Video always output at 24Hz when screen set to 4K

I have set screen resolution to xn OSMC and my Marantz NR1607 is showing the input to be 4k:24Hz which is great for 24p material. However when I play files that are 25 fps I see motion stutters, and the AVR input still says 4k:24Hz. Adjust refresh rate is set to start/stop, sync playback is not enabled.

When I set the OSMC screen resolution to 1920x1080p the AVR indicates 1080p:50Hz input when playing 25 fps material. When I enable 4K upscaling in the AVR the output is indicated as 4K:25Hz.

Isn’t OSMC supposed to switch the frame rate when the screen resolution is set to 4096x2160p ?

Side note: when OSMC is set to 1920x1080p playing 4K material still outputs as 4K (24Hz), so that seems to be the best setting for me for now.

It is.

Let’s see what your TV advertises as officially supported:

cat /sys/devices/virtual/amhdmitx/amhdmitx0/disp_cap

If you also upload a debug log, we’ll be able to see why OSMC isn’t changing the refresh rate.

Sam

I get this right now:

$ cat /sys/devices/virtual/amhdmitx/amhdmitx0/disp_cap
480i60hz
480p60hz
480p_rpt
576i50hz
576p50hz
576p_rpt
720p60hz
1080i60hz*
1080p60hz
720p50hz
1080i50hz
1080p50hz
1080p24hz

But that is with the TV being off (can’t turn it on remotely). I’ll see if it does report 4k resolution when the TV is on tonight.

The logs are at: https://paste.osmc.tv/unudedepan

Weird. I thought that command would give an empty list with the tv switched off.

Not necessarily. Sometimes if you’re using an AVR and it’s in standby, it will fake an EDID so that devices can still communicate with it.

The logs when the TV is on will be handy

When my AVR is on standby the file is empty. When I switch my AVR on (remotely over the network) it gives this list. It is probably fake. I suppose when I turn my TV on as well it will relay the actual info from the TV to the Vero4k.

Yes – it’s most likely done so you can listen to audio without
having the TV on; or have audio go to the AV receiver without
needing video to.

Now that my TV is on, I get this list:

$ cat /sys/devices/virtual/amhdmitx/amhdmitx0/disp_cap
480p60hz
480p_rpt
576p50hz
576p_rpt
720p60hz
1080i60hz
1080p60hz
720p50hz
1080i50hz
1080p30hz
1080p50hz
1080p25hz
1080p24hz
2160p30hz
2160p25hz
2160p24hz
smpte24hz
smpte25hz
smpte30hz
smpte50hz
smpte60hz
smpte50hz420
smpte60hz420
2160p50hz
2160p60hz
2160p50hz420
2160p60hz420

So for 25 fps content I would expect OSMC to switch to 2160p25hz (or maybe 2160p50hz).

Indeed. It would be good to see the full set of debug logs when you try and play with Adjust Refresh Rate on. If you give me the name of the file you try and play it will help narrow it down.

16:48:00.608 T:3893691376 NOTICE: service.libraryautoupdate-1.0.0 : Waiting for other scan to finish

This message comes up a lot in your logs. If you can disable it temporarily so logs are more legible that will help

Sam

I’ve just re-read your initial issue.

I’m guessing that if you set the GUI to 1080p, there’s no issue switching to 25Hz accordingly. At the moment this is a limitation with Kodi. I remember doing some digging in to this in March but I didn’t find an ideal solution, because some others might not anticipate this behaviour.

I suspect we need to revisit.

Sam

Yes, with the GUI set to 1080p SD material with 25 Hz plays fine (frame rate is switched correctly). Even 4K:24Hz plays fine (resolution is switched correctly). I can totally live with this, but as I have a 4K TV I set the GUI to 4K which causes problems with SD 25Hz material (played at 4K:24Hz). That is kind of counter intuitive.

Do you still need me to create debug logs? I can do so over the weekend.

Hi,

Sorry – I don’t think I was quite clear.

I’d like to know if you still have the issue with refresh rate switching to 25Hz when you have the GUI set at 1080p60 or 1080p24 for example.

As an aside, I do not recommend running the GUI at 4K. Kodi’s scaler isn’t as good as most TVs, so you’ll see a better GUI at 1080p and we’ll switch to 4K whenever you play a 4K clip,

The issue I reported is with the GUI set to 4k which I suppose is the setting most people owning a 4k TV will use. With the GUI set to 1080p everything (including playing 25Hz material) is fine. Since your recommendation is to use 1080p I have no more issues, all is working fine using this setting.

Perhaps adding a warning next to the 4k GUI resolution selection is in order?

Not sure where we could put it in the resolution screen but will think.

We currently default to 1080p.

Sam

2018 and the way it works is still not intuitive or user friendly for the great majority of users.

Given my 4k LG TV with

osmc@osmc:~$ cat /sys/devices/virtual/amhdmitx/amhdmitx0/disp_cap
480p60hz
576p50hz
720p60hz
1080i60hz
1080p60hz
720p50hz
1080i50hz
1080p30hz
1080p50hz*
1080p25hz
1080p24hz
2160p30hz
2160p25hz
2160p24hz
smpte24hz
smpte25hz
smpte30hz
smpte50hz
smpte60hz
smpte50hz420
smpte60hz420
2160p50hz

Two questions:

When I set OSMC UI to 4096x2160p, why does it only offer 24hz and 23.98hz and not all the refresh rates reported by disp_cap? i.e. 2160p25hz, 2160p30hz and 2160p50hz

When I set OSMC UI to 4096x2160p@24hz and play 1080p/50FPS content, why does OSMC not prefer at all costs avoiding judder with no quality loss whatsoever, by changing to 1080p50hz? What it does now is now is terrible and unforgivable, staying at 4096x2160p@24hz with lots of judder.

You should not set the GUI to 4K.
It should be set to 1080p with Adjust Refresh Rate on if you have a 4K Display.

This has been covered in some detail in previous posts on the forum. Your device should have arrived with 1080p as the default mode, not 4K. So for users, just enabling Adjust Refresh Rate will do the trick.

4096x2160 is not 4K, it’s an smpte mode: which is why Refresh Rate switching to 23.976 is not available.

OSMC doesn’t downgrade resolution as that’s a Kodi specific feature. We may add something for Krypton. It will definitely come in Kodi Leia.

Yes, I gathered that setting the UI to 1080p is the best option for now. But of course, understandably, proud owners of their new 4k tv’s will go into settings and set the UI at 4096, without realizing that UI resolution influences playback! (which I consider unnecessary and not good, there is no reason why they should not be independent of each other).

4096x2160 is not 4K, it’s an smpte mode: which is why Refresh Rate switching to 23.976 is not available.

That’s not right: switching to 23.976 (or 24) is available for 4096. It’s switching to 25, 30, 50 or 60 that is not available.

Anyway, ok, looking forward to Leia then. I would suggest that in any case OSMC or Kodi is more verbose and intelligent about non-matching refresh rates between UI and content. It can’t be that hard to make or suggest the right choice (for avoiding judder).

You shouldn’t set the GUI to 4K because Kodi’s scaler isn’t very good. Your TV will do a better job with a 1080p GUI than Kodi can scale up. I think the best option is to remove the 4K and SMPTE modes from Kodi’s display modes, so that users don’t make this mistake.

That’s not what I’m saying.
You shouldn’t be using SMPTE modes; they’re not the modes we expect for 4K playback. They won’t match the resolution of the video, so we won’t flip refresh rates where it would downgrade the resolution at this time.

Kodi v18 has a whitelisting mode where you can configure what modes you would like to use and for what content.

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I think Kodi should have the intelligence for that, for the great majority of users. It can easily know what will cause judder or downscaling etc.

It’s already available in Kodi v18.
Test builds are already available