s905 - hdmi handshake /color space problem with older TVs

jamfr22 · December 14, 2017 at 1:03 PM

Hi guys, I had this problem a while ago, but I was able to fix it with this guide. Maybe it will help kszaq to implement it into a bulid.

HOW TO FORCE RGB (FOR OLDER TVs)
If you have an old TV and it presents the handshake problem with green screen you should enable the Force RGB option.

1. Enable SSH connection from the LibreELEC settings on the TV Box

2. Check the IP address of the Box from connection

3. From your computer open Terminal for MAC and Linux or Start - Run - CMD for Windows.

4. Connect to your TV box (user root): ssh root@192.168.1.51

This is a MAC command. Check for windows or linux on how to connect via SSH.

5. insert the password: libreelec

6. Run:

Code:

cd .config nano autostart.sh

7. This starts an editor. Insert the following text:

Code:

#!/bin/sh echo 1 > /sys/class/amhdmitx/amhdmitx0/output_rgb

8. Save with the same name

9. Run:

Code:

chmod 755 autostart.sh reboot

Now you have the RGB enabled.

**kszaq** · December 14, 2017 at 5:22 PM

Quote from jamfr22

Hi guys, I had this problem a while ago, but I was able to fix it with this guide. Maybe it will help kszaq to implement it into a bulid.

What you described is something I implemented in Marshmallow kernel and what doesn't work in Nougat kernel. We're now trying to find a way fix it.

**kszaq** · December 14, 2017 at 5:30 PM

Today's build to test: LibreELEC-S905.arm-8.2-devel-20171214182115-r26471-gc91652d.tar

Fredouye · December 14, 2017 at 6:37 PM

I've used first test build released yerterday (20171213185420) for 2 hours, absolutely no issue.

Box is currently updating to today's build, I'll report later.

Harmonia · December 14, 2017 at 8:29 PM

Quote from kszaq

Today's build to test: LibreELEC-S905.arm-8.2-devel-20171214182115-r26471-gc91652d.tar

It works great.

Thank you

Fredouye · December 15, 2017 at 7:34 AM

Hi kszaq

absolutly no issue with this build. Many thanks for your work.

**kszaq** · December 15, 2017 at 7:48 AM

Quote from Fredouye

Hi kszaq

absolutly no issue with this build. Many thanks for your work.

Thank you for testing. I will include the fix in 8.2.1.2 for both S905 and S912.

**mmpp** · December 15, 2017 at 10:18 AM

Latest fix seems fine, could not get any discoloration after more than an hour. Will continue testing.

Thanks for the incredible work.

**kszaq** · December 15, 2017 at 10:50 PM

All test builds removed, fix has been integrated in 8.2.1.2 build for both S905 and S912.

Magnum · December 16, 2017 at 5:31 PM

Quote from kszaq

All test builds removed, fix has been integrated in 8.2.1.2 build for both S905 and S912.

Hi kszaq,

just installed your new release 8.2.1.2 in my S912.

I missed something. How do I activate the option to force the RGB setting?

Thanks

Magnum

Tim_Taylor · December 16, 2017 at 5:40 PM

Quote from Magnum

How do I activate the option to force the RGB setting?

Via SSH command

Magnum · December 16, 2017 at 5:50 PM

Yes, but... does this code work again?

#!/bin/sh echo 1 > /sys/class/amhdmitx/amhdmitx0/output_rgb

Thanks

Magnum · December 17, 2017 at 1:32 PM

Ok.

Solved whit the same code.

M.

thomaz · January 11, 2018 at 7:58 PM

i do this:

echo 1 > /sys/class/amhdmitx/amhdmitx0/output_rgb

but black is still grey.

**kszaq** · January 11, 2018 at 8:51 PM

thomas output_rgb is to force RGB colorspace instead of YPrBr, not to switch from limited to full range. Before you ask: I don't know how to do the full range switch.

**mmpp** · January 11, 2018 at 8:51 PM

Adjust black levels on your TV by choosing limited RGB range. This is about a completely different problem.

thomaz · January 11, 2018 at 9:20 PM

really sad.

in my bedroom i have got a 1280x1024 monitor.

is there any chance to use the amlogic device as my sleeping tv device with that oldskool monitor?

thomaz · January 11, 2018 at 9:31 PM

otherwise with one of those very old versions it was black after doing rgb switch.