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 718Capture Feature Selection Controls 719^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 720 721These controls are all specific to video capture. 722 723- Sensor Flipped Horizontally: 724 725 the image is flipped horizontally and the 726 V4L2_IN_ST_HFLIP input status flag is set. This emulates the case where 727 a sensor is for example mounted upside down. 728 729- Sensor Flipped Vertically: 730 731 the image is flipped vertically and the 732 V4L2_IN_ST_VFLIP input status flag is set. This emulates the case where 733 a sensor is for example mounted upside down. 734 735- Standard Aspect Ratio: 736 737 selects if the image aspect ratio as used for the TV or 738 S-Video input should be 4x3, 16x9 or anamorphic widescreen. This may 739 introduce letterboxing. 740 741- DV Timings Aspect Ratio: 742 743 selects if the image aspect ratio as used for the HDMI 744 input should be the same as the source width and height ratio, or if 745 it should be 4x3 or 16x9. This may introduce letter or pillarboxing. 746 747- Timestamp Source: 748 749 selects when the timestamp for each buffer is taken. 750 751- Colorspace: 752 753 selects which colorspace should be used when generating the image. 754 This only applies if the CSC Colorbar test pattern is selected, 755 otherwise the test pattern will go through unconverted. 756 This behavior is also what you want, since a 75% Colorbar 757 should really have 75% signal intensity and should not be affected 758 by colorspace conversions. 759 760 Changing the colorspace will result in the V4L2_EVENT_SOURCE_CHANGE 761 to be sent since it emulates a detected colorspace change. 762 763- Transfer Function: 764 765 selects which colorspace transfer function should be used when 766 generating an image. This only applies if the CSC Colorbar test pattern is 767 selected, otherwise the test pattern will go through unconverted. 768 This behavior is also what you want, since a 75% Colorbar 769 should really have 75% signal intensity and should not be affected 770 by colorspace conversions. 771 772 Changing the transfer function will result in the V4L2_EVENT_SOURCE_CHANGE 773 to be sent since it emulates a detected colorspace change. 774 775- Y'CbCr Encoding: 776 777 selects which Y'CbCr encoding should be used when generating 778 a Y'CbCr image. This only applies if the format is set to a Y'CbCr format 779 as opposed to an RGB format. 780 781 Changing the Y'CbCr encoding will result in the V4L2_EVENT_SOURCE_CHANGE 782 to be sent since it emulates a detected colorspace change. 783 784- Quantization: 785 786 selects which quantization should be used for the RGB or Y'CbCr 787 encoding when generating the test pattern. 788 789 Changing the quantization will result in the V4L2_EVENT_SOURCE_CHANGE 790 to be sent since it emulates a detected colorspace change. 791 792- Limited RGB Range (16-235): 793 794 selects if the RGB range of the HDMI source should 795 be limited or full range. This combines with the Digital Video 'Rx RGB 796 Quantization Range' control and can be used to test what happens if 797 a source provides you with the wrong quantization range information. 798 See the description of that control for more details. 799 800- Apply Alpha To Red Only: 801 802 apply the alpha channel as set by the 'Alpha Component' 803 user control to the red color of the test pattern only. 804 805- Enable Capture Cropping: 806 807 enables crop support. This control is only present if 808 the ccs_cap_mode module option is set to the default value of -1 and if 809 the no_error_inj module option is set to 0 (the default). 810 811- Enable Capture Composing: 812 813 enables composing support. This control is only 814 present if the ccs_cap_mode module option is set to the default value of 815 -1 and if the no_error_inj module option is set to 0 (the default). 816 817- Enable Capture Scaler: 818 819 enables support for a scaler (maximum 4 times upscaling 820 and downscaling). This control is only present if the ccs_cap_mode 821 module option is set to the default value of -1 and if the no_error_inj 822 module option is set to 0 (the default). 823 824- Maximum EDID Blocks: 825 826 determines how many EDID blocks the driver supports. 827 Note that the vivid driver does not actually interpret new EDID 828 data, it just stores it. It allows for up to 256 EDID blocks 829 which is the maximum supported by the standard. 830 831- Fill Percentage of Frame: 832 833 can be used to draw only the top X percent 834 of the image. Since each frame has to be drawn by the driver, this 835 demands a lot of the CPU. For large resolutions this becomes 836 problematic. By drawing only part of the image this CPU load can 837 be reduced. 838 839 840Output Feature Selection Controls 841^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 842 843These controls are all specific to video output. 844 845- Enable Output Cropping: 846 847 enables crop support. This control is only present if 848 the ccs_out_mode module option is set to the default value of -1 and if 849 the no_error_inj module option is set to 0 (the default). 850 851- Enable Output Composing: 852 853 enables composing support. This control is only 854 present if the ccs_out_mode module option is set to the default value of 855 -1 and if the no_error_inj module option is set to 0 (the default). 856 857- Enable Output Scaler: 858 859 enables support for a scaler (maximum 4 times upscaling 860 and downscaling). This control is only present if the ccs_out_mode 861 module option is set to the default value of -1 and if the no_error_inj 862 module option is set to 0 (the default). 863 864 865Error Injection Controls 866^^^^^^^^^^^^^^^^^^^^^^^^ 867 868The following two controls are only valid for video and vbi capture. 869 870- Standard Signal Mode: 871 872 selects the behavior of VIDIOC_QUERYSTD: what should it return? 873 874 Changing this control will result in the V4L2_EVENT_SOURCE_CHANGE 875 to be sent since it emulates a changed input condition (e.g. a cable 876 was plugged in or out). 877 878- Standard: 879 880 selects the standard that VIDIOC_QUERYSTD should return if the 881 previous control is set to "Selected Standard". 882 883 Changing this control will result in the V4L2_EVENT_SOURCE_CHANGE 884 to be sent since it emulates a changed input standard. 885 886 887The following two controls are only valid for video capture. 888 889- DV Timings Signal Mode: 890 891 selects the behavior of VIDIOC_QUERY_DV_TIMINGS: what 892 should it return? 893 894 Changing this control will result in the V4L2_EVENT_SOURCE_CHANGE 895 to be sent since it emulates a changed input condition (e.g. a cable 896 was plugged in or out). 897 898- DV Timings: 899 900 selects the timings the VIDIOC_QUERY_DV_TIMINGS should return 901 if the previous control is set to "Selected DV Timings". 902 903 Changing this control will result in the V4L2_EVENT_SOURCE_CHANGE 904 to be sent since it emulates changed input timings. 905 906 907The following controls are only present if the no_error_inj module option 908is set to 0 (the default). These controls are valid for video and vbi 909capture and output streams and for the SDR capture device except for the 910Disconnect control which is valid for all devices. 911 912- Wrap Sequence Number: 913 914 test what happens when you wrap the sequence number in 915 struct v4l2_buffer around. 916 917- Wrap Timestamp: 918 919 test what happens when you wrap the timestamp in struct 920 v4l2_buffer around. 921 922- Percentage of Dropped Buffers: 923 924 sets the percentage of buffers that 925 are never returned by the driver (i.e., they are dropped). 926 927- Disconnect: 928 929 emulates a USB disconnect. The device will act as if it has 930 been disconnected. Only after all open filehandles to the device 931 node have been closed will the device become 'connected' again. 932 933- Inject V4L2_BUF_FLAG_ERROR: 934 935 when pressed, the next frame returned by 936 the driver will have the error flag set (i.e. the frame is marked 937 corrupt). 938 939- Inject VIDIOC_REQBUFS Error: 940 941 when pressed, the next REQBUFS or CREATE_BUFS 942 ioctl call will fail with an error. To be precise: the videobuf2 943 queue_setup() op will return -EINVAL. 944 945- Inject VIDIOC_QBUF Error: 946 947 when pressed, the next VIDIOC_QBUF or 948 VIDIOC_PREPARE_BUFFER ioctl call will fail with an error. To be 949 precise: the videobuf2 buf_prepare() op will return -EINVAL. 950 951- Inject VIDIOC_STREAMON Error: 952 953 when pressed, the next VIDIOC_STREAMON ioctl 954 call will fail with an error. To be precise: the videobuf2 955 start_streaming() op will return -EINVAL. 956 957- Inject Fatal Streaming Error: 958 959 when pressed, the streaming core will be 960 marked as having suffered a fatal error, the only way to recover 961 from that is to stop streaming. To be precise: the videobuf2 962 vb2_queue_error() function is called. 963 964 965VBI Raw Capture Controls 966^^^^^^^^^^^^^^^^^^^^^^^^ 967 968- Interlaced VBI Format: 969 970 if set, then the raw VBI data will be interlaced instead 971 of providing it grouped by field. 972 973 974Digital Video Controls 975~~~~~~~~~~~~~~~~~~~~~~ 976 977- Rx RGB Quantization Range: 978 979 sets the RGB quantization detection of the HDMI 980 input. This combines with the Vivid 'Limited RGB Range (16-235)' 981 control and can be used to test what happens if a source provides 982 you with the wrong quantization range information. This can be tested 983 by selecting an HDMI input, setting this control to Full or Limited 984 range and selecting the opposite in the 'Limited RGB Range (16-235)' 985 control. The effect is easy to see if the 'Gray Ramp' test pattern 986 is selected. 987 988- Tx RGB Quantization Range: 989 990 sets the RGB quantization detection of the HDMI 991 output. It is currently not used for anything in vivid, but most HDMI 992 transmitters would typically have this control. 993 994- Transmit Mode: 995 996 sets the transmit mode of the HDMI output to HDMI or DVI-D. This 997 affects the reported colorspace since DVI_D outputs will always use 998 sRGB. 999 1000- Display Present: 1001 1002 sets the presence of a "display" on the HDMI output. This affects 1003 the tx_edid_present, tx_hotplug and tx_rxsense controls. 1004 1005 1006FM Radio Receiver Controls 1007~~~~~~~~~~~~~~~~~~~~~~~~~~ 1008 1009- RDS Reception: 1010 1011 set if the RDS receiver should be enabled. 1012 1013- RDS Program Type: 1014 1015 1016- RDS PS Name: 1017 1018 1019- RDS Radio Text: 1020 1021 1022- RDS Traffic Announcement: 1023 1024 1025- RDS Traffic Program: 1026 1027 1028- RDS Music: 1029 1030 these are all read-only controls. If RDS Rx I/O Mode is set to 1031 "Block I/O", then they are inactive as well. If RDS Rx I/O Mode is set 1032 to "Controls", then these controls report the received RDS data. 1033 1034.. note:: 1035 The vivid implementation of this is pretty basic: they are only 1036 updated when you set a new frequency or when you get the tuner status 1037 (VIDIOC_G_TUNER). 1038 1039- Radio HW Seek Mode: 1040 1041 can be one of "Bounded", "Wrap Around" or "Both". This 1042 determines if VIDIOC_S_HW_FREQ_SEEK will be bounded by the frequency 1043 range or wrap-around or if it is selectable by the user. 1044 1045- Radio Programmable HW Seek: 1046 1047 if set, then the user can provide the lower and 1048 upper bound of the HW Seek. Otherwise the frequency range boundaries 1049 will be used. 1050 1051- Generate RBDS Instead of RDS: 1052 1053 if set, then generate RBDS (the US variant of 1054 RDS) data instead of RDS (European-style RDS). This affects only the 1055 PICODE and PTY codes. 1056 1057- RDS Rx I/O Mode: 1058 1059 this can be "Block I/O" where the RDS blocks have to be read() 1060 by the application, or "Controls" where the RDS data is provided by 1061 the RDS controls mentioned above. 1062 1063 1064FM Radio Modulator Controls 1065~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1066 1067- RDS Program ID: 1068 1069 1070- RDS Program Type: 1071 1072 1073- RDS PS Name: 1074 1075 1076- RDS Radio Text: 1077 1078 1079- RDS Stereo: 1080 1081 1082- RDS Artificial Head: 1083 1084 1085- RDS Compressed: 1086 1087 1088- RDS Dynamic PTY: 1089 1090 1091- RDS Traffic Announcement: 1092 1093 1094- RDS Traffic Program: 1095 1096 1097- RDS Music: 1098 1099 these are all controls that set the RDS data that is transmitted by 1100 the FM modulator. 1101 1102- RDS Tx I/O Mode: 1103 1104 this can be "Block I/O" where the application has to use write() 1105 to pass the RDS blocks to the driver, or "Controls" where the RDS data 1106 is Provided by the RDS controls mentioned above. 1107 1108Metadata Capture Controls 1109~~~~~~~~~~~~~~~~~~~~~~~~~~ 1110 1111- Generate PTS 1112 1113 if set, then the generated metadata stream contains Presentation timestamp. 1114 1115- Generate SCR 1116 1117 if set, then the generated metadata stream contains Source Clock information. 1118 1119Video, VBI and RDS Looping 1120-------------------------- 1121 1122The vivid driver supports looping of video output to video input, VBI output 1123to VBI input and RDS output to RDS input. For video/VBI looping this emulates 1124as if a cable was hooked up between the output and input connector. So video 1125and VBI looping is only supported between S-Video and HDMI inputs and outputs. 1126VBI is only valid for S-Video as it makes no sense for HDMI. 1127 1128Since radio is wireless this looping always happens if the radio receiver 1129frequency is close to the radio transmitter frequency. In that case the radio 1130transmitter will 'override' the emulated radio stations. 1131 1132Looping is currently supported only between devices created by the same 1133vivid driver instance. 1134 1135 1136Video and Sliced VBI looping 1137~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1138 1139The way to enable video/VBI looping is currently fairly crude. A 'Loop Video' 1140control is available in the "Vivid" control class of the video 1141capture and VBI capture devices. When checked the video looping will be enabled. 1142Once enabled any video S-Video or HDMI input will show a static test pattern 1143until the video output has started. At that time the video output will be 1144looped to the video input provided that: 1145 1146- the input type matches the output type. So the HDMI input cannot receive 1147 video from the S-Video output. 1148 1149- the video resolution of the video input must match that of the video output. 1150 So it is not possible to loop a 50 Hz (720x576) S-Video output to a 60 Hz 1151 (720x480) S-Video input, or a 720p60 HDMI output to a 1080p30 input. 1152 1153- the pixel formats must be identical on both sides. Otherwise the driver would 1154 have to do pixel format conversion as well, and that's taking things too far. 1155 1156- the field settings must be identical on both sides. Same reason as above: 1157 requiring the driver to convert from one field format to another complicated 1158 matters too much. This also prohibits capturing with 'Field Top' or 'Field 1159 Bottom' when the output video is set to 'Field Alternate'. This combination, 1160 while legal, became too complicated to support. Both sides have to be 'Field 1161 Alternate' for this to work. Also note that for this specific case the 1162 sequence and field counting in struct v4l2_buffer on the capture side may not 1163 be 100% accurate. 1164 1165- field settings V4L2_FIELD_SEQ_TB/BT are not supported. While it is possible to 1166 implement this, it would mean a lot of work to get this right. Since these 1167 field values are rarely used the decision was made not to implement this for 1168 now. 1169 1170- on the input side the "Standard Signal Mode" for the S-Video input or the 1171 "DV Timings Signal Mode" for the HDMI input should be configured so that a 1172 valid signal is passed to the video input. 1173 1174The framerates do not have to match, although this might change in the future. 1175 1176By default you will see the OSD text superimposed on top of the looped video. 1177This can be turned off by changing the "OSD Text Mode" control of the video 1178capture device. 1179 1180For VBI looping to work all of the above must be valid and in addition the vbi 1181output must be configured for sliced VBI. The VBI capture side can be configured 1182for either raw or sliced VBI. Note that at the moment only CC/XDS (60 Hz formats) 1183and WSS (50 Hz formats) VBI data is looped. Teletext VBI data is not looped. 1184 1185 1186Radio & RDS Looping 1187~~~~~~~~~~~~~~~~~~~ 1188 1189As mentioned in section 6 the radio receiver emulates stations are regular 1190frequency intervals. Depending on the frequency of the radio receiver a 1191signal strength value is calculated (this is returned by VIDIOC_G_TUNER). 1192However, it will also look at the frequency set by the radio transmitter and 1193if that results in a higher signal strength than the settings of the radio 1194transmitter will be used as if it was a valid station. This also includes 1195the RDS data (if any) that the transmitter 'transmits'. This is received 1196faithfully on the receiver side. Note that when the driver is loaded the 1197frequencies of the radio receiver and transmitter are not identical, so 1198initially no looping takes place. 1199 1200 1201Cropping, Composing, Scaling 1202---------------------------- 1203 1204This driver supports cropping, composing and scaling in any combination. Normally 1205which features are supported can be selected through the Vivid controls, 1206but it is also possible to hardcode it when the module is loaded through the 1207ccs_cap_mode and ccs_out_mode module options. See section 1 on the details of 1208these module options. 1209 1210This allows you to test your application for all these variations. 1211 1212Note that the webcam input never supports cropping, composing or scaling. That 1213only applies to the TV/S-Video/HDMI inputs and outputs. The reason is that 1214webcams, including this virtual implementation, normally use 1215VIDIOC_ENUM_FRAMESIZES to list a set of discrete framesizes that it supports. 1216And that does not combine with cropping, composing or scaling. This is 1217primarily a limitation of the V4L2 API which is carefully reproduced here. 1218 1219The minimum and maximum resolutions that the scaler can achieve are 16x16 and 1220(4096 * 4) x (2160 x 4), but it can only scale up or down by a factor of 4 or 1221less. So for a source resolution of 1280x720 the minimum the scaler can do is 1222320x180 and the maximum is 5120x2880. You can play around with this using the 1223qv4l2 test tool and you will see these dependencies. 1224 1225This driver also supports larger 'bytesperline' settings, something that 1226VIDIOC_S_FMT allows but that few drivers implement. 1227 1228The scaler is a simple scaler that uses the Coarse Bresenham algorithm. It's 1229designed for speed and simplicity, not quality. 1230 1231If the combination of crop, compose and scaling allows it, then it is possible 1232to change crop and compose rectangles on the fly. 1233 1234 1235Formats 1236------- 1237 1238The driver supports all the regular packed and planar 4:4:4, 4:2:2 and 4:2:0 1239YUYV formats, 8, 16, 24 and 32 RGB packed formats and various multiplanar 1240formats. 1241 1242The alpha component can be set through the 'Alpha Component' User control 1243for those formats that support it. If the 'Apply Alpha To Red Only' control 1244is set, then the alpha component is only used for the color red and set to 12450 otherwise. 1246 1247The driver has to be configured to support the multiplanar formats. By default 1248the driver instances are single-planar. This can be changed by setting the 1249multiplanar module option, see section 1 for more details on that option. 1250 1251If the driver instance is using the multiplanar formats/API, then the first 1252single planar format (YUYV) and the multiplanar NV16M and NV61M formats the 1253will have a plane that has a non-zero data_offset of 128 bytes. It is rare for 1254data_offset to be non-zero, so this is a useful feature for testing applications. 1255 1256Video output will also honor any data_offset that the application set. 1257 1258 1259Capture Overlay 1260--------------- 1261 1262Note: capture overlay support is implemented primarily to test the existing 1263V4L2 capture overlay API. In practice few if any GPUs support such overlays 1264anymore, and neither are they generally needed anymore since modern hardware 1265is so much more capable. By setting flag 0x10000 in the node_types module 1266option the vivid driver will create a simple framebuffer device that can be 1267used for testing this API. Whether this API should be used for new drivers is 1268questionable. 1269 1270This driver has support for a destructive capture overlay with bitmap clipping 1271and list clipping (up to 16 rectangles) capabilities. Overlays are not 1272supported for multiplanar formats. It also honors the struct v4l2_window field 1273setting: if it is set to FIELD_TOP or FIELD_BOTTOM and the capture setting is 1274FIELD_ALTERNATE, then only the top or bottom fields will be copied to the overlay. 1275 1276The overlay only works if you are also capturing at that same time. This is a 1277vivid limitation since it copies from a buffer to the overlay instead of 1278filling the overlay directly. And if you are not capturing, then no buffers 1279are available to fill. 1280 1281In addition, the pixelformat of the capture format and that of the framebuffer 1282must be the same for the overlay to work. Otherwise VIDIOC_OVERLAY will return 1283an error. 1284 1285In order to really see what it going on you will need to create two vivid 1286instances: the first with a framebuffer enabled. You configure the capture 1287overlay of the second instance to use the framebuffer of the first, then 1288you start capturing in the second instance. For the first instance you setup 1289the output overlay for the video output, turn on video looping and capture 1290to see the blended framebuffer overlay that's being written to by the second 1291instance. This setup would require the following commands: 1292 1293.. code-block:: none 1294 1295 $ sudo modprobe vivid n_devs=2 node_types=0x10101,0x1 1296 $ v4l2-ctl -d1 --find-fb 1297 /dev/fb1 is the framebuffer associated with base address 0x12800000 1298 $ sudo v4l2-ctl -d2 --set-fbuf fb=1 1299 $ v4l2-ctl -d1 --set-fbuf fb=1 1300 $ v4l2-ctl -d0 --set-fmt-video=pixelformat='AR15' 1301 $ v4l2-ctl -d1 --set-fmt-video-out=pixelformat='AR15' 1302 $ v4l2-ctl -d2 --set-fmt-video=pixelformat='AR15' 1303 $ v4l2-ctl -d0 -i2 1304 $ v4l2-ctl -d2 -i2 1305 $ v4l2-ctl -d2 -c horizontal_movement=4 1306 $ v4l2-ctl -d1 --overlay=1 1307 $ v4l2-ctl -d1 -c loop_video=1 1308 $ v4l2-ctl -d2 --stream-mmap --overlay=1 1309 1310And from another console: 1311 1312.. code-block:: none 1313 1314 $ v4l2-ctl -d1 --stream-out-mmap 1315 1316And yet another console: 1317 1318.. code-block:: none 1319 1320 $ qv4l2 1321 1322and start streaming. 1323 1324As you can see, this is not for the faint of heart... 1325 1326 1327Output Overlay 1328-------------- 1329 1330Note: output overlays are primarily implemented in order to test the existing 1331V4L2 output overlay API. Whether this API should be used for new drivers is 1332questionable. 1333 1334This driver has support for an output overlay and is capable of: 1335 1336 - bitmap clipping, 1337 - list clipping (up to 16 rectangles) 1338 - chromakey 1339 - source chromakey 1340 - global alpha 1341 - local alpha 1342 - local inverse alpha 1343 1344Output overlays are not supported for multiplanar formats. In addition, the 1345pixelformat of the capture format and that of the framebuffer must be the 1346same for the overlay to work. Otherwise VIDIOC_OVERLAY will return an error. 1347 1348Output overlays only work if the driver has been configured to create a 1349framebuffer by setting flag 0x10000 in the node_types module option. The 1350created framebuffer has a size of 720x576 and supports ARGB 1:5:5:5 and 1351RGB 5:6:5. 1352 1353In order to see the effects of the various clipping, chromakeying or alpha 1354processing capabilities you need to turn on video looping and see the results 1355on the capture side. The use of the clipping, chromakeying or alpha processing 1356capabilities will slow down the video loop considerably as a lot of checks have 1357to be done per pixel. 1358 1359 1360CEC (Consumer Electronics Control) 1361---------------------------------- 1362 1363If there are HDMI inputs then a CEC adapter will be created that has 1364the same number of input ports. This is the equivalent of e.g. a TV that 1365has that number of inputs. Each HDMI output will also create a 1366CEC adapter that is hooked up to the corresponding input port, or (if there 1367are more outputs than inputs) is not hooked up at all. In other words, 1368this is the equivalent of hooking up each output device to an input port of 1369the TV. Any remaining output devices remain unconnected. 1370 1371The EDID that each output reads reports a unique CEC physical address that is 1372based on the physical address of the EDID of the input. So if the EDID of the 1373receiver has physical address A.B.0.0, then each output will see an EDID 1374containing physical address A.B.C.0 where C is 1 to the number of inputs. If 1375there are more outputs than inputs then the remaining outputs have a CEC adapter 1376that is disabled and reports an invalid physical address. 1377 1378 1379Some Future Improvements 1380------------------------ 1381 1382Just as a reminder and in no particular order: 1383 1384- Add a virtual alsa driver to test audio 1385- Add virtual sub-devices and media controller support 1386- Some support for testing compressed video 1387- Add support to loop raw VBI output to raw VBI input 1388- Add support to loop teletext sliced VBI output to VBI input 1389- Fix sequence/field numbering when looping of video with alternate fields 1390- Add support for V4L2_CID_BG_COLOR for video outputs 1391- Add ARGB888 overlay support: better testing of the alpha channel 1392- Improve pixel aspect support in the tpg code by passing a real v4l2_fract 1393- Use per-queue locks and/or per-device locks to improve throughput 1394- Add support to loop from a specific output to a specific input across 1395 vivid instances 1396- The SDR radio should use the same 'frequencies' for stations as the normal 1397 radio receiver, and give back noise if the frequency doesn't match up with 1398 a station frequency 1399- Make a thread for the RDS generation, that would help in particular for the 1400 "Controls" RDS Rx I/O Mode as the read-only RDS controls could be updated 1401 in real-time. 1402- Changing the EDID should cause hotplug detect emulation to happen. 1403