Apps Plex 4K HDR Stuttering on AppleTV is Thermal Throttling

[MrTemple]

Heads up if you've been struggling with this for the past few years like so many of us...

Most of the AppleTV 4K HDR stuttering issue appears to be thermal throttling due to too much CPU use by the Plex app. Because its home-grown player is not making use of the hardware acceleration available on the AppleTV, which other players (like Infuse) do, and play the same file perfectly.

This is a new development and the Plex staff have confirmed it. They're looking into it and we're all hopeful that this means possibly a fix will finally arrive now that the underlying issue is known for all these various issues with stuttering.

Detailed thread here:

https://forums.plex.tv/t/plex-4k-hdr-stuttering-on-appletv-is-thermal-throttling/856227/56

While we wait for a fix, there's a workaround to the thermal throttling. I have a movie that consistently stuttered after the first 20min of playback (when the heat got too high).

By laying the AppleTV on its side and pointing a small USB fan at it, I'm now able to play it all the way through (and then some, even repeating the most complicated scenes on loop for 10min at a time, which would usually trigger the thermal throttling after as little as 2min instead of 20min).

With no fan but a pair of amazon $15 heat-sinks thermal-taped to the outside of the AppleTV, I could play it without stuttering for about 70min.

 

[Juicy Box]

I’m not surprised. I have been experiencing thermal throttling on the 2022 ATV4K3 with some games. There really should be an active cooled version of the ATV.

None of my Plex content is HDR, but maybe I will add something HDR and give it a try.

 

[gnomeisland]

I’m not surprised. I have been experiencing thermal throttling on the 2022 ATV4K3 with some games. There really should be an active cooled version of the ATV.

None of my Plex content is HDR, but maybe I will add something HDR and give it a try.

Earlier versions did have a fan! Seems like a strange regression.

 

[MrTemple]

Earlier versions did have a fan! Seems like a strange regression.

Completely agree, though this thermal throttling due to Plex has been happening for years on the first two AppleTV 4K with fans. A fan would definitely help, but Plex updating its player to use all the hardware acceleration available would solve the issue.

 

[Juicy Box]

I’m not surprised. I have been experiencing thermal throttling on the 2022 ATV4K3 with some games. There really should be an active cooled version of the ATV.

Earlier versions did have a fan! Seems like a strange regression.

It is pretty bad, too. The 2021 ATV4K2 with the actively cooled A12 actually outperforms the newest ATV4K3 with the A15 on some games due to thermal throttling of the passively cooled A15.

I think Apple removed the fan of the ATV4K3 to make it smaller, lighter, and reduce the cost. It it priced a lot lower than the ATV4, ATV4K1, and ATV4K2, making it much more appealing for people that just want it for streaming Netflix and such. Which to be fair, that is most likely the huge majority of potential customers.

The issue is for the few that use it for casual games, the removal of the fan makes the experience worse. The A15 should make the ATV4K3 on par with at least the eight gen consoles, but it is gimped by not having a fan, and Apple reduced the clock speed of it as well. Probably to keep heat down to reduce the thermal throttling issue.

I don't have an issue with a fanless ATV, I just think Apple should also have an actively cooled model as well. Maybe make the cheaper one, no Ethernet, no Thread, no fan, 32GB storage and the more expensive one with Ethernet, Thread, and a fan, as well with larger storage, 25GB would be nice.

Completely agree, though this thermal throttling due to Plex has been happening for years on the first two AppleTV 4K with fans. A fan would definitely help, but Plex updating its player to use all the hardware acceleration available would solve the issue.

Yeah, sounds like a Plex issue, but having a Fan would probably reduce the problem until Plex comes up with a fix. Does this happen with the 2021 ATV4K2 with a A12 or the ATV4K1 with a A10X?

Also, does this only happen on the ATV? or also iOS devices and iPads?

 

[HDFan]

What is the format of the files that you are streaming via Plex?

Never had any overheating problems on any Apple TV including very high bitrate 4k (up to 110 Mbps) MKV files.

 

[priitv8]

Does the Infuse player do a better job on tvOS?
Infuse can be a good Plex client. Wonder if it uses hardware features of aTV to the fullest?

 

[HDFan]

Does the Infuse player do a better job on tvOS?

How do you define "better"? Both Plex and Infuse have worked without major glitches on many generatiorns of my Apple TVs.

 

[MrTemple]

Does the Infuse player do a better job on tvOS?
Infuse can be a good Plex client. Wonder if it uses hardware features of aTV to the fullest?

Infuse does work a lot better because it does use hardware acceleration for its whole player stack.

Plex uses software-only OpenGL for a lot of things that Infuse runs on Metal.

This is a VERY common issue with 4K HDR files. Many work. Many do not. Or not for long. Dating back on all three 4K ATVs.

Typically when a file starts stuttering (15-30min into a movie when the thermal load hits capacity), we just switch to Infuse and it plays fine.

Of course there is a TON of variability because there are like 17 different distinct things that affect thermal throttling and 17,000 different ways a 4K HDR movie’s video/audio can muxex/encoded, all affecting the CPU/thermal load.

I’ve got some 86gb movies that play flawlessly. Some 14gb ones that start stuttering within 12min.

Until just this month, despite Plex staff having devoted a ton of time playing whack-a-mole, the’ve had a hellish time reproducing the issues consistently.

They’ve finally been able to reproduce thermal throttling as a cause of much of the stuttering issues. They’re looking to add reporting on the debug overlay to show CPU state and thermal state, so it will help all of us figure out what exactly is happening.

 

[priitv8]

Infuse does work a lot better because it does use hardware acceleration for its whole player stack.

Plex uses software-only OpenGL for a lot of things that Infuse runs on Metal.

That is good news!
I never liked Plex on tvOS and have always been using Infuse as its client.
So that must also explain why I know nothing about stuttering on my aTV 4K (1st gen).