Why is it direct-playing 4K media on a non-4k Projector?

Plex Media Server
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1

So, i have a Sony VPL-HW65es, its a projector with 1080p. that afaik cant handle 4k. atleast thats what the specs says.

But i noticed today that when i play a 4K movie and have the plex client set at direct play, it actually direct plays it. No transcoding at all. atleast thats what it says when checking the dashboard in PMS. and it plays it without any issues.

i then manually forced it to transcode and it transcoded it with hw and also without any issues.

It was a H.265 2160p mkv movie
plex server has hw transcoding enabled.

im running plex server in a LXC on proxmox, on an intel nuc 7i7dnh2e.

any ideas on why … or how… it manages to direct play something it shouldnt be able to direct play?

2

@nmbrg It’s no different from when you play a 4K media file on a PC with a 1080P monitor, it just plays at 1080P. This is perfectly normal.

3

What client are you using?

The client is probably scaling the movie to 1080p.

For example, I have a Amazon FireStick 4K connected to a SDR 1080p TV. It direct plays 4K HDR movies. The client scales the movie to 1080p and tonemaps it to SDR. The Plex server is unaware (there is no feedback loop), and reports direct play.

The Plex Desktop does the same thing. It direct plays 4K HDR media even though my PC is connected to a 1080p SDR display.

4

@FordGuy61 Exactly, it’s known as downscaling.

5

im using the plex app on nvidia shield.

6

nowhere does it say that my projector can downscale 4k.
or is that something every device can do? if so, why does transcoding exists?

7

The Shield is perfectly able to direct play 4K HEVC. And it can also downscale or upscale and perform tone mapping, depending on the connected display/screen/projector.
They do talk to each other over HDMI and negotiate the technical data of the video stream which will be delivered by the Shield.

8

The Shield is downscaling the video, not the projector.

Not every Plex client can do it.

9

ok, here i was thinking if the display couldnt handle 4k plex needed to transcode.
so it turns out im just ignorant.

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