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1 | <title>Changes</title> |
2 | ||
3 | <para>The following chapters document the evolution of the V4L2 API, | |
4 | errata or extensions. They are also intended to help application and | |
5 | driver writers to port or update their code.</para> | |
6 | ||
7 | <section id="diff-v4l"> | |
8 | <title>Differences between V4L and V4L2</title> | |
9 | ||
10 | <para>The Video For Linux API was first introduced in Linux 2.1 to | |
11 | unify and replace various TV and radio device related interfaces, | |
12 | developed independently by driver writers in prior years. Starting | |
13 | with Linux 2.5 the much improved V4L2 API replaces the V4L API, | |
14 | although existing drivers will continue to support V4L applications in | |
15 | the future, either directly or through the V4L2 compatibility layer in | |
16 | the <filename>videodev</filename> kernel module translating ioctls on | |
17 | the fly. For a transition period not all drivers will support the V4L2 | |
18 | API.</para> | |
19 | ||
20 | <section> | |
21 | <title>Opening and Closing Devices</title> | |
22 | ||
23 | <para>For compatibility reasons the character device file names | |
f44026db | 24 | recommended for V4L2 video capture, overlay, radio and raw |
8e080c2e MCC |
25 | vbi capture devices did not change from those used by V4L. They are |
26 | listed in <xref linkend="devices" /> and below in <xref | |
27 | linkend="v4l-dev" />.</para> | |
28 | ||
f44026db HV |
29 | <para>The teletext devices (minor range 192-223) have been removed in |
30 | V4L2 and no longer exist. There is no hardware available anymore for handling | |
31 | pure teletext. Instead raw or sliced VBI is used.</para> | |
32 | ||
8e080c2e MCC |
33 | <para>The V4L <filename>videodev</filename> module automatically |
34 | assigns minor numbers to drivers in load order, depending on the | |
35 | registered device type. We recommend that V4L2 drivers by default | |
36 | register devices with the same numbers, but the system administrator | |
37 | can assign arbitrary minor numbers using driver module options. The | |
38 | major device number remains 81.</para> | |
39 | ||
40 | <table id="v4l-dev"> | |
41 | <title>V4L Device Types, Names and Numbers</title> | |
42 | <tgroup cols="3"> | |
43 | <thead> | |
44 | <row> | |
45 | <entry>Device Type</entry> | |
46 | <entry>File Name</entry> | |
47 | <entry>Minor Numbers</entry> | |
48 | </row> | |
49 | </thead> | |
50 | <tbody valign="top"> | |
51 | <row> | |
52 | <entry>Video capture and overlay</entry> | |
53 | <entry><para><filename>/dev/video</filename> and | |
54 | <filename>/dev/bttv0</filename><footnote> <para>According to | |
55 | Documentation/devices.txt these should be symbolic links to | |
56 | <filename>/dev/video0</filename>. Note the original bttv interface is | |
57 | not compatible with V4L or V4L2.</para> </footnote>, | |
58 | <filename>/dev/video0</filename> to | |
59 | <filename>/dev/video63</filename></para></entry> | |
60 | <entry>0-63</entry> | |
61 | </row> | |
62 | <row> | |
63 | <entry>Radio receiver</entry> | |
64 | <entry><para><filename>/dev/radio</filename><footnote> | |
65 | <para>According to | |
66 | <filename>Documentation/devices.txt</filename> a symbolic link to | |
67 | <filename>/dev/radio0</filename>.</para> | |
68 | </footnote>, <filename>/dev/radio0</filename> to | |
69 | <filename>/dev/radio63</filename></para></entry> | |
70 | <entry>64-127</entry> | |
71 | </row> | |
8e080c2e MCC |
72 | <row> |
73 | <entry>Raw VBI capture</entry> | |
74 | <entry><para><filename>/dev/vbi</filename>, | |
75 | <filename>/dev/vbi0</filename> to | |
76 | <filename>/dev/vbi31</filename></para></entry> | |
77 | <entry>224-255</entry> | |
78 | </row> | |
79 | </tbody> | |
80 | </tgroup> | |
81 | </table> | |
82 | ||
83 | <para>V4L prohibits (or used to prohibit) multiple opens of a | |
84 | device file. V4L2 drivers <emphasis>may</emphasis> support multiple | |
85 | opens, see <xref linkend="open" /> for details and consequences.</para> | |
86 | ||
87 | <para>V4L drivers respond to V4L2 ioctls with an &EINVAL;. The | |
88 | compatibility layer in the V4L2 <filename>videodev</filename> module | |
89 | can translate V4L ioctl requests to their V4L2 counterpart, however a | |
90 | V4L2 driver usually needs more preparation to become fully V4L | |
91 | compatible. This is covered in more detail in <xref | |
92 | linkend="driver" />.</para> | |
93 | </section> | |
94 | ||
95 | <section> | |
96 | <title>Querying Capabilities</title> | |
97 | ||
98 | <para>The V4L <constant>VIDIOCGCAP</constant> ioctl is | |
99 | equivalent to V4L2's &VIDIOC-QUERYCAP;.</para> | |
100 | ||
101 | <para>The <structfield>name</structfield> field in struct | |
102 | <structname>video_capability</structname> became | |
103 | <structfield>card</structfield> in &v4l2-capability;, | |
104 | <structfield>type</structfield> was replaced by | |
105 | <structfield>capabilities</structfield>. Note V4L2 does not | |
106 | distinguish between device types like this, better think of basic | |
107 | video input, video output and radio devices supporting a set of | |
108 | related functions like video capturing, video overlay and VBI | |
109 | capturing. See <xref linkend="open" /> for an | |
110 | introduction.<informaltable> | |
111 | <tgroup cols="3"> | |
112 | <thead> | |
113 | <row> | |
114 | <entry>struct | |
115 | <structname>video_capability</structname> | |
116 | <structfield>type</structfield></entry> | |
117 | <entry>&v4l2-capability; | |
118 | <structfield>capabilities</structfield> flags</entry> | |
119 | <entry>Purpose</entry> | |
120 | </row> | |
121 | </thead> | |
122 | <tbody valign="top"> | |
123 | <row> | |
124 | <entry><constant>VID_TYPE_CAPTURE</constant></entry> | |
125 | <entry><constant>V4L2_CAP_VIDEO_CAPTURE</constant></entry> | |
126 | <entry>The <link linkend="capture">video | |
127 | capture</link> interface is supported.</entry> | |
128 | </row> | |
129 | <row> | |
130 | <entry><constant>VID_TYPE_TUNER</constant></entry> | |
131 | <entry><constant>V4L2_CAP_TUNER</constant></entry> | |
132 | <entry>The device has a <link linkend="tuner">tuner or | |
133 | modulator</link>.</entry> | |
134 | </row> | |
135 | <row> | |
136 | <entry><constant>VID_TYPE_TELETEXT</constant></entry> | |
137 | <entry><constant>V4L2_CAP_VBI_CAPTURE</constant></entry> | |
138 | <entry>The <link linkend="raw-vbi">raw VBI | |
139 | capture</link> interface is supported.</entry> | |
140 | </row> | |
141 | <row> | |
142 | <entry><constant>VID_TYPE_OVERLAY</constant></entry> | |
143 | <entry><constant>V4L2_CAP_VIDEO_OVERLAY</constant></entry> | |
144 | <entry>The <link linkend="overlay">video | |
145 | overlay</link> interface is supported.</entry> | |
146 | </row> | |
147 | <row> | |
148 | <entry><constant>VID_TYPE_CHROMAKEY</constant></entry> | |
149 | <entry><constant>V4L2_FBUF_CAP_CHROMAKEY</constant> in | |
150 | field <structfield>capability</structfield> of | |
151 | &v4l2-framebuffer;</entry> | |
152 | <entry>Whether chromakey overlay is supported. For | |
153 | more information on overlay see | |
154 | <xref linkend="overlay" />.</entry> | |
155 | </row> | |
156 | <row> | |
157 | <entry><constant>VID_TYPE_CLIPPING</constant></entry> | |
158 | <entry><constant>V4L2_FBUF_CAP_LIST_CLIPPING</constant> | |
159 | and <constant>V4L2_FBUF_CAP_BITMAP_CLIPPING</constant> in field | |
160 | <structfield>capability</structfield> of &v4l2-framebuffer;</entry> | |
161 | <entry>Whether clipping the overlaid image is | |
162 | supported, see <xref linkend="overlay" />.</entry> | |
163 | </row> | |
164 | <row> | |
165 | <entry><constant>VID_TYPE_FRAMERAM</constant></entry> | |
166 | <entry><constant>V4L2_FBUF_CAP_EXTERNOVERLAY</constant> | |
167 | <emphasis>not set</emphasis> in field | |
168 | <structfield>capability</structfield> of &v4l2-framebuffer;</entry> | |
169 | <entry>Whether overlay overwrites frame buffer memory, | |
170 | see <xref linkend="overlay" />.</entry> | |
171 | </row> | |
172 | <row> | |
173 | <entry><constant>VID_TYPE_SCALES</constant></entry> | |
174 | <entry><constant>-</constant></entry> | |
175 | <entry>This flag indicates if the hardware can scale | |
176 | images. The V4L2 API implies the scale factor by setting the cropping | |
177 | dimensions and image size with the &VIDIOC-S-CROP; and &VIDIOC-S-FMT; | |
178 | ioctl, respectively. The driver returns the closest sizes possible. | |
179 | For more information on cropping and scaling see <xref | |
180 | linkend="crop" />.</entry> | |
181 | </row> | |
182 | <row> | |
183 | <entry><constant>VID_TYPE_MONOCHROME</constant></entry> | |
184 | <entry><constant>-</constant></entry> | |
185 | <entry>Applications can enumerate the supported image | |
186 | formats with the &VIDIOC-ENUM-FMT; ioctl to determine if the device | |
187 | supports grey scale capturing only. For more information on image | |
188 | formats see <xref linkend="pixfmt" />.</entry> | |
189 | </row> | |
190 | <row> | |
191 | <entry><constant>VID_TYPE_SUBCAPTURE</constant></entry> | |
192 | <entry><constant>-</constant></entry> | |
193 | <entry>Applications can call the &VIDIOC-G-CROP; ioctl | |
194 | to determine if the device supports capturing a subsection of the full | |
195 | picture ("cropping" in V4L2). If not, the ioctl returns the &EINVAL;. | |
196 | For more information on cropping and scaling see <xref | |
197 | linkend="crop" />.</entry> | |
198 | </row> | |
199 | <row> | |
200 | <entry><constant>VID_TYPE_MPEG_DECODER</constant></entry> | |
201 | <entry><constant>-</constant></entry> | |
202 | <entry>Applications can enumerate the supported image | |
203 | formats with the &VIDIOC-ENUM-FMT; ioctl to determine if the device | |
204 | supports MPEG streams.</entry> | |
205 | </row> | |
206 | <row> | |
207 | <entry><constant>VID_TYPE_MPEG_ENCODER</constant></entry> | |
208 | <entry><constant>-</constant></entry> | |
209 | <entry>See above.</entry> | |
210 | </row> | |
211 | <row> | |
212 | <entry><constant>VID_TYPE_MJPEG_DECODER</constant></entry> | |
213 | <entry><constant>-</constant></entry> | |
214 | <entry>See above.</entry> | |
215 | </row> | |
216 | <row> | |
217 | <entry><constant>VID_TYPE_MJPEG_ENCODER</constant></entry> | |
218 | <entry><constant>-</constant></entry> | |
219 | <entry>See above.</entry> | |
220 | </row> | |
221 | </tbody> | |
222 | </tgroup> | |
223 | </informaltable></para> | |
224 | ||
225 | <para>The <structfield>audios</structfield> field was replaced | |
226 | by <structfield>capabilities</structfield> flag | |
227 | <constant>V4L2_CAP_AUDIO</constant>, indicating | |
228 | <emphasis>if</emphasis> the device has any audio inputs or outputs. To | |
229 | determine their number applications can enumerate audio inputs with | |
230 | the &VIDIOC-G-AUDIO; ioctl. The audio ioctls are described in <xref | |
231 | linkend="audio" />.</para> | |
232 | ||
233 | <para>The <structfield>maxwidth</structfield>, | |
234 | <structfield>maxheight</structfield>, | |
235 | <structfield>minwidth</structfield> and | |
236 | <structfield>minheight</structfield> fields were removed. Calling the | |
237 | &VIDIOC-S-FMT; or &VIDIOC-TRY-FMT; ioctl with the desired dimensions | |
238 | returns the closest size possible, taking into account the current | |
239 | video standard, cropping and scaling limitations.</para> | |
240 | </section> | |
241 | ||
242 | <section> | |
243 | <title>Video Sources</title> | |
244 | ||
245 | <para>V4L provides the <constant>VIDIOCGCHAN</constant> and | |
246 | <constant>VIDIOCSCHAN</constant> ioctl using struct | |
247 | <structname>video_channel</structname> to enumerate | |
248 | the video inputs of a V4L device. The equivalent V4L2 ioctls | |
249 | are &VIDIOC-ENUMINPUT;, &VIDIOC-G-INPUT; and &VIDIOC-S-INPUT; | |
250 | using &v4l2-input; as discussed in <xref linkend="video" />.</para> | |
251 | ||
252 | <para>The <structfield>channel</structfield> field counting | |
253 | inputs was renamed to <structfield>index</structfield>, the video | |
254 | input types were renamed as follows: <informaltable> | |
255 | <tgroup cols="2"> | |
256 | <thead> | |
257 | <row> | |
258 | <entry>struct <structname>video_channel</structname> | |
259 | <structfield>type</structfield></entry> | |
260 | <entry>&v4l2-input; | |
261 | <structfield>type</structfield></entry> | |
262 | </row> | |
263 | </thead> | |
264 | <tbody valign="top"> | |
265 | <row> | |
266 | <entry><constant>VIDEO_TYPE_TV</constant></entry> | |
267 | <entry><constant>V4L2_INPUT_TYPE_TUNER</constant></entry> | |
268 | </row> | |
269 | <row> | |
270 | <entry><constant>VIDEO_TYPE_CAMERA</constant></entry> | |
271 | <entry><constant>V4L2_INPUT_TYPE_CAMERA</constant></entry> | |
272 | </row> | |
273 | </tbody> | |
274 | </tgroup> | |
275 | </informaltable></para> | |
276 | ||
277 | <para>Unlike the <structfield>tuners</structfield> field | |
278 | expressing the number of tuners of this input, V4L2 assumes each video | |
279 | input is connected to at most one tuner. However a tuner can have more | |
280 | than one input, &ie; RF connectors, and a device can have multiple | |
281 | tuners. The index number of the tuner associated with the input, if | |
282 | any, is stored in field <structfield>tuner</structfield> of | |
283 | &v4l2-input;. Enumeration of tuners is discussed in <xref | |
284 | linkend="tuner" />.</para> | |
285 | ||
286 | <para>The redundant <constant>VIDEO_VC_TUNER</constant> flag was | |
287 | dropped. Video inputs associated with a tuner are of type | |
288 | <constant>V4L2_INPUT_TYPE_TUNER</constant>. The | |
289 | <constant>VIDEO_VC_AUDIO</constant> flag was replaced by the | |
290 | <structfield>audioset</structfield> field. V4L2 considers devices with | |
291 | up to 32 audio inputs. Each set bit in the | |
292 | <structfield>audioset</structfield> field represents one audio input | |
293 | this video input combines with. For information about audio inputs and | |
294 | how to switch between them see <xref linkend="audio" />.</para> | |
295 | ||
296 | <para>The <structfield>norm</structfield> field describing the | |
297 | supported video standards was replaced by | |
298 | <structfield>std</structfield>. The V4L specification mentions a flag | |
299 | <constant>VIDEO_VC_NORM</constant> indicating whether the standard can | |
300 | be changed. This flag was a later addition together with the | |
301 | <structfield>norm</structfield> field and has been removed in the | |
302 | meantime. V4L2 has a similar, albeit more comprehensive approach | |
303 | to video standards, see <xref linkend="standard" /> for more | |
304 | information.</para> | |
305 | </section> | |
306 | ||
307 | <section> | |
308 | <title>Tuning</title> | |
309 | ||
310 | <para>The V4L <constant>VIDIOCGTUNER</constant> and | |
311 | <constant>VIDIOCSTUNER</constant> ioctl and struct | |
312 | <structname>video_tuner</structname> can be used to enumerate the | |
313 | tuners of a V4L TV or radio device. The equivalent V4L2 ioctls are | |
314 | &VIDIOC-G-TUNER; and &VIDIOC-S-TUNER; using &v4l2-tuner;. Tuners are | |
315 | covered in <xref linkend="tuner" />.</para> | |
316 | ||
317 | <para>The <structfield>tuner</structfield> field counting tuners | |
318 | was renamed to <structfield>index</structfield>. The fields | |
319 | <structfield>name</structfield>, <structfield>rangelow</structfield> | |
320 | and <structfield>rangehigh</structfield> remained unchanged.</para> | |
321 | ||
322 | <para>The <constant>VIDEO_TUNER_PAL</constant>, | |
323 | <constant>VIDEO_TUNER_NTSC</constant> and | |
324 | <constant>VIDEO_TUNER_SECAM</constant> flags indicating the supported | |
325 | video standards were dropped. This information is now contained in the | |
326 | associated &v4l2-input;. No replacement exists for the | |
327 | <constant>VIDEO_TUNER_NORM</constant> flag indicating whether the | |
328 | video standard can be switched. The <structfield>mode</structfield> | |
329 | field to select a different video standard was replaced by a whole new | |
330 | set of ioctls and structures described in <xref linkend="standard" />. | |
331 | Due to its ubiquity it should be mentioned the BTTV driver supports | |
332 | several standards in addition to the regular | |
333 | <constant>VIDEO_MODE_PAL</constant> (0), | |
334 | <constant>VIDEO_MODE_NTSC</constant>, | |
335 | <constant>VIDEO_MODE_SECAM</constant> and | |
336 | <constant>VIDEO_MODE_AUTO</constant> (3). Namely N/PAL Argentina, | |
337 | M/PAL, N/PAL, and NTSC Japan with numbers 3-6 (sic).</para> | |
338 | ||
339 | <para>The <constant>VIDEO_TUNER_STEREO_ON</constant> flag | |
340 | indicating stereo reception became | |
341 | <constant>V4L2_TUNER_SUB_STEREO</constant> in field | |
342 | <structfield>rxsubchans</structfield>. This field also permits the | |
343 | detection of monaural and bilingual audio, see the definition of | |
344 | &v4l2-tuner; for details. Presently no replacement exists for the | |
345 | <constant>VIDEO_TUNER_RDS_ON</constant> and | |
346 | <constant>VIDEO_TUNER_MBS_ON</constant> flags.</para> | |
347 | ||
348 | <para> The <constant>VIDEO_TUNER_LOW</constant> flag was renamed | |
349 | to <constant>V4L2_TUNER_CAP_LOW</constant> in the &v4l2-tuner; | |
350 | <structfield>capability</structfield> field.</para> | |
351 | ||
352 | <para>The <constant>VIDIOCGFREQ</constant> and | |
353 | <constant>VIDIOCSFREQ</constant> ioctl to change the tuner frequency | |
354 | where renamed to &VIDIOC-G-FREQUENCY; and &VIDIOC-S-FREQUENCY;. They | |
355 | take a pointer to a &v4l2-frequency; instead of an unsigned long | |
356 | integer.</para> | |
357 | </section> | |
358 | ||
359 | <section id="v4l-image-properties"> | |
360 | <title>Image Properties</title> | |
361 | ||
362 | <para>V4L2 has no equivalent of the | |
363 | <constant>VIDIOCGPICT</constant> and <constant>VIDIOCSPICT</constant> | |
364 | ioctl and struct <structname>video_picture</structname>. The following | |
365 | fields where replaced by V4L2 controls accessible with the | |
366 | &VIDIOC-QUERYCTRL;, &VIDIOC-G-CTRL; and &VIDIOC-S-CTRL; ioctls:<informaltable> | |
367 | <tgroup cols="2"> | |
368 | <thead> | |
369 | <row> | |
370 | <entry>struct <structname>video_picture</structname></entry> | |
371 | <entry>V4L2 Control ID</entry> | |
372 | </row> | |
373 | </thead> | |
374 | <tbody valign="top"> | |
375 | <row> | |
376 | <entry><structfield>brightness</structfield></entry> | |
377 | <entry><constant>V4L2_CID_BRIGHTNESS</constant></entry> | |
378 | </row> | |
379 | <row> | |
380 | <entry><structfield>hue</structfield></entry> | |
381 | <entry><constant>V4L2_CID_HUE</constant></entry> | |
382 | </row> | |
383 | <row> | |
384 | <entry><structfield>colour</structfield></entry> | |
385 | <entry><constant>V4L2_CID_SATURATION</constant></entry> | |
386 | </row> | |
387 | <row> | |
388 | <entry><structfield>contrast</structfield></entry> | |
389 | <entry><constant>V4L2_CID_CONTRAST</constant></entry> | |
390 | </row> | |
391 | <row> | |
392 | <entry><structfield>whiteness</structfield></entry> | |
393 | <entry><constant>V4L2_CID_WHITENESS</constant></entry> | |
394 | </row> | |
395 | </tbody> | |
396 | </tgroup> | |
397 | </informaltable></para> | |
398 | ||
399 | <para>The V4L picture controls are assumed to range from 0 to | |
400 | 65535 with no particular reset value. The V4L2 API permits arbitrary | |
401 | limits and defaults which can be queried with the &VIDIOC-QUERYCTRL; | |
402 | ioctl. For general information about controls see <xref | |
403 | linkend="control" />.</para> | |
404 | ||
405 | <para>The <structfield>depth</structfield> (average number of | |
406 | bits per pixel) of a video image is implied by the selected image | |
407 | format. V4L2 does not explicitely provide such information assuming | |
408 | applications recognizing the format are aware of the image depth and | |
409 | others need not know. The <structfield>palette</structfield> field | |
410 | moved into the &v4l2-pix-format;:<informaltable> | |
411 | <tgroup cols="2"> | |
412 | <thead> | |
413 | <row> | |
414 | <entry>struct <structname>video_picture</structname> | |
415 | <structfield>palette</structfield></entry> | |
416 | <entry>&v4l2-pix-format; | |
417 | <structfield>pixfmt</structfield></entry> | |
418 | </row> | |
419 | </thead> | |
420 | <tbody valign="top"> | |
421 | <row> | |
422 | <entry><constant>VIDEO_PALETTE_GREY</constant></entry> | |
423 | <entry><para><link | |
424 | linkend="V4L2-PIX-FMT-GREY"><constant>V4L2_PIX_FMT_GREY</constant></link></para></entry> | |
425 | </row> | |
426 | <row> | |
427 | <entry><constant>VIDEO_PALETTE_HI240</constant></entry> | |
428 | <entry><para><link | |
429 | linkend="pixfmt-reserved"><constant>V4L2_PIX_FMT_HI240</constant></link><footnote> | |
430 | <para>This is a custom format used by the BTTV | |
431 | driver, not one of the V4L2 standard formats.</para> | |
432 | </footnote></para></entry> | |
433 | </row> | |
434 | <row> | |
435 | <entry><constant>VIDEO_PALETTE_RGB565</constant></entry> | |
436 | <entry><para><link | |
437 | linkend="pixfmt-rgb"><constant>V4L2_PIX_FMT_RGB565</constant></link></para></entry> | |
438 | </row> | |
439 | <row> | |
440 | <entry><constant>VIDEO_PALETTE_RGB555</constant></entry> | |
441 | <entry><para><link | |
442 | linkend="pixfmt-rgb"><constant>V4L2_PIX_FMT_RGB555</constant></link></para></entry> | |
443 | </row> | |
444 | <row> | |
445 | <entry><constant>VIDEO_PALETTE_RGB24</constant></entry> | |
446 | <entry><para><link | |
447 | linkend="pixfmt-rgb"><constant>V4L2_PIX_FMT_BGR24</constant></link></para></entry> | |
448 | </row> | |
449 | <row> | |
450 | <entry><constant>VIDEO_PALETTE_RGB32</constant></entry> | |
451 | <entry><para><link | |
452 | linkend="pixfmt-rgb"><constant>V4L2_PIX_FMT_BGR32</constant></link><footnote> | |
453 | <para>Presumably all V4L RGB formats are | |
454 | little-endian, although some drivers might interpret them according to machine endianess. V4L2 defines little-endian, big-endian and red/blue | |
455 | swapped variants. For details see <xref linkend="pixfmt-rgb" />.</para> | |
456 | </footnote></para></entry> | |
457 | </row> | |
458 | <row> | |
459 | <entry><constant>VIDEO_PALETTE_YUV422</constant></entry> | |
460 | <entry><para><link | |
461 | linkend="V4L2-PIX-FMT-YUYV"><constant>V4L2_PIX_FMT_YUYV</constant></link></para></entry> | |
462 | </row> | |
463 | <row> | |
464 | <entry><para><constant>VIDEO_PALETTE_YUYV</constant><footnote> | |
465 | <para><constant>VIDEO_PALETTE_YUV422</constant> | |
466 | and <constant>VIDEO_PALETTE_YUYV</constant> are the same formats. Some | |
467 | V4L drivers respond to one, some to the other.</para> | |
468 | </footnote></para></entry> | |
469 | <entry><para><link | |
470 | linkend="V4L2-PIX-FMT-YUYV"><constant>V4L2_PIX_FMT_YUYV</constant></link></para></entry> | |
471 | </row> | |
472 | <row> | |
473 | <entry><constant>VIDEO_PALETTE_UYVY</constant></entry> | |
474 | <entry><para><link | |
475 | linkend="V4L2-PIX-FMT-UYVY"><constant>V4L2_PIX_FMT_UYVY</constant></link></para></entry> | |
476 | </row> | |
477 | <row> | |
478 | <entry><constant>VIDEO_PALETTE_YUV420</constant></entry> | |
479 | <entry>None</entry> | |
480 | </row> | |
481 | <row> | |
482 | <entry><constant>VIDEO_PALETTE_YUV411</constant></entry> | |
483 | <entry><para><link | |
484 | linkend="V4L2-PIX-FMT-Y41P"><constant>V4L2_PIX_FMT_Y41P</constant></link><footnote> | |
485 | <para>Not to be confused with | |
486 | <constant>V4L2_PIX_FMT_YUV411P</constant>, which is a planar | |
487 | format.</para> </footnote></para></entry> | |
488 | </row> | |
489 | <row> | |
490 | <entry><constant>VIDEO_PALETTE_RAW</constant></entry> | |
491 | <entry><para>None<footnote> <para>V4L explains this | |
492 | as: "RAW capture (BT848)"</para> </footnote></para></entry> | |
493 | </row> | |
494 | <row> | |
495 | <entry><constant>VIDEO_PALETTE_YUV422P</constant></entry> | |
496 | <entry><para><link | |
497 | linkend="V4L2-PIX-FMT-YUV422P"><constant>V4L2_PIX_FMT_YUV422P</constant></link></para></entry> | |
498 | </row> | |
499 | <row> | |
500 | <entry><constant>VIDEO_PALETTE_YUV411P</constant></entry> | |
501 | <entry><para><link | |
502 | linkend="V4L2-PIX-FMT-YUV411P"><constant>V4L2_PIX_FMT_YUV411P</constant></link><footnote> | |
503 | <para>Not to be confused with | |
504 | <constant>V4L2_PIX_FMT_Y41P</constant>, which is a packed | |
505 | format.</para> </footnote></para></entry> | |
506 | </row> | |
507 | <row> | |
508 | <entry><constant>VIDEO_PALETTE_YUV420P</constant></entry> | |
509 | <entry><para><link | |
510 | linkend="V4L2-PIX-FMT-YVU420"><constant>V4L2_PIX_FMT_YVU420</constant></link></para></entry> | |
511 | </row> | |
512 | <row> | |
513 | <entry><constant>VIDEO_PALETTE_YUV410P</constant></entry> | |
514 | <entry><para><link | |
515 | linkend="V4L2-PIX-FMT-YVU410"><constant>V4L2_PIX_FMT_YVU410</constant></link></para></entry> | |
516 | </row> | |
517 | </tbody> | |
518 | </tgroup> | |
519 | </informaltable></para> | |
520 | ||
521 | <para>V4L2 image formats are defined in <xref | |
522 | linkend="pixfmt" />. The image format can be selected with the | |
523 | &VIDIOC-S-FMT; ioctl.</para> | |
524 | </section> | |
525 | ||
526 | <section> | |
527 | <title>Audio</title> | |
528 | ||
529 | <para>The <constant>VIDIOCGAUDIO</constant> and | |
530 | <constant>VIDIOCSAUDIO</constant> ioctl and struct | |
531 | <structname>video_audio</structname> are used to enumerate the | |
532 | audio inputs of a V4L device. The equivalent V4L2 ioctls are | |
533 | &VIDIOC-G-AUDIO; and &VIDIOC-S-AUDIO; using &v4l2-audio; as | |
534 | discussed in <xref linkend="audio" />.</para> | |
535 | ||
536 | <para>The <structfield>audio</structfield> "channel number" | |
537 | field counting audio inputs was renamed to | |
538 | <structfield>index</structfield>.</para> | |
539 | ||
540 | <para>On <constant>VIDIOCSAUDIO</constant> the | |
541 | <structfield>mode</structfield> field selects <emphasis>one</emphasis> | |
542 | of the <constant>VIDEO_SOUND_MONO</constant>, | |
543 | <constant>VIDEO_SOUND_STEREO</constant>, | |
544 | <constant>VIDEO_SOUND_LANG1</constant> or | |
545 | <constant>VIDEO_SOUND_LANG2</constant> audio demodulation modes. When | |
546 | the current audio standard is BTSC | |
547 | <constant>VIDEO_SOUND_LANG2</constant> refers to SAP and | |
548 | <constant>VIDEO_SOUND_LANG1</constant> is meaningless. Also | |
549 | undocumented in the V4L specification, there is no way to query the | |
550 | selected mode. On <constant>VIDIOCGAUDIO</constant> the driver returns | |
551 | the <emphasis>actually received</emphasis> audio programmes in this | |
552 | field. In the V4L2 API this information is stored in the &v4l2-tuner; | |
553 | <structfield>rxsubchans</structfield> and | |
554 | <structfield>audmode</structfield> fields, respectively. See <xref | |
555 | linkend="tuner" /> for more information on tuners. Related to audio | |
556 | modes &v4l2-audio; also reports if this is a mono or stereo | |
557 | input, regardless if the source is a tuner.</para> | |
558 | ||
559 | <para>The following fields where replaced by V4L2 controls | |
560 | accessible with the &VIDIOC-QUERYCTRL;, &VIDIOC-G-CTRL; and | |
561 | &VIDIOC-S-CTRL; ioctls:<informaltable> | |
562 | <tgroup cols="2"> | |
563 | <thead> | |
564 | <row> | |
565 | <entry>struct | |
566 | <structname>video_audio</structname></entry> | |
567 | <entry>V4L2 Control ID</entry> | |
568 | </row> | |
569 | </thead> | |
570 | <tbody valign="top"> | |
571 | <row> | |
572 | <entry><structfield>volume</structfield></entry> | |
573 | <entry><constant>V4L2_CID_AUDIO_VOLUME</constant></entry> | |
574 | </row> | |
575 | <row> | |
576 | <entry><structfield>bass</structfield></entry> | |
577 | <entry><constant>V4L2_CID_AUDIO_BASS</constant></entry> | |
578 | </row> | |
579 | <row> | |
580 | <entry><structfield>treble</structfield></entry> | |
581 | <entry><constant>V4L2_CID_AUDIO_TREBLE</constant></entry> | |
582 | </row> | |
583 | <row> | |
584 | <entry><structfield>balance</structfield></entry> | |
585 | <entry><constant>V4L2_CID_AUDIO_BALANCE</constant></entry> | |
586 | </row> | |
587 | </tbody> | |
588 | </tgroup> | |
589 | </informaltable></para> | |
590 | ||
591 | <para>To determine which of these controls are supported by a | |
592 | driver V4L provides the <structfield>flags</structfield> | |
593 | <constant>VIDEO_AUDIO_VOLUME</constant>, | |
594 | <constant>VIDEO_AUDIO_BASS</constant>, | |
595 | <constant>VIDEO_AUDIO_TREBLE</constant> and | |
596 | <constant>VIDEO_AUDIO_BALANCE</constant>. In the V4L2 API the | |
597 | &VIDIOC-QUERYCTRL; ioctl reports if the respective control is | |
598 | supported. Accordingly the <constant>VIDEO_AUDIO_MUTABLE</constant> | |
599 | and <constant>VIDEO_AUDIO_MUTE</constant> flags where replaced by the | |
600 | boolean <constant>V4L2_CID_AUDIO_MUTE</constant> control.</para> | |
601 | ||
602 | <para>All V4L2 controls have a <structfield>step</structfield> | |
603 | attribute replacing the struct <structname>video_audio</structname> | |
604 | <structfield>step</structfield> field. The V4L audio controls are | |
605 | assumed to range from 0 to 65535 with no particular reset value. The | |
606 | V4L2 API permits arbitrary limits and defaults which can be queried | |
607 | with the &VIDIOC-QUERYCTRL; ioctl. For general information about | |
608 | controls see <xref linkend="control" />.</para> | |
609 | </section> | |
610 | ||
611 | <section> | |
612 | <title>Frame Buffer Overlay</title> | |
613 | ||
614 | <para>The V4L2 ioctls equivalent to | |
615 | <constant>VIDIOCGFBUF</constant> and <constant>VIDIOCSFBUF</constant> | |
616 | are &VIDIOC-G-FBUF; and &VIDIOC-S-FBUF;. The | |
617 | <structfield>base</structfield> field of struct | |
618 | <structname>video_buffer</structname> remained unchanged, except V4L2 | |
619 | defines a flag to indicate non-destructive overlays instead of a | |
620 | <constant>NULL</constant> pointer. All other fields moved into the | |
621 | &v4l2-pix-format; <structfield>fmt</structfield> substructure of | |
622 | &v4l2-framebuffer;. The <structfield>depth</structfield> field was | |
623 | replaced by <structfield>pixelformat</structfield>. See <xref | |
624 | linkend="pixfmt-rgb" /> for a list of RGB formats and their | |
625 | respective color depths.</para> | |
626 | ||
627 | <para>Instead of the special ioctls | |
628 | <constant>VIDIOCGWIN</constant> and <constant>VIDIOCSWIN</constant> | |
629 | V4L2 uses the general-purpose data format negotiation ioctls | |
630 | &VIDIOC-G-FMT; and &VIDIOC-S-FMT;. They take a pointer to a | |
631 | &v4l2-format; as argument. Here the <structfield>win</structfield> | |
632 | member of the <structfield>fmt</structfield> union is used, a | |
633 | &v4l2-window;.</para> | |
634 | ||
635 | <para>The <structfield>x</structfield>, | |
636 | <structfield>y</structfield>, <structfield>width</structfield> and | |
637 | <structfield>height</structfield> fields of struct | |
638 | <structname>video_window</structname> moved into &v4l2-rect; | |
639 | substructure <structfield>w</structfield> of struct | |
640 | <structname>v4l2_window</structname>. The | |
641 | <structfield>chromakey</structfield>, | |
642 | <structfield>clips</structfield>, and | |
643 | <structfield>clipcount</structfield> fields remained unchanged. Struct | |
644 | <structname>video_clip</structname> was renamed to &v4l2-clip;, also | |
645 | containing a struct <structname>v4l2_rect</structname>, but the | |
646 | semantics are still the same.</para> | |
647 | ||
648 | <para>The <constant>VIDEO_WINDOW_INTERLACE</constant> flag was | |
649 | dropped. Instead applications must set the | |
650 | <structfield>field</structfield> field to | |
651 | <constant>V4L2_FIELD_ANY</constant> or | |
652 | <constant>V4L2_FIELD_INTERLACED</constant>. The | |
653 | <constant>VIDEO_WINDOW_CHROMAKEY</constant> flag moved into | |
654 | &v4l2-framebuffer;, under the new name | |
655 | <constant>V4L2_FBUF_FLAG_CHROMAKEY</constant>.</para> | |
656 | ||
657 | <para>In V4L, storing a bitmap pointer in | |
658 | <structfield>clips</structfield> and setting | |
659 | <structfield>clipcount</structfield> to | |
660 | <constant>VIDEO_CLIP_BITMAP</constant> (-1) requests bitmap | |
661 | clipping, using a fixed size bitmap of 1024 × 625 bits. Struct | |
662 | <structname>v4l2_window</structname> has a separate | |
663 | <structfield>bitmap</structfield> pointer field for this purpose and | |
664 | the bitmap size is determined by <structfield>w.width</structfield> and | |
665 | <structfield>w.height</structfield>.</para> | |
666 | ||
667 | <para>The <constant>VIDIOCCAPTURE</constant> ioctl to enable or | |
668 | disable overlay was renamed to &VIDIOC-OVERLAY;.</para> | |
669 | </section> | |
670 | ||
671 | <section> | |
672 | <title>Cropping</title> | |
673 | ||
674 | <para>To capture only a subsection of the full picture V4L | |
675 | defines the <constant>VIDIOCGCAPTURE</constant> and | |
676 | <constant>VIDIOCSCAPTURE</constant> ioctls using struct | |
677 | <structname>video_capture</structname>. The equivalent V4L2 ioctls are | |
678 | &VIDIOC-G-CROP; and &VIDIOC-S-CROP; using &v4l2-crop;, and the related | |
679 | &VIDIOC-CROPCAP; ioctl. This is a rather complex matter, see | |
680 | <xref linkend="crop" /> for details.</para> | |
681 | ||
682 | <para>The <structfield>x</structfield>, | |
683 | <structfield>y</structfield>, <structfield>width</structfield> and | |
684 | <structfield>height</structfield> fields moved into &v4l2-rect; | |
685 | substructure <structfield>c</structfield> of struct | |
686 | <structname>v4l2_crop</structname>. The | |
687 | <structfield>decimation</structfield> field was dropped. In the V4L2 | |
688 | API the scaling factor is implied by the size of the cropping | |
689 | rectangle and the size of the captured or overlaid image.</para> | |
690 | ||
691 | <para>The <constant>VIDEO_CAPTURE_ODD</constant> | |
692 | and <constant>VIDEO_CAPTURE_EVEN</constant> flags to capture only the | |
693 | odd or even field, respectively, were replaced by | |
694 | <constant>V4L2_FIELD_TOP</constant> and | |
695 | <constant>V4L2_FIELD_BOTTOM</constant> in the field named | |
696 | <structfield>field</structfield> of &v4l2-pix-format; and | |
697 | &v4l2-window;. These structures are used to select a capture or | |
698 | overlay format with the &VIDIOC-S-FMT; ioctl.</para> | |
699 | </section> | |
700 | ||
701 | <section> | |
702 | <title>Reading Images, Memory Mapping</title> | |
703 | ||
704 | <section> | |
705 | <title>Capturing using the read method</title> | |
706 | ||
707 | <para>There is no essential difference between reading images | |
708 | from a V4L or V4L2 device using the &func-read; function, however V4L2 | |
709 | drivers are not required to support this I/O method. Applications can | |
710 | determine if the function is available with the &VIDIOC-QUERYCAP; | |
711 | ioctl. All V4L2 devices exchanging data with applications must support | |
712 | the &func-select; and &func-poll; functions.</para> | |
713 | ||
714 | <para>To select an image format and size, V4L provides the | |
715 | <constant>VIDIOCSPICT</constant> and <constant>VIDIOCSWIN</constant> | |
716 | ioctls. V4L2 uses the general-purpose data format negotiation ioctls | |
717 | &VIDIOC-G-FMT; and &VIDIOC-S-FMT;. They take a pointer to a | |
718 | &v4l2-format; as argument, here the &v4l2-pix-format; named | |
719 | <structfield>pix</structfield> of its <structfield>fmt</structfield> | |
720 | union is used.</para> | |
721 | ||
722 | <para>For more information about the V4L2 read interface see | |
723 | <xref linkend="rw" />.</para> | |
724 | </section> | |
725 | <section> | |
726 | <title>Capturing using memory mapping</title> | |
727 | ||
728 | <para>Applications can read from V4L devices by mapping | |
729 | buffers in device memory, or more often just buffers allocated in | |
730 | DMA-able system memory, into their address space. This avoids the data | |
731 | copying overhead of the read method. V4L2 supports memory mapping as | |
732 | well, with a few differences.</para> | |
733 | ||
734 | <informaltable> | |
735 | <tgroup cols="2"> | |
736 | <thead> | |
737 | <row> | |
738 | <entry>V4L</entry> | |
739 | <entry>V4L2</entry> | |
740 | </row> | |
741 | </thead> | |
742 | <tbody valign="top"> | |
743 | <row> | |
744 | <entry></entry> | |
745 | <entry>The image format must be selected before | |
746 | buffers are allocated, with the &VIDIOC-S-FMT; ioctl. When no format | |
747 | is selected the driver may use the last, possibly by another | |
748 | application requested format.</entry> | |
749 | </row> | |
750 | <row> | |
751 | <entry><para>Applications cannot change the number of | |
752 | buffers. The it is built into the driver, unless it has a module | |
753 | option to change the number when the driver module is | |
754 | loaded.</para></entry> | |
755 | <entry><para>The &VIDIOC-REQBUFS; ioctl allocates the | |
756 | desired number of buffers, this is a required step in the initialization | |
757 | sequence.</para></entry> | |
758 | </row> | |
759 | <row> | |
760 | <entry><para>Drivers map all buffers as one contiguous | |
761 | range of memory. The <constant>VIDIOCGMBUF</constant> ioctl is | |
762 | available to query the number of buffers, the offset of each buffer | |
763 | from the start of the virtual file, and the overall amount of memory | |
764 | used, which can be used as arguments for the &func-mmap; | |
765 | function.</para></entry> | |
766 | <entry><para>Buffers are individually mapped. The | |
767 | offset and size of each buffer can be determined with the | |
768 | &VIDIOC-QUERYBUF; ioctl.</para></entry> | |
769 | </row> | |
770 | <row> | |
771 | <entry><para>The <constant>VIDIOCMCAPTURE</constant> | |
772 | ioctl prepares a buffer for capturing. It also determines the image | |
773 | format for this buffer. The ioctl returns immediately, eventually with | |
774 | an &EAGAIN; if no video signal had been detected. When the driver | |
775 | supports more than one buffer applications can call the ioctl multiple | |
776 | times and thus have multiple outstanding capture | |
777 | requests.</para><para>The <constant>VIDIOCSYNC</constant> ioctl | |
778 | suspends execution until a particular buffer has been | |
779 | filled.</para></entry> | |
780 | <entry><para>Drivers maintain an incoming and outgoing | |
781 | queue. &VIDIOC-QBUF; enqueues any empty buffer into the incoming | |
782 | queue. Filled buffers are dequeued from the outgoing queue with the | |
783 | &VIDIOC-DQBUF; ioctl. To wait until filled buffers become available this | |
784 | function, &func-select; or &func-poll; can be used. The | |
785 | &VIDIOC-STREAMON; ioctl must be called once after enqueuing one or | |
786 | more buffers to start capturing. Its counterpart | |
787 | &VIDIOC-STREAMOFF; stops capturing and dequeues all buffers from both | |
788 | queues. Applications can query the signal status, if known, with the | |
789 | &VIDIOC-ENUMINPUT; ioctl.</para></entry> | |
790 | </row> | |
791 | </tbody> | |
792 | </tgroup> | |
793 | </informaltable> | |
794 | ||
795 | <para>For a more in-depth discussion of memory mapping and | |
796 | examples, see <xref linkend="mmap" />.</para> | |
797 | </section> | |
798 | </section> | |
799 | ||
800 | <section> | |
801 | <title>Reading Raw VBI Data</title> | |
802 | ||
803 | <para>Originally the V4L API did not specify a raw VBI capture | |
804 | interface, only the device file <filename>/dev/vbi</filename> was | |
805 | reserved for this purpose. The only driver supporting this interface | |
806 | was the BTTV driver, de-facto defining the V4L VBI interface. Reading | |
807 | from the device yields a raw VBI image with the following | |
808 | parameters:<informaltable> | |
809 | <tgroup cols="2"> | |
810 | <thead> | |
811 | <row> | |
812 | <entry>&v4l2-vbi-format;</entry> | |
813 | <entry>V4L, BTTV driver</entry> | |
814 | </row> | |
815 | </thead> | |
816 | <tbody valign="top"> | |
817 | <row> | |
818 | <entry>sampling_rate</entry> | |
819 | <entry>28636363 Hz NTSC (or any other 525-line | |
820 | standard); 35468950 Hz PAL and SECAM (625-line standards)</entry> | |
821 | </row> | |
822 | <row> | |
823 | <entry>offset</entry> | |
824 | <entry>?</entry> | |
825 | </row> | |
826 | <row> | |
827 | <entry>samples_per_line</entry> | |
828 | <entry>2048</entry> | |
829 | </row> | |
830 | <row> | |
831 | <entry>sample_format</entry> | |
832 | <entry>V4L2_PIX_FMT_GREY. The last four bytes (a | |
833 | machine endianess integer) contain a frame counter.</entry> | |
834 | </row> | |
835 | <row> | |
836 | <entry>start[]</entry> | |
837 | <entry>10, 273 NTSC; 22, 335 PAL and SECAM</entry> | |
838 | </row> | |
839 | <row> | |
840 | <entry>count[]</entry> | |
841 | <entry><para>16, 16<footnote><para>Old driver | |
842 | versions used different values, eventually the custom | |
843 | <constant>BTTV_VBISIZE</constant> ioctl was added to query the | |
844 | correct values.</para></footnote></para></entry> | |
845 | </row> | |
846 | <row> | |
847 | <entry>flags</entry> | |
848 | <entry>0</entry> | |
849 | </row> | |
850 | </tbody> | |
851 | </tgroup> | |
852 | </informaltable></para> | |
853 | ||
854 | <para>Undocumented in the V4L specification, in Linux 2.3 the | |
855 | <constant>VIDIOCGVBIFMT</constant> and | |
856 | <constant>VIDIOCSVBIFMT</constant> ioctls using struct | |
857 | <structname>vbi_format</structname> were added to determine the VBI | |
858 | image parameters. These ioctls are only partially compatible with the | |
859 | V4L2 VBI interface specified in <xref linkend="raw-vbi" />.</para> | |
860 | ||
861 | <para>An <structfield>offset</structfield> field does not | |
862 | exist, <structfield>sample_format</structfield> is supposed to be | |
863 | <constant>VIDEO_PALETTE_RAW</constant>, equivalent to | |
864 | <constant>V4L2_PIX_FMT_GREY</constant>. The remaining fields are | |
865 | probably equivalent to &v4l2-vbi-format;.</para> | |
866 | ||
867 | <para>Apparently only the Zoran (ZR 36120) driver implements | |
868 | these ioctls. The semantics differ from those specified for V4L2 in two | |
869 | ways. The parameters are reset on &func-open; and | |
870 | <constant>VIDIOCSVBIFMT</constant> always returns an &EINVAL; if the | |
871 | parameters are invalid.</para> | |
872 | </section> | |
873 | ||
874 | <section> | |
875 | <title>Miscellaneous</title> | |
876 | ||
877 | <para>V4L2 has no equivalent of the | |
878 | <constant>VIDIOCGUNIT</constant> ioctl. Applications can find the VBI | |
879 | device associated with a video capture device (or vice versa) by | |
880 | reopening the device and requesting VBI data. For details see | |
881 | <xref linkend="open" />.</para> | |
882 | ||
883 | <para>No replacement exists for <constant>VIDIOCKEY</constant>, | |
884 | and the V4L functions for microcode programming. A new interface for | |
885 | MPEG compression and playback devices is documented in <xref | |
886 | linkend="extended-controls" />.</para> | |
887 | </section> | |
888 | ||
889 | </section> | |
890 | ||
891 | <section id="hist-v4l2"> | |
892 | <title>Changes of the V4L2 API</title> | |
893 | ||
894 | <para>Soon after the V4L API was added to the kernel it was | |
895 | criticised as too inflexible. In August 1998 Bill Dirks proposed a | |
896 | number of improvements and began to work on documentation, example | |
897 | drivers and applications. With the help of other volunteers this | |
898 | eventually became the V4L2 API, not just an extension but a | |
899 | replacement for the V4L API. However it took another four years and | |
900 | two stable kernel releases until the new API was finally accepted for | |
901 | inclusion into the kernel in its present form.</para> | |
902 | ||
903 | <section> | |
904 | <title>Early Versions</title> | |
905 | <para>1998-08-20: First version.</para> | |
906 | ||
907 | <para>1998-08-27: The &func-select; function was introduced.</para> | |
908 | ||
909 | <para>1998-09-10: New video standard interface.</para> | |
910 | ||
911 | <para>1998-09-18: The <constant>VIDIOC_NONCAP</constant> ioctl | |
912 | was replaced by the otherwise meaningless <constant>O_TRUNC</constant> | |
913 | &func-open; flag, and the aliases <constant>O_NONCAP</constant> and | |
914 | <constant>O_NOIO</constant> were defined. Applications can set this | |
915 | flag if they intend to access controls only, as opposed to capture | |
916 | applications which need exclusive access. The | |
917 | <constant>VIDEO_STD_XXX</constant> identifiers are now ordinals | |
918 | instead of flags, and the <function>video_std_construct()</function> | |
919 | helper function takes id and transmission arguments.</para> | |
920 | ||
921 | <para>1998-09-28: Revamped video standard. Made video controls | |
922 | individually enumerable.</para> | |
923 | ||
924 | <para>1998-10-02: The <structfield>id</structfield> field was | |
925 | removed from struct <structname>video_standard</structname> and the | |
926 | color subcarrier fields were renamed. The &VIDIOC-QUERYSTD; ioctl was | |
927 | renamed to &VIDIOC-ENUMSTD;, &VIDIOC-G-INPUT; to &VIDIOC-ENUMINPUT;. A | |
928 | first draft of the Codec API was released.</para> | |
929 | ||
930 | <para>1998-11-08: Many minor changes. Most symbols have been | |
931 | renamed. Some material changes to &v4l2-capability;.</para> | |
932 | ||
933 | <para>1998-11-12: The read/write directon of some ioctls was misdefined.</para> | |
934 | ||
935 | <para>1998-11-14: <constant>V4L2_PIX_FMT_RGB24</constant> | |
936 | changed to <constant>V4L2_PIX_FMT_BGR24</constant>, and | |
937 | <constant>V4L2_PIX_FMT_RGB32</constant> changed to | |
938 | <constant>V4L2_PIX_FMT_BGR32</constant>. Audio controls are now | |
939 | accessible with the &VIDIOC-G-CTRL; and &VIDIOC-S-CTRL; ioctls under | |
940 | names starting with <constant>V4L2_CID_AUDIO</constant>. The | |
941 | <constant>V4L2_MAJOR</constant> define was removed from | |
942 | <filename>videodev.h</filename> since it was only used once in the | |
943 | <filename>videodev</filename> kernel module. The | |
944 | <constant>YUV422</constant> and <constant>YUV411</constant> planar | |
945 | image formats were added.</para> | |
946 | ||
947 | <para>1998-11-28: A few ioctl symbols changed. Interfaces for codecs and | |
948 | video output devices were added.</para> | |
949 | ||
950 | <para>1999-01-14: A raw VBI capture interface was added.</para> | |
951 | ||
952 | <para>1999-01-19: The <constant>VIDIOC_NEXTBUF</constant> ioctl | |
953 | was removed.</para> | |
954 | </section> | |
955 | ||
956 | <section> | |
957 | <title>V4L2 Version 0.16 1999-01-31</title> | |
958 | <para>1999-01-27: There is now one QBUF ioctl, VIDIOC_QWBUF and VIDIOC_QRBUF | |
959 | are gone. VIDIOC_QBUF takes a v4l2_buffer as a parameter. Added | |
960 | digital zoom (cropping) controls.</para> | |
961 | </section> | |
962 | ||
963 | <!-- Where's 0.17? mhs couldn't find that videodev.h, perhaps Bill | |
964 | forgot to bump the version number or never released it. --> | |
965 | ||
966 | <section> | |
967 | <title>V4L2 Version 0.18 1999-03-16</title> | |
968 | <para>Added a v4l to V4L2 ioctl compatibility layer to | |
969 | videodev.c. Driver writers, this changes how you implement your ioctl | |
970 | handler. See the Driver Writer's Guide. Added some more control id | |
971 | codes.</para> | |
972 | </section> | |
973 | ||
974 | <section> | |
975 | <title>V4L2 Version 0.19 1999-06-05</title> | |
976 | <para>1999-03-18: Fill in the category and catname fields of | |
977 | v4l2_queryctrl objects before passing them to the driver. Required a | |
978 | minor change to the VIDIOC_QUERYCTRL handlers in the sample | |
979 | drivers.</para> | |
980 | <para>1999-03-31: Better compatibility for v4l memory capture | |
981 | ioctls. Requires changes to drivers to fully support new compatibility | |
982 | features, see Driver Writer's Guide and v4l2cap.c. Added new control | |
983 | IDs: V4L2_CID_HFLIP, _VFLIP. Changed V4L2_PIX_FMT_YUV422P to _YUV422P, | |
984 | and _YUV411P to _YUV411P.</para> | |
985 | <para>1999-04-04: Added a few more control IDs.</para> | |
986 | <para>1999-04-07: Added the button control type.</para> | |
987 | <para>1999-05-02: Fixed a typo in videodev.h, and added the | |
988 | V4L2_CTRL_FLAG_GRAYED (later V4L2_CTRL_FLAG_GRABBED) flag.</para> | |
989 | <para>1999-05-20: Definition of VIDIOC_G_CTRL was wrong causing | |
990 | a malfunction of this ioctl.</para> | |
991 | <para>1999-06-05: Changed the value of | |
992 | V4L2_CID_WHITENESS.</para> | |
993 | </section> | |
994 | ||
995 | <section> | |
996 | <title>V4L2 Version 0.20 (1999-09-10)</title> | |
997 | ||
998 | <para>Version 0.20 introduced a number of changes which were | |
999 | <emphasis>not backward compatible</emphasis> with 0.19 and earlier | |
1000 | versions. Purpose of these changes was to simplify the API, while | |
1001 | making it more extensible and following common Linux driver API | |
1002 | conventions.</para> | |
1003 | ||
1004 | <orderedlist> | |
1005 | <listitem> | |
1006 | <para>Some typos in <constant>V4L2_FMT_FLAG</constant> | |
1007 | symbols were fixed. &v4l2-clip; was changed for compatibility with | |
1008 | v4l. (1999-08-30)</para> | |
1009 | </listitem> | |
1010 | ||
1011 | <listitem> | |
1012 | <para><constant>V4L2_TUNER_SUB_LANG1</constant> was added. | |
1013 | (1999-09-05)</para> | |
1014 | </listitem> | |
1015 | ||
1016 | <listitem> | |
1017 | <para>All ioctl() commands that used an integer argument now | |
1018 | take a pointer to an integer. Where it makes sense, ioctls will return | |
1019 | the actual new value in the integer pointed to by the argument, a | |
1020 | common convention in the V4L2 API. The affected ioctls are: | |
1021 | VIDIOC_PREVIEW, VIDIOC_STREAMON, VIDIOC_STREAMOFF, VIDIOC_S_FREQ, | |
1022 | VIDIOC_S_INPUT, VIDIOC_S_OUTPUT, VIDIOC_S_EFFECT. For example | |
1023 | <programlisting> | |
1024 | err = ioctl (fd, VIDIOC_XXX, V4L2_XXX); | |
1025 | </programlisting> becomes <programlisting> | |
1026 | int a = V4L2_XXX; err = ioctl(fd, VIDIOC_XXX, &a); | |
1027 | </programlisting> | |
1028 | </para> | |
1029 | </listitem> | |
1030 | ||
1031 | <listitem> | |
1032 | <para>All the different get- and set-format commands were | |
1033 | swept into one &VIDIOC-G-FMT; and &VIDIOC-S-FMT; ioctl taking a union | |
1034 | and a type field selecting the union member as parameter. Purpose is to | |
1035 | simplify the API by eliminating several ioctls and to allow new and | |
1036 | driver private data streams without adding new ioctls.</para> | |
1037 | ||
1038 | <para>This change obsoletes the following ioctls: | |
1039 | <constant>VIDIOC_S_INFMT</constant>, | |
1040 | <constant>VIDIOC_G_INFMT</constant>, | |
1041 | <constant>VIDIOC_S_OUTFMT</constant>, | |
1042 | <constant>VIDIOC_G_OUTFMT</constant>, | |
1043 | <constant>VIDIOC_S_VBIFMT</constant> and | |
1044 | <constant>VIDIOC_G_VBIFMT</constant>. The image format structure | |
1045 | <structname>v4l2_format</structname> was renamed to &v4l2-pix-format;, | |
1046 | while &v4l2-format; is now the envelopping structure for all format | |
1047 | negotiations.</para> | |
1048 | </listitem> | |
1049 | ||
1050 | <listitem> | |
1051 | <para>Similar to the changes above, the | |
1052 | <constant>VIDIOC_G_PARM</constant> and | |
1053 | <constant>VIDIOC_S_PARM</constant> ioctls were merged with | |
1054 | <constant>VIDIOC_G_OUTPARM</constant> and | |
1055 | <constant>VIDIOC_S_OUTPARM</constant>. A | |
1056 | <structfield>type</structfield> field in the new &v4l2-streamparm; | |
1057 | selects the respective union member.</para> | |
1058 | ||
1059 | <para>This change obsoletes the | |
1060 | <constant>VIDIOC_G_OUTPARM</constant> and | |
1061 | <constant>VIDIOC_S_OUTPARM</constant> ioctls.</para> | |
1062 | </listitem> | |
1063 | ||
1064 | <listitem> | |
1065 | <para>Control enumeration was simplified, and two new | |
1066 | control flags were introduced and one dropped. The | |
1067 | <structfield>catname</structfield> field was replaced by a | |
1068 | <structfield>group</structfield> field.</para> | |
1069 | ||
1070 | <para>Drivers can now flag unsupported and temporarily | |
1071 | unavailable controls with <constant>V4L2_CTRL_FLAG_DISABLED</constant> | |
1072 | and <constant>V4L2_CTRL_FLAG_GRABBED</constant> respectively. The | |
1073 | <structfield>group</structfield> name indicates a possibly narrower | |
1074 | classification than the <structfield>category</structfield>. In other | |
1075 | words, there may be multiple groups within a category. Controls within | |
1076 | a group would typically be drawn within a group box. Controls in | |
1077 | different categories might have a greater separation, or may even | |
1078 | appear in separate windows.</para> | |
1079 | </listitem> | |
1080 | ||
1081 | <listitem> | |
1082 | <para>The &v4l2-buffer; <structfield>timestamp</structfield> | |
1083 | was changed to a 64 bit integer, containing the sampling or output | |
1084 | time of the frame in nanoseconds. Additionally timestamps will be in | |
1085 | absolute system time, not starting from zero at the beginning of a | |
1086 | stream. The data type name for timestamps is stamp_t, defined as a | |
1087 | signed 64-bit integer. Output devices should not send a buffer out | |
1088 | until the time in the timestamp field has arrived. I would like to | |
1089 | follow SGI's lead, and adopt a multimedia timestamping system like | |
1090 | their UST (Unadjusted System Time). See | |
0ea6e611 JM |
1091 | http://web.archive.org/web/*/http://reality.sgi.com |
1092 | /cpirazzi_engr/lg/time/intro.html. | |
1093 | UST uses timestamps that are 64-bit signed integers | |
8e080c2e MCC |
1094 | (not struct timeval's) and given in nanosecond units. The UST clock |
1095 | starts at zero when the system is booted and runs continuously and | |
1096 | uniformly. It takes a little over 292 years for UST to overflow. There | |
1097 | is no way to set the UST clock. The regular Linux time-of-day clock | |
1098 | can be changed periodically, which would cause errors if it were being | |
1099 | used for timestamping a multimedia stream. A real UST style clock will | |
1100 | require some support in the kernel that is not there yet. But in | |
1101 | anticipation, I will change the timestamp field to a 64-bit integer, | |
1102 | and I will change the v4l2_masterclock_gettime() function (used only | |
1103 | by drivers) to return a 64-bit integer.</para> | |
1104 | </listitem> | |
1105 | ||
1106 | <listitem> | |
1107 | <para>A <structfield>sequence</structfield> field was added | |
1108 | to &v4l2-buffer;. The <structfield>sequence</structfield> field counts | |
1109 | captured frames, it is ignored by output devices. When a capture | |
1110 | driver drops a frame, the sequence number of that frame is | |
1111 | skipped.</para> | |
1112 | </listitem> | |
1113 | </orderedlist> | |
1114 | </section> | |
1115 | ||
1116 | <section> | |
1117 | <title>V4L2 Version 0.20 incremental changes</title> | |
1118 | <!-- Version number didn't change anymore, reason unknown. --> | |
1119 | ||
1120 | <para>1999-12-23: In &v4l2-vbi-format; the | |
1121 | <structfield>reserved1</structfield> field became | |
1122 | <structfield>offset</structfield>. Previously drivers were required to | |
1123 | clear the <structfield>reserved1</structfield> field.</para> | |
1124 | ||
1125 | <para>2000-01-13: The | |
1126 | <constant>V4L2_FMT_FLAG_NOT_INTERLACED</constant> flag was added.</para> | |
1127 | ||
1128 | <para>2000-07-31: The <filename>linux/poll.h</filename> header | |
1129 | is now included by <filename>videodev.h</filename> for compatibility | |
1130 | with the original <filename>videodev.h</filename> file.</para> | |
1131 | ||
1132 | <para>2000-11-20: <constant>V4L2_TYPE_VBI_OUTPUT</constant> and | |
1133 | <constant>V4L2_PIX_FMT_Y41P</constant> were added.</para> | |
1134 | ||
1135 | <para>2000-11-25: <constant>V4L2_TYPE_VBI_INPUT</constant> was | |
1136 | added.</para> | |
1137 | ||
1138 | <para>2000-12-04: A couple typos in symbol names were fixed.</para> | |
1139 | ||
1140 | <para>2001-01-18: To avoid namespace conflicts the | |
1141 | <constant>fourcc</constant> macro defined in the | |
1142 | <filename>videodev.h</filename> header file was renamed to | |
1143 | <constant>v4l2_fourcc</constant>.</para> | |
1144 | ||
1145 | <para>2001-01-25: A possible driver-level compatibility problem | |
1146 | between the <filename>videodev.h</filename> file in Linux 2.4.0 and | |
1147 | the <filename>videodev.h</filename> file included in the | |
1148 | <filename>videodevX</filename> patch was fixed. Users of an earlier | |
1149 | version of <filename>videodevX</filename> on Linux 2.4.0 should | |
1150 | recompile their V4L and V4L2 drivers.</para> | |
1151 | ||
1152 | <para>2001-01-26: A possible kernel-level incompatibility | |
1153 | between the <filename>videodev.h</filename> file in the | |
1154 | <filename>videodevX</filename> patch and the | |
1155 | <filename>videodev.h</filename> file in Linux 2.2.x with devfs patches | |
1156 | applied was fixed.</para> | |
1157 | ||
1158 | <para>2001-03-02: Certain V4L ioctls which pass data in both | |
1159 | direction although they are defined with read-only parameter, did not | |
1160 | work correctly through the backward compatibility layer. | |
1161 | [Solution?]</para> | |
1162 | ||
1163 | <para>2001-04-13: Big endian 16-bit RGB formats were added.</para> | |
1164 | ||
1165 | <para>2001-09-17: New YUV formats and the &VIDIOC-G-FREQUENCY; and | |
1166 | &VIDIOC-S-FREQUENCY; ioctls were added. (The old | |
1167 | <constant>VIDIOC_G_FREQ</constant> and | |
1168 | <constant>VIDIOC_S_FREQ</constant> ioctls did not take multiple tuners | |
1169 | into account.)</para> | |
1170 | ||
1171 | <para>2000-09-18: <constant>V4L2_BUF_TYPE_VBI</constant> was | |
1172 | added. This may <emphasis>break compatibility</emphasis> as the | |
1173 | &VIDIOC-G-FMT; and &VIDIOC-S-FMT; ioctls may fail now if the struct | |
1174 | <structname>v4l2_fmt</structname> <structfield>type</structfield> | |
1175 | field does not contain <constant>V4L2_BUF_TYPE_VBI</constant>. In the | |
1176 | documentation of the &v4l2-vbi-format; | |
1177 | <structfield>offset</structfield> field the ambiguous phrase "rising | |
1178 | edge" was changed to "leading edge".</para> | |
1179 | </section> | |
1180 | ||
1181 | <section> | |
1182 | <title>V4L2 Version 0.20 2000-11-23</title> | |
1183 | ||
1184 | <para>A number of changes were made to the raw VBI | |
1185 | interface.</para> | |
1186 | ||
1187 | <orderedlist> | |
1188 | <listitem> | |
1189 | <para>Figures clarifying the line numbering scheme were | |
1190 | added to the V4L2 API specification. The | |
1191 | <structfield>start</structfield>[0] and | |
1192 | <structfield>start</structfield>[1] fields no longer count line | |
1193 | numbers beginning at zero. Rationale: a) The previous definition was | |
1194 | unclear. b) The <structfield>start</structfield>[] values are ordinal | |
1195 | numbers. c) There is no point in inventing a new line numbering | |
1196 | scheme. We now use line number as defined by ITU-R, period. | |
1197 | Compatibility: Add one to the start values. Applications depending on | |
1198 | the previous semantics may not function correctly.</para> | |
1199 | </listitem> | |
1200 | ||
1201 | <listitem> | |
1202 | <para>The restriction "count[0] > 0 and count[1] > 0" | |
1203 | has been relaxed to "(count[0] + count[1]) > 0". Rationale: | |
1204 | Drivers may allocate resources at scan line granularity and some data | |
1205 | services are transmitted only on the first field. The comment that | |
1206 | both <structfield>count</structfield> values will usually be equal is | |
1207 | misleading and pointless and has been removed. This change | |
1208 | <emphasis>breaks compatibility</emphasis> with earlier versions: | |
1209 | Drivers may return EINVAL, applications may not function | |
1210 | correctly.</para> | |
1211 | </listitem> | |
1212 | ||
1213 | <listitem> | |
1214 | <para>Drivers are again permitted to return negative | |
1215 | (unknown) start values as proposed earlier. Why this feature was | |
1216 | dropped is unclear. This change may <emphasis>break | |
1217 | compatibility</emphasis> with applications depending on the start | |
1218 | values being positive. The use of <constant>EBUSY</constant> and | |
1219 | <constant>EINVAL</constant> error codes with the &VIDIOC-S-FMT; ioctl | |
1220 | was clarified. The &EBUSY; was finally documented, and the | |
1221 | <structfield>reserved2</structfield> field which was previously | |
1222 | mentioned only in the <filename>videodev.h</filename> header | |
1223 | file.</para> | |
1224 | </listitem> | |
1225 | ||
1226 | <listitem> | |
1227 | <para>New buffer types | |
1228 | <constant>V4L2_TYPE_VBI_INPUT</constant> and | |
1229 | <constant>V4L2_TYPE_VBI_OUTPUT</constant> were added. The former is an | |
1230 | alias for the old <constant>V4L2_TYPE_VBI</constant>, the latter was | |
1231 | missing in the <filename>videodev.h</filename> file.</para> | |
1232 | </listitem> | |
1233 | </orderedlist> | |
1234 | </section> | |
1235 | ||
1236 | <section> | |
1237 | <title>V4L2 Version 0.20 2002-07-25</title> | |
1238 | <para>Added sliced VBI interface proposal.</para> | |
1239 | </section> | |
1240 | ||
1241 | <section> | |
1242 | <title>V4L2 in Linux 2.5.46, 2002-10</title> | |
1243 | ||
1244 | <para>Around October-November 2002, prior to an announced | |
1245 | feature freeze of Linux 2.5, the API was revised, drawing from | |
1246 | experience with V4L2 0.20. This unnamed version was finally merged | |
1247 | into Linux 2.5.46.</para> | |
1248 | ||
1249 | <orderedlist> | |
1250 | <listitem> | |
1251 | <para>As specified in <xref linkend="related" />, drivers | |
1252 | must make related device functions available under all minor device | |
1253 | numbers.</para> | |
1254 | </listitem> | |
1255 | ||
1256 | <listitem> | |
1257 | <para>The &func-open; function requires access mode | |
1258 | <constant>O_RDWR</constant> regardless of the device type. All V4L2 | |
1259 | drivers exchanging data with applications must support the | |
1260 | <constant>O_NONBLOCK</constant> flag. The <constant>O_NOIO</constant> | |
1261 | flag, a V4L2 symbol which aliased the meaningless | |
1262 | <constant>O_TRUNC</constant> to indicate accesses without data | |
1263 | exchange (panel applications) was dropped. Drivers must stay in "panel | |
1264 | mode" until the application attempts to initiate a data exchange, see | |
1265 | <xref linkend="open" />.</para> | |
1266 | </listitem> | |
1267 | ||
1268 | <listitem> | |
1269 | <para>The &v4l2-capability; changed dramatically. Note that | |
1270 | also the size of the structure changed, which is encoded in the ioctl | |
1271 | request code, thus older V4L2 devices will respond with an &EINVAL; to | |
1272 | the new &VIDIOC-QUERYCAP; ioctl.</para> | |
1273 | ||
1274 | <para>There are new fields to identify the driver, a new RDS | |
1275 | device function <constant>V4L2_CAP_RDS_CAPTURE</constant>, the | |
1276 | <constant>V4L2_CAP_AUDIO</constant> flag indicates if the device has | |
1277 | any audio connectors, another I/O capability | |
1278 | <constant>V4L2_CAP_ASYNCIO</constant> can be flagged. In response to | |
1279 | these changes the <structfield>type</structfield> field became a bit | |
1280 | set and was merged into the <structfield>flags</structfield> field. | |
1281 | <constant>V4L2_FLAG_TUNER</constant> was renamed to | |
1282 | <constant>V4L2_CAP_TUNER</constant>, | |
1283 | <constant>V4L2_CAP_VIDEO_OVERLAY</constant> replaced | |
1284 | <constant>V4L2_FLAG_PREVIEW</constant> and | |
1285 | <constant>V4L2_CAP_VBI_CAPTURE</constant> and | |
1286 | <constant>V4L2_CAP_VBI_OUTPUT</constant> replaced | |
1287 | <constant>V4L2_FLAG_DATA_SERVICE</constant>. | |
1288 | <constant>V4L2_FLAG_READ</constant> and | |
1289 | <constant>V4L2_FLAG_WRITE</constant> were merged into | |
1290 | <constant>V4L2_CAP_READWRITE</constant>.</para> | |
1291 | ||
1292 | <para>The redundant fields | |
1293 | <structfield>inputs</structfield>, <structfield>outputs</structfield> | |
1294 | and <structfield>audios</structfield> were removed. These properties | |
1295 | can be determined as described in <xref linkend="video" /> and <xref | |
1296 | linkend="audio" />.</para> | |
1297 | ||
1298 | <para>The somewhat volatile and therefore barely useful | |
1299 | fields <structfield>maxwidth</structfield>, | |
1300 | <structfield>maxheight</structfield>, | |
1301 | <structfield>minwidth</structfield>, | |
1302 | <structfield>minheight</structfield>, | |
1303 | <structfield>maxframerate</structfield> were removed. This information | |
1304 | is available as described in <xref linkend="format" /> and | |
1305 | <xref linkend="standard" />.</para> | |
1306 | ||
1307 | <para><constant>V4L2_FLAG_SELECT</constant> was removed. We | |
1308 | believe the select() function is important enough to require support | |
1309 | of it in all V4L2 drivers exchanging data with applications. The | |
1310 | redundant <constant>V4L2_FLAG_MONOCHROME</constant> flag was removed, | |
1311 | this information is available as described in <xref | |
1312 | linkend="format" />.</para> | |
1313 | </listitem> | |
1314 | ||
1315 | <listitem> | |
1316 | <para>In &v4l2-input; the | |
1317 | <structfield>assoc_audio</structfield> field and the | |
1318 | <structfield>capability</structfield> field and its only flag | |
1319 | <constant>V4L2_INPUT_CAP_AUDIO</constant> was replaced by the new | |
1320 | <structfield>audioset</structfield> field. Instead of linking one | |
1321 | video input to one audio input this field reports all audio inputs | |
1322 | this video input combines with.</para> | |
1323 | ||
1324 | <para>New fields are <structfield>tuner</structfield> | |
1325 | (reversing the former link from tuners to video inputs), | |
1326 | <structfield>std</structfield> and | |
1327 | <structfield>status</structfield>.</para> | |
1328 | ||
1329 | <para>Accordingly &v4l2-output; lost its | |
1330 | <structfield>capability</structfield> and | |
1331 | <structfield>assoc_audio</structfield> fields. | |
1332 | <structfield>audioset</structfield>, | |
1333 | <structfield>modulator</structfield> and | |
1334 | <structfield>std</structfield> where added instead.</para> | |
1335 | </listitem> | |
1336 | ||
1337 | <listitem> | |
1338 | <para>The &v4l2-audio; field | |
1339 | <structfield>audio</structfield> was renamed to | |
1340 | <structfield>index</structfield>, for consistency with other | |
1341 | structures. A new capability flag | |
1342 | <constant>V4L2_AUDCAP_STEREO</constant> was added to indicated if the | |
1343 | audio input in question supports stereo sound. | |
1344 | <constant>V4L2_AUDCAP_EFFECTS</constant> and the corresponding | |
1345 | <constant>V4L2_AUDMODE</constant> flags where removed. This can be | |
1346 | easily implemented using controls. (However the same applies to AVL | |
1347 | which is still there.)</para> | |
1348 | ||
1349 | <para>Again for consistency the &v4l2-audioout; field | |
1350 | <structfield>audio</structfield> was renamed to | |
1351 | <structfield>index</structfield>.</para> | |
1352 | </listitem> | |
1353 | ||
1354 | <listitem> | |
1355 | <para>The &v4l2-tuner; | |
1356 | <structfield>input</structfield> field was replaced by an | |
1357 | <structfield>index</structfield> field, permitting devices with | |
1358 | multiple tuners. The link between video inputs and tuners is now | |
1359 | reversed, inputs point to their tuner. The | |
1360 | <structfield>std</structfield> substructure became a | |
1361 | simple set (more about this below) and moved into &v4l2-input;. A | |
1362 | <structfield>type</structfield> field was added.</para> | |
1363 | ||
1364 | <para>Accordingly in &v4l2-modulator; the | |
1365 | <structfield>output</structfield> was replaced by an | |
1366 | <structfield>index</structfield> field.</para> | |
1367 | ||
1368 | <para>In &v4l2-frequency; the | |
1369 | <structfield>port</structfield> field was replaced by a | |
1370 | <structfield>tuner</structfield> field containing the respective tuner | |
1371 | or modulator index number. A tuner <structfield>type</structfield> | |
1372 | field was added and the <structfield>reserved</structfield> field | |
1373 | became larger for future extensions (satellite tuners in | |
1374 | particular).</para> | |
1375 | </listitem> | |
1376 | ||
1377 | <listitem> | |
1378 | <para>The idea of completely transparent video standards was | |
1379 | dropped. Experience showed that applications must be able to work with | |
1380 | video standards beyond presenting the user a menu. Instead of | |
1381 | enumerating supported standards with an ioctl applications can now | |
1382 | refer to standards by &v4l2-std-id; and symbols defined in the | |
1383 | <filename>videodev2.h</filename> header file. For details see <xref | |
1384 | linkend="standard" />. The &VIDIOC-G-STD; and | |
1385 | &VIDIOC-S-STD; now take a pointer to this type as argument. | |
1386 | &VIDIOC-QUERYSTD; was added to autodetect the received standard, if | |
1387 | the hardware has this capability. In &v4l2-standard; an | |
1388 | <structfield>index</structfield> field was added for &VIDIOC-ENUMSTD;. | |
1389 | A &v4l2-std-id; field named <structfield>id</structfield> was added as | |
1390 | machine readable identifier, also replacing the | |
1391 | <structfield>transmission</structfield> field. The misleading | |
1392 | <structfield>framerate</structfield> field was renamed | |
1393 | to <structfield>frameperiod</structfield>. The now obsolete | |
1394 | <structfield>colorstandard</structfield> information, originally | |
1395 | needed to distguish between variations of standards, were | |
1396 | removed.</para> | |
1397 | ||
1398 | <para>Struct <structname>v4l2_enumstd</structname> ceased to | |
1399 | be. &VIDIOC-ENUMSTD; now takes a pointer to a &v4l2-standard; | |
1400 | directly. The information which standards are supported by a | |
1401 | particular video input or output moved into &v4l2-input; and | |
1402 | &v4l2-output; fields named <structfield>std</structfield>, | |
1403 | respectively.</para> | |
1404 | </listitem> | |
1405 | ||
1406 | <listitem> | |
1407 | <para>The &v4l2-queryctrl; fields | |
1408 | <structfield>category</structfield> and | |
1409 | <structfield>group</structfield> did not catch on and/or were not | |
1410 | implemented as expected and therefore removed.</para> | |
1411 | </listitem> | |
1412 | ||
1413 | <listitem> | |
1414 | <para>The &VIDIOC-TRY-FMT; ioctl was added to negotiate data | |
1415 | formats as with &VIDIOC-S-FMT;, but without the overhead of | |
1416 | programming the hardware and regardless of I/O in progress.</para> | |
1417 | ||
1418 | <para>In &v4l2-format; the <structfield>fmt</structfield> | |
1419 | union was extended to contain &v4l2-window;. All image format | |
1420 | negotiations are now possible with <constant>VIDIOC_G_FMT</constant>, | |
1421 | <constant>VIDIOC_S_FMT</constant> and | |
1422 | <constant>VIDIOC_TRY_FMT</constant>; ioctl. The | |
1423 | <constant>VIDIOC_G_WIN</constant> and | |
1424 | <constant>VIDIOC_S_WIN</constant> ioctls to prepare for a video | |
1425 | overlay were removed. The <structfield>type</structfield> field | |
1426 | changed to type &v4l2-buf-type; and the buffer type names changed as | |
1427 | follows.<informaltable> | |
1428 | <tgroup cols="2"> | |
1429 | <thead> | |
1430 | <row> | |
1431 | <entry>Old defines</entry> | |
1432 | <entry>&v4l2-buf-type;</entry> | |
1433 | </row> | |
1434 | </thead> | |
1435 | <tbody valign="top"> | |
1436 | <row> | |
1437 | <entry><constant>V4L2_BUF_TYPE_CAPTURE</constant></entry> | |
1438 | <entry><constant>V4L2_BUF_TYPE_VIDEO_CAPTURE</constant></entry> | |
1439 | </row> | |
1440 | <row> | |
1441 | <entry><constant>V4L2_BUF_TYPE_CODECIN</constant></entry> | |
1442 | <entry>Omitted for now</entry> | |
1443 | </row> | |
1444 | <row> | |
1445 | <entry><constant>V4L2_BUF_TYPE_CODECOUT</constant></entry> | |
1446 | <entry>Omitted for now</entry> | |
1447 | </row> | |
1448 | <row> | |
1449 | <entry><constant>V4L2_BUF_TYPE_EFFECTSIN</constant></entry> | |
1450 | <entry>Omitted for now</entry> | |
1451 | </row> | |
1452 | <row> | |
1453 | <entry><constant>V4L2_BUF_TYPE_EFFECTSIN2</constant></entry> | |
1454 | <entry>Omitted for now</entry> | |
1455 | </row> | |
1456 | <row> | |
1457 | <entry><constant>V4L2_BUF_TYPE_EFFECTSOUT</constant></entry> | |
1458 | <entry>Omitted for now</entry> | |
1459 | </row> | |
1460 | <row> | |
1461 | <entry><constant>V4L2_BUF_TYPE_VIDEOOUT</constant></entry> | |
1462 | <entry><constant>V4L2_BUF_TYPE_VIDEO_OUTPUT</constant></entry> | |
1463 | </row> | |
1464 | <row> | |
1465 | <entry><constant>-</constant></entry> | |
1466 | <entry><constant>V4L2_BUF_TYPE_VIDEO_OVERLAY</constant></entry> | |
1467 | </row> | |
1468 | <row> | |
1469 | <entry><constant>-</constant></entry> | |
1470 | <entry><constant>V4L2_BUF_TYPE_VBI_CAPTURE</constant></entry> | |
1471 | </row> | |
1472 | <row> | |
1473 | <entry><constant>-</constant></entry> | |
1474 | <entry><constant>V4L2_BUF_TYPE_VBI_OUTPUT</constant></entry> | |
1475 | </row> | |
1476 | <row> | |
1477 | <entry><constant>-</constant></entry> | |
1478 | <entry><constant>V4L2_BUF_TYPE_SLICED_VBI_CAPTURE</constant></entry> | |
1479 | </row> | |
1480 | <row> | |
1481 | <entry><constant>-</constant></entry> | |
1482 | <entry><constant>V4L2_BUF_TYPE_SLICED_VBI_OUTPUT</constant></entry> | |
1483 | </row> | |
1484 | <row> | |
1485 | <entry><constant>V4L2_BUF_TYPE_PRIVATE_BASE</constant></entry> | |
1486 | <entry><constant>V4L2_BUF_TYPE_PRIVATE</constant></entry> | |
1487 | </row> | |
1488 | </tbody> | |
1489 | </tgroup> | |
1490 | </informaltable></para> | |
1491 | </listitem> | |
1492 | ||
1493 | <listitem> | |
1494 | <para>In &v4l2-fmtdesc; a &v4l2-buf-type; field named | |
1495 | <structfield>type</structfield> was added as in &v4l2-format;. The | |
1496 | <constant>VIDIOC_ENUM_FBUFFMT</constant> ioctl is no longer needed and | |
1497 | was removed. These calls can be replaced by &VIDIOC-ENUM-FMT; with | |
1498 | type <constant>V4L2_BUF_TYPE_VIDEO_OVERLAY</constant>.</para> | |
1499 | </listitem> | |
1500 | ||
1501 | <listitem> | |
1502 | <para>In &v4l2-pix-format; the | |
1503 | <structfield>depth</structfield> field was removed, assuming | |
1504 | applications which recognize the format by its four-character-code | |
1505 | already know the color depth, and others do not care about it. The | |
1506 | same rationale lead to the removal of the | |
1507 | <constant>V4L2_FMT_FLAG_COMPRESSED</constant> flag. The | |
1508 | <constant>V4L2_FMT_FLAG_SWCONVECOMPRESSED</constant> flag was removed | |
1509 | because drivers are not supposed to convert images in kernel space. A | |
1510 | user library of conversion functions should be provided instead. The | |
1511 | <constant>V4L2_FMT_FLAG_BYTESPERLINE</constant> flag was redundant. | |
1512 | Applications can set the <structfield>bytesperline</structfield> field | |
1513 | to zero to get a reasonable default. Since the remaining flags were | |
1514 | replaced as well, the <structfield>flags</structfield> field itself | |
1515 | was removed.</para> | |
1516 | <para>The interlace flags were replaced by a &v4l2-field; | |
1517 | value in a newly added <structfield>field</structfield> | |
1518 | field.<informaltable> | |
1519 | <tgroup cols="2"> | |
1520 | <thead> | |
1521 | <row> | |
1522 | <entry>Old flag</entry> | |
1523 | <entry>&v4l2-field;</entry> | |
1524 | </row> | |
1525 | </thead> | |
1526 | <tbody valign="top"> | |
1527 | <row> | |
1528 | <entry><constant>V4L2_FMT_FLAG_NOT_INTERLACED</constant></entry> | |
1529 | <entry>?</entry> | |
1530 | </row> | |
1531 | <row> | |
1532 | <entry><constant>V4L2_FMT_FLAG_INTERLACED</constant> | |
1533 | = <constant>V4L2_FMT_FLAG_COMBINED</constant></entry> | |
1534 | <entry><constant>V4L2_FIELD_INTERLACED</constant></entry> | |
1535 | </row> | |
1536 | <row> | |
1537 | <entry><constant>V4L2_FMT_FLAG_TOPFIELD</constant> | |
1538 | = <constant>V4L2_FMT_FLAG_ODDFIELD</constant></entry> | |
1539 | <entry><constant>V4L2_FIELD_TOP</constant></entry> | |
1540 | </row> | |
1541 | <row> | |
1542 | <entry><constant>V4L2_FMT_FLAG_BOTFIELD</constant> | |
1543 | = <constant>V4L2_FMT_FLAG_EVENFIELD</constant></entry> | |
1544 | <entry><constant>V4L2_FIELD_BOTTOM</constant></entry> | |
1545 | </row> | |
1546 | <row> | |
1547 | <entry><constant>-</constant></entry> | |
1548 | <entry><constant>V4L2_FIELD_SEQ_TB</constant></entry> | |
1549 | </row> | |
1550 | <row> | |
1551 | <entry><constant>-</constant></entry> | |
1552 | <entry><constant>V4L2_FIELD_SEQ_BT</constant></entry> | |
1553 | </row> | |
1554 | <row> | |
1555 | <entry><constant>-</constant></entry> | |
1556 | <entry><constant>V4L2_FIELD_ALTERNATE</constant></entry> | |
1557 | </row> | |
1558 | </tbody> | |
1559 | </tgroup> | |
1560 | </informaltable></para> | |
1561 | ||
1562 | <para>The color space flags were replaced by a | |
1563 | &v4l2-colorspace; value in a newly added | |
1564 | <structfield>colorspace</structfield> field, where one of | |
1565 | <constant>V4L2_COLORSPACE_SMPTE170M</constant>, | |
1566 | <constant>V4L2_COLORSPACE_BT878</constant>, | |
1567 | <constant>V4L2_COLORSPACE_470_SYSTEM_M</constant> or | |
1568 | <constant>V4L2_COLORSPACE_470_SYSTEM_BG</constant> replaces | |
1569 | <constant>V4L2_FMT_CS_601YUV</constant>.</para> | |
1570 | </listitem> | |
1571 | ||
1572 | <listitem> | |
1573 | <para>In &v4l2-requestbuffers; the | |
1574 | <structfield>type</structfield> field was properly defined as | |
1575 | &v4l2-buf-type;. Buffer types changed as mentioned above. A new | |
1576 | <structfield>memory</structfield> field of type &v4l2-memory; was | |
1577 | added to distinguish between I/O methods using buffers allocated | |
1578 | by the driver or the application. See <xref linkend="io" /> for | |
1579 | details.</para> | |
1580 | </listitem> | |
1581 | ||
1582 | <listitem> | |
1583 | <para>In &v4l2-buffer; the <structfield>type</structfield> | |
1584 | field was properly defined as &v4l2-buf-type;. Buffer types changed as | |
1585 | mentioned above. A <structfield>field</structfield> field of type | |
1586 | &v4l2-field; was added to indicate if a buffer contains a top or | |
1587 | bottom field. The old field flags were removed. Since no unadjusted | |
1588 | system time clock was added to the kernel as planned, the | |
1589 | <structfield>timestamp</structfield> field changed back from type | |
1590 | stamp_t, an unsigned 64 bit integer expressing the sample time in | |
1591 | nanoseconds, to struct <structname>timeval</structname>. With the | |
1592 | addition of a second memory mapping method the | |
1593 | <structfield>offset</structfield> field moved into union | |
1594 | <structfield>m</structfield>, and a new | |
1595 | <structfield>memory</structfield> field of type &v4l2-memory; was | |
1596 | added to distinguish between I/O methods. See <xref linkend="io" /> | |
1597 | for details.</para> | |
1598 | ||
1599 | <para>The <constant>V4L2_BUF_REQ_CONTIG</constant> | |
1600 | flag was used by the V4L compatibility layer, after changes to this | |
1601 | code it was no longer needed. The | |
1602 | <constant>V4L2_BUF_ATTR_DEVICEMEM</constant> flag would indicate if | |
1603 | the buffer was indeed allocated in device memory rather than DMA-able | |
1604 | system memory. It was barely useful and so was removed.</para> | |
1605 | </listitem> | |
1606 | ||
1607 | <listitem> | |
1608 | <para>In &v4l2-framebuffer; the | |
1609 | <structfield>base[3]</structfield> array anticipating double- and | |
1610 | triple-buffering in off-screen video memory, however without defining | |
1611 | a synchronization mechanism, was replaced by a single pointer. The | |
1612 | <constant>V4L2_FBUF_CAP_SCALEUP</constant> and | |
1613 | <constant>V4L2_FBUF_CAP_SCALEDOWN</constant> flags were removed. | |
1614 | Applications can determine this capability more accurately using the | |
1615 | new cropping and scaling interface. The | |
1616 | <constant>V4L2_FBUF_CAP_CLIPPING</constant> flag was replaced by | |
1617 | <constant>V4L2_FBUF_CAP_LIST_CLIPPING</constant> and | |
1618 | <constant>V4L2_FBUF_CAP_BITMAP_CLIPPING</constant>.</para> | |
1619 | </listitem> | |
1620 | ||
1621 | <listitem> | |
1622 | <para>In &v4l2-clip; the <structfield>x</structfield>, | |
1623 | <structfield>y</structfield>, <structfield>width</structfield> and | |
1624 | <structfield>height</structfield> field moved into a | |
1625 | <structfield>c</structfield> substructure of type &v4l2-rect;. The | |
1626 | <structfield>x</structfield> and <structfield>y</structfield> fields | |
1627 | were renamed to <structfield>left</structfield> and | |
1628 | <structfield>top</structfield>, &ie; offsets to a context dependent | |
1629 | origin.</para> | |
1630 | </listitem> | |
1631 | ||
1632 | <listitem> | |
1633 | <para>In &v4l2-window; the <structfield>x</structfield>, | |
1634 | <structfield>y</structfield>, <structfield>width</structfield> and | |
1635 | <structfield>height</structfield> field moved into a | |
1636 | <structfield>w</structfield> substructure as above. A | |
1637 | <structfield>field</structfield> field of type %v4l2-field; was added | |
1638 | to distinguish between field and frame (interlaced) overlay.</para> | |
1639 | </listitem> | |
1640 | ||
1641 | <listitem> | |
1642 | <para>The digital zoom interface, including struct | |
1643 | <structname>v4l2_zoomcap</structname>, struct | |
1644 | <structname>v4l2_zoom</structname>, | |
1645 | <constant>V4L2_ZOOM_NONCAP</constant> and | |
1646 | <constant>V4L2_ZOOM_WHILESTREAMING</constant> was replaced by a new | |
1647 | cropping and scaling interface. The previously unused struct | |
1648 | <structname>v4l2_cropcap</structname> and | |
1649 | <structname>v4l2_crop</structname> where redefined for this purpose. | |
1650 | See <xref linkend="crop" /> for details.</para> | |
1651 | </listitem> | |
1652 | ||
1653 | <listitem> | |
1654 | <para>In &v4l2-vbi-format; the | |
1655 | <structfield>SAMPLE_FORMAT</structfield> field now contains a | |
1656 | four-character-code as used to identify video image formats and | |
1657 | <constant>V4L2_PIX_FMT_GREY</constant> replaces the | |
1658 | <constant>V4L2_VBI_SF_UBYTE</constant> define. The | |
1659 | <structfield>reserved</structfield> field was extended.</para> | |
1660 | </listitem> | |
1661 | ||
1662 | <listitem> | |
1663 | <para>In &v4l2-captureparm; the type of the | |
1664 | <structfield>timeperframe</structfield> field changed from unsigned | |
1665 | long to &v4l2-fract;. This allows the accurate expression of multiples | |
1666 | of the NTSC-M frame rate 30000 / 1001. A new field | |
1667 | <structfield>readbuffers</structfield> was added to control the driver | |
1668 | behaviour in read I/O mode.</para> | |
1669 | ||
1670 | <para>Similar changes were made to &v4l2-outputparm;.</para> | |
1671 | </listitem> | |
1672 | ||
1673 | <listitem> | |
1674 | <para>The struct <structname>v4l2_performance</structname> | |
1675 | and <constant>VIDIOC_G_PERF</constant> ioctl were dropped. Except when | |
1676 | using the <link linkend="rw">read/write I/O method</link>, which is | |
1677 | limited anyway, this information is already available to | |
1678 | applications.</para> | |
1679 | </listitem> | |
1680 | ||
1681 | <listitem> | |
1682 | <para>The example transformation from RGB to YCbCr color | |
1683 | space in the old V4L2 documentation was inaccurate, this has been | |
1684 | corrected in <xref linkend="pixfmt" />.<!-- 0.5670G should be | |
1685 | 0.587, and 127/112 != 255/224 --></para> | |
1686 | </listitem> | |
1687 | </orderedlist> | |
1688 | </section> | |
1689 | ||
1690 | <section> | |
1691 | <title>V4L2 2003-06-19</title> | |
1692 | ||
1693 | <orderedlist> | |
1694 | <listitem> | |
1695 | <para>A new capability flag | |
1696 | <constant>V4L2_CAP_RADIO</constant> was added for radio devices. Prior | |
1697 | to this change radio devices would identify solely by having exactly one | |
1698 | tuner whose type field reads <constant>V4L2_TUNER_RADIO</constant>.</para> | |
1699 | </listitem> | |
1700 | ||
1701 | <listitem> | |
1702 | <para>An optional driver access priority mechanism was | |
1703 | added, see <xref linkend="app-pri" /> for details.</para> | |
1704 | </listitem> | |
1705 | ||
1706 | <listitem> | |
1707 | <para>The audio input and output interface was found to be | |
1708 | incomplete.</para> | |
1709 | <para>Previously the &VIDIOC-G-AUDIO; | |
1710 | ioctl would enumerate the available audio inputs. An ioctl to | |
1711 | determine the current audio input, if more than one combines with the | |
1712 | current video input, did not exist. So | |
1713 | <constant>VIDIOC_G_AUDIO</constant> was renamed to | |
1714 | <constant>VIDIOC_G_AUDIO_OLD</constant>, this ioctl will be removed in | |
1715 | the future. The &VIDIOC-ENUMAUDIO; ioctl was added to enumerate | |
1716 | audio inputs, while &VIDIOC-G-AUDIO; now reports the current audio | |
1717 | input.</para> | |
1718 | <para>The same changes were made to &VIDIOC-G-AUDOUT; and | |
1719 | &VIDIOC-ENUMAUDOUT;.</para> | |
1720 | <para>Until further the "videodev" module will automatically | |
1721 | translate between the old and new ioctls, but drivers and applications | |
1722 | must be updated to successfully compile again.</para> | |
1723 | </listitem> | |
1724 | ||
1725 | <listitem> | |
1726 | <para>The &VIDIOC-OVERLAY; ioctl was incorrectly defined with | |
1727 | write-read parameter. It was changed to write-only, while the write-read | |
1728 | version was renamed to <constant>VIDIOC_OVERLAY_OLD</constant>. The old | |
1729 | ioctl will be removed in the future. Until further the "videodev" | |
1730 | kernel module will automatically translate to the new version, so drivers | |
1731 | must be recompiled, but not applications.</para> | |
1732 | </listitem> | |
1733 | ||
1734 | <listitem> | |
1735 | <para><xref linkend="overlay" /> incorrectly stated that | |
1736 | clipping rectangles define regions where the video can be seen. | |
1737 | Correct is that clipping rectangles define regions where | |
1738 | <emphasis>no</emphasis> video shall be displayed and so the graphics | |
1739 | surface can be seen.</para> | |
1740 | </listitem> | |
1741 | ||
1742 | <listitem> | |
1743 | <para>The &VIDIOC-S-PARM; and &VIDIOC-S-CTRL; ioctls were | |
1744 | defined with write-only parameter, inconsistent with other ioctls | |
1745 | modifying their argument. They were changed to write-read, while a | |
1746 | <constant>_OLD</constant> suffix was added to the write-only versions. | |
1747 | The old ioctls will be removed in the future. Drivers and | |
1748 | applications assuming a constant parameter need an update.</para> | |
1749 | </listitem> | |
1750 | </orderedlist> | |
1751 | </section> | |
1752 | ||
1753 | <section> | |
1754 | <title>V4L2 2003-11-05</title> | |
1755 | <orderedlist> | |
1756 | <listitem> | |
1757 | <para>In <xref linkend="pixfmt-rgb" /> the following pixel | |
1758 | formats were incorrectly transferred from Bill Dirks' V4L2 | |
1759 | specification. Descriptions below refer to bytes in memory, in | |
1760 | ascending address order.<informaltable> | |
1761 | <tgroup cols="3"> | |
1762 | <thead> | |
1763 | <row> | |
1764 | <entry>Symbol</entry> | |
1765 | <entry>In this document prior to revision | |
1766 | 0.5</entry> | |
1767 | <entry>Corrected</entry> | |
1768 | </row> | |
1769 | </thead> | |
1770 | <tbody valign="top"> | |
1771 | <row> | |
1772 | <entry><constant>V4L2_PIX_FMT_RGB24</constant></entry> | |
1773 | <entry>B, G, R</entry> | |
1774 | <entry>R, G, B</entry> | |
1775 | </row> | |
1776 | <row> | |
1777 | <entry><constant>V4L2_PIX_FMT_BGR24</constant></entry> | |
1778 | <entry>R, G, B</entry> | |
1779 | <entry>B, G, R</entry> | |
1780 | </row> | |
1781 | <row> | |
1782 | <entry><constant>V4L2_PIX_FMT_RGB32</constant></entry> | |
1783 | <entry>B, G, R, X</entry> | |
1784 | <entry>R, G, B, X</entry> | |
1785 | </row> | |
1786 | <row> | |
1787 | <entry><constant>V4L2_PIX_FMT_BGR32</constant></entry> | |
1788 | <entry>R, G, B, X</entry> | |
1789 | <entry>B, G, R, X</entry> | |
1790 | </row> | |
1791 | </tbody> | |
1792 | </tgroup> | |
1793 | </informaltable> The | |
1794 | <constant>V4L2_PIX_FMT_BGR24</constant> example was always | |
1795 | correct.</para> | |
1796 | <para>In <xref linkend="v4l-image-properties" /> the mapping | |
1797 | of the V4L <constant>VIDEO_PALETTE_RGB24</constant> and | |
1798 | <constant>VIDEO_PALETTE_RGB32</constant> formats to V4L2 pixel formats | |
1799 | was accordingly corrected.</para> | |
1800 | </listitem> | |
1801 | ||
1802 | <listitem> | |
1803 | <para>Unrelated to the fixes above, drivers may still | |
1804 | interpret some V4L2 RGB pixel formats differently. These issues have | |
1805 | yet to be addressed, for details see <xref | |
1806 | linkend="pixfmt-rgb" />.</para> | |
1807 | </listitem> | |
1808 | </orderedlist> | |
1809 | </section> | |
1810 | ||
1811 | <section> | |
1812 | <title>V4L2 in Linux 2.6.6, 2004-05-09</title> | |
1813 | <orderedlist> | |
1814 | <listitem> | |
1815 | <para>The &VIDIOC-CROPCAP; ioctl was incorrectly defined | |
1816 | with read-only parameter. It is now defined as write-read ioctl, while | |
1817 | the read-only version was renamed to | |
1818 | <constant>VIDIOC_CROPCAP_OLD</constant>. The old ioctl will be removed | |
1819 | in the future.</para> | |
1820 | </listitem> | |
1821 | </orderedlist> | |
1822 | </section> | |
1823 | ||
1824 | <section> | |
1825 | <title>V4L2 in Linux 2.6.8</title> | |
1826 | <orderedlist> | |
1827 | <listitem> | |
1828 | <para>A new field <structfield>input</structfield> (former | |
1829 | <structfield>reserved[0]</structfield>) was added to the &v4l2-buffer; | |
1830 | structure. Purpose of this field is to alternate between video inputs | |
1831 | (⪚ cameras) in step with the video capturing process. This function | |
1832 | must be enabled with the new <constant>V4L2_BUF_FLAG_INPUT</constant> | |
1833 | flag. The <structfield>flags</structfield> field is no longer | |
1834 | read-only.</para> | |
1835 | </listitem> | |
1836 | </orderedlist> | |
1837 | </section> | |
1838 | ||
1839 | <section> | |
1840 | <title>V4L2 spec erratum 2004-08-01</title> | |
1841 | ||
1842 | <orderedlist> | |
1843 | <listitem> | |
1844 | <para>The return value of the | |
1845 | <xref linkend="func-open" /> function was incorrectly documented.</para> | |
1846 | </listitem> | |
1847 | ||
1848 | <listitem> | |
1849 | <para>Audio output ioctls end in -AUDOUT, not -AUDIOOUT.</para> | |
1850 | </listitem> | |
1851 | ||
1852 | <listitem> | |
1853 | <para>In the Current Audio Input example the | |
1854 | <constant>VIDIOC_G_AUDIO</constant> ioctl took the wrong | |
1855 | argument.</para> | |
1856 | </listitem> | |
1857 | ||
1858 | <listitem> | |
1859 | <para>The documentation of the &VIDIOC-QBUF; and | |
1860 | &VIDIOC-DQBUF; ioctls did not mention the &v4l2-buffer; | |
1861 | <structfield>memory</structfield> field. It was also missing from | |
1862 | examples. Also on the <constant>VIDIOC_DQBUF</constant> page the &EIO; | |
1863 | was not documented.</para> | |
1864 | </listitem> | |
1865 | </orderedlist> | |
1866 | </section> | |
1867 | ||
1868 | <section> | |
1869 | <title>V4L2 in Linux 2.6.14</title> | |
1870 | <orderedlist> | |
1871 | <listitem> | |
1872 | <para>A new sliced VBI interface was added. It is documented | |
1873 | in <xref linkend="sliced" /> and replaces the interface first | |
1874 | proposed in V4L2 specification 0.8.</para> | |
1875 | </listitem> | |
1876 | </orderedlist> | |
1877 | </section> | |
1878 | ||
1879 | <section> | |
1880 | <title>V4L2 in Linux 2.6.15</title> | |
1881 | <orderedlist> | |
1882 | <listitem> | |
1883 | <para>The &VIDIOC-LOG-STATUS; ioctl was added.</para> | |
1884 | </listitem> | |
1885 | ||
1886 | <listitem> | |
1887 | <para>New video standards | |
1888 | <constant>V4L2_STD_NTSC_443</constant>, | |
1889 | <constant>V4L2_STD_SECAM_LC</constant>, | |
1890 | <constant>V4L2_STD_SECAM_DK</constant> (a set of SECAM D, K and K1), | |
1891 | and <constant>V4L2_STD_ATSC</constant> (a set of | |
1892 | <constant>V4L2_STD_ATSC_8_VSB</constant> and | |
1893 | <constant>V4L2_STD_ATSC_16_VSB</constant>) were defined. Note the | |
1894 | <constant>V4L2_STD_525_60</constant> set now includes | |
1895 | <constant>V4L2_STD_NTSC_443</constant>. See also <xref | |
1896 | linkend="v4l2-std-id" />.</para> | |
1897 | </listitem> | |
1898 | ||
1899 | <listitem> | |
1900 | <para>The <constant>VIDIOC_G_COMP</constant> and | |
1901 | <constant>VIDIOC_S_COMP</constant> ioctl were renamed to | |
1902 | <constant>VIDIOC_G_MPEGCOMP</constant> and | |
1903 | <constant>VIDIOC_S_MPEGCOMP</constant> respectively. Their argument | |
1904 | was replaced by a struct | |
1905 | <structname>v4l2_mpeg_compression</structname> pointer. (The | |
1906 | <constant>VIDIOC_G_MPEGCOMP</constant> and | |
1907 | <constant>VIDIOC_S_MPEGCOMP</constant> ioctls where removed in Linux | |
1908 | 2.6.25.)</para> | |
1909 | </listitem> | |
1910 | </orderedlist> | |
1911 | </section> | |
1912 | ||
1913 | <section> | |
1914 | <title>V4L2 spec erratum 2005-11-27</title> | |
1915 | <para>The capture example in <xref linkend="capture-example" /> | |
1916 | called the &VIDIOC-S-CROP; ioctl without checking if cropping is | |
1917 | supported. In the video standard selection example in | |
1918 | <xref linkend="standard" /> the &VIDIOC-S-STD; call used the wrong | |
1919 | argument type.</para> | |
1920 | </section> | |
1921 | ||
1922 | <section> | |
1923 | <title>V4L2 spec erratum 2006-01-10</title> | |
1924 | <orderedlist> | |
1925 | <listitem> | |
1926 | <para>The <constant>V4L2_IN_ST_COLOR_KILL</constant> flag in | |
1927 | &v4l2-input; not only indicates if the color killer is enabled, but | |
1928 | also if it is active. (The color killer disables color decoding when | |
1929 | it detects no color in the video signal to improve the image | |
1930 | quality.)</para> | |
1931 | </listitem> | |
1932 | ||
1933 | <listitem> | |
1934 | <para>&VIDIOC-S-PARM; is a write-read ioctl, not write-only as | |
1935 | stated on its reference page. The ioctl changed in 2003 as noted above.</para> | |
1936 | </listitem> | |
1937 | </orderedlist> | |
1938 | </section> | |
1939 | ||
1940 | <section> | |
1941 | <title>V4L2 spec erratum 2006-02-03</title> | |
1942 | <orderedlist> | |
1943 | <listitem> | |
1944 | <para>In &v4l2-captureparm; and &v4l2-outputparm; the | |
1945 | <structfield>timeperframe</structfield> field gives the time in | |
1946 | seconds, not microseconds.</para> | |
1947 | </listitem> | |
1948 | </orderedlist> | |
1949 | </section> | |
1950 | ||
1951 | <section> | |
1952 | <title>V4L2 spec erratum 2006-02-04</title> | |
1953 | <orderedlist> | |
1954 | <listitem> | |
1955 | <para>The <structfield>clips</structfield> field in | |
1956 | &v4l2-window; must point to an array of &v4l2-clip;, not a linked | |
1957 | list, because drivers ignore the struct | |
1958 | <structname>v4l2_clip</structname>.<structfield>next</structfield> | |
1959 | pointer.</para> | |
1960 | </listitem> | |
1961 | </orderedlist> | |
1962 | </section> | |
1963 | ||
1964 | <section> | |
1965 | <title>V4L2 in Linux 2.6.17</title> | |
1966 | <orderedlist> | |
1967 | <listitem> | |
1968 | <para>New video standard macros were added: | |
1969 | <constant>V4L2_STD_NTSC_M_KR</constant> (NTSC M South Korea), and the | |
1970 | sets <constant>V4L2_STD_MN</constant>, | |
1971 | <constant>V4L2_STD_B</constant>, <constant>V4L2_STD_GH</constant> and | |
1972 | <constant>V4L2_STD_DK</constant>. The | |
1973 | <constant>V4L2_STD_NTSC</constant> and | |
1974 | <constant>V4L2_STD_SECAM</constant> sets now include | |
1975 | <constant>V4L2_STD_NTSC_M_KR</constant> and | |
1976 | <constant>V4L2_STD_SECAM_LC</constant> respectively.</para> | |
1977 | </listitem> | |
1978 | ||
1979 | <listitem> | |
1980 | <para>A new <constant>V4L2_TUNER_MODE_LANG1_LANG2</constant> | |
1981 | was defined to record both languages of a bilingual program. The | |
1982 | use of <constant>V4L2_TUNER_MODE_STEREO</constant> for this purpose | |
1983 | is deprecated now. See the &VIDIOC-G-TUNER; section for | |
1984 | details.</para> | |
1985 | </listitem> | |
1986 | </orderedlist> | |
1987 | </section> | |
1988 | ||
1989 | <section> | |
1990 | <title>V4L2 spec erratum 2006-09-23 (Draft 0.15)</title> | |
1991 | <orderedlist> | |
1992 | <listitem> | |
1993 | <para>In various places | |
1994 | <constant>V4L2_BUF_TYPE_SLICED_VBI_CAPTURE</constant> and | |
1995 | <constant>V4L2_BUF_TYPE_SLICED_VBI_OUTPUT</constant> of the sliced VBI | |
1996 | interface were not mentioned along with other buffer types.</para> | |
1997 | </listitem> | |
1998 | ||
1999 | <listitem> | |
2000 | <para>In <xref linkend="vidioc-g-audio" /> it was clarified | |
2001 | that the &v4l2-audio; <structfield>mode</structfield> field is a flags | |
2002 | field.</para> | |
2003 | </listitem> | |
2004 | ||
2005 | <listitem> | |
2006 | <para><xref linkend="vidioc-querycap" /> did not mention the | |
2007 | sliced VBI and radio capability flags.</para> | |
2008 | </listitem> | |
2009 | ||
2010 | <listitem> | |
2011 | <para>In <xref linkend="vidioc-g-frequency" /> it was | |
2012 | clarified that applications must initialize the tuner | |
2013 | <structfield>type</structfield> field of &v4l2-frequency; before | |
2014 | calling &VIDIOC-S-FREQUENCY;.</para> | |
2015 | </listitem> | |
2016 | ||
2017 | <listitem> | |
2018 | <para>The <structfield>reserved</structfield> array | |
2019 | in &v4l2-requestbuffers; has 2 elements, not 32.</para> | |
2020 | </listitem> | |
2021 | ||
2022 | <listitem> | |
2023 | <para>In <xref linkend="output" /> and <xref | |
2024 | linkend="raw-vbi" /> the device file names | |
2025 | <filename>/dev/vout</filename> which never caught on were replaced | |
2026 | by <filename>/dev/video</filename>.</para> | |
2027 | </listitem> | |
2028 | ||
2029 | <listitem> | |
2030 | <para>With Linux 2.6.15 the possible range for VBI device minor | |
2031 | numbers was extended from 224-239 to 224-255. Accordingly device file names | |
2032 | <filename>/dev/vbi0</filename> to <filename>/dev/vbi31</filename> are | |
2033 | possible now.</para> | |
2034 | </listitem> | |
2035 | </orderedlist> | |
2036 | </section> | |
2037 | ||
2038 | <section> | |
2039 | <title>V4L2 in Linux 2.6.18</title> | |
2040 | <orderedlist> | |
2041 | <listitem> | |
2042 | <para>New ioctls &VIDIOC-G-EXT-CTRLS;, &VIDIOC-S-EXT-CTRLS; | |
2043 | and &VIDIOC-TRY-EXT-CTRLS; were added, a flag to skip unsupported | |
2044 | controls with &VIDIOC-QUERYCTRL;, new control types | |
2045 | <constant>V4L2_CTRL_TYPE_INTEGER64</constant> and | |
2046 | <constant>V4L2_CTRL_TYPE_CTRL_CLASS</constant> (<xref | |
2047 | linkend="v4l2-ctrl-type" />), and new control flags | |
2048 | <constant>V4L2_CTRL_FLAG_READ_ONLY</constant>, | |
2049 | <constant>V4L2_CTRL_FLAG_UPDATE</constant>, | |
2050 | <constant>V4L2_CTRL_FLAG_INACTIVE</constant> and | |
2051 | <constant>V4L2_CTRL_FLAG_SLIDER</constant> (<xref | |
2052 | linkend="control-flags" />). See <xref | |
2053 | linkend="extended-controls" /> for details.</para> | |
2054 | </listitem> | |
2055 | </orderedlist> | |
2056 | </section> | |
2057 | ||
2058 | <section> | |
2059 | <title>V4L2 in Linux 2.6.19</title> | |
2060 | <orderedlist> | |
2061 | <listitem> | |
2062 | <para>In &v4l2-sliced-vbi-cap; a buffer type field was added | |
2063 | replacing a reserved field. Note on architectures where the size of | |
2064 | enum types differs from int types the size of the structure changed. | |
2065 | The &VIDIOC-G-SLICED-VBI-CAP; ioctl was redefined from being read-only | |
2066 | to write-read. Applications must initialize the type field and clear | |
2067 | the reserved fields now. These changes may <emphasis>break the | |
2068 | compatibility</emphasis> with older drivers and applications.</para> | |
2069 | </listitem> | |
2070 | ||
2071 | <listitem> | |
2072 | <para>The ioctls &VIDIOC-ENUM-FRAMESIZES; and | |
2073 | &VIDIOC-ENUM-FRAMEINTERVALS; were added.</para> | |
2074 | </listitem> | |
2075 | ||
2076 | <listitem> | |
2077 | <para>A new pixel format <constant>V4L2_PIX_FMT_RGB444</constant> (<xref | |
2078 | linkend="rgb-formats" />) was added.</para> | |
2079 | </listitem> | |
2080 | </orderedlist> | |
2081 | </section> | |
2082 | ||
2083 | <section> | |
2084 | <title>V4L2 spec erratum 2006-10-12 (Draft 0.17)</title> | |
2085 | <orderedlist> | |
2086 | <listitem> | |
2087 | <para><constant>V4L2_PIX_FMT_HM12</constant> (<xref | |
2088 | linkend="reserved-formats" />) is a YUV 4:2:0, not 4:2:2 format.</para> | |
2089 | </listitem> | |
2090 | </orderedlist> | |
2091 | </section> | |
2092 | ||
2093 | <section> | |
2094 | <title>V4L2 in Linux 2.6.21</title> | |
2095 | <orderedlist> | |
2096 | <listitem> | |
2097 | <para>The <filename>videodev2.h</filename> header file is | |
2098 | now dual licensed under GNU General Public License version two or | |
2099 | later, and under a 3-clause BSD-style license.</para> | |
2100 | </listitem> | |
2101 | </orderedlist> | |
2102 | </section> | |
2103 | ||
2104 | <section> | |
2105 | <title>V4L2 in Linux 2.6.22</title> | |
2106 | <orderedlist> | |
2107 | <listitem> | |
2108 | <para>Two new field orders | |
2109 | <constant>V4L2_FIELD_INTERLACED_TB</constant> and | |
2110 | <constant>V4L2_FIELD_INTERLACED_BT</constant> were | |
2111 | added. See <xref linkend="v4l2-field" /> for details.</para> | |
2112 | </listitem> | |
2113 | ||
2114 | <listitem> | |
2115 | <para>Three new clipping/blending methods with a global or | |
2116 | straight or inverted local alpha value were added to the video overlay | |
2117 | interface. See the description of the &VIDIOC-G-FBUF; and | |
2118 | &VIDIOC-S-FBUF; ioctls for details.</para> | |
2119 | <para>A new <structfield>global_alpha</structfield> field | |
2120 | was added to <link | |
2121 | linkend="v4l2-window"><structname>v4l2_window</structname></link>, | |
2122 | extending the structure. This may <emphasis>break | |
2123 | compatibility</emphasis> with applications using a struct | |
2124 | <structname>v4l2_window</structname> directly. However the <link | |
2125 | linkend="vidioc-g-fmt">VIDIOC_G/S/TRY_FMT</link> ioctls, which take a | |
2126 | pointer to a <link linkend="v4l2-format">v4l2_format</link> parent | |
2127 | structure with padding bytes at the end, are not affected.</para> | |
2128 | </listitem> | |
2129 | ||
2130 | <listitem> | |
2131 | <para>The format of the <structfield>chromakey</structfield> | |
2132 | field in &v4l2-window; changed from "host order RGB32" to a pixel | |
2133 | value in the same format as the framebuffer. This may <emphasis>break | |
2134 | compatibility</emphasis> with existing applications. Drivers | |
2135 | supporting the "host order RGB32" format are not known.</para> | |
2136 | </listitem> | |
2137 | ||
2138 | </orderedlist> | |
2139 | </section> | |
2140 | ||
2141 | <section> | |
2142 | <title>V4L2 in Linux 2.6.24</title> | |
2143 | <orderedlist> | |
2144 | <listitem> | |
2145 | <para>The pixel formats | |
2146 | <constant>V4L2_PIX_FMT_PAL8</constant>, | |
2147 | <constant>V4L2_PIX_FMT_YUV444</constant>, | |
2148 | <constant>V4L2_PIX_FMT_YUV555</constant>, | |
2149 | <constant>V4L2_PIX_FMT_YUV565</constant> and | |
2150 | <constant>V4L2_PIX_FMT_YUV32</constant> were added.</para> | |
2151 | </listitem> | |
2152 | </orderedlist> | |
2153 | </section> | |
2154 | ||
2155 | <section> | |
2156 | <title>V4L2 in Linux 2.6.25</title> | |
2157 | <orderedlist> | |
2158 | <listitem> | |
2159 | <para>The pixel formats <link linkend="V4L2-PIX-FMT-Y16"> | |
2160 | <constant>V4L2_PIX_FMT_Y16</constant></link> and <link | |
2161 | linkend="V4L2-PIX-FMT-SBGGR16"> | |
2162 | <constant>V4L2_PIX_FMT_SBGGR16</constant></link> were added.</para> | |
2163 | </listitem> | |
2164 | <listitem> | |
2165 | <para>New <link linkend="control">controls</link> | |
2166 | <constant>V4L2_CID_POWER_LINE_FREQUENCY</constant>, | |
2167 | <constant>V4L2_CID_HUE_AUTO</constant>, | |
2168 | <constant>V4L2_CID_WHITE_BALANCE_TEMPERATURE</constant>, | |
2169 | <constant>V4L2_CID_SHARPNESS</constant> and | |
2170 | <constant>V4L2_CID_BACKLIGHT_COMPENSATION</constant> were added. The | |
2171 | controls <constant>V4L2_CID_BLACK_LEVEL</constant>, | |
2172 | <constant>V4L2_CID_WHITENESS</constant>, | |
2173 | <constant>V4L2_CID_HCENTER</constant> and | |
2174 | <constant>V4L2_CID_VCENTER</constant> were deprecated. | |
2175 | </para> | |
2176 | </listitem> | |
2177 | <listitem> | |
2178 | <para>A <link linkend="camera-controls">Camera controls | |
2179 | class</link> was added, with the new controls | |
2180 | <constant>V4L2_CID_EXPOSURE_AUTO</constant>, | |
2181 | <constant>V4L2_CID_EXPOSURE_ABSOLUTE</constant>, | |
2182 | <constant>V4L2_CID_EXPOSURE_AUTO_PRIORITY</constant>, | |
2183 | <constant>V4L2_CID_PAN_RELATIVE</constant>, | |
2184 | <constant>V4L2_CID_TILT_RELATIVE</constant>, | |
2185 | <constant>V4L2_CID_PAN_RESET</constant>, | |
2186 | <constant>V4L2_CID_TILT_RESET</constant>, | |
2187 | <constant>V4L2_CID_PAN_ABSOLUTE</constant>, | |
2188 | <constant>V4L2_CID_TILT_ABSOLUTE</constant>, | |
2189 | <constant>V4L2_CID_FOCUS_ABSOLUTE</constant>, | |
2190 | <constant>V4L2_CID_FOCUS_RELATIVE</constant> and | |
2191 | <constant>V4L2_CID_FOCUS_AUTO</constant>.</para> | |
2192 | </listitem> | |
2193 | <listitem> | |
2194 | <para>The <constant>VIDIOC_G_MPEGCOMP</constant> and | |
2195 | <constant>VIDIOC_S_MPEGCOMP</constant> ioctls, which were superseded | |
2196 | by the <link linkend="extended-controls">extended controls</link> | |
2197 | interface in Linux 2.6.18, where finally removed from the | |
2198 | <filename>videodev2.h</filename> header file.</para> | |
2199 | </listitem> | |
2200 | </orderedlist> | |
2201 | </section> | |
2202 | ||
2203 | <section> | |
2204 | <title>V4L2 in Linux 2.6.26</title> | |
2205 | <orderedlist> | |
2206 | <listitem> | |
2207 | <para>The pixel formats | |
2208 | <constant>V4L2_PIX_FMT_Y16</constant> and | |
2209 | <constant>V4L2_PIX_FMT_SBGGR16</constant> were added.</para> | |
2210 | </listitem> | |
2211 | <listitem> | |
2212 | <para>Added user controls | |
2213 | <constant>V4L2_CID_CHROMA_AGC</constant> and | |
2214 | <constant>V4L2_CID_COLOR_KILLER</constant>.</para> | |
2215 | </listitem> | |
2216 | </orderedlist> | |
2217 | </section> | |
2218 | ||
2219 | <section> | |
2220 | <title>V4L2 in Linux 2.6.27</title> | |
2221 | <orderedlist> | |
2222 | <listitem> | |
2223 | <para>The &VIDIOC-S-HW-FREQ-SEEK; ioctl and the | |
2224 | <constant>V4L2_CAP_HW_FREQ_SEEK</constant> capability were added.</para> | |
2225 | </listitem> | |
2226 | <listitem> | |
2227 | <para>The pixel formats | |
2228 | <constant>V4L2_PIX_FMT_YVYU</constant>, | |
2229 | <constant>V4L2_PIX_FMT_PCA501</constant>, | |
2230 | <constant>V4L2_PIX_FMT_PCA505</constant>, | |
2231 | <constant>V4L2_PIX_FMT_PCA508</constant>, | |
2232 | <constant>V4L2_PIX_FMT_PCA561</constant>, | |
2233 | <constant>V4L2_PIX_FMT_SGBRG8</constant>, | |
2234 | <constant>V4L2_PIX_FMT_PAC207</constant> and | |
2235 | <constant>V4L2_PIX_FMT_PJPG</constant> were added.</para> | |
2236 | </listitem> | |
2237 | </orderedlist> | |
2238 | </section> | |
2239 | ||
2240 | <section> | |
2241 | <title>V4L2 in Linux 2.6.28</title> | |
2242 | <orderedlist> | |
2243 | <listitem> | |
2244 | <para>Added <constant>V4L2_MPEG_AUDIO_ENCODING_AAC</constant> and | |
2245 | <constant>V4L2_MPEG_AUDIO_ENCODING_AC3</constant> MPEG audio encodings.</para> | |
2246 | </listitem> | |
2247 | <listitem> | |
2248 | <para>Added <constant>V4L2_MPEG_VIDEO_ENCODING_MPEG_4_AVC</constant> MPEG | |
2249 | video encoding.</para> | |
2250 | </listitem> | |
2251 | <listitem> | |
2252 | <para>The pixel formats | |
2253 | <constant>V4L2_PIX_FMT_SGRBG10</constant> and | |
2254 | <constant>V4L2_PIX_FMT_SGRBG10DPCM8</constant> were added.</para> | |
2255 | </listitem> | |
2256 | </orderedlist> | |
2257 | </section> | |
2258 | ||
2259 | <section> | |
2260 | <title>V4L2 in Linux 2.6.29</title> | |
2261 | <orderedlist> | |
2262 | <listitem> | |
2263 | <para>The <constant>VIDIOC_G_CHIP_IDENT</constant> ioctl was renamed | |
2264 | to <constant>VIDIOC_G_CHIP_IDENT_OLD</constant> and &VIDIOC-DBG-G-CHIP-IDENT; | |
2265 | was introduced in its place. The old struct <structname>v4l2_chip_ident</structname> | |
2266 | was renamed to <structname id="v4l2-chip-ident-old">v4l2_chip_ident_old</structname>.</para> | |
2267 | </listitem> | |
2268 | <listitem> | |
2269 | <para>The pixel formats | |
2270 | <constant>V4L2_PIX_FMT_VYUY</constant>, | |
2271 | <constant>V4L2_PIX_FMT_NV16</constant> and | |
2272 | <constant>V4L2_PIX_FMT_NV61</constant> were added.</para> | |
2273 | </listitem> | |
2274 | <listitem> | |
2275 | <para>Added camera controls | |
2276 | <constant>V4L2_CID_ZOOM_ABSOLUTE</constant>, | |
2277 | <constant>V4L2_CID_ZOOM_RELATIVE</constant>, | |
2278 | <constant>V4L2_CID_ZOOM_CONTINUOUS</constant> and | |
2279 | <constant>V4L2_CID_PRIVACY</constant>.</para> | |
2280 | </listitem> | |
2281 | </orderedlist> | |
2282 | </section> | |
2283 | <section> | |
2284 | <title>V4L2 in Linux 2.6.30</title> | |
2285 | <orderedlist> | |
2286 | <listitem> | |
2287 | <para>New control flag <constant>V4L2_CTRL_FLAG_WRITE_ONLY</constant> was added.</para> | |
2288 | </listitem> | |
2289 | <listitem> | |
2290 | <para>New control <constant>V4L2_CID_COLORFX</constant> was added.</para> | |
2291 | </listitem> | |
b33f5f8a HV |
2292 | </orderedlist> |
2293 | </section> | |
8e080c2e MCC |
2294 | <section> |
2295 | <title>V4L2 in Linux 2.6.32</title> | |
2296 | <orderedlist> | |
2297 | <listitem> | |
2298 | <para>In order to be easier to compare a V4L2 API and a kernel | |
2299 | version, now V4L2 API is numbered using the Linux Kernel version numeration.</para> | |
2300 | </listitem> | |
2301 | <listitem> | |
2302 | <para>Finalized the RDS capture API. See <xref linkend="rds" /> for | |
2303 | more information.</para> | |
2304 | </listitem> | |
2305 | <listitem> | |
2306 | <para>Added new capabilities for modulators and RDS encoders.</para> | |
2307 | </listitem> | |
2308 | <listitem> | |
2309 | <para>Add description for libv4l API.</para> | |
2310 | </listitem> | |
2311 | <listitem> | |
2312 | <para>Added support for string controls via new type <constant>V4L2_CTRL_TYPE_STRING</constant>.</para> | |
2313 | </listitem> | |
2314 | <listitem> | |
2315 | <para>Added <constant>V4L2_CID_BAND_STOP_FILTER</constant> documentation.</para> | |
2316 | </listitem> | |
2317 | <listitem> | |
2318 | <para>Added FM Modulator (FM TX) Extended Control Class: <constant>V4L2_CTRL_CLASS_FM_TX</constant> and their Control IDs.</para> | |
2319 | </listitem> | |
2320 | <listitem> | |
2321 | <para>Added Remote Controller chapter, describing the default Remote Controller mapping for media devices.</para> | |
2322 | </listitem> | |
b33f5f8a HV |
2323 | </orderedlist> |
2324 | </section> | |
2325 | <section> | |
2326 | <title>V4L2 in Linux 2.6.33</title> | |
2327 | <orderedlist> | |
2328 | <listitem> | |
2329 | <para>Added support for Digital Video timings in order to support HDTV receivers and transmitters.</para> | |
2330 | </listitem> | |
2331 | </orderedlist> | |
2332 | </section> | |
48213fe3 LP |
2333 | <section> |
2334 | <title>V4L2 in Linux 2.6.34</title> | |
2335 | <orderedlist> | |
2336 | <listitem> | |
2337 | <para>Added | |
2338 | <constant>V4L2_CID_IRIS_ABSOLUTE</constant> and | |
2339 | <constant>V4L2_CID_IRIS_RELATIVE</constant> controls to the | |
2340 | <link linkend="camera-controls">Camera controls class</link>. | |
2341 | </para> | |
2342 | </listitem> | |
2343 | </orderedlist> | |
e426e866 | 2344 | </section> |
f44026db HV |
2345 | <section> |
2346 | <title>V4L2 in Linux 2.6.37</title> | |
2347 | <orderedlist> | |
2348 | <listitem> | |
2349 | <para>Remove the vtx (videotext/teletext) API. This API was no longer | |
2350 | used and no hardware exists to verify the API. Nor were any userspace applications found | |
2351 | that used it. It was originally scheduled for removal in 2.6.35. | |
2352 | </para> | |
2353 | </listitem> | |
2354 | </orderedlist> | |
2355 | </section> | |
8e080c2e | 2356 | |
e426e866 HV |
2357 | <section id="other"> |
2358 | <title>Relation of V4L2 to other Linux multimedia APIs</title> | |
8e080c2e | 2359 | |
e426e866 HV |
2360 | <section id="xvideo"> |
2361 | <title>X Video Extension</title> | |
8e080c2e | 2362 | |
e426e866 | 2363 | <para>The X Video Extension (abbreviated XVideo or just Xv) is |
8e080c2e MCC |
2364 | an extension of the X Window system, implemented for example by the |
2365 | XFree86 project. Its scope is similar to V4L2, an API to video capture | |
2366 | and output devices for X clients. Xv allows applications to display | |
2367 | live video in a window, send window contents to a TV output, and | |
2368 | capture or output still images in XPixmaps<footnote> | |
2369 | <para>This is not implemented in XFree86.</para> | |
2370 | </footnote>. With their implementation XFree86 makes the | |
2371 | extension available across many operating systems and | |
2372 | architectures.</para> | |
2373 | ||
e426e866 | 2374 | <para>Because the driver is embedded into the X server Xv has a |
8e080c2e MCC |
2375 | number of advantages over the V4L2 <link linkend="overlay">video |
2376 | overlay interface</link>. The driver can easily determine the overlay | |
2377 | target, &ie; visible graphics memory or off-screen buffers for a | |
2378 | destructive overlay. It can program the RAMDAC for a non-destructive | |
2379 | overlay, scaling or color-keying, or the clipping functions of the | |
2380 | video capture hardware, always in sync with drawing operations or | |
2381 | windows moving or changing their stacking order.</para> | |
2382 | ||
e426e866 | 2383 | <para>To combine the advantages of Xv and V4L a special Xv |
8e080c2e MCC |
2384 | driver exists in XFree86 and XOrg, just programming any overlay capable |
2385 | Video4Linux device it finds. To enable it | |
2386 | <filename>/etc/X11/XF86Config</filename> must contain these lines:</para> | |
e426e866 | 2387 | <para><screen> |
8e080c2e MCC |
2388 | Section "Module" |
2389 | Load "v4l" | |
2390 | EndSection</screen></para> | |
2391 | ||
e426e866 | 2392 | <para>As of XFree86 4.2 this driver still supports only V4L |
8e080c2e MCC |
2393 | ioctls, however it should work just fine with all V4L2 devices through |
2394 | the V4L2 backward-compatibility layer. Since V4L2 permits multiple | |
2395 | opens it is possible (if supported by the V4L2 driver) to capture | |
2396 | video while an X client requested video overlay. Restrictions of | |
2397 | simultaneous capturing and overlay are discussed in <xref | |
2398 | linkend="overlay" /> apply.</para> | |
2399 | ||
e426e866 | 2400 | <para>Only marginally related to V4L2, XFree86 extended Xv to |
8e080c2e MCC |
2401 | support hardware YUV to RGB conversion and scaling for faster video |
2402 | playback, and added an interface to MPEG-2 decoding hardware. This API | |
2403 | is useful to display images captured with V4L2 devices.</para> | |
e426e866 | 2404 | </section> |
8e080c2e | 2405 | |
e426e866 HV |
2406 | <section> |
2407 | <title>Digital Video</title> | |
8e080c2e | 2408 | |
e426e866 | 2409 | <para>V4L2 does not support digital terrestrial, cable or |
8e080c2e MCC |
2410 | satellite broadcast. A separate project aiming at digital receivers |
2411 | exists. You can find its homepage at <ulink | |
2412 | url="http://linuxtv.org">http://linuxtv.org</ulink>. The Linux DVB API | |
2413 | has no connection to the V4L2 API except that drivers for hybrid | |
2414 | hardware may support both.</para> | |
e426e866 | 2415 | </section> |
8e080c2e | 2416 | |
e426e866 HV |
2417 | <section> |
2418 | <title>Audio Interfaces</title> | |
8e080c2e | 2419 | |
e426e866 HV |
2420 | <para>[to do - OSS/ALSA]</para> |
2421 | </section> | |
8e080c2e | 2422 | </section> |
8e080c2e | 2423 | |
e426e866 HV |
2424 | <section id="experimental"> |
2425 | <title>Experimental API Elements</title> | |
8e080c2e | 2426 | |
e426e866 | 2427 | <para>The following V4L2 API elements are currently experimental |
8e080c2e MCC |
2428 | and may change in the future.</para> |
2429 | ||
e426e866 HV |
2430 | <itemizedlist> |
2431 | <listitem> | |
2432 | <para>Video Output Overlay (OSD) Interface, <xref | |
8e080c2e | 2433 | linkend="osd" />.</para> |
e426e866 | 2434 | </listitem> |
8e080c2e | 2435 | <listitem> |
e426e866 | 2436 | <para><constant>V4L2_BUF_TYPE_VIDEO_OUTPUT_OVERLAY</constant>, |
8e080c2e | 2437 | &v4l2-buf-type;, <xref linkend="v4l2-buf-type" />.</para> |
e426e866 HV |
2438 | </listitem> |
2439 | <listitem> | |
2440 | <para><constant>V4L2_CAP_VIDEO_OUTPUT_OVERLAY</constant>, | |
8e080c2e | 2441 | &VIDIOC-QUERYCAP; ioctl, <xref linkend="device-capabilities" />.</para> |
e426e866 HV |
2442 | </listitem> |
2443 | <listitem> | |
2444 | <para>&VIDIOC-ENUM-FRAMESIZES; and | |
8e080c2e | 2445 | &VIDIOC-ENUM-FRAMEINTERVALS; ioctls.</para> |
e426e866 HV |
2446 | </listitem> |
2447 | <listitem> | |
2448 | <para>&VIDIOC-G-ENC-INDEX; ioctl.</para> | |
2449 | </listitem> | |
2450 | <listitem> | |
2451 | <para>&VIDIOC-ENCODER-CMD; and &VIDIOC-TRY-ENCODER-CMD; | |
8e080c2e | 2452 | ioctls.</para> |
e426e866 HV |
2453 | </listitem> |
2454 | <listitem> | |
2455 | <para>&VIDIOC-DBG-G-REGISTER; and &VIDIOC-DBG-S-REGISTER; | |
8e080c2e | 2456 | ioctls.</para> |
e426e866 HV |
2457 | </listitem> |
2458 | <listitem> | |
2459 | <para>&VIDIOC-DBG-G-CHIP-IDENT; ioctl.</para> | |
2460 | </listitem> | |
2461 | </itemizedlist> | |
2462 | </section> | |
8e080c2e | 2463 | |
e426e866 HV |
2464 | <section id="obsolete"> |
2465 | <title>Obsolete API Elements</title> | |
8e080c2e | 2466 | |
e426e866 | 2467 | <para>The following V4L2 API elements were superseded by new |
8e080c2e MCC |
2468 | interfaces and should not be implemented in new drivers.</para> |
2469 | ||
e426e866 HV |
2470 | <itemizedlist> |
2471 | <listitem> | |
2472 | <para><constant>VIDIOC_G_MPEGCOMP</constant> and | |
8e080c2e MCC |
2473 | <constant>VIDIOC_S_MPEGCOMP</constant> ioctls. Use Extended Controls, |
2474 | <xref linkend="extended-controls" />.</para> | |
e426e866 HV |
2475 | </listitem> |
2476 | </itemizedlist> | |
2477 | </section> | |
8e080c2e MCC |
2478 | </section> |
2479 | ||
2480 | <!-- | |
2481 | Local Variables: | |
2482 | mode: sgml | |
2483 | sgml-parent-document: "v4l2.sgml" | |
2484 | indent-tabs-mode: nil | |
2485 | End: | |
2486 | --> |