[TESTING] Vero 4K / 4K + video improvements

[The_Chief]

@grahamh

ut just to be clear is the problem with 444,10bit only on this test kernel or do you get a problem with that with the release kernel?

I get this problem with both test & release kernels. «444,10bit» mode, autodetected or forced, leads to ‘no signal’.

PS: I’ve got an answer! LG OLED C8 supports 4:4:4 10bit input ONLY when corresponding input is in «PC mode»!

[grahamh]

… and I’m guessing the problem only applies to 24-30Hz streams. 50/60Hz should send 4:2:0 at 10bit.

[grahamh]

@The_Chief

PS: I’ve got an answer! LG OLED C8 supports 4:4:4 10bit input ONLY when corresponding input is in « PC mode »!

So is that something you can just set on the TV, or do we need to signal it? It would have to be user-configurable so it didn’t screw up other ppl’s viewing.

[The_Chief]

@grahamh

So is that something you can just set on the TV

It’s a mode you can switch selected HDMI input on modern LG OLED TV (2017/2018yr models, i presume). TV HDMI input in this mode also becomes able to handle not only YCbCr 4:4:4, but also RGB 4:4:4 input from PC.

[grahamh]

Bonkers! Flagship HDR TV needs special setting to play HDR.

For reference, could you post the output of cat /sys/class/amhdmitx/amhdmitx0/rawedid for your TV in normal mode and PC mode.

[The_Chief]

@grahamh

Bonkers! Flagship HDR TV needs special setting to play HDR.

Modern 4K HDR titles do not need 4:4:4 anyway, all of them are 4:2:0 encoded. Why to mess with uncommon colorspaces? Why to do unnecessary conversion? 4:4:4 is only for PC/*-Box/SPS (say ‘games’).

[grahamh]

The files are 4:2:0. HDMI does not support 4:2:0 except at 4kp50/60, so sources must output 4:4:4 (usually YUV but RGB is mandatory).

[angry.sardine]

@grahamh

sources must output 4:4:4 (usually YUV but RGB is mandatory).

Outputting YUV 4:2:2 is much more common than 4:4:4 for HDR.

I own a 2016 LG OLED TV. It can handle 4:2:0 or 4:2:2 HDR signals just fine without engaging PC mode.

Later models may work differently, but engaging PC mode on mine is bad news: it disables a number of the standard image processing options, which causes all kinds of problems.

[grahamh]

@angry.sardine

Outputting YUV 4:2:2 is much more common than 4:4:4 for HDR.

You mean across different devices? Maybe we will default to that, then. Thanks for the info.

[The_Chief]

@angry.sardine

Later models may work differently, but engaging PC mode on mine is bad news: it disables a number of the standard image processing options, which causes all kinds of problems.

Exactly.

@grahamh

The files are 4:2:0. HDMI does not support 4:2:0 except at 4kp50/60, so sources must output 4:4:4 (usually YUV but RGB is mandatory).

Why not to go 4:2:2?
Meanwhile, no LG, no Samsung. no Sony TVs up to 2018yr models can’t support 4:4:4/10 in standard mode, only in ‘PC mode’(‘Graphics’ mode in SONY TVs) with all picture processing disabled — no TruMotion, etc. That’s it — «flagship HDR TVs», as you’ve said.

[sam_nazarko]

@The_Chief

Meanwhile, no LG, no Samsung. no Sony TVs up to 2018yr models can’t support 4:4:4/10 in standard mode, only in ‘PC mode’(‘Graphics’ mode in SONY TVs) with all picture processing disabled — no TruMotion, etc. That’s it — «flagship HDR TVs», as you’ve said.

Hi – do you have a source for this?

Cheers

Sam

[angry.sardine]

@grahamh

You mean across different devices? Maybe we will default to that, then. Thanks for the info.

YUV 4:2:2 is the most common format for source-to-display video information for almost all formats - or at least it is in the realm of consumer AV. PCs and monitors generally use full-range (0-255) RGB, but blu ray players and TVs use limited range (16-235) 4:2:2 YUV.

4:4:4 YUV is also used by a fair number of devices for resolutions up to 1080p; and (less often) 4:4:4 can be used for 4K SDR rec.709.

But for 4K 10-bit HDR rec.2020, 4:4:4 is almost unheard of. Your options are generally 4:2:0 at 50 or 60Hz only, or 4:2:2 at any refresh rate. (You may possibly need to convert from 10-bit to 12-bit too - that varies).

Anyway, 4K HDR 4:4:4 is very rare, hence why you have to put TVs into a non-standard mode to handle that signal.

[HDRpotato]

@grahamh

Bonkers! Flagship HDR TV needs special setting to play HDR.

I feel like this thread caused some confusion. 4:4:4 10bit with 4k HDR @ 24hz works on the LG OLED without having to engange any PC mode. 4:4:4 10bit with 4k HDR @ 60hz does not work on the LG, which is expected because HDMI 2.0 spec says so.

[grahamh]

@HDRpotato

4:4:4 10bit with 4k HDR @ 24hz works on the LG OLED without having to engange any PC mode.

This is from @The_Chief’s debug log which is a clip he could not play:

Stream #0:0: Video: hevc (Main 10), yuv420p10le(tv, bt2020nc/bt2020/smpte2084), 3840x2160 [SAR 1:1 DAR 16:9], 23.98 fps, 23.98 tbr, 1k tbn, 23.98 tbc (default)

[HDRpotato]

My apologies, this must be a weird issue with the C8 then. The C7 works as described.

[mattmarsden]

4:4:4 is a better mode for 24hz as you don’t need to convert 10bit to 12bit. On another note 4K REC709 is still being output as BT2020.

[grahamh]

@mattmarsden

On another note 4K REC709 is still being output as BT2020.

You will have to remind me where this was reported.

[mattmarsden]

Hi Graham - here:

Forcing Vero 4K to 10bit has an unfortunate side-effect...?

When I tried the auto HDR rec709 sdr 4K was still coming through as BT2020

444 10bit output from vero 4k

Yes – if you set it in rc.local it’s permanent, what have you tried currently? Are you saying that you would only like HDR10 content to change to BT2020 and everything else to stay as 8-bit Rec709? This has already been requested by another user and is being worked on. Sam

[TESTING] 4K HDR playback with banding & flickering fixes

The hdr auto switch from my understanding is for 10bit rec709 videos which is not a standard and hasn’t crossed my path yet. Most 10bit stuff will be bt2020 hdr so just leave that line for now imo

[grahamh]

Thanks. Things have changed a bit in the last 4 months. Can you post a debug log and mediainfo for your 4k rec709 vid? With this testing kernel installed.

[jahutchi]

I’m having problems on my new Vero4k+ with Live TV stuttering when using this kernel. I would like to revert to the stable kernel to see whether the problem persists, since I dived straight into using this test build as soon as I received my Vero4k+.

I used the instructions at the top of this post to revert…

However, are we sure this link is correct: http://apt.osmc.tv/pool/main/v/vero364-source-3.14.29-119-osmc/vero364-image-3.14.29-119-osmc_119_arm64.deb

Only reason I ask, is that before reverting, my kernel was reported as:
osmc@vero4k:~$ uname -a
Linux vero4k 3.14.29-119-osmc #1 SMP Wed Sep 5 19:09:21 UTC 2018 aarch64 GNU/Linux

And after reverting, the exact same version is showing:
osmc@vero4k:~$ uname -a
Linux vero4k 3.14.29-119-osmc #1 SMP Wed Sep 5 19:09:21 UTC 2018 aarch64 GNU/Linux