diff options
Diffstat (limited to 'Documentation/admin-guide/media/vivid.rst')
| -rw-r--r-- | Documentation/admin-guide/media/vivid.rst | 1416 |
1 files changed, 1416 insertions, 0 deletions
diff --git a/Documentation/admin-guide/media/vivid.rst b/Documentation/admin-guide/media/vivid.rst new file mode 100644 index 0000000000..58ac25b2c3 --- /dev/null +++ b/Documentation/admin-guide/media/vivid.rst @@ -0,0 +1,1416 @@ +.. SPDX-License-Identifier: GPL-2.0 + +The Virtual Video Test Driver (vivid) +===================================== + +This driver emulates video4linux hardware of various types: video capture, video +output, vbi capture and output, metadata capture and output, radio receivers and +transmitters, touch capture and a software defined radio receiver. In addition a +simple framebuffer device is available for testing capture and output overlays. + +Up to 64 vivid instances can be created, each with up to 16 inputs and 16 outputs. + +Each input can be a webcam, TV capture device, S-Video capture device or an HDMI +capture device. Each output can be an S-Video output device or an HDMI output +device. + +These inputs and outputs act exactly as a real hardware device would behave. This +allows you to use this driver as a test input for application development, since +you can test the various features without requiring special hardware. + +This document describes the features implemented by this driver: + +- Support for read()/write(), MMAP, USERPTR and DMABUF streaming I/O. +- A large list of test patterns and variations thereof +- Working brightness, contrast, saturation and hue controls +- Support for the alpha color component +- Full colorspace support, including limited/full RGB range +- All possible control types are present +- Support for various pixel aspect ratios and video aspect ratios +- Error injection to test what happens if errors occur +- Supports crop/compose/scale in any combination for both input and output +- Can emulate up to 4K resolutions +- All Field settings are supported for testing interlaced capturing +- Supports all standard YUV and RGB formats, including two multiplanar YUV formats +- Raw and Sliced VBI capture and output support +- Radio receiver and transmitter support, including RDS support +- Software defined radio (SDR) support +- Capture and output overlay support +- Metadata capture and output support +- Touch capture support + +These features will be described in more detail below. + +Configuring the driver +---------------------- + +By default the driver will create a single instance that has a video capture +device with webcam, TV, S-Video and HDMI inputs, a video output device with +S-Video and HDMI outputs, one vbi capture device, one vbi output device, one +radio receiver device, one radio transmitter device and one SDR device. + +The number of instances, devices, video inputs and outputs and their types are +all configurable using the following module options: + +- n_devs: + + number of driver instances to create. By default set to 1. Up to 64 + instances can be created. + +- node_types: + + which devices should each driver instance create. An array of + hexadecimal values, one for each instance. The default is 0x1d3d. + Each value is a bitmask with the following meaning: + + - bit 0: Video Capture node + - bit 2-3: VBI Capture node: 0 = none, 1 = raw vbi, 2 = sliced vbi, 3 = both + - bit 4: Radio Receiver node + - bit 5: Software Defined Radio Receiver node + - bit 8: Video Output node + - bit 10-11: VBI Output node: 0 = none, 1 = raw vbi, 2 = sliced vbi, 3 = both + - bit 12: Radio Transmitter node + - bit 16: Framebuffer for testing overlays + - bit 17: Metadata Capture node + - bit 18: Metadata Output node + - bit 19: Touch Capture node + + So to create four instances, the first two with just one video capture + device, the second two with just one video output device you would pass + these module options to vivid: + + .. code-block:: none + + n_devs=4 node_types=0x1,0x1,0x100,0x100 + +- num_inputs: + + the number of inputs, one for each instance. By default 4 inputs + are created for each video capture device. At most 16 inputs can be created, + and there must be at least one. + +- input_types: + + the input types for each instance, the default is 0xe4. This defines + what the type of each input is when the inputs are created for each driver + instance. This is a hexadecimal value with up to 16 pairs of bits, each + pair gives the type and bits 0-1 map to input 0, bits 2-3 map to input 1, + 30-31 map to input 15. Each pair of bits has the following meaning: + + - 00: this is a webcam input + - 01: this is a TV tuner input + - 10: this is an S-Video input + - 11: this is an HDMI input + + So to create a video capture device with 8 inputs where input 0 is a TV + tuner, inputs 1-3 are S-Video inputs and inputs 4-7 are HDMI inputs you + would use the following module options: + + .. code-block:: none + + num_inputs=8 input_types=0xffa9 + +- num_outputs: + + the number of outputs, one for each instance. By default 2 outputs + are created for each video output device. At most 16 outputs can be + created, and there must be at least one. + +- output_types: + + the output types for each instance, the default is 0x02. This defines + what the type of each output is when the outputs are created for each + driver instance. This is a hexadecimal value with up to 16 bits, each bit + gives the type and bit 0 maps to output 0, bit 1 maps to output 1, bit + 15 maps to output 15. The meaning of each bit is as follows: + + - 0: this is an S-Video output + - 1: this is an HDMI output + + So to create a video output device with 8 outputs where outputs 0-3 are + S-Video outputs and outputs 4-7 are HDMI outputs you would use the + following module options: + + .. code-block:: none + + num_outputs=8 output_types=0xf0 + +- vid_cap_nr: + + give the desired videoX start number for each video capture device. + The default is -1 which will just take the first free number. This allows + you to map capture video nodes to specific videoX device nodes. Example: + + .. code-block:: none + + n_devs=4 vid_cap_nr=2,4,6,8 + + This will attempt to assign /dev/video2 for the video capture device of + the first vivid instance, video4 for the next up to video8 for the last + instance. If it can't succeed, then it will just take the next free + number. + +- vid_out_nr: + + give the desired videoX start number for each video output device. + The default is -1 which will just take the first free number. + +- vbi_cap_nr: + + give the desired vbiX start number for each vbi capture device. + The default is -1 which will just take the first free number. + +- vbi_out_nr: + + give the desired vbiX start number for each vbi output device. + The default is -1 which will just take the first free number. + +- radio_rx_nr: + + give the desired radioX start number for each radio receiver device. + The default is -1 which will just take the first free number. + +- radio_tx_nr: + + give the desired radioX start number for each radio transmitter + device. The default is -1 which will just take the first free number. + +- sdr_cap_nr: + + give the desired swradioX start number for each SDR capture device. + The default is -1 which will just take the first free number. + +- meta_cap_nr: + + give the desired videoX start number for each metadata capture device. + The default is -1 which will just take the first free number. + +- meta_out_nr: + + give the desired videoX start number for each metadata output device. + The default is -1 which will just take the first free number. + +- touch_cap_nr: + + give the desired v4l-touchX start number for each touch capture device. + The default is -1 which will just take the first free number. + +- ccs_cap_mode: + + specify the allowed video capture crop/compose/scaling combination + for each driver instance. Video capture devices can have any combination + of cropping, composing and scaling capabilities and this will tell the + vivid driver which of those is should emulate. By default the user can + select this through controls. + + The value is either -1 (controlled by the user) or a set of three bits, + each enabling (1) or disabling (0) one of the features: + + - bit 0: + + Enable crop support. Cropping will take only part of the + incoming picture. + - bit 1: + + Enable compose support. Composing will copy the incoming + picture into a larger buffer. + + - bit 2: + + Enable scaling support. Scaling can scale the incoming + picture. The scaler of the vivid driver can enlarge up + or down to four times the original size. The scaler is + very simple and low-quality. Simplicity and speed were + key, not quality. + + Note that this value is ignored by webcam inputs: those enumerate + discrete framesizes and that is incompatible with cropping, composing + or scaling. + +- ccs_out_mode: + + specify the allowed video output crop/compose/scaling combination + for each driver instance. Video output devices can have any combination + of cropping, composing and scaling capabilities and this will tell the + vivid driver which of those is should emulate. By default the user can + select this through controls. + + The value is either -1 (controlled by the user) or a set of three bits, + each enabling (1) or disabling (0) one of the features: + + - bit 0: + + Enable crop support. Cropping will take only part of the + outgoing buffer. + + - bit 1: + + Enable compose support. Composing will copy the incoming + buffer into a larger picture frame. + + - bit 2: + + Enable scaling support. Scaling can scale the incoming + buffer. The scaler of the vivid driver can enlarge up + or down to four times the original size. The scaler is + very simple and low-quality. Simplicity and speed were + key, not quality. + +- multiplanar: + + select whether each device instance supports multi-planar formats, + and thus the V4L2 multi-planar API. By default device instances are + single-planar. + + This module option can override that for each instance. Values are: + + - 1: this is a single-planar instance. + - 2: this is a multi-planar instance. + +- vivid_debug: + + enable driver debugging info + +- no_error_inj: + + if set disable the error injecting controls. This option is + needed in order to run a tool like v4l2-compliance. Tools like that + exercise all controls including a control like 'Disconnect' which + emulates a USB disconnect, making the device inaccessible and so + all tests that v4l2-compliance is doing will fail afterwards. + + There may be other situations as well where you want to disable the + error injection support of vivid. When this option is set, then the + controls that select crop, compose and scale behavior are also + removed. Unless overridden by ccs_cap_mode and/or ccs_out_mode the + will default to enabling crop, compose and scaling. + +- allocators: + + memory allocator selection, default is 0. It specifies the way buffers + will be allocated. + + - 0: vmalloc + - 1: dma-contig + +- cache_hints: + + specifies if the device should set queues' user-space cache and memory + consistency hint capability (V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS). + The hints are valid only when using MMAP streaming I/O. Default is 0. + + - 0: forbid hints + - 1: allow hints + +Taken together, all these module options allow you to precisely customize +the driver behavior and test your application with all sorts of permutations. +It is also very suitable to emulate hardware that is not yet available, e.g. +when developing software for a new upcoming device. + + +Video Capture +------------- + +This is probably the most frequently used feature. The video capture device +can be configured by using the module options num_inputs, input_types and +ccs_cap_mode (see section 1 for more detailed information), but by default +four inputs are configured: a webcam, a TV tuner, an S-Video and an HDMI +input, one input for each input type. Those are described in more detail +below. + +Special attention has been given to the rate at which new frames become +available. The jitter will be around 1 jiffie (that depends on the HZ +configuration of your kernel, so usually 1/100, 1/250 or 1/1000 of a second), +but the long-term behavior is exactly following the framerate. So a +framerate of 59.94 Hz is really different from 60 Hz. If the framerate +exceeds your kernel's HZ value, then you will get dropped frames, but the +frame/field sequence counting will keep track of that so the sequence +count will skip whenever frames are dropped. + + +Webcam Input +~~~~~~~~~~~~ + +The webcam input supports three framesizes: 320x180, 640x360 and 1280x720. It +supports frames per second settings of 10, 15, 25, 30, 50 and 60 fps. Which ones +are available depends on the chosen framesize: the larger the framesize, the +lower the maximum frames per second. + +The initially selected colorspace when you switch to the webcam input will be +sRGB. + + +TV and S-Video Inputs +~~~~~~~~~~~~~~~~~~~~~ + +The only difference between the TV and S-Video input is that the TV has a +tuner. Otherwise they behave identically. + +These inputs support audio inputs as well: one TV and one Line-In. They +both support all TV standards. If the standard is queried, then the Vivid +controls 'Standard Signal Mode' and 'Standard' determine what +the result will be. + +These inputs support all combinations of the field setting. Special care has +been taken to faithfully reproduce how fields are handled for the different +TV standards. This is particularly noticeable when generating a horizontally +moving image so the temporal effect of using interlaced formats becomes clearly +visible. For 50 Hz standards the top field is the oldest and the bottom field +is the newest in time. For 60 Hz standards that is reversed: the bottom field +is the oldest and the top field is the newest in time. + +When you start capturing in V4L2_FIELD_ALTERNATE mode the first buffer will +contain the top field for 50 Hz standards and the bottom field for 60 Hz +standards. This is what capture hardware does as well. + +Finally, for PAL/SECAM standards the first half of the top line contains noise. +This simulates the Wide Screen Signal that is commonly placed there. + +The initially selected colorspace when you switch to the TV or S-Video input +will be SMPTE-170M. + +The pixel aspect ratio will depend on the TV standard. The video aspect ratio +can be selected through the 'Standard Aspect Ratio' Vivid control. +Choices are '4x3', '16x9' which will give letterboxed widescreen video and +'16x9 Anamorphic' which will give full screen squashed anamorphic widescreen +video that will need to be scaled accordingly. + +The TV 'tuner' supports a frequency range of 44-958 MHz. Channels are available +every 6 MHz, starting from 49.25 MHz. For each channel the generated image +will be in color for the +/- 0.25 MHz around it, and in grayscale for ++/- 1 MHz around the channel. Beyond that it is just noise. The VIDIOC_G_TUNER +ioctl will return 100% signal strength for +/- 0.25 MHz and 50% for +/- 1 MHz. +It will also return correct afc values to show whether the frequency is too +low or too high. + +The audio subchannels that are returned are MONO for the +/- 1 MHz range around +a valid channel frequency. When the frequency is within +/- 0.25 MHz of the +channel it will return either MONO, STEREO, either MONO | SAP (for NTSC) or +LANG1 | LANG2 (for others), or STEREO | SAP. + +Which one is returned depends on the chosen channel, each next valid channel +will cycle through the possible audio subchannel combinations. This allows +you to test the various combinations by just switching channels.. + +Finally, for these inputs the v4l2_timecode struct is filled in the +dequeued v4l2_buffer struct. + + +HDMI Input +~~~~~~~~~~ + +The HDMI inputs supports all CEA-861 and DMT timings, both progressive and +interlaced, for pixelclock frequencies between 25 and 600 MHz. The field +mode for interlaced formats is always V4L2_FIELD_ALTERNATE. For HDMI the +field order is always top field first, and when you start capturing an +interlaced format you will receive the top field first. + +The initially selected colorspace when you switch to the HDMI input or +select an HDMI timing is based on the format resolution: for resolutions +less than or equal to 720x576 the colorspace is set to SMPTE-170M, for +others it is set to REC-709 (CEA-861 timings) or sRGB (VESA DMT timings). + +The pixel aspect ratio will depend on the HDMI timing: for 720x480 is it +set as for the NTSC TV standard, for 720x576 it is set as for the PAL TV +standard, and for all others a 1:1 pixel aspect ratio is returned. + +The video aspect ratio can be selected through the 'DV Timings Aspect Ratio' +Vivid control. Choices are 'Source Width x Height' (just use the +same ratio as the chosen format), '4x3' or '16x9', either of which can +result in pillarboxed or letterboxed video. + +For HDMI inputs it is possible to set the EDID. By default a simple EDID +is provided. You can only set the EDID for HDMI inputs. Internally, however, +the EDID is shared between all HDMI inputs. + +No interpretation is done of the EDID data with the exception of the +physical address. See the CEC section for more details. + +There is a maximum of 15 HDMI inputs (if there are more, then they will be +reduced to 15) since that's the limitation of the EDID physical address. + + +Video Output +------------ + +The video output device can be configured by using the module options +num_outputs, output_types and ccs_out_mode (see section 1 for more detailed +information), but by default two outputs are configured: an S-Video and an +HDMI input, one output for each output type. Those are described in more detail +below. + +Like with video capture the framerate is also exact in the long term. + + +S-Video Output +~~~~~~~~~~~~~~ + +This output supports audio outputs as well: "Line-Out 1" and "Line-Out 2". +The S-Video output supports all TV standards. + +This output supports all combinations of the field setting. + +The initially selected colorspace when you switch to the TV or S-Video input +will be SMPTE-170M. + + +HDMI Output +~~~~~~~~~~~ + +The HDMI output supports all CEA-861 and DMT timings, both progressive and +interlaced, for pixelclock frequencies between 25 and 600 MHz. The field +mode for interlaced formats is always V4L2_FIELD_ALTERNATE. + +The initially selected colorspace when you switch to the HDMI output or +select an HDMI timing is based on the format resolution: for resolutions +less than or equal to 720x576 the colorspace is set to SMPTE-170M, for +others it is set to REC-709 (CEA-861 timings) or sRGB (VESA DMT timings). + +The pixel aspect ratio will depend on the HDMI timing: for 720x480 is it +set as for the NTSC TV standard, for 720x576 it is set as for the PAL TV +standard, and for all others a 1:1 pixel aspect ratio is returned. + +An HDMI output has a valid EDID which can be obtained through VIDIOC_G_EDID. + +There is a maximum of 15 HDMI outputs (if there are more, then they will be +reduced to 15) since that's the limitation of the EDID physical address. See +also the CEC section for more details. + +VBI Capture +----------- + +There are three types of VBI capture devices: those that only support raw +(undecoded) VBI, those that only support sliced (decoded) VBI and those that +support both. This is determined by the node_types module option. In all +cases the driver will generate valid VBI data: for 60 Hz standards it will +generate Closed Caption and XDS data. The closed caption stream will +alternate between "Hello world!" and "Closed captions test" every second. +The XDS stream will give the current time once a minute. For 50 Hz standards +it will generate the Wide Screen Signal which is based on the actual Video +Aspect Ratio control setting and teletext pages 100-159, one page per frame. + +The VBI device will only work for the S-Video and TV inputs, it will give +back an error if the current input is a webcam or HDMI. + + +VBI Output +---------- + +There are three types of VBI output devices: those that only support raw +(undecoded) VBI, those that only support sliced (decoded) VBI and those that +support both. This is determined by the node_types module option. + +The sliced VBI output supports the Wide Screen Signal and the teletext signal +for 50 Hz standards and Closed Captioning + XDS for 60 Hz standards. + +The VBI device will only work for the S-Video output, it will give +back an error if the current output is HDMI. + + +Radio Receiver +-------------- + +The radio receiver emulates an FM/AM/SW receiver. The FM band also supports RDS. +The frequency ranges are: + + - FM: 64 MHz - 108 MHz + - AM: 520 kHz - 1710 kHz + - SW: 2300 kHz - 26.1 MHz + +Valid channels are emulated every 1 MHz for FM and every 100 kHz for AM and SW. +The signal strength decreases the further the frequency is from the valid +frequency until it becomes 0% at +/- 50 kHz (FM) or 5 kHz (AM/SW) from the +ideal frequency. The initial frequency when the driver is loaded is set to +95 MHz. + +The FM receiver supports RDS as well, both using 'Block I/O' and 'Controls' +modes. In the 'Controls' mode the RDS information is stored in read-only +controls. These controls are updated every time the frequency is changed, +or when the tuner status is requested. The Block I/O method uses the read() +interface to pass the RDS blocks on to the application for decoding. + +The RDS signal is 'detected' for +/- 12.5 kHz around the channel frequency, +and the further the frequency is away from the valid frequency the more RDS +errors are randomly introduced into the block I/O stream, up to 50% of all +blocks if you are +/- 12.5 kHz from the channel frequency. All four errors +can occur in equal proportions: blocks marked 'CORRECTED', blocks marked +'ERROR', blocks marked 'INVALID' and dropped blocks. + +The generated RDS stream contains all the standard fields contained in a +0B group, and also radio text and the current time. + +The receiver supports HW frequency seek, either in Bounded mode, Wrap Around +mode or both, which is configurable with the "Radio HW Seek Mode" control. + + +Radio Transmitter +----------------- + +The radio transmitter emulates an FM/AM/SW transmitter. The FM band also supports RDS. +The frequency ranges are: + + - FM: 64 MHz - 108 MHz + - AM: 520 kHz - 1710 kHz + - SW: 2300 kHz - 26.1 MHz + +The initial frequency when the driver is loaded is 95.5 MHz. + +The FM transmitter supports RDS as well, both using 'Block I/O' and 'Controls' +modes. In the 'Controls' mode the transmitted RDS information is configured +using controls, and in 'Block I/O' mode the blocks are passed to the driver +using write(). + + +Software Defined Radio Receiver +------------------------------- + +The SDR receiver has three frequency bands for the ADC tuner: + + - 300 kHz + - 900 kHz - 2800 kHz + - 3200 kHz + +The RF tuner supports 50 MHz - 2000 MHz. + +The generated data contains the In-phase and Quadrature components of a +1 kHz tone that has an amplitude of sqrt(2). + + +Metadata Capture +---------------- + +The Metadata capture generates UVC format metadata. The PTS and SCR are +transmitted based on the values set in vivid controls. + +The Metadata device will only work for the Webcam input, it will give +back an error for all other inputs. + + +Metadata Output +--------------- + +The Metadata output can be used to set brightness, contrast, saturation and hue. + +The Metadata device will only work for the Webcam output, it will give +back an error for all other outputs. + + +Touch Capture +------------- + +The Touch capture generates touch patterns simulating single tap, double tap, +triple tap, move from left to right, zoom in, zoom out, palm press (simulating +a large area being pressed on a touchpad), and simulating 16 simultaneous +touch points. + +Controls +-------- + +Different devices support different controls. The sections below will describe +each control and which devices support them. + + +User Controls - Test Controls +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The Button, Boolean, Integer 32 Bits, Integer 64 Bits, Menu, String, Bitmask and +Integer Menu are controls that represent all possible control types. The Menu +control and the Integer Menu control both have 'holes' in their menu list, +meaning that one or more menu items return EINVAL when VIDIOC_QUERYMENU is called. +Both menu controls also have a non-zero minimum control value. These features +allow you to check if your application can handle such things correctly. +These controls are supported for every device type. + + +User Controls - Video Capture +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The following controls are specific to video capture. + +The Brightness, Contrast, Saturation and Hue controls actually work and are +standard. There is one special feature with the Brightness control: each +video input has its own brightness value, so changing input will restore +the brightness for that input. In addition, each video input uses a different +brightness range (minimum and maximum control values). Switching inputs will +cause a control event to be sent with the V4L2_EVENT_CTRL_CH_RANGE flag set. +This allows you to test controls that can change their range. + +The 'Gain, Automatic' and Gain controls can be used to test volatile controls: +if 'Gain, Automatic' is set, then the Gain control is volatile and changes +constantly. If 'Gain, Automatic' is cleared, then the Gain control is a normal +control. + +The 'Horizontal Flip' and 'Vertical Flip' controls can be used to flip the +image. These combine with the 'Sensor Flipped Horizontally/Vertically' Vivid +controls. + +The 'Alpha Component' control can be used to set the alpha component for +formats containing an alpha channel. + + +User Controls - Audio +~~~~~~~~~~~~~~~~~~~~~ + +The following controls are specific to video capture and output and radio +receivers and transmitters. + +The 'Volume' and 'Mute' audio controls are typical for such devices to +control the volume and mute the audio. They don't actually do anything in +the vivid driver. + + +Vivid Controls +~~~~~~~~~~~~~~ + +These vivid custom controls control the image generation, error injection, etc. + + +Test Pattern Controls +^^^^^^^^^^^^^^^^^^^^^ + +The Test Pattern Controls are all specific to video capture. + +- Test Pattern: + + selects which test pattern to use. Use the CSC Colorbar for + testing colorspace conversions: the colors used in that test pattern + map to valid colors in all colorspaces. The colorspace conversion + is disabled for the other test patterns. + +- OSD Text Mode: + + selects whether the text superimposed on the + test pattern should be shown, and if so, whether only counters should + be displayed or the full text. + +- Horizontal Movement: + + selects whether the test pattern should + move to the left or right and at what speed. + +- Vertical Movement: + + does the same for the vertical direction. + +- Show Border: + + show a two-pixel wide border at the edge of the actual image, + excluding letter or pillarboxing. + +- Show Square: + + show a square in the middle of the image. If the image is + displayed with the correct pixel and image aspect ratio corrections, + then the width and height of the square on the monitor should be + the same. + +- Insert SAV Code in Image: + + adds a SAV (Start of Active Video) code to the image. + This can be used to check if such codes in the image are inadvertently + interpreted instead of being ignored. + +- Insert EAV Code in Image: + + does the same for the EAV (End of Active Video) code. + +- Insert Video Guard Band + + adds 4 columns of pixels with the HDMI Video Guard Band code at the + left hand side of the image. This only works with 3 or 4 byte RGB pixel + formats. The RGB pixel value 0xab/0x55/0xab turns out to be equivalent + to the HDMI Video Guard Band code that precedes each active video line + (see section 5.2.2.1 in the HDMI 1.3 Specification). To test if a video + receiver has correct HDMI Video Guard Band processing, enable this + control and then move the image to the left hand side of the screen. + That will result in video lines that start with multiple pixels that + have the same value as the Video Guard Band that precedes them. + Receivers that will just keep skipping Video Guard Band values will + now fail and either loose sync or these video lines will shift. + + +Capture Feature Selection Controls +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +These controls are all specific to video capture. + +- Sensor Flipped Horizontally: + + the image is flipped horizontally and the + V4L2_IN_ST_HFLIP input status flag is set. This emulates the case where + a sensor is for example mounted upside down. + +- Sensor Flipped Vertically: + + the image is flipped vertically and the + V4L2_IN_ST_VFLIP input status flag is set. This emulates the case where + a sensor is for example mounted upside down. + +- Standard Aspect Ratio: + + selects if the image aspect ratio as used for the TV or + S-Video input should be 4x3, 16x9 or anamorphic widescreen. This may + introduce letterboxing. + +- DV Timings Aspect Ratio: + + selects if the image aspect ratio as used for the HDMI + input should be the same as the source width and height ratio, or if + it should be 4x3 or 16x9. This may introduce letter or pillarboxing. + +- Timestamp Source: + + selects when the timestamp for each buffer is taken. + +- Colorspace: + + selects which colorspace should be used when generating the image. + This only applies if the CSC Colorbar test pattern is selected, + otherwise the test pattern will go through unconverted. + This behavior is also what you want, since a 75% Colorbar + should really have 75% signal intensity and should not be affected + by colorspace conversions. + + Changing the colorspace will result in the V4L2_EVENT_SOURCE_CHANGE + to be sent since it emulates a detected colorspace change. + +- Transfer Function: + + selects which colorspace transfer function should be used when + generating an image. This only applies if the CSC Colorbar test pattern is + selected, otherwise the test pattern will go through unconverted. + This behavior is also what you want, since a 75% Colorbar + should really have 75% signal intensity and should not be affected + by colorspace conversions. + + Changing the transfer function will result in the V4L2_EVENT_SOURCE_CHANGE + to be sent since it emulates a detected colorspace change. + +- Y'CbCr Encoding: + + selects which Y'CbCr encoding should be used when generating + a Y'CbCr image. This only applies if the format is set to a Y'CbCr format + as opposed to an RGB format. + + Changing the Y'CbCr encoding will result in the V4L2_EVENT_SOURCE_CHANGE + to be sent since it emulates a detected colorspace change. + +- Quantization: + + selects which quantization should be used for the RGB or Y'CbCr + encoding when generating the test pattern. + + Changing the quantization will result in the V4L2_EVENT_SOURCE_CHANGE + to be sent since it emulates a detected colorspace change. + +- Limited RGB Range (16-235): + + selects if the RGB range of the HDMI source should + be limited or full range. This combines with the Digital Video 'Rx RGB + Quantization Range' control and can be used to test what happens if + a source provides you with the wrong quantization range information. + See the description of that control for more details. + +- Apply Alpha To Red Only: + + apply the alpha channel as set by the 'Alpha Component' + user control to the red color of the test pattern only. + +- Enable Capture Cropping: + + enables crop support. This control is only present if + the ccs_cap_mode module option is set to the default value of -1 and if + the no_error_inj module option is set to 0 (the default). + +- Enable Capture Composing: + + enables composing support. This control is only + present if the ccs_cap_mode module option is set to the default value of + -1 and if the no_error_inj module option is set to 0 (the default). + +- Enable Capture Scaler: + + enables support for a scaler (maximum 4 times upscaling + and downscaling). This control is only present if the ccs_cap_mode + module option is set to the default value of -1 and if the no_error_inj + module option is set to 0 (the default). + +- Maximum EDID Blocks: + + determines how many EDID blocks the driver supports. + Note that the vivid driver does not actually interpret new EDID + data, it just stores it. It allows for up to 256 EDID blocks + which is the maximum supported by the standard. + +- Fill Percentage of Frame: + + can be used to draw only the top X percent + of the image. Since each frame has to be drawn by the driver, this + demands a lot of the CPU. For large resolutions this becomes + problematic. By drawing only part of the image this CPU load can + be reduced. + + +Output Feature Selection Controls +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +These controls are all specific to video output. + +- Enable Output Cropping: + + enables crop support. This control is only present if + the ccs_out_mode module option is set to the default value of -1 and if + the no_error_inj module option is set to 0 (the default). + +- Enable Output Composing: + + enables composing support. This control is only + present if the ccs_out_mode module option is set to the default value of + -1 and if the no_error_inj module option is set to 0 (the default). + +- Enable Output Scaler: + + enables support for a scaler (maximum 4 times upscaling + and downscaling). This control is only present if the ccs_out_mode + module option is set to the default value of -1 and if the no_error_inj + module option is set to 0 (the default). + + +Error Injection Controls +^^^^^^^^^^^^^^^^^^^^^^^^ + +The following two controls are only valid for video and vbi capture. + +- Standard Signal Mode: + + selects the behavior of VIDIOC_QUERYSTD: what should it return? + + Changing this control will result in the V4L2_EVENT_SOURCE_CHANGE + to be sent since it emulates a changed input condition (e.g. a cable + was plugged in or out). + +- Standard: + + selects the standard that VIDIOC_QUERYSTD should return if the + previous control is set to "Selected Standard". + + Changing this control will result in the V4L2_EVENT_SOURCE_CHANGE + to be sent since it emulates a changed input standard. + + +The following two controls are only valid for video capture. + +- DV Timings Signal Mode: + + selects the behavior of VIDIOC_QUERY_DV_TIMINGS: what + should it return? + + Changing this control will result in the V4L2_EVENT_SOURCE_CHANGE + to be sent since it emulates a changed input condition (e.g. a cable + was plugged in or out). + +- DV Timings: + + selects the timings the VIDIOC_QUERY_DV_TIMINGS should return + if the previous control is set to "Selected DV Timings". + + Changing this control will result in the V4L2_EVENT_SOURCE_CHANGE + to be sent since it emulates changed input timings. + + +The following controls are only present if the no_error_inj module option +is set to 0 (the default). These controls are valid for video and vbi +capture and output streams and for the SDR capture device except for the +Disconnect control which is valid for all devices. + +- Wrap Sequence Number: + + test what happens when you wrap the sequence number in + struct v4l2_buffer around. + +- Wrap Timestamp: + + test what happens when you wrap the timestamp in struct + v4l2_buffer around. + +- Percentage of Dropped Buffers: + + sets the percentage of buffers that + are never returned by the driver (i.e., they are dropped). + +- Disconnect: + + emulates a USB disconnect. The device will act as if it has + been disconnected. Only after all open filehandles to the device + node have been closed will the device become 'connected' again. + +- Inject V4L2_BUF_FLAG_ERROR: + + when pressed, the next frame returned by + the driver will have the error flag set (i.e. the frame is marked + corrupt). + +- Inject VIDIOC_REQBUFS Error: + + when pressed, the next REQBUFS or CREATE_BUFS + ioctl call will fail with an error. To be precise: the videobuf2 + queue_setup() op will return -EINVAL. + +- Inject VIDIOC_QBUF Error: + + when pressed, the next VIDIOC_QBUF or + VIDIOC_PREPARE_BUFFER ioctl call will fail with an error. To be + precise: the videobuf2 buf_prepare() op will return -EINVAL. + +- Inject VIDIOC_STREAMON Error: + + when pressed, the next VIDIOC_STREAMON ioctl + call will fail with an error. To be precise: the videobuf2 + start_streaming() op will return -EINVAL. + +- Inject Fatal Streaming Error: + + when pressed, the streaming core will be + marked as having suffered a fatal error, the only way to recover + from that is to stop streaming. To be precise: the videobuf2 + vb2_queue_error() function is called. + + +VBI Raw Capture Controls +^^^^^^^^^^^^^^^^^^^^^^^^ + +- Interlaced VBI Format: + + if set, then the raw VBI data will be interlaced instead + of providing it grouped by field. + + +Digital Video Controls +~~~~~~~~~~~~~~~~~~~~~~ + +- Rx RGB Quantization Range: + + sets the RGB quantization detection of the HDMI + input. This combines with the Vivid 'Limited RGB Range (16-235)' + control and can be used to test what happens if a source provides + you with the wrong quantization range information. This can be tested + by selecting an HDMI input, setting this control to Full or Limited + range and selecting the opposite in the 'Limited RGB Range (16-235)' + control. The effect is easy to see if the 'Gray Ramp' test pattern + is selected. + +- Tx RGB Quantization Range: + + sets the RGB quantization detection of the HDMI + output. It is currently not used for anything in vivid, but most HDMI + transmitters would typically have this control. + +- Transmit Mode: + + sets the transmit mode of the HDMI output to HDMI or DVI-D. This + affects the reported colorspace since DVI_D outputs will always use + sRGB. + +- Display Present: + + sets the presence of a "display" on the HDMI output. This affects + the tx_edid_present, tx_hotplug and tx_rxsense controls. + + +FM Radio Receiver Controls +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +- RDS Reception: + + set if the RDS receiver should be enabled. + +- RDS Program Type: + + +- RDS PS Name: + + +- RDS Radio Text: + + +- RDS Traffic Announcement: + + +- RDS Traffic Program: + + +- RDS Music: + + these are all read-only controls. If RDS Rx I/O Mode is set to + "Block I/O", then they are inactive as well. If RDS Rx I/O Mode is set + to "Controls", then these controls report the received RDS data. + +.. note:: + The vivid implementation of this is pretty basic: they are only + updated when you set a new frequency or when you get the tuner status + (VIDIOC_G_TUNER). + +- Radio HW Seek Mode: + + can be one of "Bounded", "Wrap Around" or "Both". This + determines if VIDIOC_S_HW_FREQ_SEEK will be bounded by the frequency + range or wrap-around or if it is selectable by the user. + +- Radio Programmable HW Seek: + + if set, then the user can provide the lower and + upper bound of the HW Seek. Otherwise the frequency range boundaries + will be used. + +- Generate RBDS Instead of RDS: + + if set, then generate RBDS (the US variant of + RDS) data instead of RDS (European-style RDS). This affects only the + PICODE and PTY codes. + +- RDS Rx I/O Mode: + + this can be "Block I/O" where the RDS blocks have to be read() + by the application, or "Controls" where the RDS data is provided by + the RDS controls mentioned above. + + +FM Radio Modulator Controls +~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +- RDS Program ID: + + +- RDS Program Type: + + +- RDS PS Name: + + +- RDS Radio Text: + + +- RDS Stereo: + + +- RDS Artificial Head: + + +- RDS Compressed: + + +- RDS Dynamic PTY: + + +- RDS Traffic Announcement: + + +- RDS Traffic Program: + + +- RDS Music: + + these are all controls that set the RDS data that is transmitted by + the FM modulator. + +- RDS Tx I/O Mode: + + this can be "Block I/O" where the application has to use write() + to pass the RDS blocks to the driver, or "Controls" where the RDS data + is Provided by the RDS controls mentioned above. + +Metadata Capture Controls +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +- Generate PTS + + if set, then the generated metadata stream contains Presentation timestamp. + +- Generate SCR + + if set, then the generated metadata stream contains Source Clock information. + +Video, VBI and RDS Looping +-------------------------- + +The vivid driver supports looping of video output to video input, VBI output +to VBI input and RDS output to RDS input. For video/VBI looping this emulates +as if a cable was hooked up between the output and input connector. So video +and VBI looping is only supported between S-Video and HDMI inputs and outputs. +VBI is only valid for S-Video as it makes no sense for HDMI. + +Since radio is wireless this looping always happens if the radio receiver +frequency is close to the radio transmitter frequency. In that case the radio +transmitter will 'override' the emulated radio stations. + +Looping is currently supported only between devices created by the same +vivid driver instance. + + +Video and Sliced VBI looping +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The way to enable video/VBI looping is currently fairly crude. A 'Loop Video' +control is available in the "Vivid" control class of the video +capture and VBI capture devices. When checked the video looping will be enabled. +Once enabled any video S-Video or HDMI input will show a static test pattern +until the video output has started. At that time the video output will be +looped to the video input provided that: + +- the input type matches the output type. So the HDMI input cannot receive + video from the S-Video output. + +- the video resolution of the video input must match that of the video output. + So it is not possible to loop a 50 Hz (720x576) S-Video output to a 60 Hz + (720x480) S-Video input, or a 720p60 HDMI output to a 1080p30 input. + +- the pixel formats must be identical on both sides. Otherwise the driver would + have to do pixel format conversion as well, and that's taking things too far. + +- the field settings must be identical on both sides. Same reason as above: + requiring the driver to convert from one field format to another complicated + matters too much. This also prohibits capturing with 'Field Top' or 'Field + Bottom' when the output video is set to 'Field Alternate'. This combination, + while legal, became too complicated to support. Both sides have to be 'Field + Alternate' for this to work. Also note that for this specific case the + sequence and field counting in struct v4l2_buffer on the capture side may not + be 100% accurate. + +- field settings V4L2_FIELD_SEQ_TB/BT are not supported. While it is possible to + implement this, it would mean a lot of work to get this right. Since these + field values are rarely used the decision was made not to implement this for + now. + +- on the input side the "Standard Signal Mode" for the S-Video input or the + "DV Timings Signal Mode" for the HDMI input should be configured so that a + valid signal is passed to the video input. + +The framerates do not have to match, although this might change in the future. + +By default you will see the OSD text superimposed on top of the looped video. +This can be turned off by changing the "OSD Text Mode" control of the video +capture device. + +For VBI looping to work all of the above must be valid and in addition the vbi +output must be configured for sliced VBI. The VBI capture side can be configured +for either raw or sliced VBI. Note that at the moment only CC/XDS (60 Hz formats) +and WSS (50 Hz formats) VBI data is looped. Teletext VBI data is not looped. + + +Radio & RDS Looping +~~~~~~~~~~~~~~~~~~~ + +As mentioned in section 6 the radio receiver emulates stations are regular +frequency intervals. Depending on the frequency of the radio receiver a +signal strength value is calculated (this is returned by VIDIOC_G_TUNER). +However, it will also look at the frequency set by the radio transmitter and +if that results in a higher signal strength than the settings of the radio +transmitter will be used as if it was a valid station. This also includes +the RDS data (if any) that the transmitter 'transmits'. This is received +faithfully on the receiver side. Note that when the driver is loaded the +frequencies of the radio receiver and transmitter are not identical, so +initially no looping takes place. + + +Cropping, Composing, Scaling +---------------------------- + +This driver supports cropping, composing and scaling in any combination. Normally +which features are supported can be selected through the Vivid controls, +but it is also possible to hardcode it when the module is loaded through the +ccs_cap_mode and ccs_out_mode module options. See section 1 on the details of +these module options. + +This allows you to test your application for all these variations. + +Note that the webcam input never supports cropping, composing or scaling. That +only applies to the TV/S-Video/HDMI inputs and outputs. The reason is that +webcams, including this virtual implementation, normally use +VIDIOC_ENUM_FRAMESIZES to list a set of discrete framesizes that it supports. +And that does not combine with cropping, composing or scaling. This is +primarily a limitation of the V4L2 API which is carefully reproduced here. + +The minimum and maximum resolutions that the scaler can achieve are 16x16 and +(4096 * 4) x (2160 x 4), but it can only scale up or down by a factor of 4 or +less. So for a source resolution of 1280x720 the minimum the scaler can do is +320x180 and the maximum is 5120x2880. You can play around with this using the +qv4l2 test tool and you will see these dependencies. + +This driver also supports larger 'bytesperline' settings, something that +VIDIOC_S_FMT allows but that few drivers implement. + +The scaler is a simple scaler that uses the Coarse Bresenham algorithm. It's +designed for speed and simplicity, not quality. + +If the combination of crop, compose and scaling allows it, then it is possible +to change crop and compose rectangles on the fly. + + +Formats +------- + +The driver supports all the regular packed and planar 4:4:4, 4:2:2 and 4:2:0 +YUYV formats, 8, 16, 24 and 32 RGB packed formats and various multiplanar +formats. + +The alpha component can be set through the 'Alpha Component' User control +for those formats that support it. If the 'Apply Alpha To Red Only' control +is set, then the alpha component is only used for the color red and set to +0 otherwise. + +The driver has to be configured to support the multiplanar formats. By default +the driver instances are single-planar. This can be changed by setting the +multiplanar module option, see section 1 for more details on that option. + +If the driver instance is using the multiplanar formats/API, then the first +single planar format (YUYV) and the multiplanar NV16M and NV61M formats the +will have a plane that has a non-zero data_offset of 128 bytes. It is rare for +data_offset to be non-zero, so this is a useful feature for testing applications. + +Video output will also honor any data_offset that the application set. + + +Capture Overlay +--------------- + +Note: capture overlay support is implemented primarily to test the existing +V4L2 capture overlay API. In practice few if any GPUs support such overlays +anymore, and neither are they generally needed anymore since modern hardware +is so much more capable. By setting flag 0x10000 in the node_types module +option the vivid driver will create a simple framebuffer device that can be +used for testing this API. Whether this API should be used for new drivers is +questionable. + +This driver has support for a destructive capture overlay with bitmap clipping +and list clipping (up to 16 rectangles) capabilities. Overlays are not +supported for multiplanar formats. It also honors the struct v4l2_window field +setting: if it is set to FIELD_TOP or FIELD_BOTTOM and the capture setting is +FIELD_ALTERNATE, then only the top or bottom fields will be copied to the overlay. + +The overlay only works if you are also capturing at that same time. This is a +vivid limitation since it copies from a buffer to the overlay instead of +filling the overlay directly. And if you are not capturing, then no buffers +are available to fill. + +In addition, the pixelformat of the capture format and that of the framebuffer +must be the same for the overlay to work. Otherwise VIDIOC_OVERLAY will return +an error. + +In order to really see what it going on you will need to create two vivid +instances: the first with a framebuffer enabled. You configure the capture +overlay of the second instance to use the framebuffer of the first, then +you start capturing in the second instance. For the first instance you setup +the output overlay for the video output, turn on video looping and capture +to see the blended framebuffer overlay that's being written to by the second +instance. This setup would require the following commands: + +.. code-block:: none + + $ sudo modprobe vivid n_devs=2 node_types=0x10101,0x1 + $ v4l2-ctl -d1 --find-fb + /dev/fb1 is the framebuffer associated with base address 0x12800000 + $ sudo v4l2-ctl -d2 --set-fbuf fb=1 + $ v4l2-ctl -d1 --set-fbuf fb=1 + $ v4l2-ctl -d0 --set-fmt-video=pixelformat='AR15' + $ v4l2-ctl -d1 --set-fmt-video-out=pixelformat='AR15' + $ v4l2-ctl -d2 --set-fmt-video=pixelformat='AR15' + $ v4l2-ctl -d0 -i2 + $ v4l2-ctl -d2 -i2 + $ v4l2-ctl -d2 -c horizontal_movement=4 + $ v4l2-ctl -d1 --overlay=1 + $ v4l2-ctl -d0 -c loop_video=1 + $ v4l2-ctl -d2 --stream-mmap --overlay=1 + +And from another console: + +.. code-block:: none + + $ v4l2-ctl -d1 --stream-out-mmap + +And yet another console: + +.. code-block:: none + + $ qv4l2 + +and start streaming. + +As you can see, this is not for the faint of heart... + + +Output Overlay +-------------- + +Note: output overlays are primarily implemented in order to test the existing +V4L2 output overlay API. Whether this API should be used for new drivers is +questionable. + +This driver has support for an output overlay and is capable of: + + - bitmap clipping, + - list clipping (up to 16 rectangles) + - chromakey + - source chromakey + - global alpha + - local alpha + - local inverse alpha + +Output overlays are not supported for multiplanar formats. In addition, the +pixelformat of the capture format and that of the framebuffer must be the +same for the overlay to work. Otherwise VIDIOC_OVERLAY will return an error. + +Output overlays only work if the driver has been configured to create a +framebuffer by setting flag 0x10000 in the node_types module option. The +created framebuffer has a size of 720x576 and supports ARGB 1:5:5:5 and +RGB 5:6:5. + +In order to see the effects of the various clipping, chromakeying or alpha +processing capabilities you need to turn on video looping and see the results +on the capture side. The use of the clipping, chromakeying or alpha processing +capabilities will slow down the video loop considerably as a lot of checks have +to be done per pixel. + + +CEC (Consumer Electronics Control) +---------------------------------- + +If there are HDMI inputs then a CEC adapter will be created that has +the same number of input ports. This is the equivalent of e.g. a TV that +has that number of inputs. Each HDMI output will also create a +CEC adapter that is hooked up to the corresponding input port, or (if there +are more outputs than inputs) is not hooked up at all. In other words, +this is the equivalent of hooking up each output device to an input port of +the TV. Any remaining output devices remain unconnected. + +The EDID that each output reads reports a unique CEC physical address that is +based on the physical address of the EDID of the input. So if the EDID of the +receiver has physical address A.B.0.0, then each output will see an EDID +containing physical address A.B.C.0 where C is 1 to the number of inputs. If +there are more outputs than inputs then the remaining outputs have a CEC adapter +that is disabled and reports an invalid physical address. + + +Some Future Improvements +------------------------ + +Just as a reminder and in no particular order: + +- Add a virtual alsa driver to test audio +- Add virtual sub-devices and media controller support +- Some support for testing compressed video +- Add support to loop raw VBI output to raw VBI input +- Add support to loop teletext sliced VBI output to VBI input +- Fix sequence/field numbering when looping of video with alternate fields +- Add support for V4L2_CID_BG_COLOR for video outputs +- Add ARGB888 overlay support: better testing of the alpha channel +- Improve pixel aspect support in the tpg code by passing a real v4l2_fract +- Use per-queue locks and/or per-device locks to improve throughput +- Add support to loop from a specific output to a specific input across + vivid instances +- The SDR radio should use the same 'frequencies' for stations as the normal + radio receiver, and give back noise if the frequency doesn't match up with + a station frequency +- Make a thread for the RDS generation, that would help in particular for the + "Controls" RDS Rx I/O Mode as the read-only RDS controls could be updated + in real-time. +- Changing the EDID should cause hotplug detect emulation to happen. |