Operation Manual

Modifying the Display
Usually, the Raspberry Pi will detect the type of display that’s connected and alter its settings accordingly. Sometimes, however,
this automatic detection doesn’t work. This is often the case when a Raspberry Pi from one country is connected to an older TV
from another country. If you connect your Pi to your TV and there’s nothing to see, you may need to override these defaults.
Various settings in the config.txt file can be used to improve or alter the video output. These settings, and their possible
values, are described in the following list.
Manually adjusting the HDMI or composite video output settings can leave your Pi unable to communicate with your monitor. It’s usually best to
use the automatically-detected settings, unless you’re unable to see a picture in the first place.
• overscan_left—This moves the picture inwards a set number of pixels to compensate for a TV’s overscan. If the text on the
Pi is disappearing off the edge of the screen, adjusting the overscan will fix it. Values should be given as the number of pixels
to skip.
• overscan_right—This does the same job as overscan_left, but on the right side of the screen.
• overscan_top—Again, this ignores a certain number of pixels, but this time on the top of the screen.
• overscan_bottom—This can be used to skip a number of pixels from the bottom of the display. Typically, the values for all
the overscan_ settings would be the same, creating a regular border around the display.
• disable_overscan—If you use a monitor or TV via HDMI, you may find that your image has a black border around it. To
get rid of this border, any default overscan settings can be disabled by setting this value to 1.
• framebuffer_width—This value is measured in pixels, and adjusting it will change the width of the console. If text appears
too small on your screen, try changing this to a lower value than the default width of the connected display.
• framebuffer_height—This affects the size of the console in the same way as framebuffer_width, but vertically rather than
horizontally.
• framebuffer_depth—Controls the colour depth of the console in bits per pixel. The default is 16 bits per pixel, which gives
65,536 colours. Other values, including 8 bits per pixel (256 colours), 24 bits per pixel (around 16.7 million colours) and 32
bits per pixel (around 1 billion colours) are valid, but may cause graphical corruption.
• framebuffer_ignore_alpha—Set to 1, this value disables the alpha channel, which controls transparency in the console.
Disabling the alpha channel is not normally required, but may correct graphical corruption caused when setting
framebuffer_depth to 32 bits per pixel.
• sdtv_mode—This value affects the analogue composite video output of the Pi, adjusting it to operate in various countries.
By default, the Pi uses the North American version of the NTSC video standard; users in other countries may need to change
this value to get a picture on an analogue TV. Possible values are:
• 0—NTSC, the North American video standard
• 1—NTSC-J, the Japanese video standard
• 2—PAL, the video standard for the UK and other countries
• 3—PAL-M, the Brazilian video standard
• sdtv_aspect—Controls the aspect ratio of the analogue composite output. If the picture looks stretched or squished, alter
this to correspond to your TV’s aspect ratio. Possible values are:
• 1—4:3 aspect ratio, common on older sets
• 2—14:9 aspect ratio, common for smaller widescreen TVs
• 3—16:9 aspect ratio, common for modern widescreen TVs
• hdmi_mode—In addition to setting the video mode for the analogue composite output, it’s also possible to override
automatic resolution detection on the HDMI port. This is handy if you want to run your Pi at a lower resolution than the
display’s native resolution in order to make things more readable from a distance. Appendix B, “HDMI Display Modes”, lists
the possible values for this setting.
• hdmi_drive—It’s also possible to alter the voltage output by the HDMI port. This is important when you’re using an HDMI
to DVI adapter, because HDMI and DVI voltages differ slightly. If you find that your picture is snowy or blown out with too
bright an image, try altering this setting. Possible values are:
• 1—DVI output voltages. In this mode, no audio is included on the HDMI cable.
• 2—HDMI output voltages. In this mode, audio is included on the HDMI cable.
• hdmi_force_hotplug—Forces the Raspberry Pi to use the HDMI port, even if it doesn’t detect a connected display. A