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My display is a TV with resolution of 1366x768 @60 Hz. It has HDMI input option as well as PC input option. I prefer HDMI input but I'm not getting the appropriate image of RPI 4B with 4GB with HDMI. I borrowed a monitor and found that display is excellent without me doing any configuration from the RPI 4B. I'm a noob and could not set it correctly on my tv with built in screen configuration tool of RPI 4B. When I set 1366X768 resolution my TV first shows a message 'unsupported' but after about a minute the display comes on the screen which is not the best. I ran tvservice and got the following best score by GREP: HDMI:EDID Best score mode is now DMT (81) 1366x768p @60Hz with pixel clock 85 Mhz (score 5188835). I'm confused about DMT and CEA as I read somewhere that DMT is intended for monitors while mine is a TV. Even if DMT is the right option I need step by step guidance on how to set my TV display to DMT 81. Please help. (I've very little knowledge of linux commands but I'll be able to follow a detailed guidance).

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  • add hdmi_group=2 and hdmi_mode=81 in your /boot/config.txt file - you can do this in the computer you used to burn the sd card - simply edit the config.txt file on the sd card (once inserted into your computer of course) - no knowledge of linux required – Jaromanda X May 3 '20 at 0:32
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You could try 720p mode as you have a Pi 4:

Full config details are here on the RPF site.

Add the following lines into /boot/config.txt

hdmi_group=1
hdmi_mode=69

and restart the computer.

Edit: To use dmt add:

hdmi_group=2
hdmi_mode=81

and restart the computer

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    why not use DMT 81 as reported – Jaromanda X May 3 '20 at 0:30
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    No real reason - added to answer. – user115418 May 3 '20 at 2:11
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I did a little research and ran the following commands (without quotes of course) in Terminal.

"/opt/vc/bin/tvservice -m CEA"

"/opt/vc/bin/tvservice -m DMT"

I also ran the following commands:

"/opt/vc/bin/tvservice -s"

"/opt/vc/bin/tvservice -d edid.dat"

"/opt/vc/bin/edidparser edid.dat"

As I wanted sound through HDMI, I preferred Group CEA and Mode 16 which appears as native. Next I took out the micro sd card and with a text editor uncommented and edited (in my android phone as my Windows PC is out of order) the relevant entry to change it to hdmi_group 1 and hdmi_mode 16 in the config.txt file. The following is the entry I uncommented and edited.

uncomment to force a specific HDMI mode (this will force VGA)

hdmi_group=1 hdmi_mode=4

My TV still shows a unsupported message at first but switches to 1920x1080 display after about a minute. I'll welcome further suggestions in this regard!

Here are the outputs I got from Terminal from the first two commands:

pi@raspberrypi:~ $ /opt/vc/bin/tvservice -m CEA

Group CEA has 16 modes:

       mode 1: 640x480 @ 60Hz 4:3, clock:25MHz progressive

       mode 2: 720x480 @ 60Hz 4:3, clock:27MHz progressive

       mode 3: 720x480 @ 60Hz 16:9, clock:27MHz progressive

       mode 4: 1280x720 @ 60Hz 16:9, clock:74MHz progressive

       mode 5: 1920x1080 @ 60Hz 16:9, clock:74MHz interlaced

       mode 6: 720x480 @ 60Hz 4:3, clock:27MHz x2 interlaced

       mode 7: 720x480 @ 60Hz 16:9, clock:27MHz x2 interlaced

(native) mode 16: 1920x1080 @ 60Hz 16:9, clock:148MHz progressive

       mode 17: 720x576 @ 50Hz 4:3, clock:27MHz progressive

       mode 18: 720x576 @ 50Hz 16:9, clock:27MHz progressive

       mode 19: 1280x720 @ 50Hz 16:9, clock:74MHz progressive

       mode 20: 1920x1080 @ 50Hz 16:9, clock:74MHz interlaced

       mode 21: 720x576 @ 50Hz 4:3, clock:27MHz x2 interlaced

       mode 22: 720x576 @ 50Hz 16:9, clock:27MHz x2 interlaced

       mode 31: 1920x1080 @ 50Hz 16:9, clock:148MHz progressive

       mode 32: 1920x1080 @ 24Hz 16:9, clock:74MHz progressive

pi@raspberrypi:~ $ /opt/vc/bin/tvservice -m DMT

Group DMT has 7 modes:

(prefer) mode 4: 640x480 @ 60Hz 4:3, clock:25MHz progressive

       mode 8: 800x600 @ 56Hz 4:3, clock:36MHz progressive

       mode 9: 800x600 @ 60Hz 4:3, clock:40MHz progressive

       mode 16: 1024x768 @ 60Hz 4:3, clock:65MHz progressive

       mode 22: 1280x768 @ 60Hz 15:9, clock:68MHz progressive

       mode 81: 1366x768 @ 60Hz 16:9, clock:85MHz progressive

       mode 85: 1280x720 @ 60Hz 16:9, clock:74MHz progressive 

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