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6a683493 HV |
1 | vivid: Virtual Video Test Driver |
2 | ================================ | |
3 | ||
4 | This driver emulates video4linux hardware of various types: video capture, video | |
5 | output, vbi capture and output, radio receivers and transmitters and a software | |
6 | defined radio receiver. In addition a simple framebuffer device is available for | |
7 | testing capture and output overlays. | |
8 | ||
9 | Up to 64 vivid instances can be created, each with up to 16 inputs and 16 outputs. | |
10 | ||
11 | Each input can be a webcam, TV capture device, S-Video capture device or an HDMI | |
12 | capture device. Each output can be an S-Video output device or an HDMI output | |
13 | device. | |
14 | ||
15 | These inputs and outputs act exactly as a real hardware device would behave. This | |
16 | allows you to use this driver as a test input for application development, since | |
17 | you can test the various features without requiring special hardware. | |
18 | ||
19 | This document describes the features implemented by this driver: | |
20 | ||
21 | - Support for read()/write(), MMAP, USERPTR and DMABUF streaming I/O. | |
22 | - A large list of test patterns and variations thereof | |
23 | - Working brightness, contrast, saturation and hue controls | |
24 | - Support for the alpha color component | |
25 | - Full colorspace support, including limited/full RGB range | |
26 | - All possible control types are present | |
27 | - Support for various pixel aspect ratios and video aspect ratios | |
28 | - Error injection to test what happens if errors occur | |
29 | - Supports crop/compose/scale in any combination for both input and output | |
30 | - Can emulate up to 4K resolutions | |
31 | - All Field settings are supported for testing interlaced capturing | |
32 | - Supports all standard YUV and RGB formats, including two multiplanar YUV formats | |
33 | - Raw and Sliced VBI capture and output support | |
34 | - Radio receiver and transmitter support, including RDS support | |
35 | - Software defined radio (SDR) support | |
36 | - Capture and output overlay support | |
37 | ||
38 | These features will be described in more detail below. | |
39 | ||
40 | ||
41 | Table of Contents | |
42 | ----------------- | |
43 | ||
44 | Section 1: Configuring the driver | |
45 | Section 2: Video Capture | |
46 | Section 2.1: Webcam Input | |
47 | Section 2.2: TV and S-Video Inputs | |
48 | Section 2.3: HDMI Input | |
49 | Section 3: Video Output | |
50 | Section 3.1: S-Video Output | |
51 | Section 3.2: HDMI Output | |
52 | Section 4: VBI Capture | |
53 | Section 5: VBI Output | |
54 | Section 6: Radio Receiver | |
55 | Section 7: Radio Transmitter | |
56 | Section 8: Software Defined Radio Receiver | |
57 | Section 9: Controls | |
58 | Section 9.1: User Controls - Test Controls | |
59 | Section 9.2: User Controls - Video Capture | |
60 | Section 9.3: User Controls - Audio | |
61 | Section 9.4: Vivid Controls | |
62 | Section 9.4.1: Test Pattern Controls | |
63 | Section 9.4.2: Capture Feature Selection Controls | |
64 | Section 9.4.3: Output Feature Selection Controls | |
65 | Section 9.4.4: Error Injection Controls | |
66 | Section 9.4.5: VBI Raw Capture Controls | |
67 | Section 9.5: Digital Video Controls | |
68 | Section 9.6: FM Radio Receiver Controls | |
69 | Section 9.7: FM Radio Modulator | |
70 | Section 10: Video, VBI and RDS Looping | |
71 | Section 10.1: Video and Sliced VBI looping | |
72 | Section 10.2: Radio & RDS Looping | |
73 | Section 11: Cropping, Composing, Scaling | |
74 | Section 12: Formats | |
75 | Section 13: Capture Overlay | |
76 | Section 14: Output Overlay | |
77 | Section 15: Some Future Improvements | |
78 | ||
79 | ||
80 | Section 1: Configuring the driver | |
81 | --------------------------------- | |
82 | ||
83 | By default the driver will create a single instance that has a video capture | |
84 | device with webcam, TV, S-Video and HDMI inputs, a video output device with | |
85 | S-Video and HDMI outputs, one vbi capture device, one vbi output device, one | |
86 | radio receiver device, one radio transmitter device and one SDR device. | |
87 | ||
88 | The number of instances, devices, video inputs and outputs and their types are | |
89 | all configurable using the following module options: | |
90 | ||
91 | n_devs: number of driver instances to create. By default set to 1. Up to 64 | |
92 | instances can be created. | |
93 | ||
94 | node_types: which devices should each driver instance create. An array of | |
95 | hexadecimal values, one for each instance. The default is 0x1d3d. | |
96 | Each value is a bitmask with the following meaning: | |
97 | bit 0: Video Capture node | |
98 | bit 2-3: VBI Capture node: 0 = none, 1 = raw vbi, 2 = sliced vbi, 3 = both | |
99 | bit 4: Radio Receiver node | |
100 | bit 5: Software Defined Radio Receiver node | |
101 | bit 8: Video Output node | |
102 | bit 10-11: VBI Output node: 0 = none, 1 = raw vbi, 2 = sliced vbi, 3 = both | |
103 | bit 12: Radio Transmitter node | |
104 | bit 16: Framebuffer for testing overlays | |
105 | ||
106 | So to create four instances, the first two with just one video capture | |
107 | device, the second two with just one video output device you would pass | |
108 | these module options to vivid: | |
109 | ||
110 | n_devs=4 node_types=0x1,0x1,0x100,0x100 | |
111 | ||
112 | num_inputs: the number of inputs, one for each instance. By default 4 inputs | |
113 | are created for each video capture device. At most 16 inputs can be created, | |
114 | and there must be at least one. | |
115 | ||
116 | input_types: the input types for each instance, the default is 0xe4. This defines | |
117 | what the type of each input is when the inputs are created for each driver | |
118 | instance. This is a hexadecimal value with up to 16 pairs of bits, each | |
119 | pair gives the type and bits 0-1 map to input 0, bits 2-3 map to input 1, | |
120 | 30-31 map to input 15. Each pair of bits has the following meaning: | |
121 | ||
122 | 00: this is a webcam input | |
123 | 01: this is a TV tuner input | |
124 | 10: this is an S-Video input | |
125 | 11: this is an HDMI input | |
126 | ||
127 | So to create a video capture device with 8 inputs where input 0 is a TV | |
128 | tuner, inputs 1-3 are S-Video inputs and inputs 4-7 are HDMI inputs you | |
129 | would use the following module options: | |
130 | ||
131 | num_inputs=8 input_types=0xffa9 | |
132 | ||
133 | num_outputs: the number of outputs, one for each instance. By default 2 outputs | |
134 | are created for each video output device. At most 16 outputs can be | |
135 | created, and there must be at least one. | |
136 | ||
137 | output_types: the output types for each instance, the default is 0x02. This defines | |
138 | what the type of each output is when the outputs are created for each | |
139 | driver instance. This is a hexadecimal value with up to 16 bits, each bit | |
140 | gives the type and bit 0 maps to output 0, bit 1 maps to output 1, bit | |
141 | 15 maps to output 15. The meaning of each bit is as follows: | |
142 | ||
143 | 0: this is an S-Video output | |
144 | 1: this is an HDMI output | |
145 | ||
146 | So to create a video output device with 8 outputs where outputs 0-3 are | |
147 | S-Video outputs and outputs 4-7 are HDMI outputs you would use the | |
148 | following module options: | |
149 | ||
150 | num_outputs=8 output_types=0xf0 | |
151 | ||
152 | vid_cap_nr: give the desired videoX start number for each video capture device. | |
153 | The default is -1 which will just take the first free number. This allows | |
154 | you to map capture video nodes to specific videoX device nodes. Example: | |
155 | ||
156 | n_devs=4 vid_cap_nr=2,4,6,8 | |
157 | ||
158 | This will attempt to assign /dev/video2 for the video capture device of | |
159 | the first vivid instance, video4 for the next up to video8 for the last | |
160 | instance. If it can't succeed, then it will just take the next free | |
161 | number. | |
162 | ||
163 | vid_out_nr: give the desired videoX start number for each video output device. | |
164 | The default is -1 which will just take the first free number. | |
165 | ||
166 | vbi_cap_nr: give the desired vbiX start number for each vbi capture device. | |
167 | The default is -1 which will just take the first free number. | |
168 | ||
169 | vbi_out_nr: give the desired vbiX start number for each vbi output device. | |
170 | The default is -1 which will just take the first free number. | |
171 | ||
172 | radio_rx_nr: give the desired radioX start number for each radio receiver device. | |
173 | The default is -1 which will just take the first free number. | |
174 | ||
175 | radio_tx_nr: give the desired radioX start number for each radio transmitter | |
176 | device. The default is -1 which will just take the first free number. | |
177 | ||
178 | sdr_cap_nr: give the desired swradioX start number for each SDR capture device. | |
179 | The default is -1 which will just take the first free number. | |
180 | ||
181 | ccs_cap_mode: specify the allowed video capture crop/compose/scaling combination | |
182 | for each driver instance. Video capture devices can have any combination | |
183 | of cropping, composing and scaling capabilities and this will tell the | |
184 | vivid driver which of those is should emulate. By default the user can | |
185 | select this through controls. | |
186 | ||
187 | The value is either -1 (controlled by the user) or a set of three bits, | |
188 | each enabling (1) or disabling (0) one of the features: | |
189 | ||
190 | bit 0: Enable crop support. Cropping will take only part of the | |
191 | incoming picture. | |
192 | bit 1: Enable compose support. Composing will copy the incoming | |
193 | picture into a larger buffer. | |
194 | bit 2: Enable scaling support. Scaling can scale the incoming | |
195 | picture. The scaler of the vivid driver can enlarge up | |
196 | or down to four times the original size. The scaler is | |
197 | very simple and low-quality. Simplicity and speed were | |
198 | key, not quality. | |
199 | ||
200 | Note that this value is ignored by webcam inputs: those enumerate | |
201 | discrete framesizes and that is incompatible with cropping, composing | |
202 | or scaling. | |
203 | ||
204 | ccs_out_mode: specify the allowed video output crop/compose/scaling combination | |
205 | for each driver instance. Video output devices can have any combination | |
206 | of cropping, composing and scaling capabilities and this will tell the | |
207 | vivid driver which of those is should emulate. By default the user can | |
208 | select this through controls. | |
209 | ||
210 | The value is either -1 (controlled by the user) or a set of three bits, | |
211 | each enabling (1) or disabling (0) one of the features: | |
212 | ||
213 | bit 0: Enable crop support. Cropping will take only part of the | |
214 | outgoing buffer. | |
215 | bit 1: Enable compose support. Composing will copy the incoming | |
216 | buffer into a larger picture frame. | |
217 | bit 2: Enable scaling support. Scaling can scale the incoming | |
218 | buffer. The scaler of the vivid driver can enlarge up | |
219 | or down to four times the original size. The scaler is | |
220 | very simple and low-quality. Simplicity and speed were | |
221 | key, not quality. | |
222 | ||
223 | multiplanar: select whether each device instance supports multi-planar formats, | |
224 | and thus the V4L2 multi-planar API. By default the first device instance | |
225 | is single-planar, the second multi-planar, and it keeps alternating. | |
226 | ||
227 | This module option can override that for each instance. Values are: | |
228 | ||
229 | 0: use alternating single and multi-planar devices. | |
230 | 1: this is a single-planar instance. | |
231 | 2: this is a multi-planar instance. | |
232 | ||
233 | vivid_debug: enable driver debugging info | |
234 | ||
235 | no_error_inj: if set disable the error injecting controls. This option is | |
236 | needed in order to run a tool like v4l2-compliance. Tools like that | |
237 | exercise all controls including a control like 'Disconnect' which | |
238 | emulates a USB disconnect, making the device inaccessible and so | |
239 | all tests that v4l2-compliance is doing will fail afterwards. | |
240 | ||
241 | There may be other situations as well where you want to disable the | |
242 | error injection support of vivid. When this option is set, then the | |
243 | controls that select crop, compose and scale behavior are also | |
244 | removed. Unless overridden by ccs_cap_mode and/or ccs_out_mode the | |
245 | will default to enabling crop, compose and scaling. | |
246 | ||
247 | Taken together, all these module options allow you to precisely customize | |
248 | the driver behavior and test your application with all sorts of permutations. | |
249 | It is also very suitable to emulate hardware that is not yet available, e.g. | |
250 | when developing software for a new upcoming device. | |
251 | ||
252 | ||
253 | Section 2: Video Capture | |
254 | ------------------------ | |
255 | ||
256 | This is probably the most frequently used feature. The video capture device | |
257 | can be configured by using the module options num_inputs, input_types and | |
258 | ccs_cap_mode (see section 1 for more detailed information), but by default | |
259 | four inputs are configured: a webcam, a TV tuner, an S-Video and an HDMI | |
260 | input, one input for each input type. Those are described in more detail | |
261 | below. | |
262 | ||
263 | Special attention has been given to the rate at which new frames become | |
264 | available. The jitter will be around 1 jiffie (that depends on the HZ | |
265 | configuration of your kernel, so usually 1/100, 1/250 or 1/1000 of a second), | |
266 | but the long-term behavior is exactly following the framerate. So a | |
267 | framerate of 59.94 Hz is really different from 60 Hz. If the framerate | |
268 | exceeds your kernel's HZ value, then you will get dropped frames, but the | |
269 | frame/field sequence counting will keep track of that so the sequence | |
270 | count will skip whenever frames are dropped. | |
271 | ||
272 | ||
273 | Section 2.1: Webcam Input | |
274 | ------------------------- | |
275 | ||
276 | The webcam input supports three framesizes: 320x180, 640x360 and 1280x720. It | |
277 | supports frames per second settings of 10, 15, 25, 30, 50 and 60 fps. Which ones | |
278 | are available depends on the chosen framesize: the larger the framesize, the | |
279 | lower the maximum frames per second. | |
280 | ||
281 | The initially selected colorspace when you switch to the webcam input will be | |
282 | sRGB. | |
283 | ||
284 | ||
285 | Section 2.2: TV and S-Video Inputs | |
286 | ---------------------------------- | |
287 | ||
288 | The only difference between the TV and S-Video input is that the TV has a | |
289 | tuner. Otherwise they behave identically. | |
290 | ||
291 | These inputs support audio inputs as well: one TV and one Line-In. They | |
292 | both support all TV standards. If the standard is queried, then the Vivid | |
293 | controls 'Standard Signal Mode' and 'Standard' determine what | |
294 | the result will be. | |
295 | ||
296 | These inputs support all combinations of the field setting. Special care has | |
297 | been taken to faithfully reproduce how fields are handled for the different | |
298 | TV standards. This is particularly noticable when generating a horizontally | |
299 | moving image so the temporal effect of using interlaced formats becomes clearly | |
300 | visible. For 50 Hz standards the top field is the oldest and the bottom field | |
301 | is the newest in time. For 60 Hz standards that is reversed: the bottom field | |
302 | is the oldest and the top field is the newest in time. | |
303 | ||
304 | When you start capturing in V4L2_FIELD_ALTERNATE mode the first buffer will | |
305 | contain the top field for 50 Hz standards and the bottom field for 60 Hz | |
306 | standards. This is what capture hardware does as well. | |
307 | ||
308 | Finally, for PAL/SECAM standards the first half of the top line contains noise. | |
309 | This simulates the Wide Screen Signal that is commonly placed there. | |
310 | ||
311 | The initially selected colorspace when you switch to the TV or S-Video input | |
312 | will be SMPTE-170M. | |
313 | ||
314 | The pixel aspect ratio will depend on the TV standard. The video aspect ratio | |
315 | can be selected through the 'Standard Aspect Ratio' Vivid control. | |
316 | Choices are '4x3', '16x9' which will give letterboxed widescreen video and | |
317 | '16x9 Anomorphic' which will give full screen squashed anamorphic widescreen | |
318 | video that will need to be scaled accordingly. | |
319 | ||
320 | The TV 'tuner' supports a frequency range of 44-958 MHz. Channels are available | |
321 | every 6 MHz, starting from 49.25 MHz. For each channel the generated image | |
322 | will be in color for the +/- 0.25 MHz around it, and in grayscale for | |
323 | +/- 1 MHz around the channel. Beyond that it is just noise. The VIDIOC_G_TUNER | |
324 | ioctl will return 100% signal strength for +/- 0.25 MHz and 50% for +/- 1 MHz. | |
325 | It will also return correct afc values to show whether the frequency is too | |
326 | low or too high. | |
327 | ||
328 | The audio subchannels that are returned are MONO for the +/- 1 MHz range around | |
329 | a valid channel frequency. When the frequency is within +/- 0.25 MHz of the | |
330 | channel it will return either MONO, STEREO, either MONO | SAP (for NTSC) or | |
331 | LANG1 | LANG2 (for others), or STEREO | SAP. | |
332 | ||
333 | Which one is returned depends on the chosen channel, each next valid channel | |
334 | will cycle through the possible audio subchannel combinations. This allows | |
335 | you to test the various combinations by just switching channels.. | |
336 | ||
337 | Finally, for these inputs the v4l2_timecode struct is filled in in the | |
338 | dequeued v4l2_buffer struct. | |
339 | ||
340 | ||
341 | Section 2.3: HDMI Input | |
342 | ----------------------- | |
343 | ||
344 | The HDMI inputs supports all CEA-861 and DMT timings, both progressive and | |
345 | interlaced, for pixelclock frequencies between 25 and 600 MHz. The field | |
346 | mode for interlaced formats is always V4L2_FIELD_ALTERNATE. For HDMI the | |
347 | field order is always top field first, and when you start capturing an | |
348 | interlaced format you will receive the top field first. | |
349 | ||
350 | The initially selected colorspace when you switch to the HDMI input or | |
351 | select an HDMI timing is based on the format resolution: for resolutions | |
352 | less than or equal to 720x576 the colorspace is set to SMPTE-170M, for | |
353 | others it is set to REC-709 (CEA-861 timings) or sRGB (VESA DMT timings). | |
354 | ||
355 | The pixel aspect ratio will depend on the HDMI timing: for 720x480 is it | |
356 | set as for the NTSC TV standard, for 720x576 it is set as for the PAL TV | |
357 | standard, and for all others a 1:1 pixel aspect ratio is returned. | |
358 | ||
359 | The video aspect ratio can be selected through the 'DV Timings Aspect Ratio' | |
360 | Vivid control. Choices are 'Source Width x Height' (just use the | |
361 | same ratio as the chosen format), '4x3' or '16x9', either of which can | |
362 | result in pillarboxed or letterboxed video. | |
363 | ||
364 | For HDMI inputs it is possible to set the EDID. By default a simple EDID | |
365 | is provided. You can only set the EDID for HDMI inputs. Internally, however, | |
366 | the EDID is shared between all HDMI inputs. | |
367 | ||
368 | No interpretation is done of the EDID data. | |
369 | ||
370 | ||
371 | Section 3: Video Output | |
372 | ----------------------- | |
373 | ||
374 | The video output device can be configured by using the module options | |
375 | num_outputs, output_types and ccs_out_mode (see section 1 for more detailed | |
376 | information), but by default two outputs are configured: an S-Video and an | |
377 | HDMI input, one output for each output type. Those are described in more detail | |
378 | below. | |
379 | ||
380 | Like with video capture the framerate is also exact in the long term. | |
381 | ||
382 | ||
383 | Section 3.1: S-Video Output | |
384 | --------------------------- | |
385 | ||
386 | This output supports audio outputs as well: "Line-Out 1" and "Line-Out 2". | |
387 | The S-Video output supports all TV standards. | |
388 | ||
389 | This output supports all combinations of the field setting. | |
390 | ||
391 | The initially selected colorspace when you switch to the TV or S-Video input | |
392 | will be SMPTE-170M. | |
393 | ||
394 | ||
395 | Section 3.2: HDMI Output | |
396 | ------------------------ | |
397 | ||
398 | The HDMI output supports all CEA-861 and DMT timings, both progressive and | |
399 | interlaced, for pixelclock frequencies between 25 and 600 MHz. The field | |
400 | mode for interlaced formats is always V4L2_FIELD_ALTERNATE. | |
401 | ||
402 | The initially selected colorspace when you switch to the HDMI output or | |
403 | select an HDMI timing is based on the format resolution: for resolutions | |
404 | less than or equal to 720x576 the colorspace is set to SMPTE-170M, for | |
405 | others it is set to REC-709 (CEA-861 timings) or sRGB (VESA DMT timings). | |
406 | ||
407 | The pixel aspect ratio will depend on the HDMI timing: for 720x480 is it | |
408 | set as for the NTSC TV standard, for 720x576 it is set as for the PAL TV | |
409 | standard, and for all others a 1:1 pixel aspect ratio is returned. | |
410 | ||
411 | An HDMI output has a valid EDID which can be obtained through VIDIOC_G_EDID. | |
412 | ||
413 | ||
414 | Section 4: VBI Capture | |
415 | ---------------------- | |
416 | ||
417 | There are three types of VBI capture devices: those that only support raw | |
418 | (undecoded) VBI, those that only support sliced (decoded) VBI and those that | |
419 | support both. This is determined by the node_types module option. In all | |
420 | cases the driver will generate valid VBI data: for 60 Hz standards it will | |
421 | generate Closed Caption and XDS data. The closed caption stream will | |
422 | alternate between "Hello world!" and "Closed captions test" every second. | |
423 | The XDS stream will give the current time once a minute. For 50 Hz standards | |
424 | it will generate the Wide Screen Signal which is based on the actual Video | |
62f28725 | 425 | Aspect Ratio control setting and teletext pages 100-159, one page per frame. |
6a683493 HV |
426 | |
427 | The VBI device will only work for the S-Video and TV inputs, it will give | |
428 | back an error if the current input is a webcam or HDMI. | |
429 | ||
430 | ||
431 | Section 5: VBI Output | |
432 | --------------------- | |
433 | ||
434 | There are three types of VBI output devices: those that only support raw | |
435 | (undecoded) VBI, those that only support sliced (decoded) VBI and those that | |
436 | support both. This is determined by the node_types module option. | |
437 | ||
62f28725 HV |
438 | The sliced VBI output supports the Wide Screen Signal and the teletext signal |
439 | for 50 Hz standards and Closed Captioning + XDS for 60 Hz standards. | |
6a683493 HV |
440 | |
441 | The VBI device will only work for the S-Video output, it will give | |
442 | back an error if the current output is HDMI. | |
443 | ||
444 | ||
445 | Section 6: Radio Receiver | |
446 | ------------------------- | |
447 | ||
448 | The radio receiver emulates an FM/AM/SW receiver. The FM band also supports RDS. | |
449 | The frequency ranges are: | |
450 | ||
451 | FM: 64 MHz - 108 MHz | |
452 | AM: 520 kHz - 1710 kHz | |
453 | SW: 2300 kHz - 26.1 MHz | |
454 | ||
455 | Valid channels are emulated every 1 MHz for FM and every 100 kHz for AM and SW. | |
456 | The signal strength decreases the further the frequency is from the valid | |
457 | frequency until it becomes 0% at +/- 50 kHz (FM) or 5 kHz (AM/SW) from the | |
458 | ideal frequency. The initial frequency when the driver is loaded is set to | |
459 | 95 MHz. | |
460 | ||
461 | The FM receiver supports RDS as well, both using 'Block I/O' and 'Controls' | |
462 | modes. In the 'Controls' mode the RDS information is stored in read-only | |
463 | controls. These controls are updated every time the frequency is changed, | |
464 | or when the tuner status is requested. The Block I/O method uses the read() | |
465 | interface to pass the RDS blocks on to the application for decoding. | |
466 | ||
467 | The RDS signal is 'detected' for +/- 12.5 kHz around the channel frequency, | |
468 | and the further the frequency is away from the valid frequency the more RDS | |
469 | errors are randomly introduced into the block I/O stream, up to 50% of all | |
470 | blocks if you are +/- 12.5 kHz from the channel frequency. All four errors | |
471 | can occur in equal proportions: blocks marked 'CORRECTED', blocks marked | |
472 | 'ERROR', blocks marked 'INVALID' and dropped blocks. | |
473 | ||
474 | The generated RDS stream contains all the standard fields contained in a | |
475 | 0B group, and also radio text and the current time. | |
476 | ||
477 | The receiver supports HW frequency seek, either in Bounded mode, Wrap Around | |
478 | mode or both, which is configurable with the "Radio HW Seek Mode" control. | |
479 | ||
480 | ||
481 | Section 7: Radio Transmitter | |
482 | ---------------------------- | |
483 | ||
484 | The radio transmitter emulates an FM/AM/SW transmitter. The FM band also supports RDS. | |
485 | The frequency ranges are: | |
486 | ||
487 | FM: 64 MHz - 108 MHz | |
488 | AM: 520 kHz - 1710 kHz | |
489 | SW: 2300 kHz - 26.1 MHz | |
490 | ||
491 | The initial frequency when the driver is loaded is 95.5 MHz. | |
492 | ||
493 | The FM transmitter supports RDS as well, both using 'Block I/O' and 'Controls' | |
494 | modes. In the 'Controls' mode the transmitted RDS information is configured | |
495 | using controls, and in 'Block I/O' mode the blocks are passed to the driver | |
496 | using write(). | |
497 | ||
498 | ||
499 | Section 8: Software Defined Radio Receiver | |
500 | ------------------------------------------ | |
501 | ||
502 | The SDR receiver has three frequency bands for the ADC tuner: | |
503 | ||
504 | - 300 kHz | |
505 | - 900 kHz - 2800 kHz | |
506 | - 3200 kHz | |
507 | ||
508 | The RF tuner supports 50 MHz - 2000 MHz. | |
509 | ||
510 | The generated data contains the In-phase and Quadrature components of a | |
511 | 1 kHz tone that has an amplitude of sqrt(2). | |
512 | ||
513 | ||
514 | Section 9: Controls | |
515 | ------------------- | |
516 | ||
517 | Different devices support different controls. The sections below will describe | |
518 | each control and which devices support them. | |
519 | ||
520 | ||
521 | Section 9.1: User Controls - Test Controls | |
522 | ------------------------------------------ | |
523 | ||
524 | The Button, Boolean, Integer 32 Bits, Integer 64 Bits, Menu, String, Bitmask and | |
525 | Integer Menu are controls that represent all possible control types. The Menu | |
526 | control and the Integer Menu control both have 'holes' in their menu list, | |
527 | meaning that one or more menu items return EINVAL when VIDIOC_QUERYMENU is called. | |
528 | Both menu controls also have a non-zero minimum control value. These features | |
529 | allow you to check if your application can handle such things correctly. | |
530 | These controls are supported for every device type. | |
531 | ||
532 | ||
533 | Section 9.2: User Controls - Video Capture | |
534 | ------------------------------------------ | |
535 | ||
536 | The following controls are specific to video capture. | |
537 | ||
538 | The Brightness, Contrast, Saturation and Hue controls actually work and are | |
539 | standard. There is one special feature with the Brightness control: each | |
540 | video input has its own brightness value, so changing input will restore | |
541 | the brightness for that input. In addition, each video input uses a different | |
542 | brightness range (minimum and maximum control values). Switching inputs will | |
543 | cause a control event to be sent with the V4L2_EVENT_CTRL_CH_RANGE flag set. | |
544 | This allows you to test controls that can change their range. | |
545 | ||
546 | The 'Gain, Automatic' and Gain controls can be used to test volatile controls: | |
547 | if 'Gain, Automatic' is set, then the Gain control is volatile and changes | |
548 | constantly. If 'Gain, Automatic' is cleared, then the Gain control is a normal | |
549 | control. | |
550 | ||
551 | The 'Horizontal Flip' and 'Vertical Flip' controls can be used to flip the | |
552 | image. These combine with the 'Sensor Flipped Horizontally/Vertically' Vivid | |
553 | controls. | |
554 | ||
555 | The 'Alpha Component' control can be used to set the alpha component for | |
556 | formats containing an alpha channel. | |
557 | ||
558 | ||
559 | Section 9.3: User Controls - Audio | |
560 | ---------------------------------- | |
561 | ||
562 | The following controls are specific to video capture and output and radio | |
563 | receivers and transmitters. | |
564 | ||
565 | The 'Volume' and 'Mute' audio controls are typical for such devices to | |
566 | control the volume and mute the audio. They don't actually do anything in | |
567 | the vivid driver. | |
568 | ||
569 | ||
570 | Section 9.4: Vivid Controls | |
571 | --------------------------- | |
572 | ||
573 | These vivid custom controls control the image generation, error injection, etc. | |
574 | ||
575 | ||
576 | Section 9.4.1: Test Pattern Controls | |
577 | ------------------------------------ | |
578 | ||
579 | The Test Pattern Controls are all specific to video capture. | |
580 | ||
581 | Test Pattern: selects which test pattern to use. Use the CSC Colorbar for | |
582 | testing colorspace conversions: the colors used in that test pattern | |
583 | map to valid colors in all colorspaces. The colorspace conversion | |
584 | is disabled for the other test patterns. | |
585 | ||
586 | OSD Text Mode: selects whether the text superimposed on the | |
587 | test pattern should be shown, and if so, whether only counters should | |
588 | be displayed or the full text. | |
589 | ||
590 | Horizontal Movement: selects whether the test pattern should | |
591 | move to the left or right and at what speed. | |
592 | ||
593 | Vertical Movement: does the same for the vertical direction. | |
594 | ||
595 | Show Border: show a two-pixel wide border at the edge of the actual image, | |
596 | excluding letter or pillarboxing. | |
597 | ||
598 | Show Square: show a square in the middle of the image. If the image is | |
599 | displayed with the correct pixel and image aspect ratio corrections, | |
600 | then the width and height of the square on the monitor should be | |
601 | the same. | |
602 | ||
603 | Insert SAV Code in Image: adds a SAV (Start of Active Video) code to the image. | |
604 | This can be used to check if such codes in the image are inadvertently | |
605 | interpreted instead of being ignored. | |
606 | ||
607 | Insert EAV Code in Image: does the same for the EAV (End of Active Video) code. | |
608 | ||
609 | ||
610 | Section 9.4.2: Capture Feature Selection Controls | |
611 | ------------------------------------------------- | |
612 | ||
613 | These controls are all specific to video capture. | |
614 | ||
615 | Sensor Flipped Horizontally: the image is flipped horizontally and the | |
616 | V4L2_IN_ST_HFLIP input status flag is set. This emulates the case where | |
617 | a sensor is for example mounted upside down. | |
618 | ||
619 | Sensor Flipped Vertically: the image is flipped vertically and the | |
620 | V4L2_IN_ST_VFLIP input status flag is set. This emulates the case where | |
621 | a sensor is for example mounted upside down. | |
622 | ||
623 | Standard Aspect Ratio: selects if the image aspect ratio as used for the TV or | |
624 | S-Video input should be 4x3, 16x9 or anamorphic widescreen. This may | |
625 | introduce letterboxing. | |
626 | ||
627 | DV Timings Aspect Ratio: selects if the image aspect ratio as used for the HDMI | |
628 | input should be the same as the source width and height ratio, or if | |
629 | it should be 4x3 or 16x9. This may introduce letter or pillarboxing. | |
630 | ||
631 | Timestamp Source: selects when the timestamp for each buffer is taken. | |
632 | ||
633 | Colorspace: selects which colorspace should be used when generating the image. | |
634 | This only applies if the CSC Colorbar test pattern is selected, | |
635 | otherwise the test pattern will go through unconverted (except for | |
636 | the so-called 'Transfer Function' corrections and the R'G'B' to Y'CbCr | |
637 | conversion). This behavior is also what you want, since a 75% Colorbar | |
638 | should really have 75% signal intensity and should not be affected | |
639 | by colorspace conversions. | |
640 | ||
641 | Changing the colorspace will result in the V4L2_EVENT_SOURCE_CHANGE | |
642 | to be sent since it emulates a detected colorspace change. | |
643 | ||
644 | Limited RGB Range (16-235): selects if the RGB range of the HDMI source should | |
645 | be limited or full range. This combines with the Digital Video 'Rx RGB | |
646 | Quantization Range' control and can be used to test what happens if | |
647 | a source provides you with the wrong quantization range information. | |
648 | See the description of that control for more details. | |
649 | ||
650 | Apply Alpha To Red Only: apply the alpha channel as set by the 'Alpha Component' | |
651 | user control to the red color of the test pattern only. | |
652 | ||
653 | Enable Capture Cropping: enables crop support. This control is only present if | |
654 | the ccs_cap_mode module option is set to the default value of -1 and if | |
655 | the no_error_inj module option is set to 0 (the default). | |
656 | ||
657 | Enable Capture Composing: enables composing support. This control is only | |
658 | present if the ccs_cap_mode module option is set to the default value of | |
659 | -1 and if the no_error_inj module option is set to 0 (the default). | |
660 | ||
661 | Enable Capture Scaler: enables support for a scaler (maximum 4 times upscaling | |
662 | and downscaling). This control is only present if the ccs_cap_mode | |
663 | module option is set to the default value of -1 and if the no_error_inj | |
664 | module option is set to 0 (the default). | |
665 | ||
666 | Maximum EDID Blocks: determines how many EDID blocks the driver supports. | |
667 | Note that the vivid driver does not actually interpret new EDID | |
668 | data, it just stores it. It allows for up to 256 EDID blocks | |
669 | which is the maximum supported by the standard. | |
670 | ||
671 | Fill Percentage of Frame: can be used to draw only the top X percent | |
672 | of the image. Since each frame has to be drawn by the driver, this | |
673 | demands a lot of the CPU. For large resolutions this becomes | |
674 | problematic. By drawing only part of the image this CPU load can | |
675 | be reduced. | |
676 | ||
677 | ||
678 | Section 9.4.3: Output Feature Selection Controls | |
679 | ------------------------------------------------ | |
680 | ||
681 | These controls are all specific to video output. | |
682 | ||
683 | Enable Output Cropping: enables crop support. This control is only present if | |
684 | the ccs_out_mode module option is set to the default value of -1 and if | |
685 | the no_error_inj module option is set to 0 (the default). | |
686 | ||
687 | Enable Output Composing: enables composing support. This control is only | |
688 | present if the ccs_out_mode module option is set to the default value of | |
689 | -1 and if the no_error_inj module option is set to 0 (the default). | |
690 | ||
691 | Enable Output Scaler: enables support for a scaler (maximum 4 times upscaling | |
692 | and downscaling). This control is only present if the ccs_out_mode | |
693 | module option is set to the default value of -1 and if the no_error_inj | |
694 | module option is set to 0 (the default). | |
695 | ||
696 | ||
697 | Section 9.4.4: Error Injection Controls | |
698 | --------------------------------------- | |
699 | ||
700 | The following two controls are only valid for video and vbi capture. | |
701 | ||
702 | Standard Signal Mode: selects the behavior of VIDIOC_QUERYSTD: what should | |
703 | it return? | |
704 | ||
705 | Changing this control will result in the V4L2_EVENT_SOURCE_CHANGE | |
706 | to be sent since it emulates a changed input condition (e.g. a cable | |
707 | was plugged in or out). | |
708 | ||
709 | Standard: selects the standard that VIDIOC_QUERYSTD should return if the | |
710 | previous control is set to "Selected Standard". | |
711 | ||
712 | Changing this control will result in the V4L2_EVENT_SOURCE_CHANGE | |
713 | to be sent since it emulates a changed input standard. | |
714 | ||
715 | ||
716 | The following two controls are only valid for video capture. | |
717 | ||
718 | DV Timings Signal Mode: selects the behavior of VIDIOC_QUERY_DV_TIMINGS: what | |
719 | should it return? | |
720 | ||
721 | Changing this control will result in the V4L2_EVENT_SOURCE_CHANGE | |
722 | to be sent since it emulates a changed input condition (e.g. a cable | |
723 | was plugged in or out). | |
724 | ||
725 | DV Timings: selects the timings the VIDIOC_QUERY_DV_TIMINGS should return | |
726 | if the previous control is set to "Selected DV Timings". | |
727 | ||
728 | Changing this control will result in the V4L2_EVENT_SOURCE_CHANGE | |
729 | to be sent since it emulates changed input timings. | |
730 | ||
731 | ||
732 | The following controls are only present if the no_error_inj module option | |
733 | is set to 0 (the default). These controls are valid for video and vbi | |
734 | capture and output streams and for the SDR capture device except for the | |
735 | Disconnect control which is valid for all devices. | |
736 | ||
737 | Wrap Sequence Number: test what happens when you wrap the sequence number in | |
738 | struct v4l2_buffer around. | |
739 | ||
740 | Wrap Timestamp: test what happens when you wrap the timestamp in struct | |
741 | v4l2_buffer around. | |
742 | ||
743 | Percentage of Dropped Buffers: sets the percentage of buffers that | |
744 | are never returned by the driver (i.e., they are dropped). | |
745 | ||
746 | Disconnect: emulates a USB disconnect. The device will act as if it has | |
747 | been disconnected. Only after all open filehandles to the device | |
748 | node have been closed will the device become 'connected' again. | |
749 | ||
750 | Inject V4L2_BUF_FLAG_ERROR: when pressed, the next frame returned by | |
751 | the driver will have the error flag set (i.e. the frame is marked | |
752 | corrupt). | |
753 | ||
754 | Inject VIDIOC_REQBUFS Error: when pressed, the next REQBUFS or CREATE_BUFS | |
755 | ioctl call will fail with an error. To be precise: the videobuf2 | |
756 | queue_setup() op will return -EINVAL. | |
757 | ||
758 | Inject VIDIOC_QBUF Error: when pressed, the next VIDIOC_QBUF or | |
759 | VIDIOC_PREPARE_BUFFER ioctl call will fail with an error. To be | |
760 | precise: the videobuf2 buf_prepare() op will return -EINVAL. | |
761 | ||
762 | Inject VIDIOC_STREAMON Error: when pressed, the next VIDIOC_STREAMON ioctl | |
763 | call will fail with an error. To be precise: the videobuf2 | |
764 | start_streaming() op will return -EINVAL. | |
765 | ||
766 | Inject Fatal Streaming Error: when pressed, the streaming core will be | |
767 | marked as having suffered a fatal error, the only way to recover | |
768 | from that is to stop streaming. To be precise: the videobuf2 | |
769 | vb2_queue_error() function is called. | |
770 | ||
771 | ||
772 | Section 9.4.5: VBI Raw Capture Controls | |
773 | --------------------------------------- | |
774 | ||
775 | Interlaced VBI Format: if set, then the raw VBI data will be interlaced instead | |
776 | of providing it grouped by field. | |
777 | ||
778 | ||
779 | Section 9.5: Digital Video Controls | |
780 | ----------------------------------- | |
781 | ||
782 | Rx RGB Quantization Range: sets the RGB quantization detection of the HDMI | |
783 | input. This combines with the Vivid 'Limited RGB Range (16-235)' | |
784 | control and can be used to test what happens if a source provides | |
785 | you with the wrong quantization range information. This can be tested | |
786 | by selecting an HDMI input, setting this control to Full or Limited | |
787 | range and selecting the opposite in the 'Limited RGB Range (16-235)' | |
788 | control. The effect is easy to see if the 'Gray Ramp' test pattern | |
789 | is selected. | |
790 | ||
791 | Tx RGB Quantization Range: sets the RGB quantization detection of the HDMI | |
792 | output. It is currently not used for anything in vivid, but most HDMI | |
793 | transmitters would typically have this control. | |
794 | ||
795 | Transmit Mode: sets the transmit mode of the HDMI output to HDMI or DVI-D. This | |
796 | affects the reported colorspace since DVI_D outputs will always use | |
797 | sRGB. | |
798 | ||
799 | ||
800 | Section 9.6: FM Radio Receiver Controls | |
801 | --------------------------------------- | |
802 | ||
803 | RDS Reception: set if the RDS receiver should be enabled. | |
804 | ||
805 | RDS Program Type: | |
806 | RDS PS Name: | |
807 | RDS Radio Text: | |
808 | RDS Traffic Announcement: | |
809 | RDS Traffic Program: | |
810 | RDS Music: these are all read-only controls. If RDS Rx I/O Mode is set to | |
811 | "Block I/O", then they are inactive as well. If RDS Rx I/O Mode is set | |
812 | to "Controls", then these controls report the received RDS data. Note | |
813 | that the vivid implementation of this is pretty basic: they are only | |
814 | updated when you set a new frequency or when you get the tuner status | |
815 | (VIDIOC_G_TUNER). | |
816 | ||
817 | Radio HW Seek Mode: can be one of "Bounded", "Wrap Around" or "Both". This | |
818 | determines if VIDIOC_S_HW_FREQ_SEEK will be bounded by the frequency | |
819 | range or wrap-around or if it is selectable by the user. | |
820 | ||
821 | Radio Programmable HW Seek: if set, then the user can provide the lower and | |
822 | upper bound of the HW Seek. Otherwise the frequency range boundaries | |
823 | will be used. | |
824 | ||
825 | Generate RBDS Instead of RDS: if set, then generate RBDS (the US variant of | |
826 | RDS) data instead of RDS (European-style RDS). This affects only the | |
827 | PICODE and PTY codes. | |
828 | ||
829 | RDS Rx I/O Mode: this can be "Block I/O" where the RDS blocks have to be read() | |
830 | by the application, or "Controls" where the RDS data is provided by | |
831 | the RDS controls mentioned above. | |
832 | ||
833 | ||
834 | Section 9.7: FM Radio Modulator Controls | |
835 | ---------------------------------------- | |
836 | ||
837 | RDS Program ID: | |
838 | RDS Program Type: | |
839 | RDS PS Name: | |
840 | RDS Radio Text: | |
841 | RDS Stereo: | |
842 | RDS Artificial Head: | |
843 | RDS Compressed: | |
844 | RDS Dymanic PTY: | |
845 | RDS Traffic Announcement: | |
846 | RDS Traffic Program: | |
847 | RDS Music: these are all controls that set the RDS data that is transmitted by | |
848 | the FM modulator. | |
849 | ||
850 | RDS Tx I/O Mode: this can be "Block I/O" where the application has to use write() | |
851 | to pass the RDS blocks to the driver, or "Controls" where the RDS data is | |
852 | provided by the RDS controls mentioned above. | |
853 | ||
854 | ||
855 | Section 10: Video, VBI and RDS Looping | |
856 | -------------------------------------- | |
857 | ||
858 | The vivid driver supports looping of video output to video input, VBI output | |
859 | to VBI input and RDS output to RDS input. For video/VBI looping this emulates | |
860 | as if a cable was hooked up between the output and input connector. So video | |
861 | and VBI looping is only supported between S-Video and HDMI inputs and outputs. | |
862 | VBI is only valid for S-Video as it makes no sense for HDMI. | |
863 | ||
864 | Since radio is wireless this looping always happens if the radio receiver | |
865 | frequency is close to the radio transmitter frequency. In that case the radio | |
866 | transmitter will 'override' the emulated radio stations. | |
867 | ||
868 | Looping is currently supported only between devices created by the same | |
869 | vivid driver instance. | |
870 | ||
871 | ||
872 | Section 10.1: Video and Sliced VBI looping | |
873 | ------------------------------------------ | |
874 | ||
875 | The way to enable video/VBI looping is currently fairly crude. A 'Loop Video' | |
876 | control is available in the "Vivid" control class of the video | |
877 | output and VBI output devices. When checked the video looping will be enabled. | |
878 | Once enabled any video S-Video or HDMI input will show a static test pattern | |
879 | until the video output has started. At that time the video output will be | |
880 | looped to the video input provided that: | |
881 | ||
882 | - the input type matches the output type. So the HDMI input cannot receive | |
883 | video from the S-Video output. | |
884 | ||
885 | - the video resolution of the video input must match that of the video output. | |
886 | So it is not possible to loop a 50 Hz (720x576) S-Video output to a 60 Hz | |
887 | (720x480) S-Video input, or a 720p60 HDMI output to a 1080p30 input. | |
888 | ||
889 | - the pixel formats must be identical on both sides. Otherwise the driver would | |
890 | have to do pixel format conversion as well, and that's taking things too far. | |
891 | ||
892 | - the field settings must be identical on both sides. Same reason as above: | |
893 | requiring the driver to convert from one field format to another complicated | |
894 | matters too much. This also prohibits capturing with 'Field Top' or 'Field | |
895 | Bottom' when the output video is set to 'Field Alternate'. This combination, | |
896 | while legal, became too complicated to support. Both sides have to be 'Field | |
897 | Alternate' for this to work. Also note that for this specific case the | |
898 | sequence and field counting in struct v4l2_buffer on the capture side may not | |
899 | be 100% accurate. | |
900 | ||
901 | - on the input side the "Standard Signal Mode" for the S-Video input or the | |
902 | "DV Timings Signal Mode" for the HDMI input should be configured so that a | |
903 | valid signal is passed to the video input. | |
904 | ||
905 | The framerates do not have to match, although this might change in the future. | |
906 | ||
907 | By default you will see the OSD text superimposed on top of the looped video. | |
908 | This can be turned off by changing the "OSD Text Mode" control of the video | |
909 | capture device. | |
910 | ||
911 | For VBI looping to work all of the above must be valid and in addition the vbi | |
912 | output must be configured for sliced VBI. The VBI capture side can be configured | |
62f28725 HV |
913 | for either raw or sliced VBI. Note that at the moment only CC/XDS (60 Hz formats) |
914 | and WSS (50 Hz formats) VBI data is looped. Teletext VBI data is not looped. | |
6a683493 HV |
915 | |
916 | ||
917 | Section 10.2: Radio & RDS Looping | |
918 | --------------------------------- | |
919 | ||
920 | As mentioned in section 6 the radio receiver emulates stations are regular | |
921 | frequency intervals. Depending on the frequency of the radio receiver a | |
922 | signal strength value is calculated (this is returned by VIDIOC_G_TUNER). | |
923 | However, it will also look at the frequency set by the radio transmitter and | |
924 | if that results in a higher signal strength than the settings of the radio | |
925 | transmitter will be used as if it was a valid station. This also includes | |
926 | the RDS data (if any) that the transmitter 'transmits'. This is received | |
927 | faithfully on the receiver side. Note that when the driver is loaded the | |
928 | frequencies of the radio receiver and transmitter are not identical, so | |
929 | initially no looping takes place. | |
930 | ||
931 | ||
932 | Section 11: Cropping, Composing, Scaling | |
933 | ---------------------------------------- | |
934 | ||
935 | This driver supports cropping, composing and scaling in any combination. Normally | |
936 | which features are supported can be selected through the Vivid controls, | |
937 | but it is also possible to hardcode it when the module is loaded through the | |
938 | ccs_cap_mode and ccs_out_mode module options. See section 1 on the details of | |
939 | these module options. | |
940 | ||
941 | This allows you to test your application for all these variations. | |
942 | ||
943 | Note that the webcam input never supports cropping, composing or scaling. That | |
944 | only applies to the TV/S-Video/HDMI inputs and outputs. The reason is that | |
945 | webcams, including this virtual implementation, normally use | |
946 | VIDIOC_ENUM_FRAMESIZES to list a set of discrete framesizes that it supports. | |
947 | And that does not combine with cropping, composing or scaling. This is | |
948 | primarily a limitation of the V4L2 API which is carefully reproduced here. | |
949 | ||
950 | The minimum and maximum resolutions that the scaler can achieve are 16x16 and | |
951 | (4096 * 4) x (2160 x 4), but it can only scale up or down by a factor of 4 or | |
952 | less. So for a source resolution of 1280x720 the minimum the scaler can do is | |
953 | 320x180 and the maximum is 5120x2880. You can play around with this using the | |
954 | qv4l2 test tool and you will see these dependencies. | |
955 | ||
956 | This driver also supports larger 'bytesperline' settings, something that | |
957 | VIDIOC_S_FMT allows but that few drivers implement. | |
958 | ||
959 | The scaler is a simple scaler that uses the Coarse Bresenham algorithm. It's | |
960 | designed for speed and simplicity, not quality. | |
961 | ||
962 | If the combination of crop, compose and scaling allows it, then it is possible | |
963 | to change crop and compose rectangles on the fly. | |
964 | ||
965 | ||
966 | Section 12: Formats | |
967 | ------------------- | |
968 | ||
969 | The driver supports all the regular packed YUYV formats, 16, 24 and 32 RGB | |
970 | packed formats and two multiplanar formats (one luma and one chroma plane). | |
971 | ||
972 | The alpha component can be set through the 'Alpha Component' User control | |
973 | for those formats that support it. If the 'Apply Alpha To Red Only' control | |
974 | is set, then the alpha component is only used for the color red and set to | |
975 | 0 otherwise. | |
976 | ||
977 | The driver has to be configured to support the multiplanar formats. By default | |
978 | the first driver instance is single-planar, the second is multi-planar, and it | |
979 | keeps alternating. This can be changed by setting the multiplanar module option, | |
980 | see section 1 for more details on that option. | |
981 | ||
982 | If the driver instance is using the multiplanar formats/API, then the first | |
983 | single planar format (YUYV) and the multiplanar NV16M and NV61M formats the | |
984 | will have a plane that has a non-zero data_offset of 128 bytes. It is rare for | |
985 | data_offset to be non-zero, so this is a useful feature for testing applications. | |
986 | ||
987 | Video output will also honor any data_offset that the application set. | |
988 | ||
989 | ||
990 | Section 13: Capture Overlay | |
991 | --------------------------- | |
992 | ||
993 | Note: capture overlay support is implemented primarily to test the existing | |
994 | V4L2 capture overlay API. In practice few if any GPUs support such overlays | |
995 | anymore, and neither are they generally needed anymore since modern hardware | |
996 | is so much more capable. By setting flag 0x10000 in the node_types module | |
997 | option the vivid driver will create a simple framebuffer device that can be | |
998 | used for testing this API. Whether this API should be used for new drivers is | |
999 | questionable. | |
1000 | ||
1001 | This driver has support for a destructive capture overlay with bitmap clipping | |
1002 | and list clipping (up to 16 rectangles) capabilities. Overlays are not | |
1003 | supported for multiplanar formats. It also honors the struct v4l2_window field | |
1004 | setting: if it is set to FIELD_TOP or FIELD_BOTTOM and the capture setting is | |
1005 | FIELD_ALTERNATE, then only the top or bottom fields will be copied to the overlay. | |
1006 | ||
1007 | The overlay only works if you are also capturing at that same time. This is a | |
1008 | vivid limitation since it copies from a buffer to the overlay instead of | |
1009 | filling the overlay directly. And if you are not capturing, then no buffers | |
1010 | are available to fill. | |
1011 | ||
1012 | In addition, the pixelformat of the capture format and that of the framebuffer | |
1013 | must be the same for the overlay to work. Otherwise VIDIOC_OVERLAY will return | |
1014 | an error. | |
1015 | ||
1016 | In order to really see what it going on you will need to create two vivid | |
1017 | instances: the first with a framebuffer enabled. You configure the capture | |
1018 | overlay of the second instance to use the framebuffer of the first, then | |
1019 | you start capturing in the second instance. For the first instance you setup | |
1020 | the output overlay for the video output, turn on video looping and capture | |
1021 | to see the blended framebuffer overlay that's being written to by the second | |
1022 | instance. This setup would require the following commands: | |
1023 | ||
1024 | $ sudo modprobe vivid n_devs=2 node_types=0x10101,0x1 multiplanar=1,1 | |
1025 | $ v4l2-ctl -d1 --find-fb | |
1026 | /dev/fb1 is the framebuffer associated with base address 0x12800000 | |
1027 | $ sudo v4l2-ctl -d2 --set-fbuf fb=1 | |
1028 | $ v4l2-ctl -d1 --set-fbuf fb=1 | |
1029 | $ v4l2-ctl -d0 --set-fmt-video=pixelformat='AR15' | |
1030 | $ v4l2-ctl -d1 --set-fmt-video-out=pixelformat='AR15' | |
1031 | $ v4l2-ctl -d2 --set-fmt-video=pixelformat='AR15' | |
1032 | $ v4l2-ctl -d0 -i2 | |
1033 | $ v4l2-ctl -d2 -i2 | |
1034 | $ v4l2-ctl -d2 -c horizontal_movement=4 | |
1035 | $ v4l2-ctl -d1 --overlay=1 | |
1036 | $ v4l2-ctl -d1 -c loop_video=1 | |
1037 | $ v4l2-ctl -d2 --stream-mmap --overlay=1 | |
1038 | ||
1039 | And from another console: | |
1040 | ||
1041 | $ v4l2-ctl -d1 --stream-out-mmap | |
1042 | ||
1043 | And yet another console: | |
1044 | ||
1045 | $ qv4l2 | |
1046 | ||
1047 | and start streaming. | |
1048 | ||
1049 | As you can see, this is not for the faint of heart... | |
1050 | ||
1051 | ||
1052 | Section 14: Output Overlay | |
1053 | -------------------------- | |
1054 | ||
1055 | Note: output overlays are primarily implemented in order to test the existing | |
1056 | V4L2 output overlay API. Whether this API should be used for new drivers is | |
1057 | questionable. | |
1058 | ||
1059 | This driver has support for an output overlay and is capable of: | |
1060 | ||
1061 | - bitmap clipping, | |
1062 | - list clipping (up to 16 rectangles) | |
1063 | - chromakey | |
1064 | - source chromakey | |
1065 | - global alpha | |
1066 | - local alpha | |
1067 | - local inverse alpha | |
1068 | ||
1069 | Output overlays are not supported for multiplanar formats. In addition, the | |
1070 | pixelformat of the capture format and that of the framebuffer must be the | |
1071 | same for the overlay to work. Otherwise VIDIOC_OVERLAY will return an error. | |
1072 | ||
1073 | Output overlays only work if the driver has been configured to create a | |
1074 | framebuffer by setting flag 0x10000 in the node_types module option. The | |
1075 | created framebuffer has a size of 720x576 and supports ARGB 1:5:5:5 and | |
1076 | RGB 5:6:5. | |
1077 | ||
1078 | In order to see the effects of the various clipping, chromakeying or alpha | |
1079 | processing capabilities you need to turn on video looping and see the results | |
1080 | on the capture side. The use of the clipping, chromakeying or alpha processing | |
1081 | capabilities will slow down the video loop considerably as a lot of checks have | |
1082 | to be done per pixel. | |
1083 | ||
1084 | ||
1085 | Section 15: Some Future Improvements | |
1086 | ------------------------------------ | |
1087 | ||
1088 | Just as a reminder and in no particular order: | |
1089 | ||
1090 | - Add a virtual alsa driver to test audio | |
1091 | - Add virtual sub-devices and media controller support | |
1092 | - Some support for testing compressed video | |
1093 | - Add support to loop raw VBI output to raw VBI input | |
62f28725 | 1094 | - Add support to loop teletext sliced VBI output to VBI input |
6a683493 HV |
1095 | - Fix sequence/field numbering when looping of video with alternate fields |
1096 | - Add support for V4L2_CID_BG_COLOR for video outputs | |
1097 | - Add ARGB888 overlay support: better testing of the alpha channel | |
1098 | - Add custom DV timings support | |
1099 | - Add support for V4L2_DV_FL_REDUCED_FPS | |
1100 | - Improve pixel aspect support in the tpg code by passing a real v4l2_fract | |
1101 | - Use per-queue locks and/or per-device locks to improve throughput | |
1102 | - Add support to loop from a specific output to a specific input across | |
1103 | vivid instances | |
1104 | - Add support for VIDIOC_EXPBUF once support for that has been added to vb2 | |
1105 | - The SDR radio should use the same 'frequencies' for stations as the normal | |
1106 | radio receiver, and give back noise if the frequency doesn't match up with | |
1107 | a station frequency | |
1108 | - Improve the sine generation of the SDR radio. | |
1109 | - Make a thread for the RDS generation, that would help in particular for the | |
1110 | "Controls" RDS Rx I/O Mode as the read-only RDS controls could be updated | |
1111 | in real-time. |