LG G4 OLED Display Issues

[JohnGreenan]

Hi,

I'm having issues with my Windows PC changing refresh rates and switching between SDR and HDR. I have found that using a hardware splitter helps, not splitting signal just using hdmi in and hdmi out.

HDMI 2.1 Spliiter

Is it possible to do what this splitter does with software, registry change? I have tried the CRU but I'm not sure I'm using it correctly.

Windows 24H2, i3 Intel® UHD Graphics 730 to LG G4 Oled TV, HDMI 2.1 to HDMI 2.1.

Specifically I'm using Kodi to play MKV's so its trying to change refresh rate then switch on HDR (for HDR10 mkv), at this point it manages to change to 24hz but then fails at the HDR switch and drops back to default display 4k@60hz, Kodi minimises and wont maximise and I have to force close.

I can also connect direct to hdmi in on soundbar then to tv and the refresh rate change and HDR switch works, but then another problem is any TV input switch or resume from sleep Kodi again minimises and I have to force close.

Just trying to get my head round it all and I get that this might be a software issue, but I just don't understand why a hardware splitter helps. Its a new TV, nothing changed on my PC which worked flawlessly on an LG B8 OLED (HDMI 2 ARC only) - LG G4 is HDMI 2.1 and eARC.

I did try and ask on Kodi forums and one of the Devs said it was a timing issue on my system - "On your system the timing is just right to make audio come back just a bit late and make Kodi fall back to DirectSound, which doesn't passthrough high resolution formats" which kind of makes sense as sometimes I have to change sound back to wasapi.
I see the same behaviour in MPC-BE when I have refresh rate change on and SDR to HDR on.
Makes me think it might be the intel audio driver causing my issues, but I used DDU and tried 3 different drivers back to 07/2023 and still same thing.

Lastly, changing from 8bit to 10bit seems to work but I'm then at max of 30hz refresh rate, I have 60fps videos that look bad at 30hz.

Attached is details from IGC. I can show video if needed as LG TV has a good overlay showing realtime the HZ, Resolution and colourspace.

Thanks for any help!

[ToastyX]

The only reason the splitter would help is because it also acts as an EDID emulator, so if the TV disconnects, the system still sees the TV as connected. In that case, CRU won't help because CRU only does EDID overrides, which only take effect when the display is connected.

(11-26-2024 07:56 AM)JohnGreenan Wrote:  Specifically I'm using Kodi to play MKV's so its trying to change refresh rate then switch on HDR (for HDR10 mkv), at this point it manages to change to 24hz but then fails at the HDR switch and drops back to default display 4k@60hz, Kodi minimises and wont maximise and I have to force close.

This seems like a Kodi-specific issue unless the TV is disconnecting when turning on HDR. If that's the case, Kodi might need to add a delay to work correctly.

(11-26-2024 07:56 AM)JohnGreenan Wrote:  I can also connect direct to hdmi in on soundbar then to tv and the refresh rate change and HDR switch works, but then another problem is any TV input switch or resume from sleep Kodi again minimises and I have to force close.

This is because the TV is disconnecting when switching inputs or sleeping. In this case, an EDID emulator would help.

[JohnGreenan]

Thanks for the reply. It makes a lot of sense.
Although it doesn't look like my TV is disconnecting - it does go to black screen and not what you see at change of input.

What I don't understand is, this issue happens is when my display is 60Hz RGB 8bit TM SDR.

When I switch to 30Hz RGB 10bit TM SDR it works fine (but I want to be @60).

Also of note when I start changing these settings in the Intel centre and try to go back to 60hz 8 bit (from 30hz 10bit) when I try to change the 30Hz to 60Hz it doesn't like it, and the display settings box is unresponsive.

I actually thought my PC was HDMI 2.1, but its 2.0 it shouldn't really matter but I'm limited to 30Hz at 10bit unless I change to 420 colour and then I cant get 24hz.

If you have a minute this is what happens, it will be doing refresh rate change then SDR to HDR.

8b RGB 60Hz

This is where it fails, when it briefly flashes it has changed (or tried to change to 24Hz 8bit) then it briefly flashes back to 60hz then sticks at 60Hz and program minimises and I have to force quit.

10b RGB 30Hz

This is where it works, changes correctly to 24Hz then HDR and then video plays correctly.

Starting to think its a TV issue. This worked fine, same PC on my old LG B7. I connected my laptop and got exactly the same behaviour. But I have tried so much, I'm just disillusioned by it all, so I don't know anymore.

[ToastyX]

In the first video, I see the desktop doing a zoom in animation. I've only seen that happen with Windows 11 when the display reconnects or when the graphics driver restarts. That doesn't happen in the second video. If the TV is disconnecting or the graphics driver is crashing, that might be confusing Kodi because the display wouldn't be detectable during that time. Do you hear a device disconnect/connect sound when that happens? HDR requires 10 bpc, so setting 10 bpc in advance might be preventing the TV from disconnecting when HDR is enabled.

[JohnGreenan]

(11-29-2024 04:29 PM)ToastyX Wrote:  In the first video, I see the desktop doing a zoom in animation. I've only seen that happen with Windows 11 when the display reconnects or when the graphics driver restarts. That doesn't happen in the second video. If the TV is disconnecting or the graphics driver is crashing, that might be confusing Kodi because the display wouldn't be detectable during that time. Do you hear a device disconnect/connect sound when that happens? HDR requires 10 bpc, so setting 10 bpc in advance might be preventing the TV from disconnecting when HDR is enabled.

Hi Toasty, appreciate your help, as it may not even be related to your CRU program now.
I don't hear any disconnect sound. I've been asking in the Kodi forums and posted a log when this happens, one of the devs analysed it and said this:

15:11:11.823 enumeration of available audio devices, hdmi is not back yet > Kodi decides to fallback to default device (the spdif)
15:11:11.823 attempt to open default device, fails for TrueHD (not possible with spdif).
15:11:12.500 second attempt to open hdmi device (and for some reason AE forgot about the fallback to default device) - failure, hdmi is not back yet
15:11:12.624 Windows events received about device addition and change of default device
15:11:13.007 third attempt to open hdmi device. Succeeds, but device appears as "Device not found", probably because Kodi did not re-enumerate > hypothesis: maybe it's also missing other attributes needed by AE for passthrough to work.

I also found out my motherboard is not a "true" HDMI 2.1, it is TMDS so HDMI 2.0b I think.

Do you think if I did anything in CRU to limit the FRL rate to something near my HDMI 2.0b port would make any difference. I'm a total noob in this stuff by the way. These HDMI standards are a mess from what I see.

--------------

I got hold of proper edid hdmi splitter for 2.1 (last one I had was 2.0). This works, and I think the reason it is working is that it isn't changing from 8 bpc to 10 bpc. When I view the changes on screen it stays at 8 bpc. It is passing through all the audio even the tough ones, TrueHD and DTS-MD.

Can you use CRU to force only using 8 bpc like the edid box? Or this hardware only?

[ToastyX]

(11-29-2024 06:29 PM)JohnGreenan Wrote:  I don't hear any disconnect sound. I've been asking in the Kodi forums and posted a log when this happens, one of the devs analysed it and said this:

15:11:11.823 enumeration of available audio devices, hdmi is not back yet > Kodi decides to fallback to default device (the spdif)
15:11:11.823 attempt to open default device, fails for TrueHD (not possible with spdif).
15:11:12.500 second attempt to open hdmi device (and for some reason AE forgot about the fallback to default device) - failure, hdmi is not back yet
15:11:12.624 Windows events received about device addition and change of default device
15:11:13.007 third attempt to open hdmi device. Succeeds, but device appears as "Device not found", probably because Kodi did not re-enumerate > hypothesis: maybe it's also missing other attributes needed by AE for passthrough to work.

That's basically what I'm saying. The TV is disconnecting temporarily, and Kodi is not handling that correctly.

(11-29-2024 06:29 PM)JohnGreenan Wrote:  I also found out my motherboard is not a "true" HDMI 2.1, it is TMDS so HDMI 2.0b I think.

Do you think if I did anything in CRU to limit the FRL rate to something near my HDMI 2.0b port would make any difference. I'm a total noob in this stuff by the way. These HDMI standards are a mess from what I see.

If it's using TMDS, then the FRL rate has no effect.

(11-29-2024 06:29 PM)JohnGreenan Wrote:  I got hold of proper edid hdmi splitter for 2.1 (last one I had was 2.0). This works, and I think the reason it is working is that it isn't changing from 8 bpc to 10 bpc. When I view the changes on screen it stays at 8 bpc. It is passing through all the audio even the tough ones, TrueHD and DTS-MD.

Can you use CRU to force only using 8 bpc like the edid box? Or this hardware only?

Yes, you can disable deep color in the HDMI data blocks, but HDR is supposed to use 10 bpc, otherwise it will have to dither if the GPU supports that.

[JohnGreenan]

Thanks for your help.

I finally just changed to EDID splitter mode to just copy the TV's EDID and now it switches happily from 8bpc to 10bpc.

You helped me get to the bottom of this, that the TV momentarily disconnects the signal, and now the EDID splitter stops the PC from realising it broke signal.

I cant imagine that this is intended from LG, the TV is the G4, flagship model this year. Maybe because its new, firmware updates down the line will fix (if not intended).