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Fix blurry HDMI output with DVI mode
Extracted from the old Wordpress blog.
You have connected a Monitor via HDMI and it looks blurry? Even though the resolution seems to be in full HD and Screenshot look good on other devices? I have such a Monitor and will tell you how to fix this blurry display for most operating systems. Read on.
Most TVs support this, but not all. You can select the input source like Cinch, VGA and HDMI. In this menu or any other settings menu you can try to rename the input to "PC". Then the TV recognizes the PC signal and its sharp again. That is the easiest solution, but not all Monitory support this, like mine.
Under Windows I found no real solution in case of Software. But what you can do is to use a DVI port on your PC or TV if supported and not use the HDMI port. Then you need a DVI to HDMI cable. It also worked on Display port outputs with adapter to DVI to HDMI (never tried DP - HDMI direct though). In any other case I havent found any solution yet. Sound won't work with DVI.
Tested under Ubuntu, might work as well with other Unix systems. Connect the screen with any desired cable. In my case only tested with the DP-DVI-HDMI 2x adapter cable. Setup the displays as desired. Open a terminal and enter the following commands to detect your used outputs and then set the output to DVI to make it sharp again. If you always want to use this setting at startup you need to add it to the .xprofile file as well. In this case I used 2 Monitors in full HD. Sound won't work with DVI.
xrandr xrandr --output HDMI2 --set audio force-dvi --mode 1920x1080 xrandr --output HDMI3 --set audio force-dvi --mode 1920x1080 # use this setting for every startup nano ~/.xprofile
Raspberry Pi Fix
For the Raspberry Pi I had to try a lot of configurations. I also have to admit that they improved the HDMI signal with sound significantly over the time that I normally don't apply the fix, in order to use the sound. In movies you don't see the difference but for desktops you might want to have it 100% clear. So what you have to do is to edit the /boot/config.txt file. You can also access it with a Windows PC via the FAT partition. Just edit it like this. You can also change more things here like the mode and resolution. Normally changing to DVI should do it.
# Normal DVI mode (No sound) hdmi_drive=1
Hopefully this helped you. If you have any other way to fix it, let me know. Here are some Links that helped me: