Dolby Vision Playback & True TV-Led Support on LG Evo G4 (CoreELEC, Ugoos AM6B, Emby/Kodi Setup)

[ero47a2]

Hardware & Setup:

• TV: LG Evo G4 (supports Dolby Vision, VRR, and HDMI 2.1)

• Playback Device: Ugoos AM6B running CoreELEC Omega Nightly

• Storage: Crucial X10 Pro SSD (for direct playback, no streaming)

• HDMI Cable: Ugreen HDMI 2.1 (Certified)

• Software: Kodi Omega Nightly + Emby for Kodi Next Gen

Main Issues & Observations

1. Dolby Vision Playback – TV-Led vs. Player-Led Behavior

I have tested both TV-Led and Player-Led Dolby Vision modes and encountered unexpected behavior in TV-Led mode.

TV-Led Dolby Vision (Preferred Method, but Problematic)

• Expected Behavior: TV should handle Dolby Vision processing, delivering the best picture quality.

• Actual Behavior:

• The TV does not switch to the correct Dolby Vision processing mode.

• Color gamut is incorrect, and the TV outputs in RGB instead of YCbCr.

• VRR (Variable Refresh Rate) is not enabled correctly in TV-Led mode.

• Bit depth does not seem to switch to 12-bit properly.

• Dolby Vision metadata detection seems inconsistent, as if the TV isn’t fully recognizing the signal correctly.

Player-Led Dolby Vision (Works, but Not Ideal)

• Expected Behavior: Player should send Dolby Vision in Low-Latency mode, but TV should ideally handle full processing.

• Actual Behavior:

• Output detected as YCbCr 4:2:2, 12-bit (which is correct for Player-Led).

• Dolby Vision Mode detected as DV-LL (Low Latency) BT.2020nc.

• VRR works properly in this mode.

• Color space is correct, and the picture looks as expected.

Problem:

• TV-Led mode should be the better option for Dolby Vision playback, but it forces RGB and does not engage VRR properly.

• Player-Led works but is not optimal.

2. HDMI 2.1 & VRR (Variable Refresh Rate) Issues

• VRR behavior is inconsistent:

• Works in Player-Led Dolby Vision mode.

• Does NOT work in TV-Led Dolby Vision mode.

• Using a Ugreen HDMI 2.1 cable, so bandwidth limitations should NOT be the issue.

• I want to ensure that VRR works properly in both SDR and Dolby Vision content without forcing RGB output.

• Is there a CoreELEC or LG G4 setting that forces proper TV-Led Dolby Vision with YCbCr output?

3. Emby/Kodi Player Setup for Direct Playback from SSD

• My goal: Play files directly from my Crucial X10 Pro SSD without transcoding or requiring a media server.

• I tested Emby for Kodi Next Gen, but it seems to expect a media server.

• Playback Mode Options:

• Native (Direct Paths): Allows direct playback but lacks some Emby features.

• Add-on (Default): More Emby features, but might not allow proper local playback.

• I don’t want to set up a dedicated Emby server—I just want a direct player that fully supports Dolby Vision.

What I Need Help With:

1. Why does TV-Led Dolby Vision output in RGB instead of YCbCr, and how can I force YCbCr output?

2. Why does VRR work fine in Player-Led Dolby Vision but not in TV-Led mode?

3. Are there CoreELEC or LG Evo G4 settings that properly enable TV-Led Dolby Vision without RGB issues?

4. Is Emby for Kodi the best option for direct Dolby Vision playback, or should I use another player setup?

5. Is there a way to ensure that 4:4:4 12-bit is used properly instead of getting limited to RGB?

Any Dolby Vision, CoreELEC, or LG G4 experts who can help troubleshoot this?

[rome1931]

8bit RGB is correct for TV-LED Dolby Vision. AM6B does not support VRR or HDMI 2.1.

[ero47a2]

But isn’t that just a form of ‘fake’ TV-Led? If it’s still 8-bit RGB with BT.709 showing in the info, how is the TV actually processing the Dolby Vision metadata? Shouldn’t true TV-Led output be BT.2020 with higher bit depth? Or is the RGB tunneling just a limitation of how Dolby Vision is handled over HDMI?

[Sholander]

No, it’s not fake TV-Led. As already said all is OK on your end except showing BT.709 instead of BT.2020. This is just irrelevant and wrong info, since you already get BT.2020 color depth; otherwise your displayed colors would ne wrong.
RGB tunneling is not a limitation.
Emby for Kodi is not “best option for direct DV playback”, it’s not needed for any DV picture handling/improvement, and should not, or does not, influence picture quality.

[jonnypuma]

What is the use of VRR for fixed framerate content such as video?

[ero47a2]

Thanks for the clarification! So, just to make sure I understand correctly—RGB tunneling is not a limitation, and even though BT.709 is displayed in the info, I am still getting the correct BT.2020 color depth? That makes sense, but does that mean the way Dolby Vision is being handled over HDMI (through an 8-bit RGB container) is just the standard way it works, even on higher-end setups?

Also, regarding Emby for Kodi, I wasn’t suggesting it improves Dolby Vision playback itself, but I was looking for a smoother way to handle direct play from my SSD without extra processing overhead. If it doesn’t influence picture quality, would you say using Kodi’s internal player is still the best option for that?

[ero47a2]

VRR (Variable Refresh Rate) can still help with fixed framerate content like movies and shows, especially in cases where there might be slight mismatches between the display’s refresh rate and the actual framerate of the content (e.g., 23.976 fps vs. 24.000 Hz). Some displays or playback devices don’t handle these small differences well, leading to microstutter or frame pacing issues.

VRR can allow the display to adapt dynamically, reducing judder or stutter in certain scenarios. However, for most properly matched 23.976 fps content on a 23.976 Hz-capable display, VRR isn’t strictly necessary. It’s more beneficial if you are switching between different framerates often or if your display has issues locking onto certain refresh rates smoothly.

[Sholander]

@jonnypuma

What is the use of VRR for fixed framerate content such as video?

None, it’s used in/for “Game Mode” on LG TVs.

[Sholander]

@ero47a2

Thanks for the clarification! So, just to make sure I understand correctly—RGB tunneling is not a limitation, and even though BT.709 is displayed in the info, I am still getting the correct BT.2020 color depth? That makes sense, but does that mean the way Dolby Vision is being handled over HDMI (through an 8-bit RGB container) is just the standard way it works, even on higher-end setups?

Yes.

@ero47a2

Also, regarding Emby for Kodi, I wasn’t suggesting it improves Dolby Vision playback itself, but I was looking for a smoother way to handle direct play from my SSD without extra processing overhead. If it doesn’t influence picture quality, would you say using Kodi’s internal player is still the best option for that?

Yes. The best way in CE is to use an SSD directly connected to USB 3.0 port on AM6B+ and played with Kodi internal player. What is best on Android’s Kodi is not relevant here…

[ero47a2]

Thanks for the clarification! So, using an SSD directly connected via USB 3.0 on the AM6B+ and playing via Kodi’s internal player is the most optimal setup for CoreELEC? That makes sense.

I was mainly considering Emby for Kodi to see if it could improve navigation or file management, but if it doesn’t add any benefit for direct Dolby Vision playback, then I guess there’s no reason to use it in my case.

One follow-up question: Would there be any settings or optimizations within Kodi that could help improve playback performance, especially for high-bitrate Dolby Vision files? Or is everything already running at its best when using direct play from SSD?

[Sholander]

@ero47a2

One follow-up question: Would there be any settings or optimizations within Kodi that could help improve playback performance, especially for high-bitrate Dolby Vision files? Or is everything already running at its best when using direct play from SSD?

Not to my knowledge, default settings work best for me; that means I don’t use any additional cache and no White list entries…

[ero47a2]

So, in your experience, the default settings without additional cache or whitelist entries provide the best playback performance? Have you tested this with high-bitrate Dolby Vision files as well, or is there anything else that could further improve smooth playback?

Also, do you think enabling specific Kodi settings (e.g., advanced buffer tweaks or video sync options) would make any noticeable difference when playing directly from an SSD? I’m trying to ensure that I’m getting the absolute best performance for high-quality playback without unnecessary processing overhead

[FML]

In order not to wait for HDMI2.0 interface to support hdr. Dolby Laboratories developed the compressed channel technology (Dolby Vision RGB Tunneling). The YUV422 12bit+DV data (Metadata) is compressed into the RGB 8 BIT channel to the TV, and the TV decompresses the YUV422 12bit+DV data (Metadata) information to read. Display BT.709, because CE in the code to cancel the TV LED mode to send color gamut information flag to the TV, so display as the default BT.709.

[Sholander]

@ero47a2

Have you tested this with high-bitrate Dolby Vision files as well, or is there anything else that could further improve smooth playback?

Yes, no problem with bitrates up to 250 Mbit/s videos. Typical DV videos usually don’t go over 150 Mbit/s. Also I have no problem with any very high bitrate streaming DV content that I receive via my 0.5-1GB fiber optics internet connection.

[anon62335196]

Follow the link in the guide thread that covers optimal Kodi/CE settings.

Most important one is probably to turn off DNR in terms of PQ.

[Sholander]

You mean turn on/enable the option “Disable noise reduction” in CoreElec → Display settings?
IIRC that is default setting.

[anon62335196]

Noise reduction is enabled by default without that flag being toggled