4k works in mpv, lags in Plex HTPC

Plex Players Desktop Players
1

Hi,

I’m running the latest plex HTPC version (1.23.2 at the time of writing). I have a i3-7100U.

I can perfectly watch a 4k sample file if I use:

mpv --hwdec=auto --hdr-compute-peak=no

However when I try to play the same file with Plex HTPC, it drops a lot of frames and becomes unwatchable. I have added a custom mpv.conf and I can see it loading the property in the logs.

Aug 14, 2022 09:44:46.721 [0x7f0173fff640] DEBUG - [MPVEngine/mpv] cplayer: Applying profile 'default'...
Aug 14, 2022 09:44:46.721 [0x7f0173fff640] DEBUG - [MPVEngine/mpv] cplayer: Setting option 'hdr-compute-peak' = 'no' (flags = 4)

Any idea if there are other properties that differ between standard mpv and embedded one in Plex?

Thanks a lot!
G

2

Play with the “Playback Quality” selector in the preferences. In its default position, it will already apply a lot of quality-enhancing filters which a naked mpv will not do (unless being told explicitly).

Do also toggle “Hardware decoding” back and forth and re-test after each change.

3

It seems much better with “Lower Quality”, although I still see some frame drops. Is there a way to figure out what settings Plex passes to MPV? That way I could identify the problematic flags.
Thanks!

4

Seems like the trick was to set:

hdr-compute-peak=no
cscale=bilinear
dscale=mitchell
scale=spline16

For future reference for those who have an i3-7100U :slight_smile:

5

These three are each set to bilinear in the Low Quality preset. Also, if you are on Windows, for low power GPUs we’ve found that the presets which use the (ANGLE Renderer) perform slightly better for these scalers.

1 Like
6

Thanks for the reply!

I managed to figure out which bits of the logs referred to MPV, and indeed all three are set to bilinear in the Low Quality. I found my combo by following mpv Configuration Guide for Watching Videos – Kokomins.

Unfortunately I’m on Linux / NixOS, so no luck with the renderer there :frowning:

7

On windows the better performance in ANGLE is less about ANGLE and more about inefficiency in D3D11.

In your case, it’s likely the hdr-compute-peak=no that made the difference which would have an impact on a lower-end GPU.

8

It’s very likely that hdr-compute-peak=no wouldn’t be needed if it wasn’t a workaround for this kernel bug (also tracked on the intel drm-tip repo here)

9

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.