Skipping frames on Billy Lynn's Long Halftime Walk

My Vero 4K+ seems to be skipping an awful lot of frames while playing “Billy Lynn’s Long Halftime Walk”. (I deliberately selected this as a stress-test - it’s one of the few feature-length films that is 10-bit HDR and also 60fps rather than 24).

During playback, if I hit the menu button, then OK (to get player stats), the number of frames being skipped rolls up very quickly - as much as a couple of hundred in a minute sometimes.

I’ve cut out a 30 second extract which exhibits the issue on my set-up - I can upload that if you would like (but not sure where I should put it).

I had a go at generating debug logs (haven’t done that before, so may not have done it right):

MediaInfo for my extract file:

Data source is the hard drive of a Windows PC. It’s a fairly powerful box (desktop, quad-core i7 processor running at 3.5GHz); the drive is SSD so it’s pretty fast. Everything is using gigabit ethernet. I use HaneWin NFS server on the PC to create NFS exports; these are mounted on the Vero 4K+ using autofs. On this (my replacement) Vero 4K+, there are no appreciable issues with network performance (judging by iperf3 numbers).

I’m running kernel version 121.

I don’t know what other information would be useful…

While your network may not be the issue I would still suggest to try to play from local first to see if it is network or decoder related

Someone mentioned this recently, so I need to check the file soon.
Think it was @WilliamG

If you’d like me to upload a 30 second sample, let me know where.

The result of running from local storage is a little ambiguous - it does still skip frames but definitely not as many as it does when streaming across the network.

FWIW, my Nvidia Shield TV, connected to the same network switch and streaming the same video from the same source (using Kodi-level NFS access rather than mounting) plays the video perfectly; so, if there is a networking problem, it’s the Vero 4K+ itself that’s causing it, not the server or the network.

It was indeed @WilliamG, he made about the same topic as this: “Billy Lynn’s Long Halftime Walk” UHD 60fps issues

Huh, what? Who woke me up, taking my name in vain!?

Yes, it was indeed me. Guilty as charged.

Billy Lynn’s is a really, really peculiar title for the Vero 4K and 4K+ in my experience. I’ve had times where it plays reasonably well (just a few skipped frames every now and then - which is not acceptable, still, of course), I’ve had times where you can watch the frame skips counting up like a digital timer. And then I’ve had times where it skips 0 frames. All while testing the same scenes.

It does this whether over my gigabit network, or directly connected to the Vero.

Yeah, I’ve got no idea. Thankfully this movie is more of a tech demo for me (oooh, 60fps/UHD), but still - be nice to know what the deal is with this one.

I can say, I’m absolutely sure it’s not a bandwidth issue over Ethernet/USB or anything like that.

Having played the same test clip a few times, I concur with that: the level of frame-skipping is oddly variable.

Again, concur, local storage is possibly a bit better. Definitely not perfect, but maybe better.

I tend to agree. Not only is another device able to pay the same video from the same source just fine, but my Vero 4K+ is capable of streaming the 200Mb/s jellyfish demo clip without skipping any frames at all, so it’s clearly not just a matter of bit-rate.

My best guess is that’s a CPU problem. CPU usage seems very high while playing. If a certain amount of CPU is also required to handle the fetching of the data across the network, that might be why it runs a bit better (but not well) from local storage. If the CPU is tending to overheat and be thermally throttled, then temperature variation might account for why some runs are better than others.

Could the fact that it has a TrueHD soundtrack be contributing, maybe?

For a laugh, I tried installing the latest Leia test build and running Billy Lynn on that. Rather a strange result.

The number of skipped frames the player reports is far lower: only 5 or 6 in two minutes instead of >500. But the actual video playback still isn’t smooth.

Maybe it’s skipping just as many frames but lying about it. :joy:

That is EXACTLY what it is doing. I had been having some frame skip issues with lots and lots of UHDs. I updated to Kodi v18, and was thrilled to see that all my frame skipping issues were gone. Except they’re not. Kodi just is no longer reporting them.

I’m testing Billy Lynn right now and it’s been telling me for the last half hour that it’s skipped ZERO frames, which is so laughably inaccurate I don’t even know what to think. It’s easy to test, too, because adjusting audio video offset used to report every frame skip as you adjusted it during a movie. On v18 it no longer does.

So, I go back to being disappointed with UHD playback.


Update: on the latest staging release, things are interesting:

If I have the Debug Window open, Billy Lynn runs like shit and reports zero skipped frames. If I close that overlay it runs “perfectly” so far.


I wonder now if it not reporting skipped frames is because it’s the overlay screwing with things? Either way, the movie now runs flawlessly.

So is it all UHD content that’s broken then; or just just this clip?

I have some workarounds for this clip but they will go in for v18 and not v17.

Adjusting the dynamic buffer margin will likely do the trick.

The debug overlay in v18 seems to cause some issues when active. Without it, things should generally be fine.

Just v18. I can’t get it to work with v17 at all (frame lag all over the place), but since I’m moving over to v18 as media in general tends to work better there, I won’t sweat it.

It’s funny to me that using the Debug overlay causes issues. Makes it a little tricky to monitor for stuff if the Debug overlay causes some of the issues in the first place. :smiley:

Bottom line is, though: Billy Lynn runs flawlessly on the latest v18 staging repo. Just don’t run the Debug overlay because it messes things up.

Cheers, Sam.