Setting `cm_fs_passthrough = 2` does not pass cm through when displaying HDR content in fullscreen

[holmes-software]

Already reported ? *

• I have searched the existing open and closed issues.

Regression?

Definitely a regression - something broke after update (requires bisect)

System Info and Hyprland Version

System/Version info

Hyprland 0.48.0 built from branch main at commit d1a59ec39eb4c0d6a7d3d38a26f8924e6bca5cef  (renderer: render tiled fading out above other tiled windows).
Date: Mon Mar 31 16:25:09 2025
Tag: v0.48.0-33-gd1a59ec3, commits: 5955
built against:
 aquamarine 0.8.0
 hyprlang 0.6.0
 hyprutils 0.5.2
 hyprcursor 0.1.12
 hyprgraphics 0.1.2


no flags were set


System Information:
System name: Linux
Node name: archy
Release: 6.13.8-arch1-1
Version: #1 SMP PREEMPT_DYNAMIC Sun, 23 Mar 2025 17:17:30 +0000


GPU information:
09:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Navi 21 [Radeon RX 6800/6800 XT / 6900 XT] [1002:73bf] (rev c0) (prog-if 00 [VGA controller])


os-release: NAME="Arch Linux"
PRETTY_NAME="Arch Linux"
ID=arch
BUILD_ID=rolling
ANSI_COLOR="38;2;23;147;209"
HOME_URL="https://archlinux.org/"
DOCUMENTATION_URL="https://wiki.archlinux.org/"
SUPPORT_URL="https://bbs.archlinux.org/"
BUG_REPORT_URL="https://gitlab.archlinux.org/groups/archlinux/-/issues"
PRIVACY_POLICY_URL="https://terms.archlinux.org/docs/privacy-policy/"
LOGO=archlinux-logo


plugins:

Description

The cm_fs_passthrough doc says this:

cm_fs_passthrough | Passthrough color settings for fullscreen apps when possible. 0 - off, 1 - always, 2 - hdr only

So setting cm_fs_passthrough = 2, the expectation is that the cm is only passed through for a window that is fullscreen and when the window's content is HDR. However, when I playback an HDR video using MPV in fullscreen, I only see the video in SDR until I set cm_fs_passthrough = 1. My guess is the "hdr only" detection is not working when cm_fs_passthrough = 2 and that's why HDR content appears SDR until I set it to 1.

I did a git bisect of the issue and it gave me this result:

6ab5a0befb45e90eb45b8d6582e68d13147297dc is the first bad commit
commit 6ab5a0befb45e90eb45b8d6582e68d13147297dc
Author: UjinT34 <41110182+UjinT34@users.noreply.github.com>
Date:   Sat Mar 22 20:34:01 2025 +0300

    renderer: fix cm_fs_passthrough (#9698)

 src/config/ConfigDescriptions.hpp |  4 ++--
 src/config/ConfigManager.cpp      |  2 +-
 src/render/OpenGL.cpp             | 16 +++++++++-------
 src/render/Renderer.cpp           |  5 +++--
 4 files changed, 15 insertions(+), 12 deletions(-)

How to reproduce

1. Set cm_fs_passthrough = 2
2. Open an HDR video with mpv my_hdr_video and set the opened window to fullscreen. You can find the HDR video I used here.
3. The content should be shown in HDR, but shows in SDR instead.

Attach not paste

• I understand that all text files must be attached, and not pasted directly. If not respected, this issue will likely get closed as spam

Checklist of files to include below

• Hyprland config - hyprctl systeminfo -c (always include)
• Crash report (always include in case of crash)
• Video (always include in case of a visual bug)
• Logs (might contain useful info such as errors)

Additional info & File uploads

hyprland_config_dump.txt

[vaxerski]

@UjinT34

[UjinT34]

Works for me with latest git.

$ mpv --version
mpv v0.40.0 Copyright © 2000-2025 mpv/MPlayer/mplayer2 projects
libplacebo version: v7.349.0
FFmpeg version: 6.1.2
FFmpeg library versions:
   libavcodec      60.31.102
   libavdevice     60.3.100
   libavfilter     9.12.100
   libavformat     60.16.100
   libavutil       58.29.100
   libswresample   4.12.100
   libswscale      7.5.100
$ ENABLE_HDR_WSI=1 mpv --vo=gpu-next --target-colorspace-hint --gpu-api=vulkan --gpu-context=waylandvk ~/Videos/Samsung\ Travel\ With\ My\ Pet\ HDR\ UHD\ 4K\ Demo.ts

cm_fs_passthrough = 1 might result in oversaturated colors for SDR content which might trick you into thinking that it is in HDR mode.

[holmes-software]

Maybe I am misunderstanding something, but it seems to me that I should see no difference between setting cm_fs_passthrough = 1 and = 2 when watching HDR content in full screen. One option is "always", the other is "hdr only" and both are true when watching HDR content in full screen. However, when I change the setting while watching the video, I see a drastic difference in color and brightness.

[UjinT34]

If you see the difference between cm_fs_passthrough 1 and 2 for some content than it's not using HDR. Probably mpv converts HDR -> SDR internally because some settings are missing and it doesn't use the cm proto.

[UjinT34]

However, when I change the setting while watching the video, I see a drastic difference in color and brightness.

If this happens with cm,hdr and cm_fs_passthrough = 1 than mpv doesn't use the cm proto and converts HDR -> SDR. HL sees an SDR content and converts it SDR -> HDR losing the luminance info. By default SDR -> HDR is too dim, you probably tweaked your monitor's brightness to compensate. When an SDR content goes fullscreen with cm,hdr and cm_fs_passthrough = 1 HL disables HDR and switches back to sRGB mode. Which looks very bright and colorfull compared to HDR -> SDR -> HDR conversion. Check mpv settings needed for HDR with the cm proto. You should be able to see correct HDR colors in windowed mode with cm,hdr and if you do it's better to have cm_fs_passthrough = 0.

Altering cm settings while some client is fullscreen wasn't tested. Some things might not apply correctly without toggling fullscreen mode.

[vaxerski]

Hello there!

This issue has been closed, as we are moving from issues to discussions. More about this can be found here and in #9854.

Firstly, please make sure this issue is still relevant in latest Hyprland. If so, we ask you to open a discussion (please read the discussion guidelines first, in the pinned post)

Thank you for your understanding!

[holmes-software]

This makes a lot of sense, thanks! Apologies for misunderstanding. I appreciate the work on Hyprland!