. <entry>Stereo</entry>
  1081. </row>
  1082. <row>
  1083. <entry><constant>V4L2_MPEG_AUDIO_MODE_JOINT_STEREO</constant>&nbsp;</entry>
  1084. <entry>Joint Stereo</entry>
  1085. </row>
  1086. <row>
  1087. <entry><constant>V4L2_MPEG_AUDIO_MODE_DUAL</constant>&nbsp;</entry>
  1088. <entry>Bilingual</entry>
  1089. </row>
  1090. <row>
  1091. <entry><constant>V4L2_MPEG_AUDIO_MODE_MONO</constant>&nbsp;</entry>
  1092. <entry>Mono</entry>
  1093. </row>
  1094. </tbody>
  1095. </entrytbl>
  1096. </row>
  1097. <row><entry></entry></row>
  1098. <row id="v4l2-mpeg-audio-mode-extension">
  1099. <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_MODE_EXTENSION</constant>&nbsp;</entry>
  1100. <entry>enum&nbsp;v4l2_mpeg_audio_mode_extension</entry>
  1101. </row><row><entry spanname="descr">Joint Stereo
  1102. audio mode extension. In Layer I and II they indicate which subbands
  1103. are in intensity stereo. All other subbands are coded in stereo. Layer
  1104. III is not (yet) supported. Possible values
  1105. are:</entry>
  1106. </row>
  1107. <row>
  1108. <entrytbl spanname="descr" cols="2">
  1109. <tbody valign="top">
  1110. <row>
  1111. <entry><constant>V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_4</constant>&nbsp;</entry>
  1112. <entry>Subbands 4-31 in intensity stereo</entry>
  1113. </row>
  1114. <row>
  1115. <entry><constant>V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_8</constant>&nbsp;</entry>
  1116. <entry>Subbands 8-31 in intensity stereo</entry>
  1117. </row>
  1118. <row>
  1119. <entry><constant>V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_12</constant>&nbsp;</entry>
  1120. <entry>Subbands 12-31 in intensity stereo</entry>
  1121. </row>
  1122. <row>
  1123. <entry><constant>V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_16</constant>&nbsp;</entry>
  1124. <entry>Subbands 16-31 in intensity stereo</entry>
  1125. </row>
  1126. </tbody>
  1127. </entrytbl>
  1128. </row>
  1129. <row><entry></entry></row>
  1130. <row id="v4l2-mpeg-audio-emphasis">
  1131. <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_EMPHASIS</constant>&nbsp;</entry>
  1132. <entry>enum&nbsp;v4l2_mpeg_audio_emphasis</entry>
  1133. </row><row><entry spanname="descr">Audio Emphasis.
  1134. Possible values are:</entry>
  1135. </row>
  1136. <row>
  1137. <entrytbl spanname="descr" cols="2">
  1138. <tbody valign="top">
  1139. <row>
  1140. <entry><constant>V4L2_MPEG_AUDIO_EMPHASIS_NONE</constant>&nbsp;</entry>
  1141. <entry>None</entry>
  1142. </row>
  1143. <row>
  1144. <entry><constant>V4L2_MPEG_AUDIO_EMPHASIS_50_DIV_15_uS</constant>&nbsp;</entry>
  1145. <entry>50/15 microsecond emphasis</entry>
  1146. </row>
  1147. <row>
  1148. <entry><constant>V4L2_MPEG_AUDIO_EMPHASIS_CCITT_J17</constant>&nbsp;</entry>
  1149. <entry>CCITT J.17</entry>
  1150. </row>
  1151. </tbody>
  1152. </entrytbl>
  1153. </row>
  1154. <row><entry></entry></row>
  1155. <row id="v4l2-mpeg-audio-crc">
  1156. <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_CRC</constant>&nbsp;</entry>
  1157. <entry>enum&nbsp;v4l2_mpeg_audio_crc</entry>
  1158. </row><row><entry spanname="descr">CRC method. Possible
  1159. values are:</entry>
  1160. </row>
  1161. <row>
  1162. <entrytbl spanname="descr" cols="2">
  1163. <tbody valign="top">
  1164. <row>
  1165. <entry><constant>V4L2_MPEG_AUDIO_CRC_NONE</constant>&nbsp;</entry>
  1166. <entry>None</entry>
  1167. </row>
  1168. <row>
  1169. <entry><constant>V4L2_MPEG_AUDIO_CRC_CRC16</constant>&nbsp;</entry>
  1170. <entry>16 bit parity check</entry>
  1171. </row>
  1172. </tbody>
  1173. </entrytbl>
  1174. </row>
  1175. <row><entry></entry></row>
  1176. <row>
  1177. <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_MUTE</constant>&nbsp;</entry>
  1178. <entry>boolean</entry>
  1179. </row><row><entry spanname="descr">Mutes the audio when
  1180. capturing. This is not done by muting audio hardware, which can still
  1181. produce a slight hiss, but in the encoder itself, guaranteeing a fixed
  1182. and reproducable audio bitstream. 0 = unmuted, 1 = muted.</entry>
  1183. </row>
  1184. <row><entry></entry></row>
  1185. <row id="v4l2-mpeg-video-encoding">
  1186. <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_ENCODING</constant>&nbsp;</entry>
  1187. <entry>enum&nbsp;v4l2_mpeg_video_encoding</entry>
  1188. </row><row><entry spanname="descr">MPEG Video encoding
  1189. method. Possible values are:</entry>
  1190. </row>
  1191. <row>
  1192. <entrytbl spanname="descr" cols="2">
  1193. <tbody valign="top">
  1194. <row>
  1195. <entry><constant>V4L2_MPEG_VIDEO_ENCODING_MPEG_1</constant>&nbsp;</entry>
  1196. <entry>MPEG-1 Video encoding</entry>
  1197. </row>
  1198. <row>
  1199. <entry><constant>V4L2_MPEG_VIDEO_ENCODING_MPEG_2</constant>&nbsp;</entry>
  1200. <entry>MPEG-2 Video encoding</entry>
  1201. </row>
  1202. <row>
  1203. <entry><constant>V4L2_MPEG_VIDEO_ENCODING_MPEG_4_AVC</constant>&nbsp;</entry>
  1204. <entry>MPEG-4 AVC (H.264) Video encoding</entry>
  1205. </row>
  1206. </tbody>
  1207. </entrytbl>
  1208. </row>
  1209. <row><entry></entry></row>
  1210. <row id="v4l2-mpeg-video-aspect">
  1211. <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_ASPECT</constant>&nbsp;</entry>
  1212. <entry>enum&nbsp;v4l2_mpeg_video_aspect</entry>
  1213. </row><row><entry spanname="descr">Video aspect.
  1214. Possible values are:</entry>
  1215. </row>
  1216. <row>
  1217. <entrytbl spanname="descr" cols="2">
  1218. <tbody valign="top">
  1219. <row>
  1220. <entry><constant>V4L2_MPEG_VIDEO_ASPECT_1x1</constant>&nbsp;</entry>
  1221. </row>
  1222. <row>
  1223. <entry><constant>V4L2_MPEG_VIDEO_ASPECT_4x3</constant>&nbsp;</entry>
  1224. </row>
  1225. <row>
  1226. <entry><constant>V4L2_MPEG_VIDEO_ASPECT_16x9</constant>&nbsp;</entry>
  1227. </row>
  1228. <row>
  1229. <entry><constant>V4L2_MPEG_VIDEO_ASPECT_221x100</constant>&nbsp;</entry>
  1230. </row>
  1231. </tbody>
  1232. </entrytbl>
  1233. </row>
  1234. <row><entry></entry></row>
  1235. <row>
  1236. <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_B_FRAMES</constant>&nbsp;</entry>
  1237. <entry>integer</entry>
  1238. </row><row><entry spanname="descr">Number of B-Frames
  1239. (default 2)</entry>
  1240. </row>
  1241. <row><entry></entry></row>
  1242. <row>
  1243. <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_GOP_SIZE</constant>&nbsp;</entry>
  1244. <entry>integer</entry>
  1245. </row><row><entry spanname="descr">GOP size (default
  1246. 12)</entry>
  1247. </row>
  1248. <row><entry></entry></row>
  1249. <row>
  1250. <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_GOP_CLOSURE</constant>&nbsp;</entry>
  1251. <entry>boolean</entry>
  1252. </row><row><entry spanname="descr">GOP closure (default
  1253. 1)</entry>
  1254. </row>
  1255. <row><entry></entry></row>
  1256. <row>
  1257. <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_PULLDOWN</constant>&nbsp;</entry>
  1258. <entry>boolean</entry>
  1259. </row><row><entry spanname="descr">Enable 3:2 pulldown
  1260. (default 0)</entry>
  1261. </row>
  1262. <row><entry></entry></row>
  1263. <row id="v4l2-mpeg-video-bitrate-mode">
  1264. <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_BITRATE_MODE</constant>&nbsp;</entry>
  1265. <entry>enum&nbsp;v4l2_mpeg_video_bitrate_mode</entry>
  1266. </row><row><entry spanname="descr">Video bitrate mode.
  1267. Possible values are:</entry>
  1268. </row>
  1269. <row>
  1270. <entrytbl spanname="descr" cols="2">
  1271. <tbody valign="top">
  1272. <row>
  1273. <entry><constant>V4L2_MPEG_VIDEO_BITRATE_MODE_VBR</constant>&nbsp;</entry>
  1274. <entry>Variable bitrate</entry>
  1275. </row>
  1276. <row>
  1277. <entry><constant>V4L2_MPEG_VIDEO_BITRATE_MODE_CBR</constant>&nbsp;</entry>
  1278. <entry>Constant bitrate</entry>
  1279. </row>
  1280. </tbody>
  1281. </entrytbl>
  1282. </row>
  1283. <row><entry></entry></row>
  1284. <row>
  1285. <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_BITRATE</constant>&nbsp;</entry>
  1286. <entry>integer</entry>
  1287. </row><row><entry spanname="descr">Video bitrate in bits
  1288. per second.</entry>
  1289. </row>
  1290. <row><entry></entry></row>
  1291. <row>
  1292. <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_BITRATE_PEAK</constant>&nbsp;</entry>
  1293. <entry>integer</entry>
  1294. </row><row><entry spanname="descr">Peak video bitrate in
  1295. bits per second. Must be larger or equal to the average video bitrate.
  1296. It is ignored if the video bitrate mode is set to constant
  1297. bitrate.</entry>
  1298. </row>
  1299. <row><entry></entry></row>
  1300. <row>
  1301. <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_TEMPORAL_DECIMATION</constant>&nbsp;</entry>
  1302. <entry>integer</entry>
  1303. </row><row><entry spanname="descr">For every captured
  1304. frame, skip this many subsequent frames (default 0).</entry>
  1305. </row>
  1306. <row><entry></entry></row>
  1307. <row>
  1308. <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_MUTE</constant>&nbsp;</entry>
  1309. <entry>boolean</entry>
  1310. </row>
  1311. <row><entry spanname="descr">"Mutes" the video to a
  1312. fixed color when capturing. This is useful for testing, to produce a
  1313. fixed video bitstream. 0 = unmuted, 1 = muted.</entry>
  1314. </row>
  1315. <row><entry></entry></row>
  1316. <row>
  1317. <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_MUTE_YUV</constant>&nbsp;</entry>
  1318. <entry>integer</entry>
  1319. </row><row><entry spanname="descr">Sets the "mute" color
  1320. of the video. The supplied 32-bit integer is interpreted as follows (bit
  1321. 0 = least significant bit):</entry>
  1322. </row>
  1323. <row>
  1324. <entrytbl spanname="descr" cols="2">
  1325. <tbody valign="top">
  1326. <row>
  1327. <entry>Bit 0:7</entry>
  1328. <entry>V chrominance information</entry>
  1329. </row>
  1330. <row>
  1331. <entry>Bit 8:15</entry>
  1332. <entry>U chrominance information</entry>
  1333. </row>
  1334. <row>
  1335. <entry>Bit 16:23</entry>
  1336. <entry>Y luminance information</entry>
  1337. </row>
  1338. <row>
  1339. <entry>Bit 24:31</entry>
  1340. <entry>Must be zero.</entry>
  1341. </row>
  1342. </tbody>
  1343. </entrytbl>
  1344. </row>
  1345. </tbody>
  1346. </tgroup>
  1347. </table>
  1348. </section>
  1349. <section>
  1350. <title>CX2341x MPEG Controls</title>
  1351. <para>The following MPEG class controls deal with MPEG
  1352. encoding settings that are specific to the Conexant CX23415 and
  1353. CX23416 MPEG encoding chips.</para>
  1354. <table pgwide="1" frame="none" id="cx2341x-control-id">
  1355. <title>CX2341x Control IDs</title>
  1356. <tgroup cols="4">
  1357. <colspec colname="c1" colwidth="1*" />
  1358. <colspec colname="c2" colwidth="6*" />
  1359. <colspec colname="c3" colwidth="2*" />
  1360. <colspec colname="c4" colwidth="6*" />
  1361. <spanspec namest="c1" nameend="c2" spanname="id" />
  1362. <spanspec namest="c2" nameend="c4" spanname="descr" />
  1363. <thead>
  1364. <row>
  1365. <entry spanname="id" align="left">ID</entry>
  1366. <entry align="left">Type</entry>
  1367. </row><row><entry spanname="descr" align="left">Description</entry>
  1368. </row>
  1369. </thead>
  1370. <tbody valign="top">
  1371. <row><entry></entry></row>
  1372. <row id="v4l2-mpeg-cx2341x-video-spatial-filter-mode">
  1373. <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE</constant>&nbsp;</entry>
  1374. <entry>enum&nbsp;v4l2_mpeg_cx2341x_video_spatial_filter_mode</entry>
  1375. </row><row><entry spanname="descr">Sets the Spatial
  1376. Filter mode (default <constant>MANUAL</constant>). Possible values
  1377. are:</entry>
  1378. </row>
  1379. <row>
  1380. <entrytbl spanname="descr" cols="2">
  1381. <tbody valign="top">
  1382. <row>
  1383. <entry><constant>V4L2_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE_MANUAL</constant>&nbsp;</entry>
  1384. <entry>Choose the filter manually</entry>
  1385. </row>
  1386. <row>
  1387. <entry><constant>V4L2_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE_AUTO</constant>&nbsp;</entry>
  1388. <entry>Choose the filter automatically</entry>
  1389. </row>
  1390. </tbody>
  1391. </entrytbl>
  1392. </row>
  1393. <row><entry></entry></row>
  1394. <row>
  1395. <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER</constant>&nbsp;</entry>
  1396. <entry>integer&nbsp;(0-15)</entry>
  1397. </row><row><entry spanname="descr">The setting for the
  1398. Spatial Filter. 0 = off, 15 = maximum. (Default is 0.)</entry>
  1399. </row>
  1400. <row><entry></entry></row>
  1401. <row id="luma-spatial-filter-type">
  1402. <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE</constant>&nbsp;</entry>
  1403. <entry>enum&nbsp;v4l2_mpeg_cx2341x_video_luma_spatial_filter_type</entry>
  1404. </row><row><entry spanname="descr">Select the algorithm
  1405. to use for the Luma Spatial Filter (default
  1406. <constant>1D_HOR</constant>). Possible values:</entry>
  1407. </row>
  1408. <row>
  1409. <entrytbl spanname="descr" cols="2">
  1410. <tbody valign="top">
  1411. <row>
  1412. <entry><constant>V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_OFF</constant>&nbsp;</entry>
  1413. <entry>No filter</entry>
  1414. </row>
  1415. <row>
  1416. <entry><constant>V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_1D_HOR</constant>&nbsp;</entry>
  1417. <entry>One-dimensional horizontal</entry>
  1418. </row>
  1419. <row>
  1420. <entry><constant>V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_1D_VERT</constant>&nbsp;</entry>
  1421. <entry>One-dimensional vertical</entry>
  1422. </row>
  1423. <row>
  1424. <entry><constant>V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_2D_HV_SEPARABLE</constant>&nbsp;</entry>
  1425. <entry>Two-dimensional separable</entry>
  1426. </row>
  1427. <row>
  1428. <entry><constant>V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_2D_SYM_NON_SEPARABLE</constant>&nbsp;</entry>
  1429. <entry>Two-dimensional symmetrical
  1430. non-separable</entry>
  1431. </row>
  1432. </tbody>
  1433. </entrytbl>
  1434. </row>
  1435. <row><entry></entry></row>
  1436. <row id="chroma-spatial-filter-type">
  1437. <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE</constant>&nbsp;</entry>
  1438. <entry>enum&nbsp;v4l2_mpeg_cx2341x_video_chroma_spatial_filter_type</entry>
  1439. </row><row><entry spanname="descr">Select the algorithm
  1440. for the Chroma Spatial Filter (default <constant>1D_HOR</constant>).
  1441. Possible values are:</entry>
  1442. </row>
  1443. <row>
  1444. <entrytbl spanname="descr" cols="2">
  1445. <tbody valign="top">
  1446. <row>
  1447. <entry><constant>V4L2_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE_OFF</constant>&nbsp;</entry>
  1448. <entry>No filter</entry>
  1449. </row>
  1450. <row>
  1451. <entry><constant>V4L2_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE_1D_HOR</constant>&nbsp;</entry>
  1452. <entry>One-dimensional horizontal</entry>
  1453. </row>
  1454. </tbody>
  1455. </entrytbl>
  1456. </row>
  1457. <row><entry></entry></row>
  1458. <row id="v4l2-mpeg-cx2341x-video-temporal-filter-mode">
  1459. <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE</constant>&nbsp;</entry>
  1460. <entry>enum&nbsp;v4l2_mpeg_cx2341x_video_temporal_filter_mode</entry>
  1461. </row><row><entry spanname="descr">Sets the Temporal
  1462. Filter mode (default <constant>MANUAL</constant>). Possible values
  1463. are:</entry>
  1464. </row>
  1465. <row>
  1466. <entrytbl spanname="descr" cols="2">
  1467. <tbody valign="top">
  1468. <row>
  1469. <entry><constant>V4L2_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE_MANUAL</constant>&nbsp;</entry>
  1470. <entry>Choose the filter manually</entry>
  1471. </row>
  1472. <row>
  1473. <entry><constant>V4L2_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE_AUTO</constant>&nbsp;</entry>
  1474. <entry>Choose the filter automatically</entry>
  1475. </row>
  1476. </tbody>
  1477. </entrytbl>
  1478. </row>
  1479. <row><entry></entry></row>
  1480. <row>
  1481. <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER</constant>&nbsp;</entry>
  1482. <entry>integer&nbsp;(0-31)</entry>
  1483. </row><row><entry spanname="descr">The setting for the
  1484. Temporal Filter. 0 = off, 31 = maximum. (Default is 8 for full-scale
  1485. capturing and 0 for scaled capturing.)</entry>
  1486. </row>
  1487. <row><entry></entry></row>
  1488. <row id="v4l2-mpeg-cx2341x-video-median-filter-type">
  1489. <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE</constant>&nbsp;</entry>
  1490. <entry>enum&nbsp;v4l2_mpeg_cx2341x_video_median_filter_type</entry>
  1491. </row><row><entry spanname="descr">Median Filter Type
  1492. (default <constant>OFF</constant>). Possible values are:</entry>
  1493. </row>
  1494. <row>
  1495. <entrytbl spanname="descr" cols="2">
  1496. <tbody valign="top">
  1497. <row>
  1498. <entry><constant>V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_OFF</constant>&nbsp;</entry>
  1499. <entry>No filter</entry>
  1500. </row>
  1501. <row>
  1502. <entry><constant>V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_HOR</constant>&nbsp;</entry>
  1503. <entry>Horizontal filter</entry>
  1504. </row>
  1505. <row>
  1506. <entry><constant>V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_VERT</constant>&nbsp;</entry>
  1507. <entry>Vertical filter</entry>
  1508. </row>
  1509. <row>
  1510. <entry><constant>V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_HOR_VERT</constant>&nbsp;</entry>
  1511. <entry>Horizontal and vertical filter</entry>
  1512. </row>
  1513. <row>
  1514. <entry><constant>V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_DIAG</constant>&nbsp;</entry>
  1515. <entry>Diagonal filter</entry>
  1516. </row>
  1517. </tbody>
  1518. </entrytbl>
  1519. </row>
  1520. <row><entry></entry></row>
  1521. <row>
  1522. <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_MEDIAN_FILTER_BOTTOM</constant>&nbsp;</entry>
  1523. <entry>integer&nbsp;(0-255)</entry>
  1524. </row><row><entry spanname="descr">Threshold above which
  1525. the luminance median filter is enabled (default 0)</entry>
  1526. </row>
  1527. <row><entry></entry></row>
  1528. <row>
  1529. <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_MEDIAN_FILTER_TOP</constant>&nbsp;</entry>
  1530. <entry>integer&nbsp;(0-255)</entry>
  1531. </row><row><entry spanname="descr">Threshold below which
  1532. the luminance median filter is enabled (default 255)</entry>
  1533. </row>
  1534. <row><entry></entry></row>
  1535. <row>
  1536. <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_MEDIAN_FILTER_BOTTOM</constant>&nbsp;</entry>
  1537. <entry>integer&nbsp;(0-255)</entry>
  1538. </row><row><entry spanname="descr">Threshold above which
  1539. the chroma median filter is enabled (default 0)</entry>
  1540. </row>
  1541. <row><entry></entry></row>
  1542. <row>
  1543. <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_MEDIAN_FILTER_TOP</constant>&nbsp;</entry>
  1544. <entry>integer&nbsp;(0-255)</entry>
  1545. </row><row><entry spanname="descr">Threshold below which
  1546. the chroma median filter is enabled (default 255)</entry>
  1547. </row>
  1548. <row><entry></entry></row>
  1549. <row>
  1550. <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_STREAM_INSERT_NAV_PACKETS</constant>&nbsp;</entry>
  1551. <entry>boolean</entry>
  1552. </row>
  1553. <row><entry spanname="descr">The CX2341X MPEG encoder
  1554. can insert one empty MPEG-2 PES packet into the stream between every
  1555. four video frames. The packet size is 2048 bytes, including the
  1556. packet_start_code_prefix and stream_id fields. The stream_id is 0xBF
  1557. (private stream 2). The payload consists of 0x00 bytes, to be filled
  1558. in by the application. 0 = do not insert, 1 = insert packets.</entry>
  1559. </row>
  1560. </tbody>
  1561. </tgroup>
  1562. </table>
  1563. </section>
  1564. </section>
  1565. <section id="camera-controls">
  1566. <title>Camera Control Reference</title>
  1567. <para>The Camera class includes controls for mechanical (or
  1568. equivalent digital) features of a device such as controllable lenses
  1569. or sensors.</para>
  1570. <table pgwide="1" frame="none" id="camera-control-id">
  1571. <title>Camera Control IDs</title>
  1572. <tgroup cols="4">
  1573. <colspec colname="c1" colwidth="1*" />
  1574. <colspec colname="c2" colwidth="6*" />
  1575. <colspec colname="c3" colwidth="2*" />
  1576. <colspec colname="c4" colwidth="6*" />
  1577. <spanspec namest="c1" nameend="c2" spanname="id" />
  1578. <spanspec namest="c2" nameend="c4" spanname="descr" />
  1579. <thead>
  1580. <row>
  1581. <entry spanname="id" align="left">ID</entry>
  1582. <entry align="left">Type</entry>
  1583. </row><row rowsep="1"><entry spanname="descr" align="left">Description</entry>
  1584. </row>
  1585. </thead>
  1586. <tbody valign="top">
  1587. <row><entry></entry></row>
  1588. <row>
  1589. <entry spanname="id"><constant>V4L2_CID_CAMERA_CLASS</constant>&nbsp;</entry>
  1590. <entry>class</entry>
  1591. </row><row><entry spanname="descr">The Camera class
  1592. descriptor. Calling &VIDIOC-QUERYCTRL; for this control will return a
  1593. description of this control class.</entry>
  1594. </row>
  1595. <row><entry></entry></row>
  1596. <row id="v4l2-exposure-auto-type">
  1597. <entry spanname="id"><constant>V4L2_CID_EXPOSURE_AUTO</constant>&nbsp;</entry>
  1598. <entry>enum&nbsp;v4l2_exposure_auto_type</entry>
  1599. </row><row><entry spanname="descr">Enables automatic
  1600. adjustments of the exposure time and/or iris aperture. The effect of
  1601. manual changes of the exposure time or iris aperture while these
  1602. features are enabled is undefined, drivers should ignore such
  1603. requests. Possible values are:</entry>
  1604. </row>
  1605. <row>
  1606. <entrytbl spanname="descr" cols="2">
  1607. <tbody valign="top">
  1608. <row>
  1609. <entry><constant>V4L2_EXPOSURE_AUTO</constant>&nbsp;</entry>
  1610. <entry>Automatic exposure time, automatic iris
  1611. aperture.</entry>
  1612. </row>
  1613. <row>
  1614. <entry><constant>V4L2_EXPOSURE_MANUAL</constant>&nbsp;</entry>
  1615. <entry>Manual exposure time, manual iris.</entry>
  1616. </row>
  1617. <row>
  1618. <entry><constant>V4L2_EXPOSURE_SHUTTER_PRIORITY</constant>&nbsp;</entry>
  1619. <entry>Manual exposure time, auto iris.</entry>
  1620. </row>
  1621. <row>
  1622. <entry><constant>V4L2_EXPOSURE_APERTURE_PRIORITY</constant>&nbsp;</entry>
  1623. <entry>Auto exposure time, manual iris.</entry>
  1624. </row>
  1625. </tbody>
  1626. </entrytbl>
  1627. </row>
  1628. <row><entry></entry></row>
  1629. <row>
  1630. <entry spanname="id"><constant>V4L2_CID_EXPOSURE_ABSOLUTE</constant>&nbsp;</entry>
  1631. <entry>integer</entry>
  1632. </row><row><entry spanname="descr">Determines the exposure
  1633. time of the camera sensor. The exposure time is limited by the frame
  1634. interval. Drivers should interpret the values as 100 &micro;s units,
  1635. where the value 1 stands for 1/10000th of a second, 10000 for 1 second
  1636. and 100000 for 10 seconds.</entry>
  1637. </row>
  1638. <row><entry></entry></row>
  1639. <row>
  1640. <entry spanname="id"><constant>V4L2_CID_EXPOSURE_AUTO_PRIORITY</constant>&nbsp;</entry>
  1641. <entry>boolean</entry>
  1642. </row><row><entry spanname="descr">When
  1643. <constant>V4L2_CID_EXPOSURE_AUTO</constant> is set to
  1644. <constant>AUTO</constant> or <constant>APERTURE_PRIORITY</constant>,
  1645. this control determines if the device may dynamically vary the frame
  1646. rate. By default this feature is disabled (0) and the frame rate must
  1647. remain constant.</entry>
  1648. </row>
  1649. <row><entry></entry></row>
  1650. <row>
  1651. <entry spanname="id"><constant>V4L2_CID_PAN_RELATIVE</constant>&nbsp;</entry>
  1652. <entry>integer</entry>
  1653. </row><row><entry spanname="descr">This control turns the
  1654. camera horizontally by the specified amount. The unit is undefined. A
  1655. positive value moves the camera to the right (clockwise when viewed
  1656. from above), a negative value to the left. A value of zero does not
  1657. cause motion. This is a write-only control.</entry>
  1658. </row>
  1659. <row><entry></entry></row>
  1660. <row>
  1661. <entry spanname="id"><constant>V4L2_CID_TILT_RELATIVE</constant>&nbsp;</entry>
  1662. <entry>integer</entry>
  1663. </row><row><entry spanname="descr">This control turns the
  1664. camera vertically by the specified amount. The unit is undefined. A
  1665. positive value moves the camera up, a negative value down. A value of
  1666. zero does not cause motion. This is a write-only control.</entry>
  1667. </row>
  1668. <row><entry></entry></row>
  1669. <row>
  1670. <entry spanname="id"><constant>V4L2_CID_PAN_RESET</constant>&nbsp;</entry>
  1671. <entry>button</entry>
  1672. </row><row><entry spanname="descr">When this control is set,
  1673. the camera moves horizontally to the default position.</entry>
  1674. </row>
  1675. <row><entry></entry></row>
  1676. <row>
  1677. <entry spanname="id"><constant>V4L2_CID_TILT_RESET</constant>&nbsp;</entry>
  1678. <entry>button</entry>
  1679. </row><row><entry spanname="descr">When this control is set,
  1680. the camera moves vertically to the default position.</entry>
  1681. </row>
  1682. <row><entry></entry></row>
  1683. <row>
  1684. <entry spanname="id"><constant>V4L2_CID_PAN_ABSOLUTE</constant>&nbsp;</entry>
  1685. <entry>integer</entry>
  1686. </row><row><entry spanname="descr">This control
  1687. turns the camera horizontally to the specified position. Positive
  1688. values move the camera to the right (clockwise when viewed from above),
  1689. negative values to the left. Drivers should interpret the values as arc
  1690. seconds, with valid values between -180 * 3600 and +180 * 3600
  1691. inclusive.</entry>
  1692. </row>
  1693. <row><entry></entry></row>
  1694. <row>
  1695. <entry spanname="id"><constant>V4L2_CID_TILT_ABSOLUTE</constant>&nbsp;</entry>
  1696. <entry>integer</entry>
  1697. </row><row><entry spanname="descr">This control
  1698. turns the camera vertically to the specified position. Positive values
  1699. move the camera up, negative values down. Drivers should interpret the
  1700. values as arc seconds, with valid values between -180 * 3600 and +180
  1701. * 3600 inclusive.</entry>
  1702. </row>
  1703. <row><entry></entry></row>
  1704. <row>
  1705. <entry spanname="id"><constant>V4L2_CID_FOCUS_ABSOLUTE</constant>&nbsp;</entry>
  1706. <entry>integer</entry>
  1707. </row><row><entry spanname="descr">This control sets the
  1708. focal point of the camera to the specified position. The unit is
  1709. undefined. Positive values set the focus closer to the camera,
  1710. negative values towards infinity.</entry>
  1711. </row>
  1712. <row><entry></entry></row>
  1713. <row>
  1714. <entry spanname="id"><constant>V4L2_CID_FOCUS_RELATIVE</constant>&nbsp;</entry>
  1715. <entry>integer</entry>
  1716. </row><row><entry spanname="descr">This control moves the
  1717. focal point of the camera by the specified amount. The unit is
  1718. undefined. Positive values move the focus closer to the camera,
  1719. negative values towards infinity. This is a write-only control.</entry>
  1720. </row>
  1721. <row><entry></entry></row>
  1722. <row>
  1723. <entry spanname="id"><constant>V4L2_CID_FOCUS_AUTO</constant>&nbsp;</entry>
  1724. <entry>boolean</entry>
  1725. </row><row><entry spanname="descr">Enables automatic focus
  1726. adjustments. The effect of manual focus adjustments while this feature
  1727. is enabled is undefined, drivers should ignore such requests.</entry>
  1728. </row>
  1729. <row><entry></entry></row>
  1730. <row>
  1731. <entry spanname="id"><constant>V4L2_CID_ZOOM_ABSOLUTE</constant>&nbsp;</entry>
  1732. <entry>integer</entry>
  1733. </row><row><entry spanname="descr">Specify the objective lens
  1734. focal length as an absolute value. The zoom unit is driver-specific and its
  1735. value should be a positive integer.</entry>
  1736. </row>
  1737. <row><entry></entry></row>
  1738. <row>
  1739. <entry spanname="id"><constant>V4L2_CID_ZOOM_RELATIVE</constant>&nbsp;</entry>
  1740. <entry>integer</entry>
  1741. </row><row><entry spanname="descr">Specify the objective lens
  1742. focal length relatively to the current value. Positive values move the zoom
  1743. lens group towards the telephoto direction, negative values towards the
  1744. wide-angle direction. The zoom unit is driver-specific. This is a write-only control.</entry>
  1745. </row>
  1746. <row><entry></entry></row>
  1747. <row>
  1748. <entry spanname="id"><constant>V4L2_CID_ZOOM_CONTINUOUS</constant>&nbsp;</entry>
  1749. <entry>integer</entry>
  1750. </row><row><entry spanname="descr">Move the objective lens group
  1751. at the specified speed until it reaches physical device limits or until an
  1752. explicit request to stop the movement. A positive value moves the zoom lens
  1753. group towards the telephoto direction. A value of zero stops the zoom lens
  1754. group movement. A negative value moves the zoom lens group towards the
  1755. wide-angle direction. The zoom speed unit is driver-specific.</entry>
  1756. </row>
  1757. <row><entry></entry></row>
  1758. <row>
  1759. <entry spanname="id"><constant>V4L2_CID_IRIS_ABSOLUTE</constant>&nbsp;</entry>
  1760. <entry>integer</entry>
  1761. </row><row><entry spanname="descr">This control sets the
  1762. camera's aperture to the specified value. The unit is undefined.
  1763. Larger values open the iris wider, smaller values close it.</entry>
  1764. </row>
  1765. <row><entry></entry></row>
  1766. <row>
  1767. <entry spanname="id"><constant>V4L2_CID_IRIS_RELATIVE</constant>&nbsp;</entry>
  1768. <entry>integer</entry>
  1769. </row><row><entry spanname="descr">This control modifies the
  1770. camera's aperture by the specified amount. The unit is undefined.
  1771. Positive values open the iris one step further, negative values close
  1772. it one step further. This is a write-only control.</entry>
  1773. </row>
  1774. <row><entry></entry></row>
  1775. <row>
  1776. <entry spanname="id"><constant>V4L2_CID_PRIVACY</constant>&nbsp;</entry>
  1777. <entry>boolean</entry>
  1778. </row><row><entry spanname="descr">Prevent video from being acquired
  1779. by the camera. When this control is set to <constant>TRUE</constant> (1), no
  1780. image can be captured by the camera. Common means to enforce privacy are
  1781. mechanical obturation of the sensor and firmware image processing, but the
  1782. device is not restricted to these methods. Devices that implement the privacy
  1783. control must support read access and may support write access.</entry>
  1784. </row>
  1785. <row>
  1786. <entry spanname="id"><constant>V4L2_CID_BAND_STOP_FILTER</constant>&nbsp;</entry>
  1787. <entry>integer</entry>
  1788. </row><row><entry spanname="descr">Switch the band-stop filter of a
  1789. camera sensor on or off, or specify its strength. Such band-stop filters can
  1790. be used, for example, to filter out the fluorescent light component.</entry>
  1791. </row>
  1792. <row><entry></entry></row>
  1793. </tbody>
  1794. </tgroup>
  1795. </table>
  1796. </section>
  1797. <section id="fm-tx-controls">
  1798. <title>FM Transmitter Control Reference</title>
  1799. <para>The FM Transmitter (FM_TX) class includes controls for common features of
  1800. FM transmissions capable devices. Currently this class includes parameters for audio
  1801. compression, pilot tone generation, audio deviation limiter, RDS transmission and
  1802. tuning power features.</para>
  1803. <table pgwide="1" frame="none" id="fm-tx-control-id">
  1804. <title>FM_TX Control IDs</title>
  1805. <tgroup cols="4">
  1806. <colspec colname="c1" colwidth="1*" />
  1807. <colspec colname="c2" colwidth="6*" />
  1808. <colspec colname="c3" colwidth="2*" />
  1809. <colspec colname="c4" colwidth="6*" />
  1810. <spanspec namest="c1" nameend="c2" spanname="id" />
  1811. <spanspec namest="c2" nameend="c4" spanname="descr" />
  1812. <thead>
  1813. <row>
  1814. <entry spanname="id" align="left">ID</entry>
  1815. <entry align="left">Type</entry>
  1816. </row><row rowsep="1"><entry spanname="descr" align="left">Description</entry>
  1817. </row>
  1818. </thead>
  1819. <tbody valign="top">
  1820. <row><entry></entry></row>
  1821. <row>
  1822. <entry spanname="id"><constant>V4L2_CID_FM_TX_CLASS</constant>&nbsp;</entry>
  1823. <entry>class</entry>
  1824. </row><row><entry spanname="descr">The FM_TX class
  1825. descriptor. Calling &VIDIOC-QUERYCTRL; for this control will return a
  1826. description of this control class.</entry>
  1827. </row>
  1828. <row>
  1829. <entry spanname="id"><constant>V4L2_CID_RDS_TX_DEVIATION</constant>&nbsp;</entry>
  1830. <entry>integer</entry>
  1831. </row>
  1832. <row><entry spanname="descr">Configures RDS signal frequency deviation level in Hz.
  1833. The range and step are driver-specific.</entry>
  1834. </row>
  1835. <row>
  1836. <entry spanname="id"><constant>V4L2_CID_RDS_TX_PI</constant>&nbsp;</entry>
  1837. <entry>integer</entry>
  1838. </row>
  1839. <row><entry spanname="descr">Sets the RDS Programme Identification field
  1840. for transmission.</entry>
  1841. </row>
  1842. <row>
  1843. <entry spanname="id"><constant>V4L2_CID_RDS_TX_PTY</constant>&nbsp;</entry>
  1844. <entry>integer</entry>
  1845. </row>
  1846. <row><entry spanname="descr">Sets the RDS Programme Type field for transmission.
  1847. This encodes up to 31 pre-defined programme types.</entry>
  1848. </row>
  1849. <row>
  1850. <entry spanname="id"><constant>V4L2_CID_RDS_TX_PS_NAME</constant>&nbsp;</entry>
  1851. <entry>string</entry>
  1852. </row>
  1853. <row><entry spanname="descr">Sets the Programme Service name (PS_NAME) for transmission.
  1854. It is intended for static display on a receiver. It is the primary aid to listeners in programme service
  1855. identification and selection. In Annex E of <xref linkend="en50067" />, the RDS specification,
  1856. there is a full description of the correct character encoding for Programme Service name strings.
  1857. Also from RDS specification, PS is usually a single eight character text. However, it is also possible
  1858. to find receivers which can scroll strings sized as 8 x N characters. So, this control must be configured
  1859. with steps of 8 characters. The result is it must always contain a string with size multiple of 8.</entry>
  1860. </row>
  1861. <row>
  1862. <entry spanname="id"><constant>V4L2_CID_RDS_TX_RADIO_TEXT</constant>&nbsp;</entry>
  1863. <entry>string</entry>
  1864. </row>
  1865. <row><entry spanname="descr">Sets the Radio Text info for transmission. It is a textual description of
  1866. what is being broadcasted. RDS Radio Text can be applied when broadcaster wishes to transmit longer PS names,
  1867. programme-related information or any other text. In these cases, RadioText should be used in addition to
  1868. <constant>V4L2_CID_RDS_TX_PS_NAME</constant>. The encoding for Radio Text strings is also fully described
  1869. in Annex E of <xref linkend="en50067" />. The length of Radio Text strings depends on which RDS Block is being
  1870. used to transmit it, either 32 (2A block) or 64 (2B block). However, it is also possible
  1871. to find receivers which can scroll strings sized as 32 x N or 64 x N characters. So, this control must be configured
  1872. with steps of 32 or 64 characters. The result is it must always contain a string with size multiple of 32 or 64. </entry>
  1873. </row>
  1874. <row>
  1875. <entry spanname="id"><constant>V4L2_CID_AUDIO_LIMITER_ENABLED</constant>&nbsp;</entry>
  1876. <entry>boolean</entry>
  1877. </row>
  1878. <row><entry spanname="descr">Enables or disables the audio deviation limiter feature.
  1879. The limiter is useful when trying to maximize the audio volume, minimize receiver-generated
  1880. distortion and prevent overmodulation.
  1881. </entry>
  1882. </row>
  1883. <row>
  1884. <entry spanname="id"><constant>V4L2_CID_AUDIO_LIMITER_RELEASE_TIME</constant>&nbsp;</entry>
  1885. <entry>integer</entry>
  1886. </row>
  1887. <row><entry spanname="descr">Sets the audio deviation limiter feature release time.
  1888. Unit is in useconds. Step and range are driver-specific.</entry>
  1889. </row>
  1890. <row>
  1891. <entry spanname="id"><constant>V4L2_CID_AUDIO_LIMITER_DEVIATION</constant>&nbsp;</entry>
  1892. <entry>integer</entry>
  1893. </row>
  1894. <row><entry spanname="descr">Configures audio frequency deviation level in Hz.
  1895. The range and step are driver-specific.</entry>
  1896. </row>
  1897. <row>
  1898. <entry spanname="id"><constant>V4L2_CID_AUDIO_COMPRESSION_ENABLED</constant>&nbsp;</entry>
  1899. <entry>boolean</entry>
  1900. </row>
  1901. <row><entry spanname="descr">Enables or disables the audio compression feature.
  1902. This feature amplifies signals below the threshold by a fixed gain and compresses audio
  1903. signals above the threshold by the ratio of Threshold/(Gain + Threshold).</entry>
  1904. </row>
  1905. <row>
  1906. <entry spanname="id"><constant>V4L2_CID_AUDIO_COMPRESSION_GAIN</constant>&nbsp;</entry>
  1907. <entry>integer</entry>
  1908. </row>
  1909. <row><entry spanname="descr">Sets the gain for audio compression feature. It is
  1910. a dB value. The range and step are driver-specific.</entry>
  1911. </row>
  1912. <row>
  1913. <entry spanname="id"><constant>V4L2_CID_AUDIO_COMPRESSION_THRESHOLD</constant>&nbsp;</entry>
  1914. <entry>integer</entry>
  1915. </row>
  1916. <row><entry spanname="descr">Sets the threshold level for audio compression freature.
  1917. It is a dB value. The range and step are driver-specific.</entry>
  1918. </row>
  1919. <row>
  1920. <entry spanname="id"><constant>V4L2_CID_AUDIO_COMPRESSION_ATTACK_TIME</constant>&nbsp;</entry>
  1921. <entry>integer</entry>
  1922. </row>
  1923. <row><entry spanname="descr">Sets the attack time for audio compression feature.
  1924. It is a useconds value. The range and step are driver-specific.</entry>
  1925. </row>
  1926. <row>
  1927. <entry spanname="id"><constant>V4L2_CID_AUDIO_COMPRESSION_RELEASE_TIME</constant>&nbsp;</entry>
  1928. <entry>integer</entry>
  1929. </row>
  1930. <row><entry spanname="descr">Sets the release time for audio compression feature.
  1931. It is a useconds value. The range and step are driver-specific.</entry>
  1932. </row>
  1933. <row>
  1934. <entry spanname="id"><constant>V4L2_CID_PILOT_TONE_ENABLED</constant>&nbsp;</entry>
  1935. <entry>boolean</entry>
  1936. </row>
  1937. <row><entry spanname="descr">Enables or disables the pilot tone generation feature.</entry>
  1938. </row>
  1939. <row>
  1940. <entry spanname="id"><constant>V4L2_CID_PILOT_TONE_DEVIATION</constant>&nbsp;</entry>
  1941. <entry>integer</entry>
  1942. </row>
  1943. <row><entry spanname="descr">Configures pilot tone frequency deviation level. Unit is
  1944. in Hz. The range and step are driver-specific.</entry>
  1945. </row>
  1946. <row>
  1947. <entry spanname="id"><constant>V4L2_CID_PILOT_TONE_FREQUENCY</constant>&nbsp;</entry>
  1948. <entry>integer</entry>
  1949. </row>
  1950. <row><entry spanname="descr">Configures pilot tone frequency value. Unit is
  1951. in Hz. The range and step are driver-specific.</entry>
  1952. </row>
  1953. <row>
  1954. <entry spanname="id"><constant>V4L2_CID_TUNE_PREEMPHASIS</constant>&nbsp;</entry>
  1955. <entry>integer</entry>
  1956. </row>
  1957. <row id="v4l2-preemphasis"><entry spanname="descr">Configures the pre-emphasis value for broadcasting.
  1958. A pre-emphasis filter is applied to the broadcast to accentuate the high audio frequencies.
  1959. Depending on the region, a time constant of either 50 or 75 useconds is used. The enum&nbsp;v4l2_preemphasis
  1960. defines possible values for pre-emphasis. Here they are:</entry>
  1961. </row><row>
  1962. <entrytbl spanname="descr" cols="2">
  1963. <tbody valign="top">
  1964. <row>
  1965. <entry><constant>V4L2_PREEMPHASIS_DISABLED</constant>&nbsp;</entry>
  1966. <entry>No pre-emphasis is applied.</entry>
  1967. </row>
  1968. <row>
  1969. <entry><constant>V4L2_PREEMPHASIS_50_uS</constant>&nbsp;</entry>
  1970. <entry>A pre-emphasis of 50 uS is used.</entry>
  1971. </row>
  1972. <row>
  1973. <entry><constant>V4L2_PREEMPHASIS_75_uS</constant>&nbsp;</entry>
  1974. <entry>A pre-emphasis of 75 uS is used.</entry>
  1975. </row>
  1976. </tbody>
  1977. </entrytbl>
  1978. </row>
  1979. <row>
  1980. <entry spanname="id"><constant>V4L2_CID_TUNE_POWER_LEVEL</constant>&nbsp;</entry>
  1981. <entry>integer</entry>
  1982. </row>
  1983. <row><entry spanname="descr">Sets the output power level for signal transmission.
  1984. Unit is in dBuV. Range and step are driver-specific.</entry>
  1985. </row>
  1986. <row>
  1987. <entry spanname="id"><constant>V4L2_CID_TUNE_ANTENNA_CAPACITOR</constant>&nbsp;</entry>
  1988. <entry>integer</entry>
  1989. </row>
  1990. <row><entry spanname="descr">This selects the value of antenna tuning capacitor
  1991. manually or automatically if set to zero. Unit, range and step are driver-specific.</entry>
  1992. </row>
  1993. <row><entry></entry></row>
  1994. </tbody>
  1995. </tgroup>
  1996. </table>
  1997. <para>For more details about RDS specification, refer to
  1998. <xref linkend="en50067" /> document, from CENELEC.</para>
  1999. </section>
  2000. </section>
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