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Raspberry Pi setup for HDMI ready TV

April 19, 2015

If you get blurred or poor quality images when using your Raspberry PI on an HDMI TV then this article might help you. To fix this, we have to tell the PI to reduce the quality of the image being sent via the HDMI cable.

You should edit the file config.txt located at /boot/config.txt

Add the following lines – they may already be in the file and need the leading hash # sign removing:

hdmi_group=1
hdmi_mode=4
hdmi_drive=2
config_hdmi_boost=4

hdmi_group defines the HDMI type. With this not set the Pi tries to infer it from what the TV is telling it. With older HDMI ready TVs it seems this is wrong and you need to be specific. TVs are generally hdmi_group 1 (which is CEA) where as hdmi_group 2 is for monitors (DMT).

hdmi_mode gives the specific screen resolution for your TV. For my 720p TV I needed hdmi_mode 4. For a complete list of modes check the hdmi_mode section of this page: http://elinux.org/RPiconfig

hdmi_drive can be 1 (no sound sent over HDMI) or 2 (with sound over HDMI)

config_hdmi_boost sets the signal strength. Default is 0 but you can boost as high as 7. I found 4 overcame some interference issues.

Once edited, the Raspberry Pi needs to be restarted for the changes to take effect.

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