HDR Slight flickering (Workaround available)

Enable 10-bit output

Getting 10bit now with the good ol’

cat /sys/class/amhdmitx/amhdmitx0/attr

However, the banding persists. Although it’s a remux I can’t rule out it’s the video itself so I wanted to compare this to before with the workaround which switched to 2160p60. But neither the Kodi Callback solution nor syncing video to refresh rate seems to work as my AVR keeps on reporting 24 Hz while Kodi is set to 60Hz. Do I have to revert to stable branch again?

Same results as for me. If I switch mode manually to 2160p60hz420 then i get 10bit 60hz 2160p reported by my amp, but still banding.

Likewise for me, flickering gone, banding still present. I’ve just sent logs and a test clip to Sam, I’m sure he’ll be on the case.

Getting rid of the flickering is a good start, one thing at a time and all that :slight_smile:

More observations after cross-checking material with my Sony UBP-X800. Both videos show no banding or flickering on the Sony. This is what the AVR reports:

LG New York demo
Vero 4K: 2160p50 / BT.2020 YCbCr / 10 bits
Sony: 2160p25 / BT.2020 YCbCr / 12 bits

Vero 4K: 2160p24 / BT.2020 YCbCr / 10 bits
Sony: 2160p24 / BT.2020 YCbCr / 12 bits

I tried changing

cat /sys/class/amhdmitx/amhdmitx0/attr



It makes the AVR display 12bit but the banding is still present, so it effectively makes no difference. It also seems like Sync to refresh rate doesn’t have any effect (although I have to admit that I never tried this option once before).

I reverted to 444,10bit and played Allied again.

Log: http://paste.osmc.io/hunamumuwa
MediaInfo: http://paste.osmc.io/hunokisive.coffee

For testing purposes you could use this Video which before this patch had flickering at 24hz (ok at 60) and now shows no flickering but banding (both 24/60hz)

Just gave your test file a go @Martorias - very clear banding at both 2160p24 and 1080p60 (i.e.
sync refresh on and off) using the test build.

Yours is a much better demonstration than my test file which could be a bit subjective.

No flickering though!

It’s basically the same with this file as it is with Allied. However, there’s still some kind of banding on the Sony although much less worse than on the Vero 4K. Looking at my other files there’s no banding anymore and they look right to me so I would go on testing with these.

Cool! The video is a bit extreme but good for testing purposes :slight_smile:

Hello mule,
Whilst #5 sounds ideal, am I correct in saying this setup wouldnt be ideal as Android is currently unable to automatically switch colour outputs (YCbCr) when switching between different videos?

I’d recommend we close this thread in a few days so that we can now hone efforts on further HDR improvements.


No issues at all just referred to the issues mentioned in this thread. Android brings other disadvantages as you already mentioned.

Regarding the flickering issue: I can confirm that this has been solved. @Sam: Great Job!
Sadly I can also confirm that now heavy banding exists and setting the bitdepth via “/sys/class/amhdmitx/amhdmitx0/attr” seems to have no effect anymore.

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Users have reported that the banding issue was present before; so hopefully there’s not a regression there.

When you say setting 10-bit via sysfs doesn’t work, does your TV display the output format?

I’m sorry but neither my TV, nor AVR, nor projector shows the bit depth. I only can report what I see on screen.

The banding wasn’t present (for me) before using the dev build, but instead there was flickering. So right now it seems we’re stuck with one of those issues.

I believe I had both banding and flickering previously, in that I could see flickering in specific bands, if that makes sense. Either way, I definitely have banding now, but no flickering.

Given this thread is specifically titled flickering, and the consensus is that is solved I have no issue closing this thread. So long as we (okay Sam :slight_smile: ) continue to plug away at the banding.

That is exactly what I am experiencing.

I’m also for starting a new thread (“HDR banding issues” or something) now that the flickering seems to be fixed. It’s frustrating how close the Vero 4K is to being the perfect 4K device but currently it’s just unusable for 4K HDR material :frowning:

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Indeed, I now see I got banding as well and I never had HDR flickering issues, it is in 10bit mode btw

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