HDR Autoswitch causing issues on my LG OLED65C8


#148

Thanks for trying, but you didn’t follow the instructions :wink:
after echo 2160p60Hz (config should show VIC 97 instead of 353) go straight to echo 42210bitnow.
echo 2160p60hz420 is just the escape route.

You should also be able to play 4k24Hz with echo 422now. As long as you do the echo 422now while in 1080p60 or 2160p24 modes.


#149

That works:

osmc@WoZ-Player:~$ echo 8bitnow | sudo tee /sys/class/amhdmitx/amhdmitx0/attr
8bitnow
osmc@WoZ-Player:~$ cat /sys/class/amhdmitx/amhdmitx0/config
cur_VIC: 16
VIC: 16 1920x1080p60hz
Colour depth: 8-bit
Colourspace: YUV444
Colour range: limited
EOTF: SDR
YCC colour range: limited
PLL clock: 0xc000027b, Vid clock div 0x000a339c
audio config: on
3D config: off

osmc@WoZ-Player:~$ echo 2160p60hz | sudo tee /sys/class/display/mode
2160p60hz
osmc@WoZ-Player:~$ cat /sys/class/amhdmitx/amhdmitx0/config
cur_VIC: 97
VIC: 97 3840x2160p60hz
Colour depth: 8-bit
Colourspace: YUV420
Colour range: limited
EOTF: SDR
YCC colour range: limited
PLL clock: 0xc000027b, Vid clock div 0x000a339c
audio config: on
3D config: off

osmc@WoZ-Player:~$ echo 42210bitnow | sudo tee /sys/class/amhdmitx/amhdmitx0/attr
42210bitnow
osmc@WoZ-Player:~$ cat /sys/class/amhdmitx/amhdmitx0/config cur_VIC: 97
VIC: 97 3840x2160p60hz
Colour depth: 10-bit
Colourspace: YUV422
Colour range: limited
EOTF: SDR
YCC colour range: limited
PLL clock: 0xc000027b, Vid clock div 0x000a339c
audio config: on
3D config: off

It plays (Adjust refresh rate disabled, so it stays at 422). No banding. But: Some pixels flicker… not sure how to explain it. They turn pure white for a second and then back. Always different pixels. And only like… 10 or so. Not only in the menu, but in the demo aswell.


#150

woohoo! Pixels flashing is usually a symptom of a bad cable, but I guess bad cables == issues with syncing tmds clocks which seems to be what we have here.

Funny thing is, 422,10bit needs more bandwidth than 420,10bit so it’s not just about bandwidth.

We will make it so users can force 422 on 4k24Hz and 4k60Hz. From what I hear in these two threads, that will solve 99.9% of problems.

Subject to confirmation from LG owners.


#151

I will try another cable on Wednesday. I already returned the Oehlbach one. But remember: It’s the cable that came with the Vero4k that I’m currently using. I fear another cable won’t make much of difference.

Oh I totally forgot: Thanks for the brilliant and constant support :). If the flickering is gone with another cable I’m a happy man.


#152

YW. We will be interested in what you think of the fire TV for comparison, I’m sure. It’s not clear if you can plug it into a AVR to get all that HD audio stuff, but I suppose you can.


#156

Hi Graham. First of all I updated to the latest kernel and there seems to be a big improvement with 4k60 files. Many play first time and if not they play on the second try. However 4k24 is still a problem. The cat command shows they are playing in 444 even though they are 420 files - is that expected? As before they do occasionally play properly though.

cur_VIC: 93
VIC: 93 3840x2160p24hz
Colour depth: 10-bit
Colourspace: YUV444
Colour range: limited
EOTF: HDR10
YCC colour range: limited
PLL clock: 0xc000029a, Vid clock div 0x000b0000
audio config: on
3D config: off

From the file mediainfo:

Color space : YUV
Chroma subsampling : 4:2:0 (Type 2)
Bit depth : 10 bits

I’ve also tested your steps from the other thread and it didn’t black screen.

osmc@Vero4k:~$ echo 42210bitnow | sudo tee /sys/class/amhdmitx/amhdmitx0/attr
42210bitnow
osmc@Vero4k:~$ cat /sys/class/amhdmitx/amhdmitx0/config
cur_VIC: 97
VIC: 97 3840x2160p60hz
Colour depth: 10-bit
Colourspace: YUV422
Colour range: limited
EOTF: SDR
YCC colour range: limited
PLL clock: 0xc000027b, Vid clock div 0x000a339c
audio config: on
3D config: off

Played a 4k24 file and it played… for a bit, then the signal seemed to bounce in and out. Played a different one and it played, but when I stopped it got a black screen instead of the menu:

cur_VIC: 353
VIC: 353 3840x2160p60hz
Colour depth: 10-bit
Colourspace: YUV420
Colour range: limited
EOTF: SDR
YCC colour range: limited
PLL clock: 0xc000029a, Vid clock div 0x000b0000
audio config: on
3D config: off

Could only get it back by running echo 8bitnow.


#157

Many thanks.

Yes. The output format is determined by the capabilities of the display, not the specs of the input.

All those results tend to confirm my theory: LGs seem to like 422 more than 444 or 420 when playing 4k files.

We’ll make it so you can force 422 at 4k, then maybe you guys can do some more real world testing with that.


#158

I don’t think the TV supports 4k50/60 at 444 10 bit at all. All the 4k60 files I have are 420 and they are playing at 420. I don’t understand why the GUI black screened when outputting at 4k 420 as according to LG’s own documentation that is the only format supported at 10bit!

That was why I asked about forcing 420 10bit - I was wondering if something was happening during the adjust refresh rate procedure where it was setting the resolution first (to 4k) but the chroma was still 444 from the GUI, causing the TV to lose the signal. Not sure why a longer cable would affect that though.


#159

Is there a reason why you wouldn’t just force 4:2:2 10 bit for everyone vs 4:4:4 10 bit? I admit I don’t fully understand all the details in this thread, but I have read that in movies and tv you can’t tell a difference between 4:4:4 and 4:2:2.

Wouldn’t this reduce the bandwidth and eliminate most of these bad cable issues that many users are having?


#161

Some users also had problems with 422… So, not a solution for everyone :wink:


#164

According to Wikipedia, you need more than 18gbit hdmi for 444, 10bit 60fps HDR.

" Video formats that require more bandwidth than 18.0 Gbit/s (4K 60 Hz 8 bpc RGB), such as 4K 60 Hz 10 bpc (HDR), 4K 120 Hz, and 8K 60 Hz, may require the new “Ultra High Speed” or “Ultra High Speed with Ethernet” cables.[[80]]"

(https://en.m.wikipedia.org/wiki/HDMI#cite_note-HDMI21Introduction-80) HDMI 2.1’s other new features are supported with existing HDMI cables.

I got HDMI 2.1 and this plays well on my Samsung C8 65" (not sure if it’s 444)


#166

Here’s a nice overview of the 4k formats and bandwidth required:


#167

You are correct. TVs don’t support 444,10bit generally. With 8k sets on the rise that will change, I guess. But don’t get me started on why you would want an 8k screen in the average living room.

At 24Hz, 422,10-bit needs lower bandwidth than 444,10-bit so could be called a ‘safer’ option.

But at 60Hz, 422,10-bit needs more bandwidth than the ‘default’ 420,10-bit. That’s why it’s puzzling some people can play 60Hz at 422 but not at 420.

As for @jmccrack’s point, we tried 422 for all in testing last month and Philips owners could not get a 10-bit picture.

Bottom line - we have to give people a manual selection option to suit their equipment.


#168

List of TVs with 444 support https://www.rtings.com/tv/learn/chroma-subsampling


#169

Indeed, a useful reference, but what they don’t say is the 444 will be at 8 bits unless the HDMI input supports > 18Gbits/s. So useless for HDR at 60Hz.


#170

Cool. I dumped info out of 3 files I tried. All are 4:2:0 . Any chance someone has 4:4:4 or 4:2:2 videos I could try? Just courious :D.

Anyway, looks like this thick cable behind my TV is a placebo. The 18Gbit cable shipped with Vero should just work…


#171

In the meantime, is there a way for me to manually force 422 10 bit? I am currently on the latest dev release.


#172

I’m pushing the necessary Kodi patch today and I think Sam wants to release that with other stuff this week.


#173

If you need a help from my Vertex to test it, just let me know @grahamh


#174

Just got my LG C8 (beautiful TV), but now I cannot play anything HDR.
Non HDR 4K works but HDR gives no signal, like everyone has been experiencing.
What should I do so I can play these files until the issue is fixed?