Display resolution and update rate settings in Linux

Linux display resolution and update rate settings-general Linux technology-Linux technology and application information, the following is a detailed description. 1. view video card information
Glxinfo | grep-I rend
Direct rendering: Yes
Run this command. If "Yes" is not displayed, install the driver (video card) on your own ).

1. Run the following command on a linux terminal:
[Root @ localhost ~] # Glxinfo | grep-I rend
Direct rendering: No (If you want to find out why, try setting LIBGL_DEBUG = verbose)
OpenGL renderer string: Mesa GLX Indirect

2. In txt mode:
[Root @ localhost ~] # Glxinfo | grep-I rend
Error: unable to open display
The two display results are different. The reason is that the X terminal is different from the text mode (console). In the console, the video card driver is not enabled, so the information cannot be obtained.

Ii. Display resolution and refresh rate settings

1. Resolution and refresh rate setting of the display on the X terminal
You can set the update rate and resolution in/etc/X11/xorg. conf.

(1) set the line frequency (horizontal resolution) and field frequency (vertical resolution) of the monitor

There is a similar section in xorg. conf:
Section "Monitor"
Identifier "Monitor0"
VendorName "Monitor Vendor"
ModelName "206 STUDIO"
HorizSync 30.0-70.0
VertRefresh 50.0-160.0
EndSection
Among them, HorizSync and VertRefresh are the settings of the display line frequency (horizontal resolution) and field frequency (vertical resolution) respectively.

It should be set based on the performance of the monitor. Their values determine the possible display resolution and refresh frequency values.

(2) set the first and optional resolutions
There is a similar section in xorg. conf:
Section "Screen"
Identifier "Screen0"
Device "Videocard0"
Monitor "Monitor0"
DefaultDepth 24
SubSection "Display"
Depth 24
Modes "1024x768" "800x600" "640x480" "1280x1024"
EndSubSection
EndSection
Row:
Modes "1024x768" "800x600" "640x480"
Three Optional resolutions are set. The first one is the preferred resolution, which generally takes effect. If the preferred resolution is invalid when X is started, for example, the resolution is too high.

2. Display resolution and refresh rate setting in text mode
(1) grub's:
/Boot/grub/menu. lst file
Title Debian GNU/Linux, kernel BRL. 22-3-686
Root (hd0, 5)
Kernel/vmlinuz-2.6.22-3-686 root =/dev/hda1 ro vga = 794
Initrd/initrd. img-2.6.22-3-686
Savedefault

Note:
Vga = 794. modify this value to modify the resolution in text mode.
Vga = 794 => 1280x1024x16
Vga = 788 => 800x600x16
(2) lilo is similar.

3. the kernel cannot identify whether the display cannot enter X-Windows?
(1) graphics card driver: the difference between the driver provided by the kernel and the driver provided by the display supplier is 3D. If the kernel does not recognize the video card, it cannot enter X. However, the standard driver of vesa can be used, because the graphics cards provided by various manufacturers support the vesa standard

(2) Information is automatically obtained using Xorg-configure

Monitor this entry describes the related knowledge of the Monitor. The field frequency is also called "Vertical Scan Frequency" or "update rate ". The number of times the electron gun scans the entire screen within the unit time (in seconds), usually in Hz. Taking the refreshing rate of 85Hz as an example, it indicates that the display content is refreshed 85 times per second.

The image displayed on the CRT display is composed of many fluorescent points, each of which is illuminated by an electronic beam. However, the time for the fluorescent point to emit light is very short, therefore, it is necessary to constantly launch an electron beam to attach the phosphor to make it emit light continuously.

The electron beam cannot attack two dots on the screen at the same time, so the monitor reads data from the video card at extremely fast speed during operation, at the same time, the deflection circuit of the electron gun controls the deflection coil to change the direction of the electron beam, so that the electron beam starts from the upper left corner of the screen, from left to right, from top to bottom, each vertex is bombarded sequentially, although the time is sequential.

However, since the electron beam only needs 10 ~ to scan the screen at a time ~ 20 ms, with the remaining glow of the fluorescent body and the visual persistence of the human eye, as long as the refresh speed is fast enough and the update rate is high enough, the human eye can see a continuous and stable picture, no obvious blinking or jitter. The higher the vertical scan frequency, the less obvious the blinking, and the less tired the eyes.

Theoretically, as long as the refresh rate reaches 85Hz, that is, 85 refresh times per second, the human eyes cannot feel the flickering screen, however, in actual use, we often see the difference between the refreshing rate of Hz and the refreshing rate of HZ. Therefore, from the perspective of protecting the eyes, the higher the refreshing rate, the better.

The row frequency, also known as "Horizontal Scan Frequency", refers to the number of horizontal lines swept by the electron gun on the fluorescent screen per second. Its value is equal to "field frequency × vertical resolution × 1. 04 ", in the unit of KHz (kilobytes ). The line frequency is a parameter for comprehensive resolution and field frequency. The larger the value, the higher the resolution that the monitor can provide, the better the stability.

Taking the resolution of 800*600 and the field frequency of 600Hz as an example, the line frequency of the display should be at least "* 85 = 51 kHz ".

Currently, the mainstream line frequency series of CRT display are 70 KHz, 85 (86) KHz, and 96 KHz.

Windows uses frequency and resolution to represent the display mode, while Linux's X configuration file uses three parameters: frequency, line frequency, and resolution.

Warning old or some monitors do not have protective circuits and incorrect parameter settings may cause hardware damage.