XRandR allows dynamic control of display resolution, refresh rate, position, and orientation. You can refer to the manual page of xrandr to get more information.

Besides these standard dynamic settings implemented by XRandR extension, the VIA accelerated Linux graphics driver provides some other dynamic control features. Please note that the commands described in this chapter are case sensitive.

LCD Panel Dynamic Control

To change the display mode of LCD panel. This command takes effect when the given mode is smaller than native mode.

$ xrandr --output LCD --set Feature Center
// Display the content in the center of a LCD panel.

$ xrandr --output LCD --set Feature Expand
// Scaling up the the content, and display in full screen mode.

TV Dynamic Control

Before setting a TV on the fly, it is strongly recommended to use the command:
      $ xrandr --verbose
to get the information about TV settings. That is because the TV settings are variable. For example, the following is the output of the command "$ xrandr --verbose",

Scan: Normal
    supported: Normal       Fit          Over       
PosV: 6 (0x00000006) range:  (0,100)
PosH: 39 (0x00000027) range:  (0,100)
FFilterValue: 0 (0x00000000) range:  (0,100)
FFilter: FFON
    supported: FFON         AFFON        ALLOFF     
AFFilterValue: 0 (0x00000000) range:  (0,100)
Contrast: 70 (0x00000046) range:  (0,100)
Brightness: 0 (0x00000000) range:  (0,100)
Type: NTSC
    supported: NTSC   PAL  480P  576P  720P  1080I      
Signal: YCbCr
supported: Composite  SVideo  RGB  YCbCr

From the output imformation above, the variable settings are: Scan, PosV, PosH, FFilterValue, FFilter, AFFilterValue, Contrast, Brightness, Type and Signal. Besides, possible settings could be DotCrawl, Hue, Saturation, ScaleH, ScaleV, but these settings are not supported under this situation, thus they are not included in the output information.

The meanings of each setting are demonstrated as below.

1. Scan

Scan: Normal
    supported: Normal       Fit          Over       

The string after Scan indicates the current setting, while the line below indicated the possible values. If the lines is not displayed in the output information, that indicates this setting is invariable. Otherwise, you can use the following command to change the setting on the fly.

$ xrandr --output TV --set Scan Normal

$ xrandr --output TV --set Scan Fit

$ xrandr --output TV --set Scan Over

2. FFilter

FFilter: FFON
    supported: FFON         AFFON        ALLOFF   

The string after FFilter indicates the current setting, while the line below indicated the possible values.

$ xrandr --output TV --set FFilter FFON
// Enable FF filter

$ xrandr --output TV --set FFilter AFFON
// Enable AFF filter

$ xrandr --output TV --set FFilter ALLOFF
// Disable filter

3. Type

This setting specifies the TV standard. You can use the following command to change the setting on the fly.

$ xrandr --output TV --set Type string

The valid values are: NTSC, PAL, 480P, 576P, 720P, 1080I. This setting depends on the display mode, you can refer to the map table for mode and supported TV standards.

4. Signal

Sepcify the TV output signal format. You can use the following command to change the setting on the fly.

$ xrandr --output TV --set Signal string

The valid values are: RGB, YCbCr, SVideo, Composite. This setting depends on the TV type. If TV type is NTSC or PAL, all signal formats are supported, but HDTV (480P, 576P, 720P, 1080I) only supports RGB and YCbCr.

5. DotCrawl

This setting doesn't appears often. You can use the following command to change the setting on the fly.

$ xrandr --output TV --set DotCrawl boolean

6. PosV

Set the vertical position of the screen. You can use the following command to change the setting on the fly.

$ xrandr --output TV --set PosV integer

The value ranges from 0 to 100. It represents the percentage of the position.

7. PosH

Set the horizontal position of the screen. You can use the following command to change the setting on the fly.

$ xrandr --output TV --set PosH integer

The value ranges from 0 to 100. It represents the percentage of the position.

8. FFilterValue

Adjust the FF filter. This setting only takes effect when FFilter is set to FFON. You can use the following command to change the setting on the fly.

$ xrandr --output TV --set FFilterValue integer

The value ranges from 0 to 100.

9. AFFilterValue

Adjust the AFF filter. This setting only takes effect when FFilter is set to AFFON. You can use the following command to change the setting on the fly.

$ xrandr --output TV --set AFFilterValue integer

The value ranges from 0 to 100.

10. Contrast

Adjust the contrast. You can use the following command to change the setting on the fly.

$ xrandr --output TV --set Contrast integer

The value ranges from 0 to 100.

11. Brightness

Adjust the brightness. You can use the following command to change the setting on the fly.

$ xrandr --output TV --set Brightness integer

The value ranges from 0 to 100.

12. Hue

Adjust the hue. Hue is one of the main properties of a color described with names as "red", "yellow" etc. You can use the following command to change the setting on the fly.

$ xrandr --output TV --set Hue integer

The value ranges from 0 to 100.

13. Saturation

Adjust the saturation. You can use the following command to change the setting on the fly.

$ xrandr --output TV --set Saturation integer

The value ranges from 0 to 100.

It'e better to set the properties one by one.