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 ⪚ 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 & 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_LASTP1</constant></entry> 316 <entry></entry> 317 <entry>End of the predefined control IDs (currently 318<constant>V4L2_CID_BG_COLOR</constant> + 1).</entry> 319 </row> 320 <row> 321 <entry><constant>V4L2_CID_PRIVATE_BASE</constant></entry> 322 <entry></entry> 323 <entry>ID of the first custom (driver specific) control. 324Applications depending on particular custom controls should check the 325driver name and version, see <xref linkend="querycap" />.</entry> 326 </row> 327 </tbody> 328 </tgroup> 329 </table> 330 331 <para>Applications can enumerate the available controls with the 332&VIDIOC-QUERYCTRL; and &VIDIOC-QUERYMENU; ioctls, get and set a 333control value with the &VIDIOC-G-CTRL; and &VIDIOC-S-CTRL; ioctls. 334Drivers must implement <constant>VIDIOC_QUERYCTRL</constant>, 335<constant>VIDIOC_G_CTRL</constant> and 336<constant>VIDIOC_S_CTRL</constant> when the device has one or more 337controls, <constant>VIDIOC_QUERYMENU</constant> when it has one or 338more menu type controls.</para> 339 340 <example> 341 <title>Enumerating all controls</title> 342 343 <programlisting> 344&v4l2-queryctrl; queryctrl; 345&v4l2-querymenu; querymenu; 346 347static void 348enumerate_menu (void) 349{ 350 printf (" Menu items:\n"); 351 352 memset (&querymenu, 0, sizeof (querymenu)); 353 querymenu.id = queryctrl.id; 354 355 for (querymenu.index = queryctrl.minimum; 356 querymenu.index <= queryctrl.maximum; 357 querymenu.index++) { 358 if (0 == ioctl (fd, &VIDIOC-QUERYMENU;, &querymenu)) { 359 printf (" %s\n", querymenu.name); 360 } else { 361 perror ("VIDIOC_QUERYMENU"); 362 exit (EXIT_FAILURE); 363 } 364 } 365} 366 367memset (&queryctrl, 0, sizeof (queryctrl)); 368 369for (queryctrl.id = V4L2_CID_BASE; 370 queryctrl.id < V4L2_CID_LASTP1; 371 queryctrl.id++) { 372 if (0 == ioctl (fd, &VIDIOC-QUERYCTRL;, &queryctrl)) { 373 if (queryctrl.flags & V4L2_CTRL_FLAG_DISABLED) 374 continue; 375 376 printf ("Control %s\n", queryctrl.name); 377 378 if (queryctrl.type == V4L2_CTRL_TYPE_MENU) 379 enumerate_menu (); 380 } else { 381 if (errno == EINVAL) 382 continue; 383 384 perror ("VIDIOC_QUERYCTRL"); 385 exit (EXIT_FAILURE); 386 } 387} 388 389for (queryctrl.id = V4L2_CID_PRIVATE_BASE;; 390 queryctrl.id++) { 391 if (0 == ioctl (fd, &VIDIOC-QUERYCTRL;, &queryctrl)) { 392 if (queryctrl.flags & V4L2_CTRL_FLAG_DISABLED) 393 continue; 394 395 printf ("Control %s\n", queryctrl.name); 396 397 if (queryctrl.type == V4L2_CTRL_TYPE_MENU) 398 enumerate_menu (); 399 } else { 400 if (errno == EINVAL) 401 break; 402 403 perror ("VIDIOC_QUERYCTRL"); 404 exit (EXIT_FAILURE); 405 } 406} 407</programlisting> 408 </example> 409 410 <example> 411 <title>Changing controls</title> 412 413 <programlisting> 414&v4l2-queryctrl; queryctrl; 415&v4l2-control; control; 416 417memset (&queryctrl, 0, sizeof (queryctrl)); 418queryctrl.id = V4L2_CID_BRIGHTNESS; 419 420if (-1 == ioctl (fd, &VIDIOC-QUERYCTRL;, &queryctrl)) { 421 if (errno != EINVAL) { 422 perror ("VIDIOC_QUERYCTRL"); 423 exit (EXIT_FAILURE); 424 } else { 425 printf ("V4L2_CID_BRIGHTNESS is not supported\n"); 426 } 427} else if (queryctrl.flags & V4L2_CTRL_FLAG_DISABLED) { 428 printf ("V4L2_CID_BRIGHTNESS is not supported\n"); 429} else { 430 memset (&control, 0, sizeof (control)); 431 control.id = V4L2_CID_BRIGHTNESS; 432 control.value = queryctrl.default_value; 433 434 if (-1 == ioctl (fd, &VIDIOC-S-CTRL;, &control)) { 435 perror ("VIDIOC_S_CTRL"); 436 exit (EXIT_FAILURE); 437 } 438} 439 440memset (&control, 0, sizeof (control)); 441control.id = V4L2_CID_CONTRAST; 442 443if (0 == ioctl (fd, &VIDIOC-G-CTRL;, &control)) { 444 control.value += 1; 445 446 /* The driver may clamp the value or return ERANGE, ignored here */ 447 448 if (-1 == ioctl (fd, &VIDIOC-S-CTRL;, &control) 449 && errno != ERANGE) { 450 perror ("VIDIOC_S_CTRL"); 451 exit (EXIT_FAILURE); 452 } 453/* Ignore if V4L2_CID_CONTRAST is unsupported */ 454} else if (errno != EINVAL) { 455 perror ("VIDIOC_G_CTRL"); 456 exit (EXIT_FAILURE); 457} 458 459control.id = V4L2_CID_AUDIO_MUTE; 460control.value = TRUE; /* silence */ 461 462/* Errors ignored */ 463ioctl (fd, VIDIOC_S_CTRL, &control); 464</programlisting> 465 </example> 466 </section> 467 468 <section id="extended-controls"> 469 <title>Extended Controls</title> 470 471 <section> 472 <title>Introduction</title> 473 474 <para>The control mechanism as originally designed was meant 475to be used for user settings (brightness, saturation, etc). However, 476it turned out to be a very useful model for implementing more 477complicated driver APIs where each driver implements only a subset of 478a larger API.</para> 479 480 <para>The MPEG encoding API was the driving force behind 481designing and implementing this extended control mechanism: the MPEG 482standard is quite large and the currently supported hardware MPEG 483encoders each only implement a subset of this standard. Further more, 484many parameters relating to how the video is encoded into an MPEG 485stream are specific to the MPEG encoding chip since the MPEG standard 486only defines the format of the resulting MPEG stream, not how the 487video is actually encoded into that format.</para> 488 489 <para>Unfortunately, the original control API lacked some 490features needed for these new uses and so it was extended into the 491(not terribly originally named) extended control API.</para> 492 493 <para>Even though the MPEG encoding API was the first effort 494to use the Extended Control API, nowadays there are also other classes 495of Extended Controls, such as Camera Controls and FM Transmitter Controls. 496The Extended Controls API as well as all Extended Controls classes are 497described in the following text.</para> 498 </section> 499 500 <section> 501 <title>The Extended Control API</title> 502 503 <para>Three new ioctls are available: &VIDIOC-G-EXT-CTRLS;, 504&VIDIOC-S-EXT-CTRLS; and &VIDIOC-TRY-EXT-CTRLS;. These ioctls act on 505arrays of controls (as opposed to the &VIDIOC-G-CTRL; and 506&VIDIOC-S-CTRL; ioctls that act on a single control). This is needed 507since it is often required to atomically change several controls at 508once.</para> 509 510 <para>Each of the new ioctls expects a pointer to a 511&v4l2-ext-controls;. This structure contains a pointer to the control 512array, a count of the number of controls in that array and a control 513class. Control classes are used to group similar controls into a 514single class. For example, control class 515<constant>V4L2_CTRL_CLASS_USER</constant> contains all user controls 516(&ie; all controls that can also be set using the old 517<constant>VIDIOC_S_CTRL</constant> ioctl). Control class 518<constant>V4L2_CTRL_CLASS_MPEG</constant> contains all controls 519relating to MPEG encoding, etc.</para> 520 521 <para>All controls in the control array must belong to the 522specified control class. An error is returned if this is not the 523case.</para> 524 525 <para>It is also possible to use an empty control array (count 526== 0) to check whether the specified control class is 527supported.</para> 528 529 <para>The control array is a &v4l2-ext-control; array. The 530<structname>v4l2_ext_control</structname> structure is very similar to 531&v4l2-control;, except for the fact that it also allows for 64-bit 532values and pointers to be passed.</para> 533 534 <para>It is important to realize that due to the flexibility of 535controls it is necessary to check whether the control you want to set 536actually is supported in the driver and what the valid range of values 537is. So use the &VIDIOC-QUERYCTRL; and &VIDIOC-QUERYMENU; ioctls to 538check this. Also note that it is possible that some of the menu 539indices in a control of type <constant>V4L2_CTRL_TYPE_MENU</constant> 540may not be supported (<constant>VIDIOC_QUERYMENU</constant> will 541return an error). A good example is the list of supported MPEG audio 542bitrates. Some drivers only support one or two bitrates, others 543support a wider range.</para> 544 </section> 545 546 <section> 547 <title>Enumerating Extended Controls</title> 548 549 <para>The recommended way to enumerate over the extended 550controls is by using &VIDIOC-QUERYCTRL; in combination with the 551<constant>V4L2_CTRL_FLAG_NEXT_CTRL</constant> flag:</para> 552 553 <informalexample> 554 <programlisting> 555&v4l2-queryctrl; qctrl; 556 557qctrl.id = V4L2_CTRL_FLAG_NEXT_CTRL; 558while (0 == ioctl (fd, &VIDIOC-QUERYCTRL;, &qctrl)) { 559 /* ... */ 560 qctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL; 561} 562</programlisting> 563 </informalexample> 564 565 <para>The initial control ID is set to 0 ORed with the 566<constant>V4L2_CTRL_FLAG_NEXT_CTRL</constant> flag. The 567<constant>VIDIOC_QUERYCTRL</constant> ioctl will return the first 568control with a higher ID than the specified one. When no such controls 569are found an error is returned.</para> 570 571 <para>If you want to get all controls within a specific control 572class, then you can set the initial 573<structfield>qctrl.id</structfield> value to the control class and add 574an extra check to break out of the loop when a control of another 575control class is found:</para> 576 577 <informalexample> 578 <programlisting> 579qctrl.id = V4L2_CTRL_CLASS_MPEG | V4L2_CTRL_FLAG_NEXT_CTRL; 580while (0 == ioctl (fd, &VIDIOC-QUERYCTRL;, &qctrl)) { 581 if (V4L2_CTRL_ID2CLASS (qctrl.id) != V4L2_CTRL_CLASS_MPEG) 582 break; 583 /* ... */ 584 qctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL; 585 } 586</programlisting> 587 </informalexample> 588 589 <para>The 32-bit <structfield>qctrl.id</structfield> value is 590subdivided into three bit ranges: the top 4 bits are reserved for 591flags (⪚ <constant>V4L2_CTRL_FLAG_NEXT_CTRL</constant>) and are not 592actually part of the ID. The remaining 28 bits form the control ID, of 593which the most significant 12 bits define the control class and the 594least significant 16 bits identify the control within the control 595class. It is guaranteed that these last 16 bits are always non-zero 596for controls. The range of 0x1000 and up are reserved for 597driver-specific controls. The macro 598<constant>V4L2_CTRL_ID2CLASS(id)</constant> returns the control class 599ID based on a control ID.</para> 600 601 <para>If the driver does not support extended controls, then 602<constant>VIDIOC_QUERYCTRL</constant> will fail when used in 603combination with <constant>V4L2_CTRL_FLAG_NEXT_CTRL</constant>. In 604that case the old method of enumerating control should be used (see 6051.8). But if it is supported, then it is guaranteed to enumerate over 606all controls, including driver-private controls.</para> 607 </section> 608 609 <section> 610 <title>Creating Control Panels</title> 611 612 <para>It is possible to create control panels for a graphical 613user interface where the user can select the various controls. 614Basically you will have to iterate over all controls using the method 615described above. Each control class starts with a control of type 616<constant>V4L2_CTRL_TYPE_CTRL_CLASS</constant>. 617<constant>VIDIOC_QUERYCTRL</constant> will return the name of this 618control class which can be used as the title of a tab page within a 619control panel.</para> 620 621 <para>The flags field of &v4l2-queryctrl; also contains hints on 622the behavior of the control. See the &VIDIOC-QUERYCTRL; documentation 623for more details.</para> 624 </section> 625 626 <section id="mpeg-controls"> 627 <title>MPEG Control Reference</title> 628 629 <para>Below all controls within the MPEG control class are 630described. First the generic controls, then controls specific for 631certain hardware.</para> 632 633 <section> 634 <title>Generic MPEG Controls</title> 635 636 <table pgwide="1" frame="none" id="mpeg-control-id"> 637 <title>MPEG Control IDs</title> 638 <tgroup cols="4"> 639 <colspec colname="c1" colwidth="1*" /> 640 <colspec colname="c2" colwidth="6*" /> 641 <colspec colname="c3" colwidth="2*" /> 642 <colspec colname="c4" colwidth="6*" /> 643 <spanspec namest="c1" nameend="c2" spanname="id" /> 644 <spanspec namest="c2" nameend="c4" spanname="descr" /> 645 <thead> 646 <row> 647 <entry spanname="id" align="left">ID</entry> 648 <entry align="left">Type</entry> 649 </row><row rowsep="1"><entry spanname="descr" align="left">Description</entry> 650 </row> 651 </thead> 652 <tbody valign="top"> 653 <row><entry></entry></row> 654 <row> 655 <entry spanname="id"><constant>V4L2_CID_MPEG_CLASS</constant> </entry> 656 <entry>class</entry> 657 </row><row><entry spanname="descr">The MPEG class 658descriptor. Calling &VIDIOC-QUERYCTRL; for this control will return a 659description of this control class. This description can be used as the 660caption of a Tab page in a GUI, for example.</entry> 661 </row> 662 <row><entry></entry></row> 663 <row id="v4l2-mpeg-stream-type"> 664 <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_TYPE</constant> </entry> 665 <entry>enum v4l2_mpeg_stream_type</entry> 666 </row><row><entry spanname="descr">The MPEG-1, -2 or -4 667output stream type. One cannot assume anything here. Each hardware 668MPEG encoder tends to support different subsets of the available MPEG 669stream types. The currently defined stream types are:</entry> 670 </row> 671 <row> 672 <entrytbl spanname="descr" cols="2"> 673 <tbody valign="top"> 674 <row> 675 <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG2_PS</constant> </entry> 676 <entry>MPEG-2 program stream</entry> 677 </row> 678 <row> 679 <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG2_TS</constant> </entry> 680 <entry>MPEG-2 transport stream</entry> 681 </row> 682 <row> 683 <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG1_SS</constant> </entry> 684 <entry>MPEG-1 system stream</entry> 685 </row> 686 <row> 687 <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG2_DVD</constant> </entry> 688 <entry>MPEG-2 DVD-compatible stream</entry> 689 </row> 690 <row> 691 <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG1_VCD</constant> </entry> 692 <entry>MPEG-1 VCD-compatible stream</entry> 693 </row> 694 <row> 695 <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG2_SVCD</constant> </entry> 696 <entry>MPEG-2 SVCD-compatible stream</entry> 697 </row> 698 </tbody> 699 </entrytbl> 700 </row> 701 <row><entry></entry></row> 702 <row> 703 <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PID_PMT</constant> </entry> 704 <entry>integer</entry> 705 </row><row><entry spanname="descr">Program Map Table 706Packet ID for the MPEG transport stream (default 16)</entry> 707 </row> 708 <row><entry></entry></row> 709 <row> 710 <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PID_AUDIO</constant> </entry> 711 <entry>integer</entry> 712 </row><row><entry spanname="descr">Audio Packet ID for 713the MPEG transport stream (default 256)</entry> 714 </row> 715 <row><entry></entry></row> 716 <row> 717 <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PID_VIDEO</constant> </entry> 718 <entry>integer</entry> 719 </row><row><entry spanname="descr">Video Packet ID for 720the MPEG transport stream (default 260)</entry> 721 </row> 722 <row><entry></entry></row> 723 <row> 724 <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PID_PCR</constant> </entry> 725 <entry>integer</entry> 726 </row><row><entry spanname="descr">Packet ID for the 727MPEG transport stream carrying PCR fields (default 259)</entry> 728 </row> 729 <row><entry></entry></row> 730 <row> 731 <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PES_ID_AUDIO</constant> </entry> 732 <entry>integer</entry> 733 </row><row><entry spanname="descr">Audio ID for MPEG 734PES</entry> 735 </row> 736 <row><entry></entry></row> 737 <row> 738 <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PES_ID_VIDEO</constant> </entry> 739 <entry>integer</entry> 740 </row><row><entry spanname="descr">Video ID for MPEG 741PES</entry> 742 </row> 743 <row><entry></entry></row> 744 <row id="v4l2-mpeg-stream-vbi-fmt"> 745 <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_VBI_FMT</constant> </entry> 746 <entry>enum v4l2_mpeg_stream_vbi_fmt</entry> 747 </row><row><entry spanname="descr">Some cards can embed 748VBI data (⪚ Closed Caption, Teletext) into the MPEG stream. This 749control selects whether VBI data should be embedded, and if so, what 750embedding method should be used. The list of possible VBI formats 751depends on the driver. The currently defined VBI format types 752are:</entry> 753 </row> 754 <row> 755 <entrytbl spanname="descr" cols="2"> 756 <tbody valign="top"> 757 <row> 758 <entry><constant>V4L2_MPEG_STREAM_VBI_FMT_NONE</constant> </entry> 759 <entry>No VBI in the MPEG stream</entry> 760 </row> 761 <row> 762 <entry><constant>V4L2_MPEG_STREAM_VBI_FMT_IVTV</constant> </entry> 763 <entry>VBI in private packets, IVTV format (documented 764in the kernel sources in the file <filename>Documentation/video4linux/cx2341x/README.vbi</filename>)</entry> 765 </row> 766 </tbody> 767 </entrytbl> 768 </row> 769 <row><entry></entry></row> 770 <row id="v4l2-mpeg-audio-sampling-freq"> 771 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_SAMPLING_FREQ</constant> </entry> 772 <entry>enum v4l2_mpeg_audio_sampling_freq</entry> 773 </row><row><entry spanname="descr">MPEG Audio sampling 774frequency. Possible values are:</entry> 775 </row> 776 <row> 777 <entrytbl spanname="descr" cols="2"> 778 <tbody valign="top"> 779 <row> 780 <entry><constant>V4L2_MPEG_AUDIO_SAMPLING_FREQ_44100</constant> </entry> 781 <entry>44.1 kHz</entry> 782 </row> 783 <row> 784 <entry><constant>V4L2_MPEG_AUDIO_SAMPLING_FREQ_48000</constant> </entry> 785 <entry>48 kHz</entry> 786 </row> 787 <row> 788 <entry><constant>V4L2_MPEG_AUDIO_SAMPLING_FREQ_32000</constant> </entry> 789 <entry>32 kHz</entry> 790 </row> 791 </tbody> 792 </entrytbl> 793 </row> 794 <row><entry></entry></row> 795 <row id="v4l2-mpeg-audio-encoding"> 796 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_ENCODING</constant> </entry> 797 <entry>enum v4l2_mpeg_audio_encoding</entry> 798 </row><row><entry spanname="descr">MPEG Audio encoding. 799Possible values are:</entry> 800 </row> 801 <row> 802 <entrytbl spanname="descr" cols="2"> 803 <tbody valign="top"> 804 <row> 805 <entry><constant>V4L2_MPEG_AUDIO_ENCODING_LAYER_1</constant> </entry> 806 <entry>MPEG-1/2 Layer I encoding</entry> 807 </row> 808 <row> 809 <entry><constant>V4L2_MPEG_AUDIO_ENCODING_LAYER_2</constant> </entry> 810 <entry>MPEG-1/2 Layer II encoding</entry> 811 </row> 812 <row> 813 <entry><constant>V4L2_MPEG_AUDIO_ENCODING_LAYER_3</constant> </entry> 814 <entry>MPEG-1/2 Layer III encoding</entry> 815 </row> 816 <row> 817 <entry><constant>V4L2_MPEG_AUDIO_ENCODING_AAC</constant> </entry> 818 <entry>MPEG-2/4 AAC (Advanced Audio Coding)</entry> 819 </row> 820 <row> 821 <entry><constant>V4L2_MPEG_AUDIO_ENCODING_AC3</constant> </entry> 822 <entry>AC-3 aka ATSC A/52 encoding</entry> 823 </row> 824 </tbody> 825 </entrytbl> 826 </row> 827 <row><entry></entry></row> 828 <row id="v4l2-mpeg-audio-l1-bitrate"> 829 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_L1_BITRATE</constant> </entry> 830 <entry>enum v4l2_mpeg_audio_l1_bitrate</entry> 831 </row><row><entry spanname="descr">MPEG-1/2 Layer I bitrate. 832Possible values are:</entry> 833 </row> 834 <row> 835 <entrytbl spanname="descr" cols="2"> 836 <tbody valign="top"> 837 <row> 838 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_32K</constant> </entry> 839 <entry>32 kbit/s</entry></row> 840 <row> 841 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_64K</constant> </entry> 842 <entry>64 kbit/s</entry> 843 </row> 844 <row> 845 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_96K</constant> </entry> 846 <entry>96 kbit/s</entry> 847 </row> 848 <row> 849 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_128K</constant> </entry> 850 <entry>128 kbit/s</entry> 851 </row> 852 <row> 853 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_160K</constant> </entry> 854 <entry>160 kbit/s</entry> 855 </row> 856 <row> 857 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_192K</constant> </entry> 858 <entry>192 kbit/s</entry> 859 </row> 860 <row> 861 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_224K</constant> </entry> 862 <entry>224 kbit/s</entry> 863 </row> 864 <row> 865 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_256K</constant> </entry> 866 <entry>256 kbit/s</entry> 867 </row> 868 <row> 869 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_288K</constant> </entry> 870 <entry>288 kbit/s</entry> 871 </row> 872 <row> 873 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_320K</constant> </entry> 874 <entry>320 kbit/s</entry> 875 </row> 876 <row> 877 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_352K</constant> </entry> 878 <entry>352 kbit/s</entry> 879 </row> 880 <row> 881 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_384K</constant> </entry> 882 <entry>384 kbit/s</entry> 883 </row> 884 <row> 885 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_416K</constant> </entry> 886 <entry>416 kbit/s</entry> 887 </row> 888 <row> 889 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_448K</constant> </entry> 890 <entry>448 kbit/s</entry> 891 </row> 892 </tbody> 893 </entrytbl> 894 </row> 895 <row><entry></entry></row> 896 <row id="v4l2-mpeg-audio-l2-bitrate"> 897 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_L2_BITRATE</constant> </entry> 898 <entry>enum v4l2_mpeg_audio_l2_bitrate</entry> 899 </row><row><entry spanname="descr">MPEG-1/2 Layer II bitrate. 900Possible values are:</entry> 901 </row> 902 <row> 903 <entrytbl spanname="descr" cols="2"> 904 <tbody valign="top"> 905 <row> 906 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_32K</constant> </entry> 907 <entry>32 kbit/s</entry> 908 </row> 909 <row> 910 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_48K</constant> </entry> 911 <entry>48 kbit/s</entry> 912 </row> 913 <row> 914 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_56K</constant> </entry> 915 <entry>56 kbit/s</entry> 916 </row> 917 <row> 918 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_64K</constant> </entry> 919 <entry>64 kbit/s</entry> 920 </row> 921 <row> 922 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_80K</constant> </entry> 923 <entry>80 kbit/s</entry> 924 </row> 925 <row> 926 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_96K</constant> </entry> 927 <entry>96 kbit/s</entry> 928 </row> 929 <row> 930 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_112K</constant> </entry> 931 <entry>112 kbit/s</entry> 932 </row> 933 <row> 934 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_128K</constant> </entry> 935 <entry>128 kbit/s</entry> 936 </row> 937 <row> 938 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_160K</constant> </entry> 939 <entry>160 kbit/s</entry> 940 </row> 941 <row> 942 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_192K</constant> </entry> 943 <entry>192 kbit/s</entry> 944 </row> 945 <row> 946 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_224K</constant> </entry> 947 <entry>224 kbit/s</entry> 948 </row> 949 <row> 950 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_256K</constant> </entry> 951 <entry>256 kbit/s</entry> 952 </row> 953 <row> 954 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_320K</constant> </entry> 955 <entry>320 kbit/s</entry> 956 </row> 957 <row> 958 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_384K</constant> </entry> 959 <entry>384 kbit/s</entry> 960 </row> 961 </tbody> 962 </entrytbl> 963 </row> 964 <row><entry></entry></row> 965 <row id="v4l2-mpeg-audio-l3-bitrate"> 966 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_L3_BITRATE</constant> </entry> 967 <entry>enum v4l2_mpeg_audio_l3_bitrate</entry> 968 </row><row><entry spanname="descr">MPEG-1/2 Layer III bitrate. 969Possible values are:</entry> 970 </row> 971 <row> 972 <entrytbl spanname="descr" cols="2"> 973 <tbody valign="top"> 974 <row> 975 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_32K</constant> </entry> 976 <entry>32 kbit/s</entry> 977 </row> 978 <row> 979 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_40K</constant> </entry> 980 <entry>40 kbit/s</entry> 981 </row> 982 <row> 983 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_48K</constant> </entry> 984 <entry>48 kbit/s</entry> 985 </row> 986 <row> 987 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_56K</constant> </entry> 988 <entry>56 kbit/s</entry> 989 </row> 990 <row> 991 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_64K</constant> </entry> 992 <entry>64 kbit/s</entry> 993 </row> 994 <row> 995 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_80K</constant> </entry> 996 <entry>80 kbit/s</entry> 997 </row> 998 <row> 999 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_96K</constant> </entry> 1000 <entry>96 kbit/s</entry> 1001 </row> 1002 <row> 1003 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_112K</constant> </entry> 1004 <entry>112 kbit/s</entry> 1005 </row> 1006 <row> 1007 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_128K</constant> </entry> 1008 <entry>128 kbit/s</entry> 1009 </row> 1010 <row> 1011 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_160K</constant> </entry> 1012 <entry>160 kbit/s</entry> 1013 </row> 1014 <row> 1015 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_192K</constant> </entry> 1016 <entry>192 kbit/s</entry> 1017 </row> 1018 <row> 1019 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_224K</constant> </entry> 1020 <entry>224 kbit/s</entry> 1021 </row> 1022 <row> 1023 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_256K</constant> </entry> 1024 <entry>256 kbit/s</entry> 1025 </row> 1026 <row> 1027 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_320K</constant> </entry> 1028 <entry>320 kbit/s</entry> 1029 </row> 1030 </tbody> 1031 </entrytbl> 1032 </row> 1033 <row><entry></entry></row> 1034 <row> 1035 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_AAC_BITRATE</constant> </entry> 1036 <entry>integer</entry> 1037 </row><row><entry spanname="descr">AAC bitrate in bits per second.</entry> 1038 </row> 1039 <row><entry></entry></row> 1040 <row id="v4l2-mpeg-audio-ac3-bitrate"> 1041 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_AC3_BITRATE</constant> </entry> 1042 <entry>enum v4l2_mpeg_audio_ac3_bitrate</entry> 1043 </row><row><entry spanname="descr">AC-3 bitrate. 1044Possible values are:</entry> 1045 </row> 1046 <row> 1047 <entrytbl spanname="descr" cols="2"> 1048 <tbody valign="top"> 1049 <row> 1050 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_32K</constant> </entry> 1051 <entry>32 kbit/s</entry> 1052 </row> 1053 <row> 1054 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_40K</constant> </entry> 1055 <entry>40 kbit/s</entry> 1056 </row> 1057 <row> 1058 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_48K</constant> </entry> 1059 <entry>48 kbit/s</entry> 1060 </row> 1061 <row> 1062 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_56K</constant> </entry> 1063 <entry>56 kbit/s</entry> 1064 </row> 1065 <row> 1066 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_64K</constant> </entry> 1067 <entry>64 kbit/s</entry> 1068 </row> 1069 <row> 1070 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_80K</constant> </entry> 1071 <entry>80 kbit/s</entry> 1072 </row> 1073 <row> 1074 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_96K</constant> </entry> 1075 <entry>96 kbit/s</entry> 1076 </row> 1077 <row> 1078 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_112K</constant> </entry> 1079 <entry>112 kbit/s</entry> 1080 </row> 1081 <row> 1082 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_128K</constant> </entry> 1083 <entry>128 kbit/s</entry> 1084 </row> 1085 <row> 1086 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_160K</constant> </entry> 1087 <entry>160 kbit/s</entry> 1088 </row> 1089 <row> 1090 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_192K</constant> </entry> 1091 <entry>192 kbit/s</entry> 1092 </row> 1093 <row> 1094 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_224K</constant> </entry> 1095 <entry>224 kbit/s</entry> 1096 </row> 1097 <row> 1098 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_256K</constant> </entry> 1099 <entry>256 kbit/s</entry> 1100 </row> 1101 <row> 1102 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_320K</constant> </entry> 1103 <entry>320 kbit/s</entry> 1104 </row> 1105 <row> 1106 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_384K</constant> </entry> 1107 <entry>384 kbit/s</entry> 1108 </row> 1109 <row> 1110 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_448K</constant> </entry> 1111 <entry>448 kbit/s</entry> 1112 </row> 1113 <row> 1114 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_512K</constant> </entry> 1115 <entry>512 kbit/s</entry> 1116 </row> 1117 <row> 1118 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_576K</constant> </entry> 1119 <entry>576 kbit/s</entry> 1120 </row> 1121 <row> 1122 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_640K</constant> </entry> 1123 <entry>640 kbit/s</entry> 1124 </row> 1125 </tbody> 1126 </entrytbl> 1127 </row> 1128 <row><entry></entry></row> 1129 <row id="v4l2-mpeg-audio-mode"> 1130 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_MODE</constant> </entry> 1131 <entry>enum v4l2_mpeg_audio_mode</entry> 1132 </row><row><entry spanname="descr">MPEG Audio mode. 1133Possible values are:</entry> 1134 </row> 1135 <row> 1136 <entrytbl spanname="descr" cols="2"> 1137 <tbody valign="top"> 1138 <row> 1139 <entry><constant>V4L2_MPEG_AUDIO_MODE_STEREO</constant> </entry> 1140 <entry>Stereo</entry> 1141 </row> 1142 <row> 1143 <entry><constant>V4L2_MPEG_AUDIO_MODE_JOINT_STEREO</constant> </entry> 1144 <entry>Joint Stereo</entry> 1145 </row> 1146 <row> 1147 <entry><constant>V4L2_MPEG_AUDIO_MODE_DUAL</constant> </entry> 1148 <entry>Bilingual</entry> 1149 </row> 1150 <row> 1151 <entry><constant>V4L2_MPEG_AUDIO_MODE_MONO</constant> </entry> 1152 <entry>Mono</entry> 1153 </row> 1154 </tbody> 1155 </entrytbl> 1156 </row> 1157 <row><entry></entry></row> 1158 <row id="v4l2-mpeg-audio-mode-extension"> 1159 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_MODE_EXTENSION</constant> </entry> 1160 <entry>enum v4l2_mpeg_audio_mode_extension</entry> 1161 </row><row><entry spanname="descr">Joint Stereo 1162audio mode extension. In Layer I and II they indicate which subbands 1163are in intensity stereo. All other subbands are coded in stereo. Layer 1164III is not (yet) supported. Possible values 1165are:</entry> 1166 </row> 1167 <row> 1168 <entrytbl spanname="descr" cols="2"> 1169 <tbody valign="top"> 1170 <row> 1171 <entry><constant>V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_4</constant> </entry> 1172 <entry>Subbands 4-31 in intensity stereo</entry> 1173 </row> 1174 <row> 1175 <entry><constant>V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_8</constant> </entry> 1176 <entry>Subbands 8-31 in intensity stereo</entry> 1177 </row> 1178 <row> 1179 <entry><constant>V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_12</constant> </entry> 1180 <entry>Subbands 12-31 in intensity stereo</entry> 1181 </row> 1182 <row> 1183 <entry><constant>V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_16</constant> </entry> 1184 <entry>Subbands 16-31 in intensity stereo</entry> 1185 </row> 1186 </tbody> 1187 </entrytbl> 1188 </row> 1189 <row><entry></entry></row> 1190 <row id="v4l2-mpeg-audio-emphasis"> 1191 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_EMPHASIS</constant> </entry> 1192 <entry>enum v4l2_mpeg_audio_emphasis</entry> 1193 </row><row><entry spanname="descr">Audio Emphasis. 1194Possible values are:</entry> 1195 </row> 1196 <row> 1197 <entrytbl spanname="descr" cols="2"> 1198 <tbody valign="top"> 1199 <row> 1200 <entry><constant>V4L2_MPEG_AUDIO_EMPHASIS_NONE</constant> </entry> 1201 <entry>None</entry> 1202 </row> 1203 <row> 1204 <entry><constant>V4L2_MPEG_AUDIO_EMPHASIS_50_DIV_15_uS</constant> </entry> 1205 <entry>50/15 microsecond emphasis</entry> 1206 </row> 1207 <row> 1208 <entry><constant>V4L2_MPEG_AUDIO_EMPHASIS_CCITT_J17</constant> </entry> 1209 <entry>CCITT J.17</entry> 1210 </row> 1211 </tbody> 1212 </entrytbl> 1213 </row> 1214 <row><entry></entry></row> 1215 <row id="v4l2-mpeg-audio-crc"> 1216 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_CRC</constant> </entry> 1217 <entry>enum v4l2_mpeg_audio_crc</entry> 1218 </row><row><entry spanname="descr">CRC method. Possible 1219values are:</entry> 1220 </row> 1221 <row> 1222 <entrytbl spanname="descr" cols="2"> 1223 <tbody valign="top"> 1224 <row> 1225 <entry><constant>V4L2_MPEG_AUDIO_CRC_NONE</constant> </entry> 1226 <entry>None</entry> 1227 </row> 1228 <row> 1229 <entry><constant>V4L2_MPEG_AUDIO_CRC_CRC16</constant> </entry> 1230 <entry>16 bit parity check</entry> 1231 </row> 1232 </tbody> 1233 </entrytbl> 1234 </row> 1235 <row><entry></entry></row> 1236 <row> 1237 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_MUTE</constant> </entry> 1238 <entry>boolean</entry> 1239 </row><row><entry spanname="descr">Mutes the audio when 1240capturing. This is not done by muting audio hardware, which can still 1241produce a slight hiss, but in the encoder itself, guaranteeing a fixed 1242and reproducable audio bitstream. 0 = unmuted, 1 = muted.</entry> 1243 </row> 1244 <row><entry></entry></row> 1245 <row id="v4l2-mpeg-video-encoding"> 1246 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_ENCODING</constant> </entry> 1247 <entry>enum v4l2_mpeg_video_encoding</entry> 1248 </row><row><entry spanname="descr">MPEG Video encoding 1249method. Possible values are:</entry> 1250 </row> 1251 <row> 1252 <entrytbl spanname="descr" cols="2"> 1253 <tbody valign="top"> 1254 <row> 1255 <entry><constant>V4L2_MPEG_VIDEO_ENCODING_MPEG_1</constant> </entry> 1256 <entry>MPEG-1 Video encoding</entry> 1257 </row> 1258 <row> 1259 <entry><constant>V4L2_MPEG_VIDEO_ENCODING_MPEG_2</constant> </entry> 1260 <entry>MPEG-2 Video encoding</entry> 1261 </row> 1262 <row> 1263 <entry><constant>V4L2_MPEG_VIDEO_ENCODING_MPEG_4_AVC</constant> </entry> 1264 <entry>MPEG-4 AVC (H.264) Video encoding</entry> 1265 </row> 1266 </tbody> 1267 </entrytbl> 1268 </row> 1269 <row><entry></entry></row> 1270 <row id="v4l2-mpeg-video-aspect"> 1271 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_ASPECT</constant> </entry> 1272 <entry>enum v4l2_mpeg_video_aspect</entry> 1273 </row><row><entry spanname="descr">Video aspect. 1274Possible values are:</entry> 1275 </row> 1276 <row> 1277 <entrytbl spanname="descr" cols="2"> 1278 <tbody valign="top"> 1279 <row> 1280 <entry><constant>V4L2_MPEG_VIDEO_ASPECT_1x1</constant> </entry> 1281 </row> 1282 <row> 1283 <entry><constant>V4L2_MPEG_VIDEO_ASPECT_4x3</constant> </entry> 1284 </row> 1285 <row> 1286 <entry><constant>V4L2_MPEG_VIDEO_ASPECT_16x9</constant> </entry> 1287 </row> 1288 <row> 1289 <entry><constant>V4L2_MPEG_VIDEO_ASPECT_221x100</constant> </entry> 1290 </row> 1291 </tbody> 1292 </entrytbl> 1293 </row> 1294 <row><entry></entry></row> 1295 <row> 1296 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_B_FRAMES</constant> </entry> 1297 <entry>integer</entry> 1298 </row><row><entry spanname="descr">Number of B-Frames 1299(default 2)</entry> 1300 </row> 1301 <row><entry></entry></row> 1302 <row> 1303 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_GOP_SIZE</constant> </entry> 1304 <entry>integer</entry> 1305 </row><row><entry spanname="descr">GOP size (default 130612)</entry> 1307 </row> 1308 <row><entry></entry></row> 1309 <row> 1310 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_GOP_CLOSURE</constant> </entry> 1311 <entry>boolean</entry> 1312 </row><row><entry spanname="descr">GOP closure (default 13131)</entry> 1314 </row> 1315 <row><entry></entry></row> 1316 <row> 1317 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_PULLDOWN</constant> </entry> 1318 <entry>boolean</entry> 1319 </row><row><entry spanname="descr">Enable 3:2 pulldown 1320(default 0)</entry> 1321 </row> 1322 <row><entry></entry></row> 1323 <row id="v4l2-mpeg-video-bitrate-mode"> 1324 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_BITRATE_MODE</constant> </entry> 1325 <entry>enum v4l2_mpeg_video_bitrate_mode</entry> 1326 </row><row><entry spanname="descr">Video bitrate mode. 1327Possible values are:</entry> 1328 </row> 1329 <row> 1330 <entrytbl spanname="descr" cols="2"> 1331 <tbody valign="top"> 1332 <row> 1333 <entry><constant>V4L2_MPEG_VIDEO_BITRATE_MODE_VBR</constant> </entry> 1334 <entry>Variable bitrate</entry> 1335 </row> 1336 <row> 1337 <entry><constant>V4L2_MPEG_VIDEO_BITRATE_MODE_CBR</constant> </entry> 1338 <entry>Constant bitrate</entry> 1339 </row> 1340 </tbody> 1341 </entrytbl> 1342 </row> 1343 <row><entry></entry></row> 1344 <row> 1345 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_BITRATE</constant> </entry> 1346 <entry>integer</entry> 1347 </row><row><entry spanname="descr">Video bitrate in bits 1348per second.</entry> 1349 </row> 1350 <row><entry></entry></row> 1351 <row> 1352 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_BITRATE_PEAK</constant> </entry> 1353 <entry>integer</entry> 1354 </row><row><entry spanname="descr">Peak video bitrate in 1355bits per second. Must be larger or equal to the average video bitrate. 1356It is ignored if the video bitrate mode is set to constant 1357bitrate.</entry> 1358 </row> 1359 <row><entry></entry></row> 1360 <row> 1361 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_TEMPORAL_DECIMATION</constant> </entry> 1362 <entry>integer</entry> 1363 </row><row><entry spanname="descr">For every captured 1364frame, skip this many subsequent frames (default 0).</entry> 1365 </row> 1366 <row><entry></entry></row> 1367 <row> 1368 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_MUTE</constant> </entry> 1369 <entry>boolean</entry> 1370 </row> 1371 <row><entry spanname="descr">"Mutes" the video to a 1372fixed color when capturing. This is useful for testing, to produce a 1373fixed video bitstream. 0 = unmuted, 1 = muted.</entry> 1374 </row> 1375 <row><entry></entry></row> 1376 <row> 1377 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_MUTE_YUV</constant> </entry> 1378 <entry>integer</entry> 1379 </row><row><entry spanname="descr">Sets the "mute" color 1380of the video. The supplied 32-bit integer is interpreted as follows (bit 13810 = least significant bit):</entry> 1382 </row> 1383 <row> 1384 <entrytbl spanname="descr" cols="2"> 1385 <tbody valign="top"> 1386 <row> 1387 <entry>Bit 0:7</entry> 1388 <entry>V chrominance information</entry> 1389 </row> 1390 <row> 1391 <entry>Bit 8:15</entry> 1392 <entry>U chrominance information</entry> 1393 </row> 1394 <row> 1395 <entry>Bit 16:23</entry> 1396 <entry>Y luminance information</entry> 1397 </row> 1398 <row> 1399 <entry>Bit 24:31</entry> 1400 <entry>Must be zero.</entry> 1401 </row> 1402 </tbody> 1403 </entrytbl> 1404 </row> 1405 </tbody> 1406 </tgroup> 1407 </table> 1408 </section> 1409 1410 <section> 1411 <title>CX2341x MPEG Controls</title> 1412 1413 <para>The following MPEG class controls deal with MPEG 1414encoding settings that are specific to the Conexant CX23415 and 1415CX23416 MPEG encoding chips.</para> 1416 1417 <table pgwide="1" frame="none" id="cx2341x-control-id"> 1418 <title>CX2341x Control IDs</title> 1419 <tgroup cols="4"> 1420 <colspec colname="c1" colwidth="1*" /> 1421 <colspec colname="c2" colwidth="6*" /> 1422 <colspec colname="c3" colwidth="2*" /> 1423 <colspec colname="c4" colwidth="6*" /> 1424 <spanspec namest="c1" nameend="c2" spanname="id" /> 1425 <spanspec namest="c2" nameend="c4" spanname="descr" /> 1426 <thead> 1427 <row> 1428 <entry spanname="id" align="left">ID</entry> 1429 <entry align="left">Type</entry> 1430 </row><row><entry spanname="descr" align="left">Description</entry> 1431 </row> 1432 </thead> 1433 <tbody valign="top"> 1434 <row><entry></entry></row> 1435 <row id="v4l2-mpeg-cx2341x-video-spatial-filter-mode"> 1436 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE</constant> </entry> 1437 <entry>enum v4l2_mpeg_cx2341x_video_spatial_filter_mode</entry> 1438 </row><row><entry spanname="descr">Sets the Spatial 1439Filter mode (default <constant>MANUAL</constant>). Possible values 1440are:</entry> 1441 </row> 1442 <row> 1443 <entrytbl spanname="descr" cols="2"> 1444 <tbody valign="top"> 1445 <row> 1446 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE_MANUAL</constant> </entry> 1447 <entry>Choose the filter manually</entry> 1448 </row> 1449 <row> 1450 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE_AUTO</constant> </entry> 1451 <entry>Choose the filter automatically</entry> 1452 </row> 1453 </tbody> 1454 </entrytbl> 1455 </row> 1456 <row><entry></entry></row> 1457 <row> 1458 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER</constant> </entry> 1459 <entry>integer (0-15)</entry> 1460 </row><row><entry spanname="descr">The setting for the 1461Spatial Filter. 0 = off, 15 = maximum. (Default is 0.)</entry> 1462 </row> 1463 <row><entry></entry></row> 1464 <row id="luma-spatial-filter-type"> 1465 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE</constant> </entry> 1466 <entry>enum v4l2_mpeg_cx2341x_video_luma_spatial_filter_type</entry> 1467 </row><row><entry spanname="descr">Select the algorithm 1468to use for the Luma Spatial Filter (default 1469<constant>1D_HOR</constant>). Possible values:</entry> 1470 </row> 1471 <row> 1472 <entrytbl spanname="descr" cols="2"> 1473 <tbody valign="top"> 1474 <row> 1475 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_OFF</constant> </entry> 1476 <entry>No filter</entry> 1477 </row> 1478 <row> 1479 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_1D_HOR</constant> </entry> 1480 <entry>One-dimensional horizontal</entry> 1481 </row> 1482 <row> 1483 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_1D_VERT</constant> </entry> 1484 <entry>One-dimensional vertical</entry> 1485 </row> 1486 <row> 1487 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_2D_HV_SEPARABLE</constant> </entry> 1488 <entry>Two-dimensional separable</entry> 1489 </row> 1490 <row> 1491 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_2D_SYM_NON_SEPARABLE</constant> </entry> 1492 <entry>Two-dimensional symmetrical 1493non-separable</entry> 1494 </row> 1495 </tbody> 1496 </entrytbl> 1497 </row> 1498 <row><entry></entry></row> 1499 <row id="chroma-spatial-filter-type"> 1500 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE</constant> </entry> 1501 <entry>enum v4l2_mpeg_cx2341x_video_chroma_spatial_filter_type</entry> 1502 </row><row><entry spanname="descr">Select the algorithm 1503for the Chroma Spatial Filter (default <constant>1D_HOR</constant>). 1504Possible values are:</entry> 1505 </row> 1506 <row> 1507 <entrytbl spanname="descr" cols="2"> 1508 <tbody valign="top"> 1509 <row> 1510 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE_OFF</constant> </entry> 1511 <entry>No filter</entry> 1512 </row> 1513 <row> 1514 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE_1D_HOR</constant> </entry> 1515 <entry>One-dimensional horizontal</entry> 1516 </row> 1517 </tbody> 1518 </entrytbl> 1519 </row> 1520 <row><entry></entry></row> 1521 <row id="v4l2-mpeg-cx2341x-video-temporal-filter-mode"> 1522 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE</constant> </entry> 1523 <entry>enum v4l2_mpeg_cx2341x_video_temporal_filter_mode</entry> 1524 </row><row><entry spanname="descr">Sets the Temporal 1525Filter mode (default <constant>MANUAL</constant>). Possible values 1526are:</entry> 1527 </row> 1528 <row> 1529 <entrytbl spanname="descr" cols="2"> 1530 <tbody valign="top"> 1531 <row> 1532 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE_MANUAL</constant> </entry> 1533 <entry>Choose the filter manually</entry> 1534 </row> 1535 <row> 1536 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE_AUTO</constant> </entry> 1537 <entry>Choose the filter automatically</entry> 1538 </row> 1539 </tbody> 1540 </entrytbl> 1541 </row> 1542 <row><entry></entry></row> 1543 <row> 1544 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER</constant> </entry> 1545 <entry>integer (0-31)</entry> 1546 </row><row><entry spanname="descr">The setting for the 1547Temporal Filter. 0 = off, 31 = maximum. (Default is 8 for full-scale 1548capturing and 0 for scaled capturing.)</entry> 1549 </row> 1550 <row><entry></entry></row> 1551 <row id="v4l2-mpeg-cx2341x-video-median-filter-type"> 1552 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE</constant> </entry> 1553 <entry>enum v4l2_mpeg_cx2341x_video_median_filter_type</entry> 1554 </row><row><entry spanname="descr">Median Filter Type 1555(default <constant>OFF</constant>). Possible values are:</entry> 1556 </row> 1557 <row> 1558 <entrytbl spanname="descr" cols="2"> 1559 <tbody valign="top"> 1560 <row> 1561 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_OFF</constant> </entry> 1562 <entry>No filter</entry> 1563 </row> 1564 <row> 1565 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_HOR</constant> </entry> 1566 <entry>Horizontal filter</entry> 1567 </row> 1568 <row> 1569 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_VERT</constant> </entry> 1570 <entry>Vertical filter</entry> 1571 </row> 1572 <row> 1573 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_HOR_VERT</constant> </entry> 1574 <entry>Horizontal and vertical filter</entry> 1575 </row> 1576 <row> 1577 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_DIAG</constant> </entry> 1578 <entry>Diagonal filter</entry> 1579 </row> 1580 </tbody> 1581 </entrytbl> 1582 </row> 1583 <row><entry></entry></row> 1584 <row> 1585 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_MEDIAN_FILTER_BOTTOM</constant> </entry> 1586 <entry>integer (0-255)</entry> 1587 </row><row><entry spanname="descr">Threshold above which 1588the luminance median filter is enabled (default 0)</entry> 1589 </row> 1590 <row><entry></entry></row> 1591 <row> 1592 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_MEDIAN_FILTER_TOP</constant> </entry> 1593 <entry>integer (0-255)</entry> 1594 </row><row><entry spanname="descr">Threshold below which 1595the luminance median filter is enabled (default 255)</entry> 1596 </row> 1597 <row><entry></entry></row> 1598 <row> 1599 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_MEDIAN_FILTER_BOTTOM</constant> </entry> 1600 <entry>integer (0-255)</entry> 1601 </row><row><entry spanname="descr">Threshold above which 1602the chroma median filter is enabled (default 0)</entry> 1603 </row> 1604 <row><entry></entry></row> 1605 <row> 1606 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_MEDIAN_FILTER_TOP</constant> </entry> 1607 <entry>integer (0-255)</entry> 1608 </row><row><entry spanname="descr">Threshold below which 1609the chroma median filter is enabled (default 255)</entry> 1610 </row> 1611 <row><entry></entry></row> 1612 <row> 1613 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_STREAM_INSERT_NAV_PACKETS</constant> </entry> 1614 <entry>boolean</entry> 1615 </row> 1616 <row><entry spanname="descr">The CX2341X MPEG encoder 1617can insert one empty MPEG-2 PES packet into the stream between every 1618four video frames. The packet size is 2048 bytes, including the 1619packet_start_code_prefix and stream_id fields. The stream_id is 0xBF 1620(private stream 2). The payload consists of 0x00 bytes, to be filled 1621in by the application. 0 = do not insert, 1 = insert packets.</entry> 1622 </row> 1623 </tbody> 1624 </tgroup> 1625 </table> 1626 </section> 1627 </section> 1628 1629 <section id="camera-controls"> 1630 <title>Camera Control Reference</title> 1631 1632 <para>The Camera class includes controls for mechanical (or 1633equivalent digital) features of a device such as controllable lenses 1634or sensors.</para> 1635 1636 <table pgwide="1" frame="none" id="camera-control-id"> 1637 <title>Camera Control IDs</title> 1638 <tgroup cols="4"> 1639 <colspec colname="c1" colwidth="1*" /> 1640 <colspec colname="c2" colwidth="6*" /> 1641 <colspec colname="c3" colwidth="2*" /> 1642 <colspec colname="c4" colwidth="6*" /> 1643 <spanspec namest="c1" nameend="c2" spanname="id" /> 1644 <spanspec namest="c2" nameend="c4" spanname="descr" /> 1645 <thead> 1646 <row> 1647 <entry spanname="id" align="left">ID</entry> 1648 <entry align="left">Type</entry> 1649 </row><row rowsep="1"><entry spanname="descr" align="left">Description</entry> 1650 </row> 1651 </thead> 1652 <tbody valign="top"> 1653 <row><entry></entry></row> 1654 <row> 1655 <entry spanname="id"><constant>V4L2_CID_CAMERA_CLASS</constant> </entry> 1656 <entry>class</entry> 1657 </row><row><entry spanname="descr">The Camera class 1658descriptor. Calling &VIDIOC-QUERYCTRL; for this control will return a 1659description of this control class.</entry> 1660 </row> 1661 <row><entry></entry></row> 1662 1663 <row id="v4l2-exposure-auto-type"> 1664 <entry spanname="id"><constant>V4L2_CID_EXPOSURE_AUTO</constant> </entry> 1665 <entry>enum v4l2_exposure_auto_type</entry> 1666 </row><row><entry spanname="descr">Enables automatic 1667adjustments of the exposure time and/or iris aperture. The effect of 1668manual changes of the exposure time or iris aperture while these 1669features are enabled is undefined, drivers should ignore such 1670requests. Possible values are:</entry> 1671 </row> 1672 <row> 1673 <entrytbl spanname="descr" cols="2"> 1674 <tbody valign="top"> 1675 <row> 1676 <entry><constant>V4L2_EXPOSURE_AUTO</constant> </entry> 1677 <entry>Automatic exposure time, automatic iris 1678aperture.</entry> 1679 </row> 1680 <row> 1681 <entry><constant>V4L2_EXPOSURE_MANUAL</constant> </entry> 1682 <entry>Manual exposure time, manual iris.</entry> 1683 </row> 1684 <row> 1685 <entry><constant>V4L2_EXPOSURE_SHUTTER_PRIORITY</constant> </entry> 1686 <entry>Manual exposure time, auto iris.</entry> 1687 </row> 1688 <row> 1689 <entry><constant>V4L2_EXPOSURE_APERTURE_PRIORITY</constant> </entry> 1690 <entry>Auto exposure time, manual iris.</entry> 1691 </row> 1692 </tbody> 1693 </entrytbl> 1694 </row> 1695 <row><entry></entry></row> 1696 1697 <row> 1698 <entry spanname="id"><constant>V4L2_CID_EXPOSURE_ABSOLUTE</constant> </entry> 1699 <entry>integer</entry> 1700 </row><row><entry spanname="descr">Determines the exposure 1701time of the camera sensor. The exposure time is limited by the frame 1702interval. Drivers should interpret the values as 100 µs units, 1703where the value 1 stands for 1/10000th of a second, 10000 for 1 second 1704and 100000 for 10 seconds.</entry> 1705 </row> 1706 <row><entry></entry></row> 1707 1708 <row> 1709 <entry spanname="id"><constant>V4L2_CID_EXPOSURE_AUTO_PRIORITY</constant> </entry> 1710 <entry>boolean</entry> 1711 </row><row><entry spanname="descr">When 1712<constant>V4L2_CID_EXPOSURE_AUTO</constant> is set to 1713<constant>AUTO</constant> or <constant>APERTURE_PRIORITY</constant>, 1714this control determines if the device may dynamically vary the frame 1715rate. By default this feature is disabled (0) and the frame rate must 1716remain constant.</entry> 1717 </row> 1718 <row><entry></entry></row> 1719 1720 <row> 1721 <entry spanname="id"><constant>V4L2_CID_PAN_RELATIVE</constant> </entry> 1722 <entry>integer</entry> 1723 </row><row><entry spanname="descr">This control turns the 1724camera horizontally by the specified amount. The unit is undefined. A 1725positive value moves the camera to the right (clockwise when viewed 1726from above), a negative value to the left. A value of zero does not 1727cause motion. This is a write-only control.</entry> 1728 </row> 1729 <row><entry></entry></row> 1730 1731 <row> 1732 <entry spanname="id"><constant>V4L2_CID_TILT_RELATIVE</constant> </entry> 1733 <entry>integer</entry> 1734 </row><row><entry spanname="descr">This control turns the 1735camera vertically by the specified amount. The unit is undefined. A 1736positive value moves the camera up, a negative value down. A value of 1737zero does not cause motion. This is a write-only control.</entry> 1738 </row> 1739 <row><entry></entry></row> 1740 1741 <row> 1742 <entry spanname="id"><constant>V4L2_CID_PAN_RESET</constant> </entry> 1743 <entry>button</entry> 1744 </row><row><entry spanname="descr">When this control is set, 1745the camera moves horizontally to the default position.</entry> 1746 </row> 1747 <row><entry></entry></row> 1748 1749 <row> 1750 <entry spanname="id"><constant>V4L2_CID_TILT_RESET</constant> </entry> 1751 <entry>button</entry> 1752 </row><row><entry spanname="descr">When this control is set, 1753the camera moves vertically to the default position.</entry> 1754 </row> 1755 <row><entry></entry></row> 1756 1757 <row> 1758 <entry spanname="id"><constant>V4L2_CID_PAN_ABSOLUTE</constant> </entry> 1759 <entry>integer</entry> 1760 </row><row><entry spanname="descr">This control 1761turns the camera horizontally to the specified position. Positive 1762values move the camera to the right (clockwise when viewed from above), 1763negative values to the left. Drivers should interpret the values as arc 1764seconds, with valid values between -180 * 3600 and +180 * 3600 1765inclusive.</entry> 1766 </row> 1767 <row><entry></entry></row> 1768 1769 <row> 1770 <entry spanname="id"><constant>V4L2_CID_TILT_ABSOLUTE</constant> </entry> 1771 <entry>integer</entry> 1772 </row><row><entry spanname="descr">This control 1773turns the camera vertically to the specified position. Positive values 1774move the camera up, negative values down. Drivers should interpret the 1775values as arc seconds, with valid values between -180 * 3600 and +180 1776* 3600 inclusive.</entry> 1777 </row> 1778 <row><entry></entry></row> 1779 1780 <row> 1781 <entry spanname="id"><constant>V4L2_CID_FOCUS_ABSOLUTE</constant> </entry> 1782 <entry>integer</entry> 1783 </row><row><entry spanname="descr">This control sets the 1784focal point of the camera to the specified position. The unit is 1785undefined. Positive values set the focus closer to the camera, 1786negative values towards infinity.</entry> 1787 </row> 1788 <row><entry></entry></row> 1789 1790 <row> 1791 <entry spanname="id"><constant>V4L2_CID_FOCUS_RELATIVE</constant> </entry> 1792 <entry>integer</entry> 1793 </row><row><entry spanname="descr">This control moves the 1794focal point of the camera by the specified amount. The unit is 1795undefined. Positive values move the focus closer to the camera, 1796negative values towards infinity. This is a write-only control.</entry> 1797 </row> 1798 <row><entry></entry></row> 1799 1800 <row> 1801 <entry spanname="id"><constant>V4L2_CID_FOCUS_AUTO</constant> </entry> 1802 <entry>boolean</entry> 1803 </row><row><entry spanname="descr">Enables automatic focus 1804adjustments. The effect of manual focus adjustments while this feature 1805is enabled is undefined, drivers should ignore such requests.</entry> 1806 </row> 1807 <row><entry></entry></row> 1808 1809 <row> 1810 <entry spanname="id"><constant>V4L2_CID_ZOOM_ABSOLUTE</constant> </entry> 1811 <entry>integer</entry> 1812 </row><row><entry spanname="descr">Specify the objective lens 1813focal length as an absolute value. The zoom unit is driver-specific and its 1814value should be a positive integer.</entry> 1815 </row> 1816 <row><entry></entry></row> 1817 1818 <row> 1819 <entry spanname="id"><constant>V4L2_CID_ZOOM_RELATIVE</constant> </entry> 1820 <entry>integer</entry> 1821 </row><row><entry spanname="descr">Specify the objective lens 1822focal length relatively to the current value. Positive values move the zoom 1823lens group towards the telephoto direction, negative values towards the 1824wide-angle direction. The zoom unit is driver-specific. This is a write-only control.</entry> 1825 </row> 1826 <row><entry></entry></row> 1827 1828 <row> 1829 <entry spanname="id"><constant>V4L2_CID_ZOOM_CONTINUOUS</constant> </entry> 1830 <entry>integer</entry> 1831 </row><row><entry spanname="descr">Move the objective lens group 1832at the specified speed until it reaches physical device limits or until an 1833explicit request to stop the movement. A positive value moves the zoom lens 1834group towards the telephoto direction. A value of zero stops the zoom lens 1835group movement. A negative value moves the zoom lens group towards the 1836wide-angle direction. The zoom speed unit is driver-specific.</entry> 1837 </row> 1838 <row><entry></entry></row> 1839 1840 <row> 1841 <entry spanname="id"><constant>V4L2_CID_IRIS_ABSOLUTE</constant> </entry> 1842 <entry>integer</entry> 1843 </row><row><entry spanname="descr">This control sets the 1844camera's aperture to the specified value. The unit is undefined. 1845Larger values open the iris wider, smaller values close it.</entry> 1846 </row> 1847 <row><entry></entry></row> 1848 1849 <row> 1850 <entry spanname="id"><constant>V4L2_CID_IRIS_RELATIVE</constant> </entry> 1851 <entry>integer</entry> 1852 </row><row><entry spanname="descr">This control modifies the 1853camera's aperture by the specified amount. The unit is undefined. 1854Positive values open the iris one step further, negative values close 1855it one step further. This is a write-only control.</entry> 1856 </row> 1857 <row><entry></entry></row> 1858 1859 <row> 1860 <entry spanname="id"><constant>V4L2_CID_PRIVACY</constant> </entry> 1861 <entry>boolean</entry> 1862 </row><row><entry spanname="descr">Prevent video from being acquired 1863by the camera. When this control is set to <constant>TRUE</constant> (1), no 1864image can be captured by the camera. Common means to enforce privacy are 1865mechanical obturation of the sensor and firmware image processing, but the 1866device is not restricted to these methods. Devices that implement the privacy 1867control must support read access and may support write access.</entry> 1868 </row> 1869 1870 <row> 1871 <entry spanname="id"><constant>V4L2_CID_BAND_STOP_FILTER</constant> </entry> 1872 <entry>integer</entry> 1873 </row><row><entry spanname="descr">Switch the band-stop filter of a 1874camera sensor on or off, or specify its strength. Such band-stop filters can 1875be used, for example, to filter out the fluorescent light component.</entry> 1876 </row> 1877 <row><entry></entry></row> 1878 </tbody> 1879 </tgroup> 1880 </table> 1881 </section> 1882 1883 <section id="fm-tx-controls"> 1884 <title>FM Transmitter Control Reference</title> 1885 1886 <para>The FM Transmitter (FM_TX) class includes controls for common features of 1887FM transmissions capable devices. Currently this class includes parameters for audio 1888compression, pilot tone generation, audio deviation limiter, RDS transmission and 1889tuning power features.</para> 1890 1891 <table pgwide="1" frame="none" id="fm-tx-control-id"> 1892 <title>FM_TX Control IDs</title> 1893 1894 <tgroup cols="4"> 1895 <colspec colname="c1" colwidth="1*" /> 1896 <colspec colname="c2" colwidth="6*" /> 1897 <colspec colname="c3" colwidth="2*" /> 1898 <colspec colname="c4" colwidth="6*" /> 1899 <spanspec namest="c1" nameend="c2" spanname="id" /> 1900 <spanspec namest="c2" nameend="c4" spanname="descr" /> 1901 <thead> 1902 <row> 1903 <entry spanname="id" align="left">ID</entry> 1904 <entry align="left">Type</entry> 1905 </row><row rowsep="1"><entry spanname="descr" align="left">Description</entry> 1906 </row> 1907 </thead> 1908 <tbody valign="top"> 1909 <row><entry></entry></row> 1910 <row> 1911 <entry spanname="id"><constant>V4L2_CID_FM_TX_CLASS</constant> </entry> 1912 <entry>class</entry> 1913 </row><row><entry spanname="descr">The FM_TX class 1914descriptor. Calling &VIDIOC-QUERYCTRL; for this control will return a 1915description of this control class.</entry> 1916 </row> 1917 <row> 1918 <entry spanname="id"><constant>V4L2_CID_RDS_TX_DEVIATION</constant> </entry> 1919 <entry>integer</entry> 1920 </row> 1921 <row><entry spanname="descr">Configures RDS signal frequency deviation level in Hz. 1922The range and step are driver-specific.</entry> 1923 </row> 1924 <row> 1925 <entry spanname="id"><constant>V4L2_CID_RDS_TX_PI</constant> </entry> 1926 <entry>integer</entry> 1927 </row> 1928 <row><entry spanname="descr">Sets the RDS Programme Identification field 1929for transmission.</entry> 1930 </row> 1931 <row> 1932 <entry spanname="id"><constant>V4L2_CID_RDS_TX_PTY</constant> </entry> 1933 <entry>integer</entry> 1934 </row> 1935 <row><entry spanname="descr">Sets the RDS Programme Type field for transmission. 1936This encodes up to 31 pre-defined programme types.</entry> 1937 </row> 1938 <row> 1939 <entry spanname="id"><constant>V4L2_CID_RDS_TX_PS_NAME</constant> </entry> 1940 <entry>string</entry> 1941 </row> 1942 <row><entry spanname="descr">Sets the Programme Service name (PS_NAME) for transmission. 1943It is intended for static display on a receiver. It is the primary aid to listeners in programme service 1944identification and selection. In Annex E of <xref linkend="en50067" />, the RDS specification, 1945there is a full description of the correct character encoding for Programme Service name strings. 1946Also from RDS specification, PS is usually a single eight character text. However, it is also possible 1947to find receivers which can scroll strings sized as 8 x N characters. So, this control must be configured 1948with steps of 8 characters. The result is it must always contain a string with size multiple of 8.</entry> 1949 </row> 1950 <row> 1951 <entry spanname="id"><constant>V4L2_CID_RDS_TX_RADIO_TEXT</constant> </entry> 1952 <entry>string</entry> 1953 </row> 1954 <row><entry spanname="descr">Sets the Radio Text info for transmission. It is a textual description of 1955what is being broadcasted. RDS Radio Text can be applied when broadcaster wishes to transmit longer PS names, 1956programme-related information or any other text. In these cases, RadioText should be used in addition to 1957<constant>V4L2_CID_RDS_TX_PS_NAME</constant>. The encoding for Radio Text strings is also fully described 1958in Annex E of <xref linkend="en50067" />. The length of Radio Text strings depends on which RDS Block is being 1959used to transmit it, either 32 (2A block) or 64 (2B block). However, it is also possible 1960to find receivers which can scroll strings sized as 32 x N or 64 x N characters. So, this control must be configured 1961with steps of 32 or 64 characters. The result is it must always contain a string with size multiple of 32 or 64. </entry> 1962 </row> 1963 <row> 1964 <entry spanname="id"><constant>V4L2_CID_AUDIO_LIMITER_ENABLED</constant> </entry> 1965 <entry>boolean</entry> 1966 </row> 1967 <row><entry spanname="descr">Enables or disables the audio deviation limiter feature. 1968The limiter is useful when trying to maximize the audio volume, minimize receiver-generated 1969distortion and prevent overmodulation. 1970</entry> 1971 </row> 1972 <row> 1973 <entry spanname="id"><constant>V4L2_CID_AUDIO_LIMITER_RELEASE_TIME</constant> </entry> 1974 <entry>integer</entry> 1975 </row> 1976 <row><entry spanname="descr">Sets the audio deviation limiter feature release time. 1977Unit is in useconds. Step and range are driver-specific.</entry> 1978 </row> 1979 <row> 1980 <entry spanname="id"><constant>V4L2_CID_AUDIO_LIMITER_DEVIATION</constant> </entry> 1981 <entry>integer</entry> 1982 </row> 1983 <row><entry spanname="descr">Configures audio frequency deviation level in Hz. 1984The range and step are driver-specific.</entry> 1985 </row> 1986 <row> 1987 <entry spanname="id"><constant>V4L2_CID_AUDIO_COMPRESSION_ENABLED</constant> </entry> 1988 <entry>boolean</entry> 1989 </row> 1990 <row><entry spanname="descr">Enables or disables the audio compression feature. 1991This feature amplifies signals below the threshold by a fixed gain and compresses audio 1992signals above the threshold by the ratio of Threshold/(Gain + Threshold).</entry> 1993 </row> 1994 <row> 1995 <entry spanname="id"><constant>V4L2_CID_AUDIO_COMPRESSION_GAIN</constant> </entry> 1996 <entry>integer</entry> 1997 </row> 1998 <row><entry spanname="descr">Sets the gain for audio compression feature. It is 1999a dB value. The range and step are driver-specific.</entry> 2000 </row> 2001 <row> 2002 <entry spanname="id"><constant>V4L2_CID_AUDIO_COMPRESSION_THRESHOLD</constant> </entry> 2003 <entry>integer</entry> 2004 </row> 2005 <row><entry spanname="descr">Sets the threshold level for audio compression freature. 2006It is a dB value. The range and step are driver-specific.</entry> 2007 </row> 2008 <row> 2009 <entry spanname="id"><constant>V4L2_CID_AUDIO_COMPRESSION_ATTACK_TIME</constant> </entry> 2010 <entry>integer</entry> 2011 </row> 2012 <row><entry spanname="descr">Sets the attack time for audio compression feature. 2013It is a useconds value. The range and step are driver-specific.</entry> 2014 </row> 2015 <row> 2016 <entry spanname="id"><constant>V4L2_CID_AUDIO_COMPRESSION_RELEASE_TIME</constant> </entry> 2017 <entry>integer</entry> 2018 </row> 2019 <row><entry spanname="descr">Sets the release time for audio compression feature. 2020It is a useconds value. The range and step are driver-specific.</entry> 2021 </row> 2022 <row> 2023 <entry spanname="id"><constant>V4L2_CID_PILOT_TONE_ENABLED</constant> </entry> 2024 <entry>boolean</entry> 2025 </row> 2026 <row><entry spanname="descr">Enables or disables the pilot tone generation feature.</entry> 2027 </row> 2028 <row> 2029 <entry spanname="id"><constant>V4L2_CID_PILOT_TONE_DEVIATION</constant> </entry> 2030 <entry>integer</entry> 2031 </row> 2032 <row><entry spanname="descr">Configures pilot tone frequency deviation level. Unit is 2033in Hz. The range and step are driver-specific.</entry> 2034 </row> 2035 <row> 2036 <entry spanname="id"><constant>V4L2_CID_PILOT_TONE_FREQUENCY</constant> </entry> 2037 <entry>integer</entry> 2038 </row> 2039 <row><entry spanname="descr">Configures pilot tone frequency value. Unit is 2040in Hz. The range and step are driver-specific.</entry> 2041 </row> 2042 <row> 2043 <entry spanname="id"><constant>V4L2_CID_TUNE_PREEMPHASIS</constant> </entry> 2044 <entry>integer</entry> 2045 </row> 2046 <row id="v4l2-preemphasis"><entry spanname="descr">Configures the pre-emphasis value for broadcasting. 2047A pre-emphasis filter is applied to the broadcast to accentuate the high audio frequencies. 2048Depending on the region, a time constant of either 50 or 75 useconds is used. The enum v4l2_preemphasis 2049defines possible values for pre-emphasis. Here they are:</entry> 2050 </row><row> 2051 <entrytbl spanname="descr" cols="2"> 2052 <tbody valign="top"> 2053 <row> 2054 <entry><constant>V4L2_PREEMPHASIS_DISABLED</constant> </entry> 2055 <entry>No pre-emphasis is applied.</entry> 2056 </row> 2057 <row> 2058 <entry><constant>V4L2_PREEMPHASIS_50_uS</constant> </entry> 2059 <entry>A pre-emphasis of 50 uS is used.</entry> 2060 </row> 2061 <row> 2062 <entry><constant>V4L2_PREEMPHASIS_75_uS</constant> </entry> 2063 <entry>A pre-emphasis of 75 uS is used.</entry> 2064 </row> 2065 </tbody> 2066 </entrytbl> 2067 2068 </row> 2069 <row> 2070 <entry spanname="id"><constant>V4L2_CID_TUNE_POWER_LEVEL</constant> </entry> 2071 <entry>integer</entry> 2072 </row> 2073 <row><entry spanname="descr">Sets the output power level for signal transmission. 2074Unit is in dBuV. Range and step are driver-specific.</entry> 2075 </row> 2076 <row> 2077 <entry spanname="id"><constant>V4L2_CID_TUNE_ANTENNA_CAPACITOR</constant> </entry> 2078 <entry>integer</entry> 2079 </row> 2080 <row><entry spanname="descr">This selects the value of antenna tuning capacitor 2081manually or automatically if set to zero. Unit, range and step are driver-specific.</entry> 2082 </row> 2083 <row><entry></entry></row> 2084 </tbody> 2085 </tgroup> 2086 </table> 2087 2088<para>For more details about RDS specification, refer to 2089<xref linkend="en50067" /> document, from CENELEC.</para> 2090 </section> 2091</section> 2092 2093 <!-- 2094Local Variables: 2095mode: sgml 2096sgml-parent-document: "common.sgml" 2097indent-tabs-mode: nil 2098End: 2099 --> 2100