[RPi4] LG C3 OLED TV Only Working in PC Mode

dmsaudio · December 9, 2023 at 11:08 PM

I have just upgraded my TV as per the title. When I boot Libreelect 11.03 on my Pi4b the TV detects it as PC mode and disables most of the AI video enhancements that improve picture quality. It states that these features are not available in PC mode.

Now if I go to the TV Home Hub page on the LG remote, then options, edit inputs and change the input that the Pi4-Libreelect is already plugged into, to identify it as say a streaming box or just a generic hdmi, pc mode is disabled on the TV and I then have all the TV video enhancements available. Great....

However if I then power down the Pi4b-Libreelect, the next boot, or reboot for that matter, the TV again detects it as PC mode and disables the AI video enhancements. This is even though the options in the TV home hub have not changed and still mark that input as say a Streaming Box. I then have to edit that home hub option again and toggle it to anything else and back to Streaming Box to force the TV out of PC mode.

It seems like the TV is either not honouring the ident in the home hub setting when I make it not as a PC and/or Libreelect is sending the TV an ident at boot that it is a PC. I cannot figure if this is a LG TV bug or if it just needs a Libreelect config adjustment.

**chewitt** · December 10, 2023 at 1:37 AM

I'm not sure what a Home Hub is? but if something is connected between the Pi and the TV, remove it and connect them direct to prove the connection works as expected without it. If it does, you can point fingers at the Hub device. If not, I would try a different HDMI socket on the LG as sometimes TVs are preconfigured for a certain content type on certain sockets. If that makes a difference: a) you have a workaround, b) you can point fingers at the TV firmware. LE does not otherwise send any HDMI content-type signalling that would cause the TV to detect/change something so there is nothing to adjust. The sole exception is when HDR media is being played, when we flag the Cinema (not Game) HDR profile. There is no equivalent flagging for non-HDR modes.

MatteN · December 10, 2023 at 9:26 AM

I use Pi 4 (& 5) with LG Oled (65CX), i dont see that problem. Anyway most of the "enhancements" are better left turned off as they dont improve anyting.

dmsaudio · December 10, 2023 at 3:40 PM

The home hub is a page on the TV where you can change what each of the hdmi inputs have connected to them, such as dvd player, streaming box, pc, home theatre, console etc. Since I set the hdmi input of the pi4 to be something other than a PC, the TV enables the AI video options but it reverts back to pc mode on the pi4 reboot despite still retaining the correct ident in the hub page. The TV just ignores this setting on pi4 reboot.

I mostly wanted the Tru Motion option (Cinematic mode) and some of the mpeg AI improvements on LOW. It does feel like this issue is more of an LG 'feature'. Why LG cannot honour what input type is set to seems baffling logically.

I have sent a support to LG so we will see what they say. Thank-you for the replies.

**chewitt** · December 11, 2023 at 12:50 AM

I'm with MatteN on leaving the fancy enhancements turned off (with my 65B7V) unless you like movies to look like camcorder footage. It does sound most like a software issue on the LG side though.

Worst case you could run Kodi natively: https://kodi.wiki/view/HOW-TO:Install_Kodi_for_webOS

**smp** · December 11, 2023 at 5:54 PM

I've seen a similar issue on a Samsung TV. Usually, when a HDMI source device is powered down - the TV still detects that something is plugged in to the HDMI port. But some devices stop being detected when powered down, on the next boot TV "thinks" that a new device has been connected and some HDMI-related settings reset to defaults. As a workaround, you can try to connect the Pi to TV via a self-powered HDMI splitter/switch/extender.

MaxMustermann · July 3, 2024 at 6:46 PM

dmsaudio Did you find a solution? I'm having the same problem with my LG G4. So right now, I have to do the above mentioned Home Hub thing after every cold boot.

In PC mode the 24Hz stutter is worse than in e.g. Blu-ray Player Mode, even with all motion interpolation turned off.

While I keep image enhancements off for the sake of accuracy, I definitely need subtle motion interpolation (2/10) to overcome the 24Hz stutter. Never knew I was motion sensitive when I had a 60Hz panel Samsung for 10 years. Now with low response times on contemporary panels, watching movies at 24-30Hz is unbearable without some interpolation.

HDClown · December 19, 2024 at 4:33 PM

Just got an LG C3 and ran into same issue with an RPi4 and LibreELEC 12.0.1. I am running everything through an AVR and haven't tested if behavior is different when RPi4 is plugged directly into TV because I really don't want to connect that way in general.

After a little testing, I found that if I set the Kodi interface to 1080i then the LG doesn't go into PC mode, but when I set it to 1080p it does.

When I use 1080i for the interface and then play 1080p content, the LG still does not go into PC Mode, so it seems like something that could be specific to Kodi or LibreELEC tied to the interface? I haven't tried a bunch of different 1080p content to see if it will flip after the fact.

MatteN · December 19, 2024 at 7:19 PM

I have several Pi's (4 & 5) connected to a LG 65CX without any problems.

**chewitt** · December 20, 2024 at 6:03 AM

I forget the LG setup stuff now as it's several years since I last looked at it, but not all HDMI ports are equal and there are numerous options. I'd suggest using a different HDMI port on the TV and checking the HDMI port config in LG settings to ensure the port is set-up for movies and deep colour and not PC or Game modes and such things.

noggin · December 22, 2024 at 8:39 AM

This isn't as simple as RGB vs YCbCr output is it? PCs often output RGB, most other consumer HDMI devices almost always output YCbCr - if the Pi is outputting RGB then that might be triggering PC mode? (Is there an option in the Pi version of LE+Kodi that forces YCbCr 4:2:2 output mode at all times?)

I have an LG C3 with a Pi 5 routed through a Denon AVR with all the full-bandwidth 'enhanced' HDMI stuff enabled and sometimes notice the PC stuff appear.

However I can't watch content with any motion interpolation, contrast enhancement or noise reduction enabled (I just want to see the original content - warts and all) - so PC mode poses no problems for my viewing as far as I can see. (video levels are OK - though I've not checked BTB and WTW content below 16/64 or above 235/940)

eungenue · February 21, 2025 at 10:01 AM

I have the same issue here. LG detects Pi as PC and disables all the picture enhancements. I think using enhancements is a matter of preference, but the issue is clearly about connection. I used to have Pi3 and there was exctly same problem, but in the end I somehow (!) managed to get it detected as a media player. There was no clear way - only switching HDMI ports back and forth, changing resolutions, clearing "smart" remote settings, even TV factory resets - all that kind of a hassle. But now I switched to Pi4 and the issue is back and nothing works.

I have contacted LG technical support and that was completely useless. Their answer was "you're using non-standard HW + SW - so look from that side"

On some screenshots from the Internet I can see WebOS did have "Auto detect" feature on HDMI ports, where one could just switch it off and set everything up manually, but my set doesn't have this option. (Nor it should be there according to LG support)

So my the question is - is there anything I can adjust in HDMI settings on Pi side (config.txt for example) that could affect the Pi to TV HDMI handshake?

**popcornmix** · February 21, 2025 at 3:55 PM

I don't have an LG but does changing the name of the input (away from PC) help?

From here.

eungenue · February 21, 2025 at 9:27 PM

No, the name doesn't matter. I would be surprised it it would )