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Hans Verkuil6a683492014-08-25 07:52:44 -03001vivid: Virtual Video Test Driver
2================================
3
4This driver emulates video4linux hardware of various types: video capture, video
5output, vbi capture and output, radio receivers and transmitters and a software
6defined radio receiver. In addition a simple framebuffer device is available for
7testing capture and output overlays.
8
9Up to 64 vivid instances can be created, each with up to 16 inputs and 16 outputs.
10
11Each input can be a webcam, TV capture device, S-Video capture device or an HDMI
12capture device. Each output can be an S-Video output device or an HDMI output
13device.
14
15These inputs and outputs act exactly as a real hardware device would behave. This
16allows you to use this driver as a test input for application development, since
17you can test the various features without requiring special hardware.
18
19This 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
38These features will be described in more detail below.
39
40
41Table of Contents
42-----------------
43
44Section 1: Configuring the driver
45Section 2: Video Capture
46Section 2.1: Webcam Input
47Section 2.2: TV and S-Video Inputs
48Section 2.3: HDMI Input
49Section 3: Video Output
50Section 3.1: S-Video Output
51Section 3.2: HDMI Output
52Section 4: VBI Capture
53Section 5: VBI Output
54Section 6: Radio Receiver
55Section 7: Radio Transmitter
56Section 8: Software Defined Radio Receiver
57Section 9: Controls
58Section 9.1: User Controls - Test Controls
59Section 9.2: User Controls - Video Capture
60Section 9.3: User Controls - Audio
61Section 9.4: Vivid Controls
62Section 9.4.1: Test Pattern Controls
63Section 9.4.2: Capture Feature Selection Controls
64Section 9.4.3: Output Feature Selection Controls
65Section 9.4.4: Error Injection Controls
66Section 9.4.5: VBI Raw Capture Controls
67Section 9.5: Digital Video Controls
68Section 9.6: FM Radio Receiver Controls
69Section 9.7: FM Radio Modulator
70Section 10: Video, VBI and RDS Looping
71Section 10.1: Video and Sliced VBI looping
72Section 10.2: Radio & RDS Looping
73Section 11: Cropping, Composing, Scaling
74Section 12: Formats
75Section 13: Capture Overlay
76Section 14: Output Overlay
77Section 15: Some Future Improvements
78
79
80Section 1: Configuring the driver
81---------------------------------
82
83By default the driver will create a single instance that has a video capture
84device with webcam, TV, S-Video and HDMI inputs, a video output device with
85S-Video and HDMI outputs, one vbi capture device, one vbi output device, one
86radio receiver device, one radio transmitter device and one SDR device.
87
88The number of instances, devices, video inputs and outputs and their types are
89all configurable using the following module options:
90
91n_devs: number of driver instances to create. By default set to 1. Up to 64
92 instances can be created.
93
94node_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
112num_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
116input_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
133num_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
137output_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
152vid_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
163vid_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
166vbi_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
169vbi_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
172radio_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
175radio_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
178sdr_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
181ccs_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
204ccs_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
223multiplanar: select whether each device instance supports multi-planar formats,
Hans Verkuilcba63cf2014-11-03 07:42:09 -0300224 and thus the V4L2 multi-planar API. By default device instances are
225 single-planar.
Hans Verkuil6a683492014-08-25 07:52:44 -0300226
227 This module option can override that for each instance. Values are:
228
Hans Verkuil6a683492014-08-25 07:52:44 -0300229 1: this is a single-planar instance.
230 2: this is a multi-planar instance.
231
232vivid_debug: enable driver debugging info
233
234no_error_inj: if set disable the error injecting controls. This option is
235 needed in order to run a tool like v4l2-compliance. Tools like that
236 exercise all controls including a control like 'Disconnect' which
237 emulates a USB disconnect, making the device inaccessible and so
238 all tests that v4l2-compliance is doing will fail afterwards.
239
240 There may be other situations as well where you want to disable the
241 error injection support of vivid. When this option is set, then the
242 controls that select crop, compose and scale behavior are also
243 removed. Unless overridden by ccs_cap_mode and/or ccs_out_mode the
244 will default to enabling crop, compose and scaling.
245
246Taken together, all these module options allow you to precisely customize
247the driver behavior and test your application with all sorts of permutations.
248It is also very suitable to emulate hardware that is not yet available, e.g.
249when developing software for a new upcoming device.
250
251
252Section 2: Video Capture
253------------------------
254
255This is probably the most frequently used feature. The video capture device
256can be configured by using the module options num_inputs, input_types and
257ccs_cap_mode (see section 1 for more detailed information), but by default
258four inputs are configured: a webcam, a TV tuner, an S-Video and an HDMI
259input, one input for each input type. Those are described in more detail
260below.
261
262Special attention has been given to the rate at which new frames become
263available. The jitter will be around 1 jiffie (that depends on the HZ
264configuration of your kernel, so usually 1/100, 1/250 or 1/1000 of a second),
265but the long-term behavior is exactly following the framerate. So a
266framerate of 59.94 Hz is really different from 60 Hz. If the framerate
267exceeds your kernel's HZ value, then you will get dropped frames, but the
268frame/field sequence counting will keep track of that so the sequence
269count will skip whenever frames are dropped.
270
271
272Section 2.1: Webcam Input
273-------------------------
274
275The webcam input supports three framesizes: 320x180, 640x360 and 1280x720. It
276supports frames per second settings of 10, 15, 25, 30, 50 and 60 fps. Which ones
277are available depends on the chosen framesize: the larger the framesize, the
278lower the maximum frames per second.
279
280The initially selected colorspace when you switch to the webcam input will be
281sRGB.
282
283
284Section 2.2: TV and S-Video Inputs
285----------------------------------
286
287The only difference between the TV and S-Video input is that the TV has a
288tuner. Otherwise they behave identically.
289
290These inputs support audio inputs as well: one TV and one Line-In. They
291both support all TV standards. If the standard is queried, then the Vivid
292controls 'Standard Signal Mode' and 'Standard' determine what
293the result will be.
294
295These inputs support all combinations of the field setting. Special care has
296been taken to faithfully reproduce how fields are handled for the different
297TV standards. This is particularly noticable when generating a horizontally
298moving image so the temporal effect of using interlaced formats becomes clearly
299visible. For 50 Hz standards the top field is the oldest and the bottom field
300is the newest in time. For 60 Hz standards that is reversed: the bottom field
301is the oldest and the top field is the newest in time.
302
303When you start capturing in V4L2_FIELD_ALTERNATE mode the first buffer will
304contain the top field for 50 Hz standards and the bottom field for 60 Hz
305standards. This is what capture hardware does as well.
306
307Finally, for PAL/SECAM standards the first half of the top line contains noise.
308This simulates the Wide Screen Signal that is commonly placed there.
309
310The initially selected colorspace when you switch to the TV or S-Video input
311will be SMPTE-170M.
312
313The pixel aspect ratio will depend on the TV standard. The video aspect ratio
314can be selected through the 'Standard Aspect Ratio' Vivid control.
315Choices are '4x3', '16x9' which will give letterboxed widescreen video and
316'16x9 Anomorphic' which will give full screen squashed anamorphic widescreen
317video that will need to be scaled accordingly.
318
319The TV 'tuner' supports a frequency range of 44-958 MHz. Channels are available
320every 6 MHz, starting from 49.25 MHz. For each channel the generated image
321will be in color for the +/- 0.25 MHz around it, and in grayscale for
322+/- 1 MHz around the channel. Beyond that it is just noise. The VIDIOC_G_TUNER
323ioctl will return 100% signal strength for +/- 0.25 MHz and 50% for +/- 1 MHz.
324It will also return correct afc values to show whether the frequency is too
325low or too high.
326
327The audio subchannels that are returned are MONO for the +/- 1 MHz range around
328a valid channel frequency. When the frequency is within +/- 0.25 MHz of the
329channel it will return either MONO, STEREO, either MONO | SAP (for NTSC) or
330LANG1 | LANG2 (for others), or STEREO | SAP.
331
332Which one is returned depends on the chosen channel, each next valid channel
333will cycle through the possible audio subchannel combinations. This allows
334you to test the various combinations by just switching channels..
335
336Finally, for these inputs the v4l2_timecode struct is filled in in the
337dequeued v4l2_buffer struct.
338
339
340Section 2.3: HDMI Input
341-----------------------
342
343The HDMI inputs supports all CEA-861 and DMT timings, both progressive and
344interlaced, for pixelclock frequencies between 25 and 600 MHz. The field
345mode for interlaced formats is always V4L2_FIELD_ALTERNATE. For HDMI the
346field order is always top field first, and when you start capturing an
347interlaced format you will receive the top field first.
348
349The initially selected colorspace when you switch to the HDMI input or
350select an HDMI timing is based on the format resolution: for resolutions
351less than or equal to 720x576 the colorspace is set to SMPTE-170M, for
352others it is set to REC-709 (CEA-861 timings) or sRGB (VESA DMT timings).
353
354The pixel aspect ratio will depend on the HDMI timing: for 720x480 is it
355set as for the NTSC TV standard, for 720x576 it is set as for the PAL TV
356standard, and for all others a 1:1 pixel aspect ratio is returned.
357
358The video aspect ratio can be selected through the 'DV Timings Aspect Ratio'
359Vivid control. Choices are 'Source Width x Height' (just use the
360same ratio as the chosen format), '4x3' or '16x9', either of which can
361result in pillarboxed or letterboxed video.
362
363For HDMI inputs it is possible to set the EDID. By default a simple EDID
364is provided. You can only set the EDID for HDMI inputs. Internally, however,
365the EDID is shared between all HDMI inputs.
366
367No interpretation is done of the EDID data.
368
369
370Section 3: Video Output
371-----------------------
372
373The video output device can be configured by using the module options
374num_outputs, output_types and ccs_out_mode (see section 1 for more detailed
375information), but by default two outputs are configured: an S-Video and an
376HDMI input, one output for each output type. Those are described in more detail
377below.
378
379Like with video capture the framerate is also exact in the long term.
380
381
382Section 3.1: S-Video Output
383---------------------------
384
385This output supports audio outputs as well: "Line-Out 1" and "Line-Out 2".
386The S-Video output supports all TV standards.
387
388This output supports all combinations of the field setting.
389
390The initially selected colorspace when you switch to the TV or S-Video input
391will be SMPTE-170M.
392
393
394Section 3.2: HDMI Output
395------------------------
396
397The HDMI output supports all CEA-861 and DMT timings, both progressive and
398interlaced, for pixelclock frequencies between 25 and 600 MHz. The field
399mode for interlaced formats is always V4L2_FIELD_ALTERNATE.
400
401The initially selected colorspace when you switch to the HDMI output or
402select an HDMI timing is based on the format resolution: for resolutions
403less than or equal to 720x576 the colorspace is set to SMPTE-170M, for
404others it is set to REC-709 (CEA-861 timings) or sRGB (VESA DMT timings).
405
406The pixel aspect ratio will depend on the HDMI timing: for 720x480 is it
407set as for the NTSC TV standard, for 720x576 it is set as for the PAL TV
408standard, and for all others a 1:1 pixel aspect ratio is returned.
409
410An HDMI output has a valid EDID which can be obtained through VIDIOC_G_EDID.
411
412
413Section 4: VBI Capture
414----------------------
415
416There are three types of VBI capture devices: those that only support raw
417(undecoded) VBI, those that only support sliced (decoded) VBI and those that
418support both. This is determined by the node_types module option. In all
419cases the driver will generate valid VBI data: for 60 Hz standards it will
420generate Closed Caption and XDS data. The closed caption stream will
421alternate between "Hello world!" and "Closed captions test" every second.
422The XDS stream will give the current time once a minute. For 50 Hz standards
423it will generate the Wide Screen Signal which is based on the actual Video
Hans Verkuil62f28722014-09-20 06:11:44 -0300424Aspect Ratio control setting and teletext pages 100-159, one page per frame.
Hans Verkuil6a683492014-08-25 07:52:44 -0300425
426The VBI device will only work for the S-Video and TV inputs, it will give
427back an error if the current input is a webcam or HDMI.
428
429
430Section 5: VBI Output
431---------------------
432
433There are three types of VBI output devices: those that only support raw
434(undecoded) VBI, those that only support sliced (decoded) VBI and those that
435support both. This is determined by the node_types module option.
436
Hans Verkuil62f28722014-09-20 06:11:44 -0300437The sliced VBI output supports the Wide Screen Signal and the teletext signal
438for 50 Hz standards and Closed Captioning + XDS for 60 Hz standards.
Hans Verkuil6a683492014-08-25 07:52:44 -0300439
440The VBI device will only work for the S-Video output, it will give
441back an error if the current output is HDMI.
442
443
444Section 6: Radio Receiver
445-------------------------
446
447The radio receiver emulates an FM/AM/SW receiver. The FM band also supports RDS.
448The frequency ranges are:
449
450 FM: 64 MHz - 108 MHz
451 AM: 520 kHz - 1710 kHz
452 SW: 2300 kHz - 26.1 MHz
453
454Valid channels are emulated every 1 MHz for FM and every 100 kHz for AM and SW.
455The signal strength decreases the further the frequency is from the valid
456frequency until it becomes 0% at +/- 50 kHz (FM) or 5 kHz (AM/SW) from the
457ideal frequency. The initial frequency when the driver is loaded is set to
45895 MHz.
459
460The FM receiver supports RDS as well, both using 'Block I/O' and 'Controls'
461modes. In the 'Controls' mode the RDS information is stored in read-only
462controls. These controls are updated every time the frequency is changed,
463or when the tuner status is requested. The Block I/O method uses the read()
464interface to pass the RDS blocks on to the application for decoding.
465
466The RDS signal is 'detected' for +/- 12.5 kHz around the channel frequency,
467and the further the frequency is away from the valid frequency the more RDS
468errors are randomly introduced into the block I/O stream, up to 50% of all
469blocks if you are +/- 12.5 kHz from the channel frequency. All four errors
470can occur in equal proportions: blocks marked 'CORRECTED', blocks marked
471'ERROR', blocks marked 'INVALID' and dropped blocks.
472
473The generated RDS stream contains all the standard fields contained in a
4740B group, and also radio text and the current time.
475
476The receiver supports HW frequency seek, either in Bounded mode, Wrap Around
477mode or both, which is configurable with the "Radio HW Seek Mode" control.
478
479
480Section 7: Radio Transmitter
481----------------------------
482
483The radio transmitter emulates an FM/AM/SW transmitter. The FM band also supports RDS.
484The frequency ranges are:
485
486 FM: 64 MHz - 108 MHz
487 AM: 520 kHz - 1710 kHz
488 SW: 2300 kHz - 26.1 MHz
489
490The initial frequency when the driver is loaded is 95.5 MHz.
491
492The FM transmitter supports RDS as well, both using 'Block I/O' and 'Controls'
493modes. In the 'Controls' mode the transmitted RDS information is configured
494using controls, and in 'Block I/O' mode the blocks are passed to the driver
495using write().
496
497
498Section 8: Software Defined Radio Receiver
499------------------------------------------
500
501The SDR receiver has three frequency bands for the ADC tuner:
502
503 - 300 kHz
504 - 900 kHz - 2800 kHz
505 - 3200 kHz
506
507The RF tuner supports 50 MHz - 2000 MHz.
508
509The generated data contains the In-phase and Quadrature components of a
5101 kHz tone that has an amplitude of sqrt(2).
511
512
513Section 9: Controls
514-------------------
515
516Different devices support different controls. The sections below will describe
517each control and which devices support them.
518
519
520Section 9.1: User Controls - Test Controls
521------------------------------------------
522
523The Button, Boolean, Integer 32 Bits, Integer 64 Bits, Menu, String, Bitmask and
524Integer Menu are controls that represent all possible control types. The Menu
525control and the Integer Menu control both have 'holes' in their menu list,
526meaning that one or more menu items return EINVAL when VIDIOC_QUERYMENU is called.
527Both menu controls also have a non-zero minimum control value. These features
528allow you to check if your application can handle such things correctly.
529These controls are supported for every device type.
530
531
532Section 9.2: User Controls - Video Capture
533------------------------------------------
534
535The following controls are specific to video capture.
536
537The Brightness, Contrast, Saturation and Hue controls actually work and are
538standard. There is one special feature with the Brightness control: each
539video input has its own brightness value, so changing input will restore
540the brightness for that input. In addition, each video input uses a different
541brightness range (minimum and maximum control values). Switching inputs will
542cause a control event to be sent with the V4L2_EVENT_CTRL_CH_RANGE flag set.
543This allows you to test controls that can change their range.
544
545The 'Gain, Automatic' and Gain controls can be used to test volatile controls:
546if 'Gain, Automatic' is set, then the Gain control is volatile and changes
547constantly. If 'Gain, Automatic' is cleared, then the Gain control is a normal
548control.
549
550The 'Horizontal Flip' and 'Vertical Flip' controls can be used to flip the
551image. These combine with the 'Sensor Flipped Horizontally/Vertically' Vivid
552controls.
553
554The 'Alpha Component' control can be used to set the alpha component for
555formats containing an alpha channel.
556
557
558Section 9.3: User Controls - Audio
559----------------------------------
560
561The following controls are specific to video capture and output and radio
562receivers and transmitters.
563
564The 'Volume' and 'Mute' audio controls are typical for such devices to
565control the volume and mute the audio. They don't actually do anything in
566the vivid driver.
567
568
569Section 9.4: Vivid Controls
570---------------------------
571
572These vivid custom controls control the image generation, error injection, etc.
573
574
575Section 9.4.1: Test Pattern Controls
576------------------------------------
577
578The Test Pattern Controls are all specific to video capture.
579
580Test Pattern: selects which test pattern to use. Use the CSC Colorbar for
581 testing colorspace conversions: the colors used in that test pattern
582 map to valid colors in all colorspaces. The colorspace conversion
583 is disabled for the other test patterns.
584
585OSD Text Mode: selects whether the text superimposed on the
586 test pattern should be shown, and if so, whether only counters should
587 be displayed or the full text.
588
589Horizontal Movement: selects whether the test pattern should
590 move to the left or right and at what speed.
591
592Vertical Movement: does the same for the vertical direction.
593
594Show Border: show a two-pixel wide border at the edge of the actual image,
595 excluding letter or pillarboxing.
596
597Show Square: show a square in the middle of the image. If the image is
598 displayed with the correct pixel and image aspect ratio corrections,
599 then the width and height of the square on the monitor should be
600 the same.
601
602Insert SAV Code in Image: adds a SAV (Start of Active Video) code to the image.
603 This can be used to check if such codes in the image are inadvertently
604 interpreted instead of being ignored.
605
606Insert EAV Code in Image: does the same for the EAV (End of Active Video) code.
607
608
609Section 9.4.2: Capture Feature Selection Controls
610-------------------------------------------------
611
612These controls are all specific to video capture.
613
614Sensor Flipped Horizontally: the image is flipped horizontally and the
615 V4L2_IN_ST_HFLIP input status flag is set. This emulates the case where
616 a sensor is for example mounted upside down.
617
618Sensor Flipped Vertically: the image is flipped vertically and the
619 V4L2_IN_ST_VFLIP input status flag is set. This emulates the case where
620 a sensor is for example mounted upside down.
621
622Standard Aspect Ratio: selects if the image aspect ratio as used for the TV or
623 S-Video input should be 4x3, 16x9 or anamorphic widescreen. This may
624 introduce letterboxing.
625
626DV Timings Aspect Ratio: selects if the image aspect ratio as used for the HDMI
627 input should be the same as the source width and height ratio, or if
628 it should be 4x3 or 16x9. This may introduce letter or pillarboxing.
629
630Timestamp Source: selects when the timestamp for each buffer is taken.
631
632Colorspace: selects which colorspace should be used when generating the image.
633 This only applies if the CSC Colorbar test pattern is selected,
634 otherwise the test pattern will go through unconverted (except for
635 the so-called 'Transfer Function' corrections and the R'G'B' to Y'CbCr
636 conversion). This behavior is also what you want, since a 75% Colorbar
637 should really have 75% signal intensity and should not be affected
638 by colorspace conversions.
639
640 Changing the colorspace will result in the V4L2_EVENT_SOURCE_CHANGE
641 to be sent since it emulates a detected colorspace change.
642
Hans Verkuil38913a52014-12-05 10:18:38 -0300643Y'CbCr Encoding: selects which Y'CbCr encoding should be used when generating
644 a Y'CbCr image. This only applies if the CSC Colorbar test pattern is
645 selected, and if the format is set to a Y'CbCr format as opposed to an
646 RGB format.
647
648 Changing the Y'CbCr encoding will result in the V4L2_EVENT_SOURCE_CHANGE
649 to be sent since it emulates a detected colorspace change.
650
651Quantization: selects which quantization should be used for the RGB or Y'CbCr
652 encoding when generating the test pattern. This only applies if the CSC
653 Colorbar test pattern is selected.
654
655 Changing the quantization will result in the V4L2_EVENT_SOURCE_CHANGE
656 to be sent since it emulates a detected colorspace change.
657
Hans Verkuil6a683492014-08-25 07:52:44 -0300658Limited RGB Range (16-235): selects if the RGB range of the HDMI source should
659 be limited or full range. This combines with the Digital Video 'Rx RGB
660 Quantization Range' control and can be used to test what happens if
661 a source provides you with the wrong quantization range information.
662 See the description of that control for more details.
663
664Apply Alpha To Red Only: apply the alpha channel as set by the 'Alpha Component'
665 user control to the red color of the test pattern only.
666
667Enable Capture Cropping: enables crop support. This control is only present if
668 the ccs_cap_mode module option is set to the default value of -1 and if
669 the no_error_inj module option is set to 0 (the default).
670
671Enable Capture Composing: enables composing support. This control is only
672 present if the ccs_cap_mode module option is set to the default value of
673 -1 and if the no_error_inj module option is set to 0 (the default).
674
675Enable Capture Scaler: enables support for a scaler (maximum 4 times upscaling
676 and downscaling). This control is only present if the ccs_cap_mode
677 module option is set to the default value of -1 and if the no_error_inj
678 module option is set to 0 (the default).
679
680Maximum EDID Blocks: determines how many EDID blocks the driver supports.
681 Note that the vivid driver does not actually interpret new EDID
682 data, it just stores it. It allows for up to 256 EDID blocks
683 which is the maximum supported by the standard.
684
685Fill Percentage of Frame: can be used to draw only the top X percent
686 of the image. Since each frame has to be drawn by the driver, this
687 demands a lot of the CPU. For large resolutions this becomes
688 problematic. By drawing only part of the image this CPU load can
689 be reduced.
690
691
692Section 9.4.3: Output Feature Selection Controls
693------------------------------------------------
694
695These controls are all specific to video output.
696
697Enable Output Cropping: enables crop support. This control is only present if
698 the ccs_out_mode module option is set to the default value of -1 and if
699 the no_error_inj module option is set to 0 (the default).
700
701Enable Output Composing: enables composing support. This control is only
702 present if the ccs_out_mode module option is set to the default value of
703 -1 and if the no_error_inj module option is set to 0 (the default).
704
705Enable Output Scaler: enables support for a scaler (maximum 4 times upscaling
706 and downscaling). This control is only present if the ccs_out_mode
707 module option is set to the default value of -1 and if the no_error_inj
708 module option is set to 0 (the default).
709
710
711Section 9.4.4: Error Injection Controls
712---------------------------------------
713
714The following two controls are only valid for video and vbi capture.
715
716Standard Signal Mode: selects the behavior of VIDIOC_QUERYSTD: what should
717 it return?
718
719 Changing this control will result in the V4L2_EVENT_SOURCE_CHANGE
720 to be sent since it emulates a changed input condition (e.g. a cable
721 was plugged in or out).
722
723Standard: selects the standard that VIDIOC_QUERYSTD should return if the
724 previous control is set to "Selected Standard".
725
726 Changing this control will result in the V4L2_EVENT_SOURCE_CHANGE
727 to be sent since it emulates a changed input standard.
728
729
730The following two controls are only valid for video capture.
731
732DV Timings Signal Mode: selects the behavior of VIDIOC_QUERY_DV_TIMINGS: what
733 should it return?
734
735 Changing this control will result in the V4L2_EVENT_SOURCE_CHANGE
736 to be sent since it emulates a changed input condition (e.g. a cable
737 was plugged in or out).
738
739DV Timings: selects the timings the VIDIOC_QUERY_DV_TIMINGS should return
740 if the previous control is set to "Selected DV Timings".
741
742 Changing this control will result in the V4L2_EVENT_SOURCE_CHANGE
743 to be sent since it emulates changed input timings.
744
745
746The following controls are only present if the no_error_inj module option
747is set to 0 (the default). These controls are valid for video and vbi
748capture and output streams and for the SDR capture device except for the
749Disconnect control which is valid for all devices.
750
751Wrap Sequence Number: test what happens when you wrap the sequence number in
752 struct v4l2_buffer around.
753
754Wrap Timestamp: test what happens when you wrap the timestamp in struct
755 v4l2_buffer around.
756
757Percentage of Dropped Buffers: sets the percentage of buffers that
758 are never returned by the driver (i.e., they are dropped).
759
760Disconnect: emulates a USB disconnect. The device will act as if it has
761 been disconnected. Only after all open filehandles to the device
762 node have been closed will the device become 'connected' again.
763
764Inject V4L2_BUF_FLAG_ERROR: when pressed, the next frame returned by
765 the driver will have the error flag set (i.e. the frame is marked
766 corrupt).
767
768Inject VIDIOC_REQBUFS Error: when pressed, the next REQBUFS or CREATE_BUFS
769 ioctl call will fail with an error. To be precise: the videobuf2
770 queue_setup() op will return -EINVAL.
771
772Inject VIDIOC_QBUF Error: when pressed, the next VIDIOC_QBUF or
773 VIDIOC_PREPARE_BUFFER ioctl call will fail with an error. To be
774 precise: the videobuf2 buf_prepare() op will return -EINVAL.
775
776Inject VIDIOC_STREAMON Error: when pressed, the next VIDIOC_STREAMON ioctl
777 call will fail with an error. To be precise: the videobuf2
778 start_streaming() op will return -EINVAL.
779
780Inject Fatal Streaming Error: when pressed, the streaming core will be
781 marked as having suffered a fatal error, the only way to recover
782 from that is to stop streaming. To be precise: the videobuf2
783 vb2_queue_error() function is called.
784
785
786Section 9.4.5: VBI Raw Capture Controls
787---------------------------------------
788
789Interlaced VBI Format: if set, then the raw VBI data will be interlaced instead
790 of providing it grouped by field.
791
792
793Section 9.5: Digital Video Controls
794-----------------------------------
795
796Rx RGB Quantization Range: sets the RGB quantization detection of the HDMI
797 input. This combines with the Vivid 'Limited RGB Range (16-235)'
798 control and can be used to test what happens if a source provides
799 you with the wrong quantization range information. This can be tested
800 by selecting an HDMI input, setting this control to Full or Limited
801 range and selecting the opposite in the 'Limited RGB Range (16-235)'
802 control. The effect is easy to see if the 'Gray Ramp' test pattern
803 is selected.
804
805Tx RGB Quantization Range: sets the RGB quantization detection of the HDMI
806 output. It is currently not used for anything in vivid, but most HDMI
807 transmitters would typically have this control.
808
809Transmit Mode: sets the transmit mode of the HDMI output to HDMI or DVI-D. This
810 affects the reported colorspace since DVI_D outputs will always use
811 sRGB.
812
813
814Section 9.6: FM Radio Receiver Controls
815---------------------------------------
816
817RDS Reception: set if the RDS receiver should be enabled.
818
819RDS Program Type:
820RDS PS Name:
821RDS Radio Text:
822RDS Traffic Announcement:
823RDS Traffic Program:
824RDS Music: these are all read-only controls. If RDS Rx I/O Mode is set to
825 "Block I/O", then they are inactive as well. If RDS Rx I/O Mode is set
826 to "Controls", then these controls report the received RDS data. Note
827 that the vivid implementation of this is pretty basic: they are only
828 updated when you set a new frequency or when you get the tuner status
829 (VIDIOC_G_TUNER).
830
831Radio HW Seek Mode: can be one of "Bounded", "Wrap Around" or "Both". This
832 determines if VIDIOC_S_HW_FREQ_SEEK will be bounded by the frequency
833 range or wrap-around or if it is selectable by the user.
834
835Radio Programmable HW Seek: if set, then the user can provide the lower and
836 upper bound of the HW Seek. Otherwise the frequency range boundaries
837 will be used.
838
839Generate RBDS Instead of RDS: if set, then generate RBDS (the US variant of
840 RDS) data instead of RDS (European-style RDS). This affects only the
841 PICODE and PTY codes.
842
843RDS Rx I/O Mode: this can be "Block I/O" where the RDS blocks have to be read()
844 by the application, or "Controls" where the RDS data is provided by
845 the RDS controls mentioned above.
846
847
848Section 9.7: FM Radio Modulator Controls
849----------------------------------------
850
851RDS Program ID:
852RDS Program Type:
853RDS PS Name:
854RDS Radio Text:
855RDS Stereo:
856RDS Artificial Head:
857RDS Compressed:
858RDS Dymanic PTY:
859RDS Traffic Announcement:
860RDS Traffic Program:
861RDS Music: these are all controls that set the RDS data that is transmitted by
862 the FM modulator.
863
864RDS Tx I/O Mode: this can be "Block I/O" where the application has to use write()
865 to pass the RDS blocks to the driver, or "Controls" where the RDS data is
866 provided by the RDS controls mentioned above.
867
868
869Section 10: Video, VBI and RDS Looping
870--------------------------------------
871
872The vivid driver supports looping of video output to video input, VBI output
873to VBI input and RDS output to RDS input. For video/VBI looping this emulates
874as if a cable was hooked up between the output and input connector. So video
875and VBI looping is only supported between S-Video and HDMI inputs and outputs.
876VBI is only valid for S-Video as it makes no sense for HDMI.
877
878Since radio is wireless this looping always happens if the radio receiver
879frequency is close to the radio transmitter frequency. In that case the radio
880transmitter will 'override' the emulated radio stations.
881
882Looping is currently supported only between devices created by the same
883vivid driver instance.
884
885
886Section 10.1: Video and Sliced VBI looping
887------------------------------------------
888
889The way to enable video/VBI looping is currently fairly crude. A 'Loop Video'
890control is available in the "Vivid" control class of the video
891output and VBI output devices. When checked the video looping will be enabled.
892Once enabled any video S-Video or HDMI input will show a static test pattern
893until the video output has started. At that time the video output will be
894looped to the video input provided that:
895
896- the input type matches the output type. So the HDMI input cannot receive
897 video from the S-Video output.
898
899- the video resolution of the video input must match that of the video output.
900 So it is not possible to loop a 50 Hz (720x576) S-Video output to a 60 Hz
901 (720x480) S-Video input, or a 720p60 HDMI output to a 1080p30 input.
902
903- the pixel formats must be identical on both sides. Otherwise the driver would
904 have to do pixel format conversion as well, and that's taking things too far.
905
906- the field settings must be identical on both sides. Same reason as above:
907 requiring the driver to convert from one field format to another complicated
908 matters too much. This also prohibits capturing with 'Field Top' or 'Field
909 Bottom' when the output video is set to 'Field Alternate'. This combination,
910 while legal, became too complicated to support. Both sides have to be 'Field
911 Alternate' for this to work. Also note that for this specific case the
912 sequence and field counting in struct v4l2_buffer on the capture side may not
913 be 100% accurate.
914
Hans Verkuilba24b442015-03-09 10:06:55 -0300915- field settings V4L2_FIELD_SEQ_TB/BT are not supported. While it is possible to
916 implement this, it would mean a lot of work to get this right. Since these
917 field values are rarely used the decision was made not to implement this for
918 now.
919
Hans Verkuil6a683492014-08-25 07:52:44 -0300920- on the input side the "Standard Signal Mode" for the S-Video input or the
921 "DV Timings Signal Mode" for the HDMI input should be configured so that a
922 valid signal is passed to the video input.
923
924The framerates do not have to match, although this might change in the future.
925
926By default you will see the OSD text superimposed on top of the looped video.
927This can be turned off by changing the "OSD Text Mode" control of the video
928capture device.
929
930For VBI looping to work all of the above must be valid and in addition the vbi
931output must be configured for sliced VBI. The VBI capture side can be configured
Hans Verkuil62f28722014-09-20 06:11:44 -0300932for either raw or sliced VBI. Note that at the moment only CC/XDS (60 Hz formats)
933and WSS (50 Hz formats) VBI data is looped. Teletext VBI data is not looped.
Hans Verkuil6a683492014-08-25 07:52:44 -0300934
935
936Section 10.2: Radio & RDS Looping
937---------------------------------
938
939As mentioned in section 6 the radio receiver emulates stations are regular
940frequency intervals. Depending on the frequency of the radio receiver a
941signal strength value is calculated (this is returned by VIDIOC_G_TUNER).
942However, it will also look at the frequency set by the radio transmitter and
943if that results in a higher signal strength than the settings of the radio
944transmitter will be used as if it was a valid station. This also includes
945the RDS data (if any) that the transmitter 'transmits'. This is received
946faithfully on the receiver side. Note that when the driver is loaded the
947frequencies of the radio receiver and transmitter are not identical, so
948initially no looping takes place.
949
950
951Section 11: Cropping, Composing, Scaling
952----------------------------------------
953
954This driver supports cropping, composing and scaling in any combination. Normally
955which features are supported can be selected through the Vivid controls,
956but it is also possible to hardcode it when the module is loaded through the
957ccs_cap_mode and ccs_out_mode module options. See section 1 on the details of
958these module options.
959
960This allows you to test your application for all these variations.
961
962Note that the webcam input never supports cropping, composing or scaling. That
963only applies to the TV/S-Video/HDMI inputs and outputs. The reason is that
964webcams, including this virtual implementation, normally use
965VIDIOC_ENUM_FRAMESIZES to list a set of discrete framesizes that it supports.
966And that does not combine with cropping, composing or scaling. This is
967primarily a limitation of the V4L2 API which is carefully reproduced here.
968
969The minimum and maximum resolutions that the scaler can achieve are 16x16 and
970(4096 * 4) x (2160 x 4), but it can only scale up or down by a factor of 4 or
971less. So for a source resolution of 1280x720 the minimum the scaler can do is
972320x180 and the maximum is 5120x2880. You can play around with this using the
973qv4l2 test tool and you will see these dependencies.
974
975This driver also supports larger 'bytesperline' settings, something that
976VIDIOC_S_FMT allows but that few drivers implement.
977
978The scaler is a simple scaler that uses the Coarse Bresenham algorithm. It's
979designed for speed and simplicity, not quality.
980
981If the combination of crop, compose and scaling allows it, then it is possible
982to change crop and compose rectangles on the fly.
983
984
985Section 12: Formats
986-------------------
987
988The driver supports all the regular packed YUYV formats, 16, 24 and 32 RGB
989packed formats and two multiplanar formats (one luma and one chroma plane).
990
991The alpha component can be set through the 'Alpha Component' User control
992for those formats that support it. If the 'Apply Alpha To Red Only' control
993is set, then the alpha component is only used for the color red and set to
9940 otherwise.
995
996The driver has to be configured to support the multiplanar formats. By default
Hans Verkuilcba63cf2014-11-03 07:42:09 -0300997the driver instances are single-planar. This can be changed by setting the
998multiplanar module option, see section 1 for more details on that option.
Hans Verkuil6a683492014-08-25 07:52:44 -0300999
1000If the driver instance is using the multiplanar formats/API, then the first
1001single planar format (YUYV) and the multiplanar NV16M and NV61M formats the
1002will have a plane that has a non-zero data_offset of 128 bytes. It is rare for
1003data_offset to be non-zero, so this is a useful feature for testing applications.
1004
1005Video output will also honor any data_offset that the application set.
1006
1007
1008Section 13: Capture Overlay
1009---------------------------
1010
1011Note: capture overlay support is implemented primarily to test the existing
1012V4L2 capture overlay API. In practice few if any GPUs support such overlays
1013anymore, and neither are they generally needed anymore since modern hardware
1014is so much more capable. By setting flag 0x10000 in the node_types module
1015option the vivid driver will create a simple framebuffer device that can be
1016used for testing this API. Whether this API should be used for new drivers is
1017questionable.
1018
1019This driver has support for a destructive capture overlay with bitmap clipping
1020and list clipping (up to 16 rectangles) capabilities. Overlays are not
1021supported for multiplanar formats. It also honors the struct v4l2_window field
1022setting: if it is set to FIELD_TOP or FIELD_BOTTOM and the capture setting is
1023FIELD_ALTERNATE, then only the top or bottom fields will be copied to the overlay.
1024
1025The overlay only works if you are also capturing at that same time. This is a
1026vivid limitation since it copies from a buffer to the overlay instead of
1027filling the overlay directly. And if you are not capturing, then no buffers
1028are available to fill.
1029
1030In addition, the pixelformat of the capture format and that of the framebuffer
1031must be the same for the overlay to work. Otherwise VIDIOC_OVERLAY will return
1032an error.
1033
1034In order to really see what it going on you will need to create two vivid
1035instances: the first with a framebuffer enabled. You configure the capture
1036overlay of the second instance to use the framebuffer of the first, then
1037you start capturing in the second instance. For the first instance you setup
1038the output overlay for the video output, turn on video looping and capture
1039to see the blended framebuffer overlay that's being written to by the second
1040instance. This setup would require the following commands:
1041
Hans Verkuilcba63cf2014-11-03 07:42:09 -03001042 $ sudo modprobe vivid n_devs=2 node_types=0x10101,0x1
Hans Verkuil6a683492014-08-25 07:52:44 -03001043 $ v4l2-ctl -d1 --find-fb
1044 /dev/fb1 is the framebuffer associated with base address 0x12800000
1045 $ sudo v4l2-ctl -d2 --set-fbuf fb=1
1046 $ v4l2-ctl -d1 --set-fbuf fb=1
1047 $ v4l2-ctl -d0 --set-fmt-video=pixelformat='AR15'
1048 $ v4l2-ctl -d1 --set-fmt-video-out=pixelformat='AR15'
1049 $ v4l2-ctl -d2 --set-fmt-video=pixelformat='AR15'
1050 $ v4l2-ctl -d0 -i2
1051 $ v4l2-ctl -d2 -i2
1052 $ v4l2-ctl -d2 -c horizontal_movement=4
1053 $ v4l2-ctl -d1 --overlay=1
1054 $ v4l2-ctl -d1 -c loop_video=1
1055 $ v4l2-ctl -d2 --stream-mmap --overlay=1
1056
1057And from another console:
1058
1059 $ v4l2-ctl -d1 --stream-out-mmap
1060
1061And yet another console:
1062
1063 $ qv4l2
1064
1065and start streaming.
1066
1067As you can see, this is not for the faint of heart...
1068
1069
1070Section 14: Output Overlay
1071--------------------------
1072
1073Note: output overlays are primarily implemented in order to test the existing
1074V4L2 output overlay API. Whether this API should be used for new drivers is
1075questionable.
1076
1077This driver has support for an output overlay and is capable of:
1078
1079 - bitmap clipping,
1080 - list clipping (up to 16 rectangles)
1081 - chromakey
1082 - source chromakey
1083 - global alpha
1084 - local alpha
1085 - local inverse alpha
1086
1087Output overlays are not supported for multiplanar formats. In addition, the
1088pixelformat of the capture format and that of the framebuffer must be the
1089same for the overlay to work. Otherwise VIDIOC_OVERLAY will return an error.
1090
1091Output overlays only work if the driver has been configured to create a
1092framebuffer by setting flag 0x10000 in the node_types module option. The
1093created framebuffer has a size of 720x576 and supports ARGB 1:5:5:5 and
1094RGB 5:6:5.
1095
1096In order to see the effects of the various clipping, chromakeying or alpha
1097processing capabilities you need to turn on video looping and see the results
1098on the capture side. The use of the clipping, chromakeying or alpha processing
1099capabilities will slow down the video loop considerably as a lot of checks have
1100to be done per pixel.
1101
1102
1103Section 15: Some Future Improvements
1104------------------------------------
1105
1106Just as a reminder and in no particular order:
1107
1108- Add a virtual alsa driver to test audio
1109- Add virtual sub-devices and media controller support
1110- Some support for testing compressed video
1111- Add support to loop raw VBI output to raw VBI input
Hans Verkuil62f28722014-09-20 06:11:44 -03001112- Add support to loop teletext sliced VBI output to VBI input
Hans Verkuil6a683492014-08-25 07:52:44 -03001113- Fix sequence/field numbering when looping of video with alternate fields
1114- Add support for V4L2_CID_BG_COLOR for video outputs
1115- Add ARGB888 overlay support: better testing of the alpha channel
1116- Add custom DV timings support
1117- Add support for V4L2_DV_FL_REDUCED_FPS
1118- Improve pixel aspect support in the tpg code by passing a real v4l2_fract
1119- Use per-queue locks and/or per-device locks to improve throughput
1120- Add support to loop from a specific output to a specific input across
1121 vivid instances
1122- Add support for VIDIOC_EXPBUF once support for that has been added to vb2
1123- The SDR radio should use the same 'frequencies' for stations as the normal
1124 radio receiver, and give back noise if the frequency doesn't match up with
1125 a station frequency
1126- Improve the sine generation of the SDR radio.
1127- Make a thread for the RDS generation, that would help in particular for the
1128 "Controls" RDS Rx I/O Mode as the read-only RDS controls could be updated
1129 in real-time.