1.. SPDX-License-Identifier: GPL-2.0 2 3The Virtual Video Test Driver (vivid) 4===================================== 5 6This driver emulates video4linux hardware of various types: video capture, video 7output, vbi capture and output, metadata capture and output, radio receivers and 8transmitters, touch capture and a software defined radio receiver. In addition a 9simple framebuffer device is available for testing capture and output overlays. 10 11Up to 64 vivid instances can be created, each with up to 16 inputs and 16 outputs. 12 13Each input can be a webcam, TV capture device, S-Video capture device or an HDMI 14capture device. Each output can be an S-Video output device or an HDMI output 15device. 16 17These inputs and outputs act exactly as a real hardware device would behave. This 18allows you to use this driver as a test input for application development, since 19you can test the various features without requiring special hardware. 20 21This document describes the features implemented by this driver: 22 23- Support for read()/write(), MMAP, USERPTR and DMABUF streaming I/O. 24- A large list of test patterns and variations thereof 25- Working brightness, contrast, saturation and hue controls 26- Support for the alpha color component 27- Full colorspace support, including limited/full RGB range 28- All possible control types are present 29- Support for various pixel aspect ratios and video aspect ratios 30- Error injection to test what happens if errors occur 31- Supports crop/compose/scale in any combination for both input and output 32- Can emulate up to 4K resolutions 33- All Field settings are supported for testing interlaced capturing 34- Supports all standard YUV and RGB formats, including two multiplanar YUV formats 35- Raw and Sliced VBI capture and output support 36- Radio receiver and transmitter support, including RDS support 37- Software defined radio (SDR) support 38- Capture and output overlay support 39- Metadata capture and output support 40- Touch capture support 41 42These features will be described in more detail below. 43 44Configuring the driver 45---------------------- 46 47By default the driver will create a single instance that has a video capture 48device with webcam, TV, S-Video and HDMI inputs, a video output device with 49S-Video and HDMI outputs, one vbi capture device, one vbi output device, one 50radio receiver device, one radio transmitter device and one SDR device. 51 52The number of instances, devices, video inputs and outputs and their types are 53all configurable using the following module options: 54 55- n_devs: 56 57 number of driver instances to create. By default set to 1. Up to 64 58 instances can be created. 59 60- node_types: 61 62 which devices should each driver instance create. An array of 63 hexadecimal values, one for each instance. The default is 0x1d3d. 64 Each value is a bitmask with the following meaning: 65 66 - bit 0: Video Capture node 67 - bit 2-3: VBI Capture node: 0 = none, 1 = raw vbi, 2 = sliced vbi, 3 = both 68 - bit 4: Radio Receiver node 69 - bit 5: Software Defined Radio Receiver node 70 - bit 8: Video Output node 71 - bit 10-11: VBI Output node: 0 = none, 1 = raw vbi, 2 = sliced vbi, 3 = both 72 - bit 12: Radio Transmitter node 73 - bit 16: Framebuffer for testing overlays 74 - bit 17: Metadata Capture node 75 - bit 18: Metadata Output node 76 - bit 19: Touch Capture node 77 78 So to create four instances, the first two with just one video capture 79 device, the second two with just one video output device you would pass 80 these module options to vivid: 81 82 .. code-block:: none 83 84 n_devs=4 node_types=0x1,0x1,0x100,0x100 85 86- num_inputs: 87 88 the number of inputs, one for each instance. By default 4 inputs 89 are created for each video capture device. At most 16 inputs can be created, 90 and there must be at least one. 91 92- input_types: 93 94 the input types for each instance, the default is 0xe4. This defines 95 what the type of each input is when the inputs are created for each driver 96 instance. This is a hexadecimal value with up to 16 pairs of bits, each 97 pair gives the type and bits 0-1 map to input 0, bits 2-3 map to input 1, 98 30-31 map to input 15. Each pair of bits has the following meaning: 99 100 - 00: this is a webcam input 101 - 01: this is a TV tuner input 102 - 10: this is an S-Video input 103 - 11: this is an HDMI input 104 105 So to create a video capture device with 8 inputs where input 0 is a TV 106 tuner, inputs 1-3 are S-Video inputs and inputs 4-7 are HDMI inputs you 107 would use the following module options: 108 109 .. code-block:: none 110 111 num_inputs=8 input_types=0xffa9 112 113- num_outputs: 114 115 the number of outputs, one for each instance. By default 2 outputs 116 are created for each video output device. At most 16 outputs can be 117 created, and there must be at least one. 118 119- output_types: 120 121 the output types for each instance, the default is 0x02. This defines 122 what the type of each output is when the outputs are created for each 123 driver instance. This is a hexadecimal value with up to 16 bits, each bit 124 gives the type and bit 0 maps to output 0, bit 1 maps to output 1, bit 125 15 maps to output 15. The meaning of each bit is as follows: 126 127 - 0: this is an S-Video output 128 - 1: this is an HDMI output 129 130 So to create a video output device with 8 outputs where outputs 0-3 are 131 S-Video outputs and outputs 4-7 are HDMI outputs you would use the 132 following module options: 133 134 .. code-block:: none 135 136 num_outputs=8 output_types=0xf0 137 138- vid_cap_nr: 139 140 give the desired videoX start number for each video capture device. 141 The default is -1 which will just take the first free number. This allows 142 you to map capture video nodes to specific videoX device nodes. Example: 143 144 .. code-block:: none 145 146 n_devs=4 vid_cap_nr=2,4,6,8 147 148 This will attempt to assign /dev/video2 for the video capture device of 149 the first vivid instance, video4 for the next up to video8 for the last 150 instance. If it can't succeed, then it will just take the next free 151 number. 152 153- vid_out_nr: 154 155 give the desired videoX start number for each video output device. 156 The default is -1 which will just take the first free number. 157 158- vbi_cap_nr: 159 160 give the desired vbiX start number for each vbi capture device. 161 The default is -1 which will just take the first free number. 162 163- vbi_out_nr: 164 165 give the desired vbiX start number for each vbi output device. 166 The default is -1 which will just take the first free number. 167 168- radio_rx_nr: 169 170 give the desired radioX start number for each radio receiver device. 171 The default is -1 which will just take the first free number. 172 173- radio_tx_nr: 174 175 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: 179 180 give the desired swradioX start number for each SDR capture device. 181 The default is -1 which will just take the first free number. 182 183- meta_cap_nr: 184 185 give the desired videoX start number for each metadata capture device. 186 The default is -1 which will just take the first free number. 187 188- meta_out_nr: 189 190 give the desired videoX start number for each metadata output device. 191 The default is -1 which will just take the first free number. 192 193- touch_cap_nr: 194 195 give the desired v4l-touchX start number for each touch capture device. 196 The default is -1 which will just take the first free number. 197 198- ccs_cap_mode: 199 200 specify the allowed video capture crop/compose/scaling combination 201 for each driver instance. Video capture devices can have any combination 202 of cropping, composing and scaling capabilities and this will tell the 203 vivid driver which of those is should emulate. By default the user can 204 select this through controls. 205 206 The value is either -1 (controlled by the user) or a set of three bits, 207 each enabling (1) or disabling (0) one of the features: 208 209 - bit 0: 210 211 Enable crop support. Cropping will take only part of the 212 incoming picture. 213 - bit 1: 214 215 Enable compose support. Composing will copy the incoming 216 picture into a larger buffer. 217 218 - bit 2: 219 220 Enable scaling support. Scaling can scale the incoming 221 picture. The scaler of the vivid driver can enlarge up 222 or down to four times the original size. The scaler is 223 very simple and low-quality. Simplicity and speed were 224 key, not quality. 225 226 Note that this value is ignored by webcam inputs: those enumerate 227 discrete framesizes and that is incompatible with cropping, composing 228 or scaling. 229 230- ccs_out_mode: 231 232 specify the allowed video output crop/compose/scaling combination 233 for each driver instance. Video output devices can have any combination 234 of cropping, composing and scaling capabilities and this will tell the 235 vivid driver which of those is should emulate. By default the user can 236 select this through controls. 237 238 The value is either -1 (controlled by the user) or a set of three bits, 239 each enabling (1) or disabling (0) one of the features: 240 241 - bit 0: 242 243 Enable crop support. Cropping will take only part of the 244 outgoing buffer. 245 246 - bit 1: 247 248 Enable compose support. Composing will copy the incoming 249 buffer into a larger picture frame. 250 251 - bit 2: 252 253 Enable scaling support. Scaling can scale the incoming 254 buffer. The scaler of the vivid driver can enlarge up 255 or down to four times the original size. The scaler is 256 very simple and low-quality. Simplicity and speed were 257 key, not quality. 258 259- multiplanar: 260 261 select whether each device instance supports multi-planar formats, 262 and thus the V4L2 multi-planar API. By default device instances are 263 single-planar. 264 265 This module option can override that for each instance. Values are: 266 267 - 1: this is a single-planar instance. 268 - 2: this is a multi-planar instance. 269 270- vivid_debug: 271 272 enable driver debugging info 273 274- no_error_inj: 275 276 if set disable the error injecting controls. This option is 277 needed in order to run a tool like v4l2-compliance. Tools like that 278 exercise all controls including a control like 'Disconnect' which 279 emulates a USB disconnect, making the device inaccessible and so 280 all tests that v4l2-compliance is doing will fail afterwards. 281 282 There may be other situations as well where you want to disable the 283 error injection support of vivid. When this option is set, then the 284 controls that select crop, compose and scale behavior are also 285 removed. Unless overridden by ccs_cap_mode and/or ccs_out_mode the 286 will default to enabling crop, compose and scaling. 287 288- allocators: 289 290 memory allocator selection, default is 0. It specifies the way buffers 291 will be allocated. 292 293 - 0: vmalloc 294 - 1: dma-contig 295 296- cache_hints: 297 298 specifies if the device should set queues' user-space cache and memory 299 consistency hint capability (V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS). 300 The hints are valid only when using MMAP streaming I/O. Default is 0. 301 302 - 0: forbid hints 303 - 1: allow hints 304 305Taken together, all these module options allow you to precisely customize 306the driver behavior and test your application with all sorts of permutations. 307It is also very suitable to emulate hardware that is not yet available, e.g. 308when developing software for a new upcoming device. 309 310 311Video Capture 312------------- 313 314This is probably the most frequently used feature. The video capture device 315can be configured by using the module options num_inputs, input_types and 316ccs_cap_mode (see section 1 for more detailed information), but by default 317four inputs are configured: a webcam, a TV tuner, an S-Video and an HDMI 318input, one input for each input type. Those are described in more detail 319below. 320 321Special attention has been given to the rate at which new frames become 322available. The jitter will be around 1 jiffie (that depends on the HZ 323configuration of your kernel, so usually 1/100, 1/250 or 1/1000 of a second), 324but the long-term behavior is exactly following the framerate. So a 325framerate of 59.94 Hz is really different from 60 Hz. If the framerate 326exceeds your kernel's HZ value, then you will get dropped frames, but the 327frame/field sequence counting will keep track of that so the sequence 328count will skip whenever frames are dropped. 329 330 331Webcam Input 332~~~~~~~~~~~~ 333 334The webcam input supports three framesizes: 320x180, 640x360 and 1280x720. It 335supports frames per second settings of 10, 15, 25, 30, 50 and 60 fps. Which ones 336are available depends on the chosen framesize: the larger the framesize, the 337lower the maximum frames per second. 338 339The initially selected colorspace when you switch to the webcam input will be 340sRGB. 341 342 343TV and S-Video Inputs 344~~~~~~~~~~~~~~~~~~~~~ 345 346The only difference between the TV and S-Video input is that the TV has a 347tuner. Otherwise they behave identically. 348 349These inputs support audio inputs as well: one TV and one Line-In. They 350both support all TV standards. If the standard is queried, then the Vivid 351controls 'Standard Signal Mode' and 'Standard' determine what 352the result will be. 353 354These inputs support all combinations of the field setting. Special care has 355been taken to faithfully reproduce how fields are handled for the different 356TV standards. This is particularly noticeable when generating a horizontally 357moving image so the temporal effect of using interlaced formats becomes clearly 358visible. For 50 Hz standards the top field is the oldest and the bottom field 359is the newest in time. For 60 Hz standards that is reversed: the bottom field 360is the oldest and the top field is the newest in time. 361 362When you start capturing in V4L2_FIELD_ALTERNATE mode the first buffer will 363contain the top field for 50 Hz standards and the bottom field for 60 Hz 364standards. This is what capture hardware does as well. 365 366Finally, for PAL/SECAM standards the first half of the top line contains noise. 367This simulates the Wide Screen Signal that is commonly placed there. 368 369The initially selected colorspace when you switch to the TV or S-Video input 370will be SMPTE-170M. 371 372The pixel aspect ratio will depend on the TV standard. The video aspect ratio 373can be selected through the 'Standard Aspect Ratio' Vivid control. 374Choices are '4x3', '16x9' which will give letterboxed widescreen video and 375'16x9 Anamorphic' which will give full screen squashed anamorphic widescreen 376video that will need to be scaled accordingly. 377 378The TV 'tuner' supports a frequency range of 44-958 MHz. Channels are available 379every 6 MHz, starting from 49.25 MHz. For each channel the generated image 380will be in color for the +/- 0.25 MHz around it, and in grayscale for 381+/- 1 MHz around the channel. Beyond that it is just noise. The VIDIOC_G_TUNER 382ioctl will return 100% signal strength for +/- 0.25 MHz and 50% for +/- 1 MHz. 383It will also return correct afc values to show whether the frequency is too 384low or too high. 385 386The audio subchannels that are returned are MONO for the +/- 1 MHz range around 387a valid channel frequency. When the frequency is within +/- 0.25 MHz of the 388channel it will return either MONO, STEREO, either MONO | SAP (for NTSC) or 389LANG1 | LANG2 (for others), or STEREO | SAP. 390 391Which one is returned depends on the chosen channel, each next valid channel 392will cycle through the possible audio subchannel combinations. This allows 393you to test the various combinations by just switching channels.. 394 395Finally, for these inputs the v4l2_timecode struct is filled in in the 396dequeued v4l2_buffer struct. 397 398 399HDMI Input 400~~~~~~~~~~ 401 402The HDMI inputs supports all CEA-861 and DMT timings, both progressive and 403interlaced, for pixelclock frequencies between 25 and 600 MHz. The field 404mode for interlaced formats is always V4L2_FIELD_ALTERNATE. For HDMI the 405field order is always top field first, and when you start capturing an 406interlaced format you will receive the top field first. 407 408The initially selected colorspace when you switch to the HDMI input or 409select an HDMI timing is based on the format resolution: for resolutions 410less than or equal to 720x576 the colorspace is set to SMPTE-170M, for 411others it is set to REC-709 (CEA-861 timings) or sRGB (VESA DMT timings). 412 413The pixel aspect ratio will depend on the HDMI timing: for 720x480 is it 414set as for the NTSC TV standard, for 720x576 it is set as for the PAL TV 415standard, and for all others a 1:1 pixel aspect ratio is returned. 416 417The video aspect ratio can be selected through the 'DV Timings Aspect Ratio' 418Vivid control. Choices are 'Source Width x Height' (just use the 419same ratio as the chosen format), '4x3' or '16x9', either of which can 420result in pillarboxed or letterboxed video. 421 422For HDMI inputs it is possible to set the EDID. By default a simple EDID 423is provided. You can only set the EDID for HDMI inputs. Internally, however, 424the EDID is shared between all HDMI inputs. 425 426No interpretation is done of the EDID data with the exception of the 427physical address. See the CEC section for more details. 428 429There is a maximum of 15 HDMI inputs (if there are more, then they will be 430reduced to 15) since that's the limitation of the EDID physical address. 431 432 433Video Output 434------------ 435 436The video output device can be configured by using the module options 437num_outputs, output_types and ccs_out_mode (see section 1 for more detailed 438information), but by default two outputs are configured: an S-Video and an 439HDMI input, one output for each output type. Those are described in more detail 440below. 441 442Like with video capture the framerate is also exact in the long term. 443 444 445S-Video Output 446~~~~~~~~~~~~~~ 447 448This output supports audio outputs as well: "Line-Out 1" and "Line-Out 2". 449The S-Video output supports all TV standards. 450 451This output supports all combinations of the field setting. 452 453The initially selected colorspace when you switch to the TV or S-Video input 454will be SMPTE-170M. 455 456 457HDMI Output 458~~~~~~~~~~~ 459 460The HDMI output supports all CEA-861 and DMT timings, both progressive and 461interlaced, for pixelclock frequencies between 25 and 600 MHz. The field 462mode for interlaced formats is always V4L2_FIELD_ALTERNATE. 463 464The initially selected colorspace when you switch to the HDMI output or 465select an HDMI timing is based on the format resolution: for resolutions 466less than or equal to 720x576 the colorspace is set to SMPTE-170M, for 467others it is set to REC-709 (CEA-861 timings) or sRGB (VESA DMT timings). 468 469The pixel aspect ratio will depend on the HDMI timing: for 720x480 is it 470set as for the NTSC TV standard, for 720x576 it is set as for the PAL TV 471standard, and for all others a 1:1 pixel aspect ratio is returned. 472 473An HDMI output has a valid EDID which can be obtained through VIDIOC_G_EDID. 474 475There is a maximum of 15 HDMI outputs (if there are more, then they will be 476reduced to 15) since that's the limitation of the EDID physical address. See 477also the CEC section for more details. 478 479VBI Capture 480----------- 481 482There are three types of VBI capture devices: those that only support raw 483(undecoded) VBI, those that only support sliced (decoded) VBI and those that 484support both. This is determined by the node_types module option. In all 485cases the driver will generate valid VBI data: for 60 Hz standards it will 486generate Closed Caption and XDS data. The closed caption stream will 487alternate between "Hello world!" and "Closed captions test" every second. 488The XDS stream will give the current time once a minute. For 50 Hz standards 489it will generate the Wide Screen Signal which is based on the actual Video 490Aspect Ratio control setting and teletext pages 100-159, one page per frame. 491 492The VBI device will only work for the S-Video and TV inputs, it will give 493back an error if the current input is a webcam or HDMI. 494 495 496VBI Output 497---------- 498 499There are three types of VBI output devices: those that only support raw 500(undecoded) VBI, those that only support sliced (decoded) VBI and those that 501support both. This is determined by the node_types module option. 502 503The sliced VBI output supports the Wide Screen Signal and the teletext signal 504for 50 Hz standards and Closed Captioning + XDS for 60 Hz standards. 505 506The VBI device will only work for the S-Video output, it will give 507back an error if the current output is HDMI. 508 509 510Radio Receiver 511-------------- 512 513The radio receiver emulates an FM/AM/SW receiver. The FM band also supports RDS. 514The frequency ranges are: 515 516 - FM: 64 MHz - 108 MHz 517 - AM: 520 kHz - 1710 kHz 518 - SW: 2300 kHz - 26.1 MHz 519 520Valid channels are emulated every 1 MHz for FM and every 100 kHz for AM and SW. 521The signal strength decreases the further the frequency is from the valid 522frequency until it becomes 0% at +/- 50 kHz (FM) or 5 kHz (AM/SW) from the 523ideal frequency. The initial frequency when the driver is loaded is set to 52495 MHz. 525 526The FM receiver supports RDS as well, both using 'Block I/O' and 'Controls' 527modes. In the 'Controls' mode the RDS information is stored in read-only 528controls. These controls are updated every time the frequency is changed, 529or when the tuner status is requested. The Block I/O method uses the read() 530interface to pass the RDS blocks on to the application for decoding. 531 532The RDS signal is 'detected' for +/- 12.5 kHz around the channel frequency, 533and the further the frequency is away from the valid frequency the more RDS 534errors are randomly introduced into the block I/O stream, up to 50% of all 535blocks if you are +/- 12.5 kHz from the channel frequency. All four errors 536can occur in equal proportions: blocks marked 'CORRECTED', blocks marked 537'ERROR', blocks marked 'INVALID' and dropped blocks. 538 539The generated RDS stream contains all the standard fields contained in a 5400B group, and also radio text and the current time. 541 542The receiver supports HW frequency seek, either in Bounded mode, Wrap Around 543mode or both, which is configurable with the "Radio HW Seek Mode" control. 544 545 546Radio Transmitter 547----------------- 548 549The radio transmitter emulates an FM/AM/SW transmitter. The FM band also supports RDS. 550The frequency ranges are: 551 552 - FM: 64 MHz - 108 MHz 553 - AM: 520 kHz - 1710 kHz 554 - SW: 2300 kHz - 26.1 MHz 555 556The initial frequency when the driver is loaded is 95.5 MHz. 557 558The FM transmitter supports RDS as well, both using 'Block I/O' and 'Controls' 559modes. In the 'Controls' mode the transmitted RDS information is configured 560using controls, and in 'Block I/O' mode the blocks are passed to the driver 561using write(). 562 563 564Software Defined Radio Receiver 565------------------------------- 566 567The SDR receiver has three frequency bands for the ADC tuner: 568 569 - 300 kHz 570 - 900 kHz - 2800 kHz 571 - 3200 kHz 572 573The RF tuner supports 50 MHz - 2000 MHz. 574 575The generated data contains the In-phase and Quadrature components of a 5761 kHz tone that has an amplitude of sqrt(2). 577 578 579Metadata Capture 580---------------- 581 582The Metadata capture generates UVC format metadata. The PTS and SCR are 583transmitted based on the values set in vivid contols. 584 585The Metadata device will only work for the Webcam input, it will give 586back an error for all other inputs. 587 588 589Metadata Output 590--------------- 591 592The Metadata output can be used to set brightness, contrast, saturation and hue. 593 594The Metadata device will only work for the Webcam output, it will give 595back an error for all other outputs. 596 597 598Touch Capture 599------------- 600 601The Touch capture generates touch patterns simulating single tap, double tap, 602triple tap, move from left to right, zoom in, zoom out, palm press (simulating 603a large area being pressed on a touchpad), and simulating 16 simultaneous 604touch points. 605 606Controls 607-------- 608 609Different devices support different controls. The sections below will describe 610each control and which devices support them. 611 612 613User Controls - Test Controls 614~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 615 616The Button, Boolean, Integer 32 Bits, Integer 64 Bits, Menu, String, Bitmask and 617Integer Menu are controls that represent all possible control types. The Menu 618control and the Integer Menu control both have 'holes' in their menu list, 619meaning that one or more menu items return EINVAL when VIDIOC_QUERYMENU is called. 620Both menu controls also have a non-zero minimum control value. These features 621allow you to check if your application can handle such things correctly. 622These controls are supported for every device type. 623 624 625User Controls - Video Capture 626~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 627 628The following controls are specific to video capture. 629 630The Brightness, Contrast, Saturation and Hue controls actually work and are 631standard. There is one special feature with the Brightness control: each 632video input has its own brightness value, so changing input will restore 633the brightness for that input. In addition, each video input uses a different 634brightness range (minimum and maximum control values). Switching inputs will 635cause a control event to be sent with the V4L2_EVENT_CTRL_CH_RANGE flag set. 636This allows you to test controls that can change their range. 637 638The 'Gain, Automatic' and Gain controls can be used to test volatile controls: 639if 'Gain, Automatic' is set, then the Gain control is volatile and changes 640constantly. If 'Gain, Automatic' is cleared, then the Gain control is a normal 641control. 642 643The 'Horizontal Flip' and 'Vertical Flip' controls can be used to flip the 644image. These combine with the 'Sensor Flipped Horizontally/Vertically' Vivid 645controls. 646 647The 'Alpha Component' control can be used to set the alpha component for 648formats containing an alpha channel. 649 650 651User Controls - Audio 652~~~~~~~~~~~~~~~~~~~~~ 653 654The following controls are specific to video capture and output and radio 655receivers and transmitters. 656 657The 'Volume' and 'Mute' audio controls are typical for such devices to 658control the volume and mute the audio. They don't actually do anything in 659the vivid driver. 660 661 662Vivid Controls 663~~~~~~~~~~~~~~ 664 665These vivid custom controls control the image generation, error injection, etc. 666 667 668Test Pattern Controls 669^^^^^^^^^^^^^^^^^^^^^ 670 671The Test Pattern Controls are all specific to video capture. 672 673- Test Pattern: 674 675 selects which test pattern to use. Use the CSC Colorbar for 676 testing colorspace conversions: the colors used in that test pattern 677 map to valid colors in all colorspaces. The colorspace conversion 678 is disabled for the other test patterns. 679 680- OSD Text Mode: 681 682 selects whether the text superimposed on the 683 test pattern should be shown, and if so, whether only counters should 684 be displayed or the full text. 685 686- Horizontal Movement: 687 688 selects whether the test pattern should 689 move to the left or right and at what speed. 690 691- Vertical Movement: 692 693 does the same for the vertical direction. 694 695- Show Border: 696 697 show a two-pixel wide border at the edge of the actual image, 698 excluding letter or pillarboxing. 699 700- Show Square: 701 702 show a square in the middle of the image. If the image is 703 displayed with the correct pixel and image aspect ratio corrections, 704 then the width and height of the square on the monitor should be 705 the same. 706 707- Insert SAV Code in Image: 708 709 adds a SAV (Start of Active Video) code to the image. 710 This can be used to check if such codes in the image are inadvertently 711 interpreted instead of being ignored. 712 713- Insert EAV Code in Image: 714 715 does the same for the EAV (End of Active Video) code. 716 717- Insert Video Guard Band 718 719 adds 4 columns of pixels with the HDMI Video Guard Band code at the 720 left hand side of the image. This only works with 3 or 4 byte RGB pixel 721 formats. The RGB pixel value 0xab/0x55/0xab turns out to be equivalent 722 to the HDMI Video Guard Band code that precedes each active video line 723 (see section 5.2.2.1 in the HDMI 1.3 Specification). To test if a video 724 receiver has correct HDMI Video Guard Band processing, enable this 725 control and then move the image to the left hand side of the screen. 726 That will result in video lines that start with multiple pixels that 727 have the same value as the Video Guard Band that precedes them. 728 Receivers that will just keep skipping Video Guard Band values will 729 now fail and either loose sync or these video lines will shift. 730 731 732Capture Feature Selection Controls 733^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 734 735These controls are all specific to video capture. 736 737- Sensor Flipped Horizontally: 738 739 the image is flipped horizontally and the 740 V4L2_IN_ST_HFLIP input status flag is set. This emulates the case where 741 a sensor is for example mounted upside down. 742 743- Sensor Flipped Vertically: 744 745 the image is flipped vertically and the 746 V4L2_IN_ST_VFLIP input status flag is set. This emulates the case where 747 a sensor is for example mounted upside down. 748 749- Standard Aspect Ratio: 750 751 selects if the image aspect ratio as used for the TV or 752 S-Video input should be 4x3, 16x9 or anamorphic widescreen. This may 753 introduce letterboxing. 754 755- DV Timings Aspect Ratio: 756 757 selects if the image aspect ratio as used for the HDMI 758 input should be the same as the source width and height ratio, or if 759 it should be 4x3 or 16x9. This may introduce letter or pillarboxing. 760 761- Timestamp Source: 762 763 selects when the timestamp for each buffer is taken. 764 765- Colorspace: 766 767 selects which colorspace should be used when generating the image. 768 This only applies if the CSC Colorbar test pattern is selected, 769 otherwise the test pattern will go through unconverted. 770 This behavior is also what you want, since a 75% Colorbar 771 should really have 75% signal intensity and should not be affected 772 by colorspace conversions. 773 774 Changing the colorspace will result in the V4L2_EVENT_SOURCE_CHANGE 775 to be sent since it emulates a detected colorspace change. 776 777- Transfer Function: 778 779 selects which colorspace transfer function should be used when 780 generating an image. This only applies if the CSC Colorbar test pattern is 781 selected, otherwise the test pattern will go through unconverted. 782 This behavior is also what you want, since a 75% Colorbar 783 should really have 75% signal intensity and should not be affected 784 by colorspace conversions. 785 786 Changing the transfer function will result in the V4L2_EVENT_SOURCE_CHANGE 787 to be sent since it emulates a detected colorspace change. 788 789- Y'CbCr Encoding: 790 791 selects which Y'CbCr encoding should be used when generating 792 a Y'CbCr image. This only applies if the format is set to a Y'CbCr format 793 as opposed to an RGB format. 794 795 Changing the Y'CbCr encoding will result in the V4L2_EVENT_SOURCE_CHANGE 796 to be sent since it emulates a detected colorspace change. 797 798- Quantization: 799 800 selects which quantization should be used for the RGB or Y'CbCr 801 encoding when generating the test pattern. 802 803 Changing the quantization will result in the V4L2_EVENT_SOURCE_CHANGE 804 to be sent since it emulates a detected colorspace change. 805 806- Limited RGB Range (16-235): 807 808 selects if the RGB range of the HDMI source should 809 be limited or full range. This combines with the Digital Video 'Rx RGB 810 Quantization Range' control and can be used to test what happens if 811 a source provides you with the wrong quantization range information. 812 See the description of that control for more details. 813 814- Apply Alpha To Red Only: 815 816 apply the alpha channel as set by the 'Alpha Component' 817 user control to the red color of the test pattern only. 818 819- Enable Capture Cropping: 820 821 enables crop support. This control is only present if 822 the ccs_cap_mode module option is set to the default value of -1 and if 823 the no_error_inj module option is set to 0 (the default). 824 825- Enable Capture Composing: 826 827 enables composing support. This control is only 828 present if the ccs_cap_mode module option is set to the default value of 829 -1 and if the no_error_inj module option is set to 0 (the default). 830 831- Enable Capture Scaler: 832 833 enables support for a scaler (maximum 4 times upscaling 834 and downscaling). This control is only present if the ccs_cap_mode 835 module option is set to the default value of -1 and if the no_error_inj 836 module option is set to 0 (the default). 837 838- Maximum EDID Blocks: 839 840 determines how many EDID blocks the driver supports. 841 Note that the vivid driver does not actually interpret new EDID 842 data, it just stores it. It allows for up to 256 EDID blocks 843 which is the maximum supported by the standard. 844 845- Fill Percentage of Frame: 846 847 can be used to draw only the top X percent 848 of the image. Since each frame has to be drawn by the driver, this 849 demands a lot of the CPU. For large resolutions this becomes 850 problematic. By drawing only part of the image this CPU load can 851 be reduced. 852 853 854Output Feature Selection Controls 855^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 856 857These controls are all specific to video output. 858 859- Enable Output Cropping: 860 861 enables crop support. This control is only present if 862 the ccs_out_mode module option is set to the default value of -1 and if 863 the no_error_inj module option is set to 0 (the default). 864 865- Enable Output Composing: 866 867 enables composing support. This control is only 868 present if the ccs_out_mode module option is set to the default value of 869 -1 and if the no_error_inj module option is set to 0 (the default). 870 871- Enable Output Scaler: 872 873 enables support for a scaler (maximum 4 times upscaling 874 and downscaling). This control is only present if the ccs_out_mode 875 module option is set to the default value of -1 and if the no_error_inj 876 module option is set to 0 (the default). 877 878 879Error Injection Controls 880^^^^^^^^^^^^^^^^^^^^^^^^ 881 882The following two controls are only valid for video and vbi capture. 883 884- Standard Signal Mode: 885 886 selects the behavior of VIDIOC_QUERYSTD: what should it return? 887 888 Changing this control will result in the V4L2_EVENT_SOURCE_CHANGE 889 to be sent since it emulates a changed input condition (e.g. a cable 890 was plugged in or out). 891 892- Standard: 893 894 selects the standard that VIDIOC_QUERYSTD should return if the 895 previous control is set to "Selected Standard". 896 897 Changing this control will result in the V4L2_EVENT_SOURCE_CHANGE 898 to be sent since it emulates a changed input standard. 899 900 901The following two controls are only valid for video capture. 902 903- DV Timings Signal Mode: 904 905 selects the behavior of VIDIOC_QUERY_DV_TIMINGS: what 906 should it return? 907 908 Changing this control will result in the V4L2_EVENT_SOURCE_CHANGE 909 to be sent since it emulates a changed input condition (e.g. a cable 910 was plugged in or out). 911 912- DV Timings: 913 914 selects the timings the VIDIOC_QUERY_DV_TIMINGS should return 915 if the previous control is set to "Selected DV Timings". 916 917 Changing this control will result in the V4L2_EVENT_SOURCE_CHANGE 918 to be sent since it emulates changed input timings. 919 920 921The following controls are only present if the no_error_inj module option 922is set to 0 (the default). These controls are valid for video and vbi 923capture and output streams and for the SDR capture device except for the 924Disconnect control which is valid for all devices. 925 926- Wrap Sequence Number: 927 928 test what happens when you wrap the sequence number in 929 struct v4l2_buffer around. 930 931- Wrap Timestamp: 932 933 test what happens when you wrap the timestamp in struct 934 v4l2_buffer around. 935 936- Percentage of Dropped Buffers: 937 938 sets the percentage of buffers that 939 are never returned by the driver (i.e., they are dropped). 940 941- Disconnect: 942 943 emulates a USB disconnect. The device will act as if it has 944 been disconnected. Only after all open filehandles to the device 945 node have been closed will the device become 'connected' again. 946 947- Inject V4L2_BUF_FLAG_ERROR: 948 949 when pressed, the next frame returned by 950 the driver will have the error flag set (i.e. the frame is marked 951 corrupt). 952 953- Inject VIDIOC_REQBUFS Error: 954 955 when pressed, the next REQBUFS or CREATE_BUFS 956 ioctl call will fail with an error. To be precise: the videobuf2 957 queue_setup() op will return -EINVAL. 958 959- Inject VIDIOC_QBUF Error: 960 961 when pressed, the next VIDIOC_QBUF or 962 VIDIOC_PREPARE_BUFFER ioctl call will fail with an error. To be 963 precise: the videobuf2 buf_prepare() op will return -EINVAL. 964 965- Inject VIDIOC_STREAMON Error: 966 967 when pressed, the next VIDIOC_STREAMON ioctl 968 call will fail with an error. To be precise: the videobuf2 969 start_streaming() op will return -EINVAL. 970 971- Inject Fatal Streaming Error: 972 973 when pressed, the streaming core will be 974 marked as having suffered a fatal error, the only way to recover 975 from that is to stop streaming. To be precise: the videobuf2 976 vb2_queue_error() function is called. 977 978 979VBI Raw Capture Controls 980^^^^^^^^^^^^^^^^^^^^^^^^ 981 982- Interlaced VBI Format: 983 984 if set, then the raw VBI data will be interlaced instead 985 of providing it grouped by field. 986 987 988Digital Video Controls 989~~~~~~~~~~~~~~~~~~~~~~ 990 991- Rx RGB Quantization Range: 992 993 sets the RGB quantization detection of the HDMI 994 input. This combines with the Vivid 'Limited RGB Range (16-235)' 995 control and can be used to test what happens if a source provides 996 you with the wrong quantization range information. This can be tested 997 by selecting an HDMI input, setting this control to Full or Limited 998 range and selecting the opposite in the 'Limited RGB Range (16-235)' 999 control. The effect is easy to see if the 'Gray Ramp' test pattern 1000 is selected. 1001 1002- Tx RGB Quantization Range: 1003 1004 sets the RGB quantization detection of the HDMI 1005 output. It is currently not used for anything in vivid, but most HDMI 1006 transmitters would typically have this control. 1007 1008- Transmit Mode: 1009 1010 sets the transmit mode of the HDMI output to HDMI or DVI-D. This 1011 affects the reported colorspace since DVI_D outputs will always use 1012 sRGB. 1013 1014- Display Present: 1015 1016 sets the presence of a "display" on the HDMI output. This affects 1017 the tx_edid_present, tx_hotplug and tx_rxsense controls. 1018 1019 1020FM Radio Receiver Controls 1021~~~~~~~~~~~~~~~~~~~~~~~~~~ 1022 1023- RDS Reception: 1024 1025 set if the RDS receiver should be enabled. 1026 1027- RDS Program Type: 1028 1029 1030- RDS PS Name: 1031 1032 1033- RDS Radio Text: 1034 1035 1036- RDS Traffic Announcement: 1037 1038 1039- RDS Traffic Program: 1040 1041 1042- RDS Music: 1043 1044 these are all read-only controls. If RDS Rx I/O Mode is set to 1045 "Block I/O", then they are inactive as well. If RDS Rx I/O Mode is set 1046 to "Controls", then these controls report the received RDS data. 1047 1048.. note:: 1049 The vivid implementation of this is pretty basic: they are only 1050 updated when you set a new frequency or when you get the tuner status 1051 (VIDIOC_G_TUNER). 1052 1053- Radio HW Seek Mode: 1054 1055 can be one of "Bounded", "Wrap Around" or "Both". This 1056 determines if VIDIOC_S_HW_FREQ_SEEK will be bounded by the frequency 1057 range or wrap-around or if it is selectable by the user. 1058 1059- Radio Programmable HW Seek: 1060 1061 if set, then the user can provide the lower and 1062 upper bound of the HW Seek. Otherwise the frequency range boundaries 1063 will be used. 1064 1065- Generate RBDS Instead of RDS: 1066 1067 if set, then generate RBDS (the US variant of 1068 RDS) data instead of RDS (European-style RDS). This affects only the 1069 PICODE and PTY codes. 1070 1071- RDS Rx I/O Mode: 1072 1073 this can be "Block I/O" where the RDS blocks have to be read() 1074 by the application, or "Controls" where the RDS data is provided by 1075 the RDS controls mentioned above. 1076 1077 1078FM Radio Modulator Controls 1079~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1080 1081- RDS Program ID: 1082 1083 1084- RDS Program Type: 1085 1086 1087- RDS PS Name: 1088 1089 1090- RDS Radio Text: 1091 1092 1093- RDS Stereo: 1094 1095 1096- RDS Artificial Head: 1097 1098 1099- RDS Compressed: 1100 1101 1102- RDS Dynamic PTY: 1103 1104 1105- RDS Traffic Announcement: 1106 1107 1108- RDS Traffic Program: 1109 1110 1111- RDS Music: 1112 1113 these are all controls that set the RDS data that is transmitted by 1114 the FM modulator. 1115 1116- RDS Tx I/O Mode: 1117 1118 this can be "Block I/O" where the application has to use write() 1119 to pass the RDS blocks to the driver, or "Controls" where the RDS data 1120 is Provided by the RDS controls mentioned above. 1121 1122Metadata Capture Controls 1123~~~~~~~~~~~~~~~~~~~~~~~~~~ 1124 1125- Generate PTS 1126 1127 if set, then the generated metadata stream contains Presentation timestamp. 1128 1129- Generate SCR 1130 1131 if set, then the generated metadata stream contains Source Clock information. 1132 1133Video, VBI and RDS Looping 1134-------------------------- 1135 1136The vivid driver supports looping of video output to video input, VBI output 1137to VBI input and RDS output to RDS input. For video/VBI looping this emulates 1138as if a cable was hooked up between the output and input connector. So video 1139and VBI looping is only supported between S-Video and HDMI inputs and outputs. 1140VBI is only valid for S-Video as it makes no sense for HDMI. 1141 1142Since radio is wireless this looping always happens if the radio receiver 1143frequency is close to the radio transmitter frequency. In that case the radio 1144transmitter will 'override' the emulated radio stations. 1145 1146Looping is currently supported only between devices created by the same 1147vivid driver instance. 1148 1149 1150Video and Sliced VBI looping 1151~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1152 1153The way to enable video/VBI looping is currently fairly crude. A 'Loop Video' 1154control is available in the "Vivid" control class of the video 1155capture and VBI capture devices. When checked the video looping will be enabled. 1156Once enabled any video S-Video or HDMI input will show a static test pattern 1157until the video output has started. At that time the video output will be 1158looped to the video input provided that: 1159 1160- the input type matches the output type. So the HDMI input cannot receive 1161 video from the S-Video output. 1162 1163- the video resolution of the video input must match that of the video output. 1164 So it is not possible to loop a 50 Hz (720x576) S-Video output to a 60 Hz 1165 (720x480) S-Video input, or a 720p60 HDMI output to a 1080p30 input. 1166 1167- the pixel formats must be identical on both sides. Otherwise the driver would 1168 have to do pixel format conversion as well, and that's taking things too far. 1169 1170- the field settings must be identical on both sides. Same reason as above: 1171 requiring the driver to convert from one field format to another complicated 1172 matters too much. This also prohibits capturing with 'Field Top' or 'Field 1173 Bottom' when the output video is set to 'Field Alternate'. This combination, 1174 while legal, became too complicated to support. Both sides have to be 'Field 1175 Alternate' for this to work. Also note that for this specific case the 1176 sequence and field counting in struct v4l2_buffer on the capture side may not 1177 be 100% accurate. 1178 1179- field settings V4L2_FIELD_SEQ_TB/BT are not supported. While it is possible to 1180 implement this, it would mean a lot of work to get this right. Since these 1181 field values are rarely used the decision was made not to implement this for 1182 now. 1183 1184- on the input side the "Standard Signal Mode" for the S-Video input or the 1185 "DV Timings Signal Mode" for the HDMI input should be configured so that a 1186 valid signal is passed to the video input. 1187 1188The framerates do not have to match, although this might change in the future. 1189 1190By default you will see the OSD text superimposed on top of the looped video. 1191This can be turned off by changing the "OSD Text Mode" control of the video 1192capture device. 1193 1194For VBI looping to work all of the above must be valid and in addition the vbi 1195output must be configured for sliced VBI. The VBI capture side can be configured 1196for either raw or sliced VBI. Note that at the moment only CC/XDS (60 Hz formats) 1197and WSS (50 Hz formats) VBI data is looped. Teletext VBI data is not looped. 1198 1199 1200Radio & RDS Looping 1201~~~~~~~~~~~~~~~~~~~ 1202 1203As mentioned in section 6 the radio receiver emulates stations are regular 1204frequency intervals. Depending on the frequency of the radio receiver a 1205signal strength value is calculated (this is returned by VIDIOC_G_TUNER). 1206However, it will also look at the frequency set by the radio transmitter and 1207if that results in a higher signal strength than the settings of the radio 1208transmitter will be used as if it was a valid station. This also includes 1209the RDS data (if any) that the transmitter 'transmits'. This is received 1210faithfully on the receiver side. Note that when the driver is loaded the 1211frequencies of the radio receiver and transmitter are not identical, so 1212initially no looping takes place. 1213 1214 1215Cropping, Composing, Scaling 1216---------------------------- 1217 1218This driver supports cropping, composing and scaling in any combination. Normally 1219which features are supported can be selected through the Vivid controls, 1220but it is also possible to hardcode it when the module is loaded through the 1221ccs_cap_mode and ccs_out_mode module options. See section 1 on the details of 1222these module options. 1223 1224This allows you to test your application for all these variations. 1225 1226Note that the webcam input never supports cropping, composing or scaling. That 1227only applies to the TV/S-Video/HDMI inputs and outputs. The reason is that 1228webcams, including this virtual implementation, normally use 1229VIDIOC_ENUM_FRAMESIZES to list a set of discrete framesizes that it supports. 1230And that does not combine with cropping, composing or scaling. This is 1231primarily a limitation of the V4L2 API which is carefully reproduced here. 1232 1233The minimum and maximum resolutions that the scaler can achieve are 16x16 and 1234(4096 * 4) x (2160 x 4), but it can only scale up or down by a factor of 4 or 1235less. So for a source resolution of 1280x720 the minimum the scaler can do is 1236320x180 and the maximum is 5120x2880. You can play around with this using the 1237qv4l2 test tool and you will see these dependencies. 1238 1239This driver also supports larger 'bytesperline' settings, something that 1240VIDIOC_S_FMT allows but that few drivers implement. 1241 1242The scaler is a simple scaler that uses the Coarse Bresenham algorithm. It's 1243designed for speed and simplicity, not quality. 1244 1245If the combination of crop, compose and scaling allows it, then it is possible 1246to change crop and compose rectangles on the fly. 1247 1248 1249Formats 1250------- 1251 1252The driver supports all the regular packed and planar 4:4:4, 4:2:2 and 4:2:0 1253YUYV formats, 8, 16, 24 and 32 RGB packed formats and various multiplanar 1254formats. 1255 1256The alpha component can be set through the 'Alpha Component' User control 1257for those formats that support it. If the 'Apply Alpha To Red Only' control 1258is set, then the alpha component is only used for the color red and set to 12590 otherwise. 1260 1261The driver has to be configured to support the multiplanar formats. By default 1262the driver instances are single-planar. This can be changed by setting the 1263multiplanar module option, see section 1 for more details on that option. 1264 1265If the driver instance is using the multiplanar formats/API, then the first 1266single planar format (YUYV) and the multiplanar NV16M and NV61M formats the 1267will have a plane that has a non-zero data_offset of 128 bytes. It is rare for 1268data_offset to be non-zero, so this is a useful feature for testing applications. 1269 1270Video output will also honor any data_offset that the application set. 1271 1272 1273Capture Overlay 1274--------------- 1275 1276Note: capture overlay support is implemented primarily to test the existing 1277V4L2 capture overlay API. In practice few if any GPUs support such overlays 1278anymore, and neither are they generally needed anymore since modern hardware 1279is so much more capable. By setting flag 0x10000 in the node_types module 1280option the vivid driver will create a simple framebuffer device that can be 1281used for testing this API. Whether this API should be used for new drivers is 1282questionable. 1283 1284This driver has support for a destructive capture overlay with bitmap clipping 1285and list clipping (up to 16 rectangles) capabilities. Overlays are not 1286supported for multiplanar formats. It also honors the struct v4l2_window field 1287setting: if it is set to FIELD_TOP or FIELD_BOTTOM and the capture setting is 1288FIELD_ALTERNATE, then only the top or bottom fields will be copied to the overlay. 1289 1290The overlay only works if you are also capturing at that same time. This is a 1291vivid limitation since it copies from a buffer to the overlay instead of 1292filling the overlay directly. And if you are not capturing, then no buffers 1293are available to fill. 1294 1295In addition, the pixelformat of the capture format and that of the framebuffer 1296must be the same for the overlay to work. Otherwise VIDIOC_OVERLAY will return 1297an error. 1298 1299In order to really see what it going on you will need to create two vivid 1300instances: the first with a framebuffer enabled. You configure the capture 1301overlay of the second instance to use the framebuffer of the first, then 1302you start capturing in the second instance. For the first instance you setup 1303the output overlay for the video output, turn on video looping and capture 1304to see the blended framebuffer overlay that's being written to by the second 1305instance. This setup would require the following commands: 1306 1307.. code-block:: none 1308 1309 $ sudo modprobe vivid n_devs=2 node_types=0x10101,0x1 1310 $ v4l2-ctl -d1 --find-fb 1311 /dev/fb1 is the framebuffer associated with base address 0x12800000 1312 $ sudo v4l2-ctl -d2 --set-fbuf fb=1 1313 $ v4l2-ctl -d1 --set-fbuf fb=1 1314 $ v4l2-ctl -d0 --set-fmt-video=pixelformat='AR15' 1315 $ v4l2-ctl -d1 --set-fmt-video-out=pixelformat='AR15' 1316 $ v4l2-ctl -d2 --set-fmt-video=pixelformat='AR15' 1317 $ v4l2-ctl -d0 -i2 1318 $ v4l2-ctl -d2 -i2 1319 $ v4l2-ctl -d2 -c horizontal_movement=4 1320 $ v4l2-ctl -d1 --overlay=1 1321 $ v4l2-ctl -d0 -c loop_video=1 1322 $ v4l2-ctl -d2 --stream-mmap --overlay=1 1323 1324And from another console: 1325 1326.. code-block:: none 1327 1328 $ v4l2-ctl -d1 --stream-out-mmap 1329 1330And yet another console: 1331 1332.. code-block:: none 1333 1334 $ qv4l2 1335 1336and start streaming. 1337 1338As you can see, this is not for the faint of heart... 1339 1340 1341Output Overlay 1342-------------- 1343 1344Note: output overlays are primarily implemented in order to test the existing 1345V4L2 output overlay API. Whether this API should be used for new drivers is 1346questionable. 1347 1348This driver has support for an output overlay and is capable of: 1349 1350 - bitmap clipping, 1351 - list clipping (up to 16 rectangles) 1352 - chromakey 1353 - source chromakey 1354 - global alpha 1355 - local alpha 1356 - local inverse alpha 1357 1358Output overlays are not supported for multiplanar formats. In addition, the 1359pixelformat of the capture format and that of the framebuffer must be the 1360same for the overlay to work. Otherwise VIDIOC_OVERLAY will return an error. 1361 1362Output overlays only work if the driver has been configured to create a 1363framebuffer by setting flag 0x10000 in the node_types module option. The 1364created framebuffer has a size of 720x576 and supports ARGB 1:5:5:5 and 1365RGB 5:6:5. 1366 1367In order to see the effects of the various clipping, chromakeying or alpha 1368processing capabilities you need to turn on video looping and see the results 1369on the capture side. The use of the clipping, chromakeying or alpha processing 1370capabilities will slow down the video loop considerably as a lot of checks have 1371to be done per pixel. 1372 1373 1374CEC (Consumer Electronics Control) 1375---------------------------------- 1376 1377If there are HDMI inputs then a CEC adapter will be created that has 1378the same number of input ports. This is the equivalent of e.g. a TV that 1379has that number of inputs. Each HDMI output will also create a 1380CEC adapter that is hooked up to the corresponding input port, or (if there 1381are more outputs than inputs) is not hooked up at all. In other words, 1382this is the equivalent of hooking up each output device to an input port of 1383the TV. Any remaining output devices remain unconnected. 1384 1385The EDID that each output reads reports a unique CEC physical address that is 1386based on the physical address of the EDID of the input. So if the EDID of the 1387receiver has physical address A.B.0.0, then each output will see an EDID 1388containing physical address A.B.C.0 where C is 1 to the number of inputs. If 1389there are more outputs than inputs then the remaining outputs have a CEC adapter 1390that is disabled and reports an invalid physical address. 1391 1392 1393Some Future Improvements 1394------------------------ 1395 1396Just as a reminder and in no particular order: 1397 1398- Add a virtual alsa driver to test audio 1399- Add virtual sub-devices and media controller support 1400- Some support for testing compressed video 1401- Add support to loop raw VBI output to raw VBI input 1402- Add support to loop teletext sliced VBI output to VBI input 1403- Fix sequence/field numbering when looping of video with alternate fields 1404- Add support for V4L2_CID_BG_COLOR for video outputs 1405- Add ARGB888 overlay support: better testing of the alpha channel 1406- Improve pixel aspect support in the tpg code by passing a real v4l2_fract 1407- Use per-queue locks and/or per-device locks to improve throughput 1408- Add support to loop from a specific output to a specific input across 1409 vivid instances 1410- The SDR radio should use the same 'frequencies' for stations as the normal 1411 radio receiver, and give back noise if the frequency doesn't match up with 1412 a station frequency 1413- Make a thread for the RDS generation, that would help in particular for the 1414 "Controls" RDS Rx I/O Mode as the read-only RDS controls could be updated 1415 in real-time. 1416- Changing the EDID should cause hotplug detect emulation to happen. 1417