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购进一台移动显示器（且这么叫吧，通过移动电源供电的独立显示器）,接上Pi400，亮度太高。网上找找资料，成功。记录一下。
原文章在这里
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安装ddcutil: sudo apt-get install ddcutil -y
（下面的配置我不确定是不是真的需要，等下次重做系统的时候再试） -
配置文件
sudo raspi-config –> Interfacing Options –> I2C开启 -
添加读写权限 sudo chmod a+rw /dev/i2c-*
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修改配置文件 sudo nano /boot/config.txt
在文件结尾添加 dtparam=i2c2_iknowwhatimdoing -
重启
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修改亮度为50 ddcutil setvcp 10 50
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查看当前值和最大值 ddcutil getvcp 10
ddctuil 是一个控制显示器的工具，只要显示器符合DDC/CI协议。
ddc/ci协议是Display Data Channel Command Interface的简称，基于DDC/CI协议，用户可以通过鼠标和人性化的软件界面来完成显示器的各项设置和色彩调节，而不必使用传统的OSD菜单。
ddcutil detect 检测显示器
看起来我使用了 /dev/i2c-21
ddcutil capabilities 查询显示器功能字符串
Model: RTK
MCCS version: 2.2
Commands:
Command: 01 (VCP Request)
Command: 02 (VCP Response)
Command: 03 (VCP Set)
Command: 07 (Timing Request)
Command: 0c (Save Settings)
Command: e3 (Capabilities Reply)
Command: f3 (Capabilities Request)
VCP Features:
Feature: 02 (New control value)
ddcutil vcpinfo 显示VCP功能特性
VCP code 01: Degauss
Causes a CRT to perform a degauss cycle
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Write Only, Non-Continuous (write-only)
VCP code 02: New control value
Indicates that a display user control (other than power) has been used to change and save (or autosave) a new value.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Write, Non-Continuous (complex)
VCP code 03: Soft controls
Allows display controls to be used as soft keys
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Write, Non-Continuous (simple)
VCP code 04: Restore factory defaults
Restore all factor presets including brightness/contrast, geometry, color, and TV defaults.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: COLOR
Attributes: Write Only, Non-Continuous (write-only)
VCP code 05: Restore factory brightness/contrast defaults
Restore factory defaults for brightness and contrast
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: COLOR
Attributes: Write Only, Non-Continuous (write-only)
VCP code 06: Restore factory geometry defaults
Restore factory defaults for geometry adjustments
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Write Only, Non-Continuous (write-only)
VCP code 08: Restore color defaults
Restore factory defaults for color settings.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: COLOR
Attributes: Write Only, Non-Continuous (write-only)
VCP code 0A: Restore factory TV defaults
Restore factory defaults for TV functions.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: TV
Attributes: Write Only, Non-Continuous (write-only)
VCP code 0B: Color temperature increment
Color temperature increment used by feature 0Ch Color Temperature Request
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: COLOR
Attributes: Read Only, Non-Continuous (complex)
VCP code 0C: Color temperature request
Specifies a color temperature (degrees Kelvin)
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: COLOR
Attributes: Read Write, Continuous (complex)
VCP code 0E: Clock
Increase/decrease the sampling clock frequency.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Write, Continuous (normal)
VCP code 10: Brightness
Increase/decrease the brightness of the image.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: PROFILE, COLOR
Attributes: Read Write, Continuous (normal)
VCP code 11: Flesh tone enhancement
Select contrast enhancement algorithm respecting flesh tone region
MCCS versions: 2.1, 3.0, 2.2
ddcutil feature subsets: COLOR
Attributes: Read Write, Non-Continuous (complex)
VCP code 12: Contrast
Increase/decrease the contrast of the image.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: PROFILE, COLOR
Attributes: Read Write, Continuous (normal)
VCP code 13: Backlight control
Increase/decrease the specified backlight control value
MCCS versions: 2.1, 3.0
ddcutil feature subsets: PROFILE, COLOR
Attributes (v2.1): Read Write, Continuous (complex)
Attributes (v3.0): Read Write, Continuous (complex)
Attributes (v2.2): Deprecated,
VCP code 14: Select color preset
Select a specified color temperature
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: PROFILE, COLOR
Attributes (v2.0): Read Write, Non-Continuous (simple)
Attributes (v2.1): Read Write, Non-Continuous (simple)
Attributes (v3.0): Read Write, Non-Continuous (complex)
Attributes (v2.2): Read Write, Non-Continuous (complex)
VCP code 16: Video gain: Red
Increase/decrease the luminesence of red pixels
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: PROFILE, COLOR
Attributes: Read Write, Continuous (normal)
VCP code 17: User color vision compensation
Increase/decrease the degree of compensation
MCCS versions: 2.1, 3.0, 2.2
ddcutil feature subsets: COLOR
Attributes: Read Write, Continuous (normal)
VCP code 18: Video gain: Green
Increase/decrease the luminesence of green pixels
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: PROFILE, COLOR
Attributes: Read Write, Continuous (normal)
VCP code 1A: Video gain: Blue
Increase/decrease the luminesence of blue pixels
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: PROFILE, COLOR
Attributes: Read Write, Continuous (normal)
VCP code 1C: Focus
Increase/decrease the focus of the image
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Write, Continuous (normal)
VCP code 1E: Auto setup
Perform autosetup function (H/V position, clock, clock phase, A/D converter, etc.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Write, Non-Continuous (simple)
VCP code 1F: Auto color setup
Perform color autosetup function (R/G/B gain and offset, A/D setup, etc.
MCCS versions: 2.1, 3.0, 2.2
ddcutil feature subsets: COLOR
Attributes: Read Write, Non-Continuous (simple)
VCP code 20: Horizontal Position (Phase)
Increasing (decreasing) this value moves the image toward the right (left) of the display.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Continuous (normal)
VCP code 22: Horizontal Size
Increase/decrease the width of the image.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Continuous (normal)
VCP code 24: Horizontal Pincushion
Increasing (decreasing) this value causes the right and left sides of the image to become more (less) convex.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Continuous (normal)
VCP code 26: Horizontal Pincushion Balance
Increasing (decreasing) this value moves the center section of the image toward the right (left) side of the display.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Continuous (normal)
VCP code 28: Horizontal Convergence R/B
Increasing (decreasing) this value shifts the red pixels to the right (left) and the blue pixels left (right) across the image with respect to the green pixels.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Continuous (normal)
VCP code 29: Horizontal Convergence M/G
Increasing (decreasing) this value shifts the magenta pixels to the right (left) and the green pixels left (right) across the image with respect to the magenta (sic) pixels.
MCCS versions: 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Continuous (normal)
VCP code 2A: Horizontal Linearity
Increase/decrease the density of pixels in the image center.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Continuous (normal)
VCP code 2C: Horizontal Linearity Balance
Increasing (decreasing) this value shifts the density of pixels from the left (right) side to the right (left) side of the image.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Continuous (normal)
VCP code 2E: Gray scale expansion
Gray Scale Expansion
MCCS versions: 2.1, 3.0, 2.2
ddcutil feature subsets: COLOR
Attributes: Read Write, Non-Continuous (complex)
VCP code 30: Vertical Position (Phase)
Increasing (decreasing) this value moves the image toward the top (bottom) edge of the display.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Continuous (normal)
VCP code 32: Vertical Size
Increase/decreasing the height of the image.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Continuous (normal)
VCP code 34: Vertical Pincushion
Increasing (decreasing) this value will cause the top and bottom edges of the image to become more (less) convex.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Continuous (normal)
VCP code 36: Vertical Pincushion Balance
Increasing (decreasing) this value will move the center section of the image toward the top (bottom) edge of the display.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Continuous (normal)
VCP code 38: Vertical Convergence R/B
Increasing (decreasing) this value shifts the red pixels up (down) across the image and the blue pixels down (up) across the image with respect to the green pixels.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Continuous (normal)
VCP code 39: Vertical Convergence M/G
Increasing (decreasing) this value shifts the magenta pixels up (down) across the image and the green pixels down (up) across the image with respect to the magenta (sic) pixels.
MCCS versions: 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Continuous (normal)
VCP code 3A: Vertical Linearity
Increase/decease the density of scan lines in the image center.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Continuous (normal)
VCP code 3C: Vertical Linearity Balance
Increase/decrease the density of scan lines in the image center.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Continuous (normal)
VCP code 3E: Clock phase
Increase/decrease the sampling clock phase shift
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Write, Continuous (normal)
VCP code 40: Horizontal Parallelogram
Increasing (decreasing) this value shifts the top section of the image to the right (left) with respect to the bottom section of the image.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Continuous (normal)
VCP code 41: Vertical Parallelogram
Increasing (decreasing) this value shifts the top section of the image to the right (left) with respect to the bottom section of the image. (sic)
MCCS versions: 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Continuous (normal)
VCP code 42: Horizontal Keystone
Increasing (decreasing) this value will increase (decrease) the ratio between the horizontal size at the top of the image and the horizontal size at the bottom of the image.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Continuous (normal)
VCP code 43: Vertical Keystone
Increasing (decreasing) this value will increase (decrease) the ratio between the vertical size at the left of the image and the vertical size at the right of the image.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Continuous (normal)
VCP code 44: Rotation
Increasing (decreasing) this value rotates the image (counter) clockwise around the center point of the screen.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Continuous (normal)
VCP code 46: Top Corner Flare
Increase/decrease the distance between the left and right sides at the top of the image.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Continuous (normal)
VCP code 48: Top Corner Hook
Increasing (decreasing) this value moves the top of the image to the right (left).
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Continuous (normal)
VCP code 4A: Bottom Corner Flare
Increase/decrease the distance between the left and right sides at the bottom of the image.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Continuous (normal)
VCP code 4C: Bottom Corner Hook
Increasing (decreasing) this value moves the bottom end of the image to the right (left).
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Continuous (normal)
VCP code 52: Active control
Read id of one feature that has changed, 0x00 indicates no more
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Only, Non-Continuous (complex)
VCP code 54: Performance Preservation
Controls features aimed at preserving display performance
MCCS versions: 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Write, Non-Continuous (complex)
VCP code 56: Horizontal Moire
Increase/decrease horizontal moire cancellation.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Write, Continuous (normal)
VCP code 58: Vertical Moire
Increase/decrease vertical moire cancellation.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Write, Continuous (normal)
VCP code 59: 6 axis saturation: Red
Increase/decrease red saturation
MCCS versions: 2.1, 3.0, 2.2
ddcutil feature subsets: COLOR
Attributes: Read Write, Continuous (normal)
VCP code 5A: 6 axis saturation: Yellow
Increase/decrease yellow saturation
MCCS versions: 2.1, 3.0, 2.2
ddcutil feature subsets: COLOR
Attributes: Read Write, Continuous (normal)
VCP code 5B: 6 axis saturation: Green
Increase/decrease green saturation
MCCS versions: 2.1, 3.0, 2.2
ddcutil feature subsets: COLOR
Attributes: Read Write, Continuous (normal)
VCP code 5C: 6 axis saturation: Cyan
Increase/decrease cyan saturation
MCCS versions: 2.1, 3.0, 2.2
ddcutil feature subsets: COLOR
Attributes: Read Write, Continuous (normal)
VCP code 5D: 6 axis saturation: Blue
Increase/decrease blue saturation
MCCS versions: 2.1, 3.0, 2.2
ddcutil feature subsets: COLOR
Attributes: Read Write, Continuous (normal)
VCP code 5E: 6 axis saturation: Magenta
Increase/decrease magenta saturation
MCCS versions: 2.1, 3.0, 2.2
ddcutil feature subsets: COLOR
Attributes: Read Write, Continuous (normal)
VCP code 60: Input Source
Selects active video source
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes (v2.0): Read Write, Non-Continuous (simple)
Attributes (v2.1): Read Write, Non-Continuous (simple)
Attributes (v3.0): Read Write, Table (normal)
Attributes (v2.2): Read Write, Non-Continuous (simple)
VCP code 62: Audio speaker volume
Adjusts speaker volume
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: AUDIO
Attributes (v2.0): Read Write, Continuous (normal)
Attributes (v2.1): Read Write, Continuous (normal)
Attributes (v3.0): Read Write, Non-Continuous with continuous subrange
Attributes (v2.2): Read Write, Non-Continuous with continuous subrange
VCP code 63: Speaker Select
Selects a group of speakers
MCCS versions: 2.1, 3.0, 2.2
ddcutil feature subsets: AUDIO
Attributes: Read Write, Non-Continuous (simple)
VCP code 64: Audio: Microphone Volume
Increase/decrease microphone gain
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: AUDIO
Attributes: Read Write, Continuous (normal)
VCP code 66: Ambient light sensor
Enable/Disable ambient light sensor
MCCS versions: 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Write, Non-Continuous (simple)
VCP code 6B: Backlight Level: White
Increase/decrease the white backlight level
MCCS versions: 2.2
ddcutil feature subsets: PROFILE, COLOR
Attributes: Read Write, Continuous (normal)
VCP code 6C: Video black level: Red
Increase/decrease the black level of red pixels
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: PROFILE, COLOR
Attributes: Read Write, Continuous (normal)
VCP code 6D: Backlight Level: Red
Increase/decrease the red backlight level
MCCS versions: 2.2
ddcutil feature subsets: PROFILE, COLOR
Attributes: Read Write, Continuous (normal)
VCP code 6E: Video black level: Green
Increase/decrease the black level of green pixels
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: PROFILE, COLOR
Attributes: Read Write, Continuous (normal)
VCP code 6F: Backlight Level: Green
Increase/decrease the green backlight level
MCCS versions: 2.2
ddcutil feature subsets: PROFILE, COLOR
Attributes: Read Write, Continuous (normal)
VCP code 70: Video black level: Blue
Increase/decrease the black level of blue pixels
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: PROFILE, COLOR
Attributes: Read Write, Continuous (normal)
VCP code 71: Backlight Level: Blue
Increase/decrease the blue backlight level
MCCS versions: 2.2
ddcutil feature subsets: PROFILE, COLOR
Attributes: Read Write, Continuous (normal)
VCP code 72: Gamma
Select relative or absolute gamma
MCCS versions: 2.1, 3.0, 2.2
ddcutil feature subsets: COLOR
Attributes: Read Write, Non-Continuous (complex)
VCP code 73: LUT Size
Provides the size (number of entries and number of bits/entry) for the Red, Green, and Blue LUT in the display.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: LUT
Attributes: Read Only, Table (normal)
VCP code 74: Single point LUT operation
Writes a single point within the display's LUT, reads a single point from the LUT
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: LUT
Attributes: Read Write, Table (normal)
VCP code 75: Block LUT operation
Load (read) multiple values into (from) the display's LUT
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: LUT
Attributes: Read Write, Table (normal)
VCP code 76: Remote Procedure Call
Initiates a routine resident in the display
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: LUT
Attributes: Write Only, Table (write-only)
VCP code 78: Display Identification Operation
Causes a selected 128 byte block of Display Identification Data (EDID or Display ID) to be read
MCCS versions: 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes (v2.1): Read Only, Table (normal)
Attributes (v3.0): Read Only, Table (normal)
Attributes (v2.2): Read Only, Table (normal)
VCP code 7A: Adjust Focal Plane
Increase/decrease the distance to the focal plane of the image
MCCS versions: 2.0, 2.1
ddcutil feature subsets:
Attributes (v2.0): Read Write, Continuous (normal)
Attributes (v2.1): Read Write, Continuous (normal)
Attributes (v3.0): Deprecated,
Attributes (v2.2): Deprecated,
VCP code 7C: Adjust Zoom
Increase/decrease the distance to the zoom function of the projection lens (optics)
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Write, Continuous (normal)
VCP code 7E: Trapezoid
Increase/decrease the trapezoid distortion in the image
MCCS versions: 2.0, 2.1
ddcutil feature subsets: CRT
Attributes (v2.0): Read Write, Continuous (normal)
Attributes (v2.1): Read Write, Continuous (normal)
Attributes (v3.0): Deprecated,
Attributes (v2.2): Deprecated,
VCP code 80: Keystone
Increase/decrease the keystone distortion in the image.
MCCS versions: 2.0
ddcutil feature subsets: CRT
Attributes (v2.0): Read Write, Continuous (normal)
Attributes (v2.1): Deprecated,
Attributes (v3.0): Deprecated,
Attributes (v2.2): Deprecated,
VCP code 82: Horizontal Mirror (Flip)
Flip picture horizontally
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes (v2.0): Write Only, Non-Continuous (write-only)
Attributes (v2.1): Read Write, Non-Continuous (simple)
Attributes (v3.0): Read Write, Non-Continuous (simple)
Attributes (v2.2): Read Write, Non-Continuous (simple)
VCP code 84: Vertical Mirror (Flip)
Flip picture vertically
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes (v2.0): Write Only, Non-Continuous (write-only)
Attributes (v2.1): Read Write, Non-Continuous (simple)
Attributes (v3.0): Read Write, Non-Continuous (simple)
Attributes (v2.2): Read Write, Non-Continuous (simple)
VCP code 86: Display Scaling
Control the scaling (input vs output) of the display
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Write, Non-Continuous (simple)
VCP code 87: Sharpness
Selects one of a range of algorithms. Increasing (decreasing) the value must increase (decrease) the edge sharpness of image features.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes (v2.0): Read Write, Non-Continuous (simple)
Attributes (v2.1): Read Write, Continuous (normal)
Attributes (v3.0): Read Write, Continuous (normal)
Attributes (v2.2): Read Write, Continuous (normal)
VCP code 88: Velocity Scan Modulation
Increase (decrease) the velocity modulation of the horizontal scan as a function of the change in luminescence level
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Continuous (normal)
VCP code 8A: Color Saturation
Increase/decrease the amplitude of the color difference components of the video signal
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: COLOR, TV
Attributes: Read Write, Continuous (normal)
VCP code 8B: TV Channel Up/Down
Increment (1) or decrement (2) television channel
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: TV
Attributes: Write Only, Non-Continuous (write-only)
VCP code 8C: TV Sharpness
Increase/decrease the amplitude of the high frequency components of the video signal
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: TV
Attributes: Read Write, Continuous (normal)
VCP code 8D: Audio mute/Screen blank
Mute/unmute audio, and (v2.2) screen blank
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: TV, AUDIO
Attributes (v2.0): Read Write, Non-Continuous (simple)
Attributes (v2.1): Read Write, Non-Continuous (simple)
Attributes (v3.0): Read Write, Non-Continuous (simple)
Attributes (v2.2): Read Write, Non-Continuous (complex)
VCP code 8E: TV Contrast
Increase/decrease the ratio between blacks and whites in the image
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: TV
Attributes: Read Write, Continuous (normal)
VCP code 8F: Audio Treble
Emphasize/de-emphasize high frequency audio
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: AUDIO
Attributes (v2.0): Read Write, Continuous (normal)
Attributes (v2.1): Read Write, Continuous (normal)
Attributes (v3.0): Read Write, Non-Continuous with continuous subrange
Attributes (v2.2): Read Write, Non-Continuous with continuous subrange
VCP code 90: Hue
Increase/decrease the wavelength of the color component of the video signal. AKA tint. Applies to currently active interface
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: COLOR, TV
Attributes: Read Write, Continuous (normal)
VCP code 91: Audio Bass
Emphasize/de-emphasize low frequency audio
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: AUDIO
Attributes (v2.0): Read Write, Continuous (normal)
Attributes (v2.1): Read Write, Continuous (normal)
Attributes (v3.0): Read Write, Non-Continuous with continuous subrange
Attributes (v2.2): Read Write, Non-Continuous with continuous subrange
VCP code 92: TV Black level/Luminesence
Increase/decrease the black level of the video
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: TV
Attributes: Read Write, Continuous (normal)
VCP code 93: Audio Balance L/R
Controls left/right audio balance
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: AUDIO
Attributes (v2.0): Read Write, Continuous (normal)
Attributes (v2.1): Read Write, Continuous (normal)
Attributes (v3.0): Read Write, Non-Continuous with continuous subrange
Attributes (v2.2): Read Write, Non-Continuous with continuous subrange
VCP code 94: Audio Processor Mode
Select audio mode
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: TV, AUDIO
Attributes: Read Write, Non-Continuous (simple)
VCP code 95: Window Position(TL_X)
Top left X pixel of an area of the image
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: WINDOW
Attributes: Read Write, Continuous (normal)
VCP code 96: Window Position(TL_Y)
Top left Y pixel of an area of the image
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: WINDOW
Attributes: Read Write, Continuous (normal)
VCP code 97: Window Position(BR_X)
Bottom right X pixel of an area of the image
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: WINDOW
Attributes: Read Write, Continuous (normal)
VCP code 98: Window Position(BR_Y)
Bottom right Y pixel of an area of the image
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: WINDOW
Attributes: Read Write, Continuous (normal)
VCP code 99: Window control on/off
Enables the brightness and color within a window to be different from the desktop.
MCCS versions: 2.0, 2.1, 2.2
ddcutil feature subsets: WINDOW
Attributes (v2.0): Read Write, Non-Continuous (simple)
Attributes (v2.1): Read Write, Non-Continuous (simple)
Attributes (v3.0): Deprecated,
Attributes (v2.2): Read Write, Non-Continuous (simple)
VCP code 9A: Window background
Changes the contrast ratio between the area of the window and the rest of the desktop
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: WINDOW
Attributes: Read Write, Continuous (normal)
VCP code 9B: 6 axis hue control: Red
Decrease shifts toward magenta, increase shifts toward yellow
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: PROFILE, COLOR
Attributes: Read Write, Continuous (normal)
VCP code 9C: 6 axis hue control: Yellow
Decrease shifts toward green, increase shifts toward red
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: PROFILE, COLOR
Attributes: Read Write, Continuous (normal)
VCP code 9D: 6 axis hue control: Green
Decrease shifts toward yellow, increase shifts toward cyan
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: PROFILE, COLOR
Attributes: Read Write, Continuous (normal)
VCP code 9E: 6 axis hue control: Cyan
Decrease shifts toward green, increase shifts toward blue
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: PROFILE, COLOR
Attributes: Read Write, Continuous (normal)
VCP code 9F: 6 axis hue control: Blue
Decrease shifts toward cyan, increase shifts toward magenta
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: PROFILE, COLOR
Attributes: Read Write, Continuous (normal)
VCP code A0: 6 axis hue control: Magenta
Decrease shifts toward blue, 127 no effect, increase shifts toward red
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: PROFILE, COLOR
Attributes: Read Write, Continuous (normal)
VCP code A2: Auto setup on/off
Turn on/off an auto setup function
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Write Only, Non-Continuous (write-only)
VCP code A4: Window mask control
Turn selected window operation on/off, window mask
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: WINDOW
Attributes (v2.0): Read Write, Non-Continuous (complex)
Attributes (v2.1): Read Write, Non-Continuous (complex)
Attributes (v3.0): Read Write, Table (normal)
Attributes (v2.2): Read Write, Table (normal)
VCP code A5: Change the selected window
Change selected window (as defined by 95h..98h)
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: WINDOW
Attributes: Read Write, Non-Continuous (simple)
VCP code AA: Screen Orientation
Indicates screen orientation
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Only, Non-Continuous (simple)
VCP code AC: Horizontal frequency
Horizontal sync signal frequency as determined by the display
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Only, Continuous (complex)
VCP code AE: Vertical frequency
Vertical sync signal frequency as determined by the display, in .01 hz
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Only, Continuous (complex)
VCP code B0: Settings
Store/restore the user saved values for the current mode.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Write Only, Non-Continuous (write-only)
VCP code B2: Flat panel sub-pixel layout
LCD sub-pixel structure
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Only, Non-Continuous (simple)
VCP code B4: Source Timing Mode
Indicates timing mode being sent by host
MCCS versions: 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes (v2.1): Read Write, Non-Continuous (complex)
Attributes (v3.0): Read Write, Table (normal)
Attributes (v2.2): Read Write, Table (normal)
VCP code B6: Display technology type
Indicates the base technology type
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Only, Non-Continuous (simple)
VCP code B7: Monitor status
Video mode and status of a DPVL capable monitor
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: DPVL
Attributes: Read Only, Non-Continuous (complex)
VCP code B8: Packet count
Counter for DPVL packets received
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: DPVL
Attributes: Read Write, Continuous (complex)
VCP code B9: Monitor X origin
X origin of the monitor in the vertical screen
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: DPVL
Attributes: Read Write, Continuous (complex)
VCP code BA: Monitor Y origin
Y origin of the monitor in the vertical screen
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: DPVL
Attributes: Read Write, Continuous (complex)
VCP code BB: Header error count
Error counter for the DPVL header
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: DPVL
Attributes: Read Write, Continuous (complex)
VCP code BC: Body CRC error count
CRC error counter for the DPVL body
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: DPVL
Attributes: Read Write, Continuous (complex)
VCP code BD: Client ID
Assigned identification number for the monitor
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: DPVL
Attributes: Read Write, Continuous (complex)
VCP code BE: Link control
Indicates status of the DVI link
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: DPVL
Attributes: Read Write, Non-Continuous (complex)
VCP code C0: Display usage time
Active power on time in hours
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Only, Continuous (complex)
VCP code C2: Display descriptor length
Length in bytes of non-volatile storage in the display available for writing a display descriptor, max 256
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Only, Continuous (normal)
VCP code C3: Transmit display descriptor
Reads (writes) a display descriptor from (to) non-volatile storage in the display.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Write, Table (normal)
VCP code C4: Enable display of 'display descriptor'
If enabled, the display descriptor shall be displayed when no video is being received.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Write, Non-Continuous (complex)
VCP code C6: Application enable key
A 2 byte value used to allow an application to only operate with known products.
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Only, Non-Continuous (complex)
VCP code C8: Display controller type
Mfg id of controller and 2 byte manufacturer-specific controller type
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Only, Non-Continuous (complex)
VCP code C9: Display firmware level
2 byte firmware level
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Only, Non-Continuous (complex)
VCP code CA: OSD/Button Control
Sets and indicates the current operational state of OSD (and buttons in v2.2)
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes (v2.0): Read Write, Non-Continuous (simple)
Attributes (v2.1): Read Write, Non-Continuous (simple)
Attributes (v3.0): Read Write, Non-Continuous (simple)
Attributes (v2.2): Read Write, Non-Continuous (complex)
VCP code CC: OSD Language
On Screen Display language
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Write, Non-Continuous (simple)
VCP code CD: Status Indicators
Control up to 16 LED (or similar) indicators to indicate system status
MCCS versions: 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Write, Non-Continuous (complex)
VCP code CE: Auxiliary display size
Rows and characters/row of auxiliary display
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Only, Non-Continuous (complex)
VCP code CF: Auxiliary display data
Sets contents of auxiliary display device
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Write Only, Table (write-only)
VCP code D0: Output select
Selects the active output
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes (v2.0): Read Write, Non-Continuous (simple)
Attributes (v2.1): Read Write, Non-Continuous (simple)
Attributes (v3.0): Read Write, Table (normal)
Attributes (v2.2): Read Write, Non-Continuous (simple)
VCP code D2: Asset Tag
Read an Asset Tag to/from the display
MCCS versions: 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Write, Table (normal)
VCP code D4: Stereo video mode
Stereo video mode
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Write, Non-Continuous (complex)
VCP code D6: Power mode
DPM and DPMS status
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Write, Non-Continuous (simple)
VCP code D7: Auxiliary power output
Controls an auxiliary power output from a display to a host device
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Write, Non-Continuous (simple)
VCP code DA: Scan mode
Controls scan characteristics (aka format)
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets: CRT
Attributes: Read Write, Non-Continuous (simple)
VCP code DB: Image Mode
Controls aspects of the displayed image (TV applications)
MCCS versions: 2.1, 3.0, 2.2
ddcutil feature subsets: TV
Attributes: Read Write, Non-Continuous (simple)
VCP code DC: Display Mode
Type of application used on display
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Write, Non-Continuous (simple)
VCP code DE: Scratch Pad
Operation mode (2.0) or scratch pad (3.0/2.2)
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes (v2.0): Write Only, Non-Continuous (write-only)
Attributes (v2.1): Read Write, Non-Continuous (complex)
Attributes (v3.0): Read Write, Non-Continuous (complex)
Attributes (v2.2): Read Write, Non-Continuous (complex)
VCP code DF: VCP Version
MCCS version
MCCS versions: 2.0, 2.1, 3.0, 2.2
ddcutil feature subsets:
Attributes: Read Only, Non-Continuous (complex)
在这里，我看到了代码10，看起来它应该是十六进制，作用是调节亮度。
ddcutil getvcp 报告VCP功能值(获取值)
ddcutil setvcp 功能代码 [+/-] 值 设置VCP功能值
ddcutil scs 将当前设置存储在监视器的非易失性存储器中
ddcutil environment 探测执行环境
ddcutil probe 探测监视器功能
...
Readable features declared in capabilities string: 02
MCCS (VCP) version reported by capabilities: 2.2
MCCS (VCP) version reported by feature 0xDf: 2.2
All readable features declared in capabilities were found by scanning.
Features found by scanning but not declared as capabilities:
Feature x0b - Color temperature increment
Feature x0c - Color temperature request
Feature x10 - Brightness
Feature x12 - Contrast
Feature x14 - Select color preset
Feature x16 - Video gain: Red
Feature x18 - Video gain: Green
Feature x1a - Video gain: Blue
Feature x1e - Auto setup
Feature x20 - Horizontal Position (Phase)
Feature x30 - Vertical Position (Phase)
Feature x52 - Active control
Feature x60 - Input Source
Feature x62 - Audio speaker volume
Feature x6c - Video black level: Red
Feature x6e - Video black level: Green
Feature x70 - Video black level: Blue
Feature x87 - Sharpness
Feature xac - Horizontal frequency
Feature xae - Vertical frequency
Feature xb2 - Flat panel sub-pixel layout
Feature xb6 - Display technology type
Feature xc6 - Application enable key
Feature xc8 - Display controller type
Feature xc9 - Display firmware level
Feature xca - OSD/Button Control
Feature xcc - OSD Language
Feature xd6 - Power mode
Feature xdf - VCP Version
Feature xe6 - Manufacturer Specific
Color temperature increment (x0b) = 100 degrees Kelvin
Color temperature request (x0c) = 35
Requested color temperature = (3000 deg Kelvin) + 35 * (100 degrees Kelvin) = 6500 degrees Kelvin
–display 显示器编号
–bus 总线编号 /dev/i2c-?