4k HDR too dim/dark


Logs: http://paste.osmc.tv/aqaxehoney

I am using a 2017 vizio m55-e0 and am having issues with HDR. Within the OSMC menu everything is vibrant but whenever a 4k hdr movie is played it is dim and washed out. I have HDR turned on and HDR 10 is confirmed according to the info overlay with the television.

I am using Mad Max Fury Road to try and get HDR working properly here is the mediainfo: GeneralUnique ID : 2473825423449410324582897273 - Pastebin.com

I am almost certain that it is osmc/vero 4k and not my televison. Open to any suggestions.


I don’t know the answer, but from the mediainfo, kodi should be converting that file to RGB. There are some commandline incantations which may help, @sam_nazarko knows which ones work with the latest OSMC release.

This may help: HDR video too dark on a HDR TV.

Thanks for the reply Graham. I looked through that thread and I do not have a rc.local file in the etc folder. Not sure if that could be the problem.

Do you know how to use SSH?
First thing I’d do is manually enable 10-bit output to see if that helps


I have the same issue with some videos, and I’m very familiar with ssh and Linux. What’s the proposed solution?

I do know how to use SSH. What are the steps to enabling 10-bit outbit via SSH?

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echo "444,10bit" | sudo tee /sys/class/amhdmitx/amhdmitx0/attr
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Ran that command in putty and I still have the same results.

I said this before in the thread but shouldn’t there be an rc.local file in /etc/? Would that cause issues?

The /etc/rc.local file will run on boot, so having

echo "444,10bit" > /sys/class/amhdmitx/amhdmitx0/attr

in rc.local will do the same thing on bootup as running

echo "444,10bit" | sudo tee /sys/class/amhdmitx/amhdmitx0/attr

from the command line.

It depends when you installed OSMC / received your device.
There was a brief period (Nov 17 - Dec 17) where this file wouldn’t exist.


I am not sure when that would have been. I did order my vero 4k right around that time. Would backing up my current install and reinstalling possibly help?

If you do not have /etc/tc.local and you do the command I’ve given you:

echo "444,10bit" | sudo tee /sys/class/amhdmitx/amhdmitx0/attr

then there is something else going on. Logs would help. And mediainfo.

If you don’t have that file just create it with sudo nano /etc/rc.local and write that line in. It should look like:

#!/bin/sh -e

echo "444,10bit" > /sys/class/amhdmitx/amhdmitx0/attr
exit 0

Save the file then go sudo chmod +x /etc/rc.local

Pretty sure I got that right. Still no changes.

However, I just found out my TV has the following specs:

340MHz pixel clock rate:
2160@60fps 4:2:0 8 bit

600MHz pixel clock rate:
2160p@60fps, 4:4:4, 8-bit
2160p@60fps, 4:2:2, 12-bit

Should I change the

echo “444,10bit”


echo “4:2:0 8 bit”


echo “444,8bit”


echo “422,12bit”

Apologies for not knowing this information.

Your Mad Max rip is 24fps not 60fps, so those specs for 60fps are irrelevant.

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Ok, I am not sure what else to do here. I am beginning to think it may be an issue with the TV. I just found out there have been some issues with the latest firmware with this television. As seen here: https://www.reddit.com/r/VIZIO_Official/comments/88jcti/firmware_40232_is_an_absolute_disaster_and_vizio/

This sound very much like a tone-mapping issue. Many people report that HRD looks dim on their sets. I believe this comes from the fact that HDR material is graded for a given peak brightness and when the display cannot reach these peaks, brightness levels for most of the content of the media will look dim. It might also be that you must select HDR mode manually (that the TV does not autodetect HDR-content). I do not know the exact details, but you should research HDR tone-mapping. I do not think that the set is damaged/broken. Many people report the same problems from HDR players/disc. It is just poor implementation of the technology.

I tested HDR out on PS4 on Horizon Zero Dawn and I could notice quite a difference when turning HDR on and off. So could there be some sort of issue related with HDR between kodi or vero with my specific TV?

Are you turning HDR off on the TV or the PlayStation?