Compatibility Issue Between Pegasus-Frontend and Windows HDR Mode

[Dreamvoe]

Bug Report: Compatibility Issue Between Pegasus-Frontend and Windows HDR Mode

Overview:
We have identified a compatibility issue between Pegasus-Frontend (Tianma 前端) and Windows operating systems when HDR (High Dynamic Range) display mode is enabled. Specifically, launching Pegasus-Frontend in fullscreen mode results in abnormal behavior where the Windows system forcibly adjusts the screen brightness — either making it excessively bright or unusually dark. This occurs without any clear user intent and persists even after the application is closed.

Detailed Description:
When HDR mode is active on a Windows system and the user launches Pegasus-Frontend in fullscreen mode, the screen undergoes a sudden and unexplained brightness shift. This shift appears to be system-level, likely triggered by how Pegasus-Frontend interfaces with the display pipeline in fullscreen. Even after exiting the application, the display remains in this altered state, continuing to exhibit the incorrect brightness. This forces users to manually intervene to restore normal viewing conditions.

Steps to Reproduce:

Enable HDR mode in Windows Display Settings.

Launch Pegasus-Frontend in fullscreen mode.

Observe that the screen becomes overly bright or dark without user adjustment.

Exit Pegasus-Frontend.

Note that the brightness issue remains after exiting the application.

Temporary Workaround:
The only known way to restore normal brightness is to manually turn HDR off and then back on again in Windows settings. This is not an ideal solution, especially for users who frequently use Pegasus-Frontend alongside other HDR-dependent applications.

Expected Behavior:
Pegasus-Frontend should respect Windows HDR settings and not trigger any system-wide display changes. Upon exiting the application, the display should return to its original HDR state automatically and without side effects.

Questions and Request for Resolution:

Is this a known issue with Pegasus-Frontend's rendering pipeline or display handling in fullscreen mode?

Could this be addressed in a future update to ensure proper HDR compatibility?

Are there any recommended settings or startup flags that might help avoid this behavior?

Environment:

Windows 10/11 with HDR enabled

Latest version of Pegasus-Frontend (please specify version if needed)

HDR-capable display/monitor

We would appreciate any guidance on whether a permanent fix or workaround is possible.

[Lokito23]

Potential AI issue. El jue., 10 jul. 2025 9:22, Dreamvoe ***@***.***> escribió:

…

*Dreamvoe* created an issue (mmatyas/pegasus-frontend#1159) <#1159> Bug Report: Compatibility Issue Between Pegasus-Frontend and Windows HDR Mode Overview: We have identified a compatibility issue between Pegasus-Frontend (Tianma 前端) and Windows operating systems when HDR (High Dynamic Range) display mode is enabled. Specifically, launching Pegasus-Frontend in fullscreen mode results in abnormal behavior where the Windows system forcibly adjusts the screen brightness — either making it excessively bright or unusually dark. This occurs without any clear user intent and persists even after the application is closed. Detailed Description: When HDR mode is active on a Windows system and the user launches Pegasus-Frontend in fullscreen mode, the screen undergoes a sudden and unexplained brightness shift. This shift appears to be system-level, likely triggered by how Pegasus-Frontend interfaces with the display pipeline in fullscreen. Even after exiting the application, the display remains in this altered state, continuing to exhibit the incorrect brightness. This forces users to manually intervene to restore normal viewing conditions. Steps to Reproduce: Enable HDR mode in Windows Display Settings. Launch Pegasus-Frontend in fullscreen mode. Observe that the screen becomes overly bright or dark without user adjustment. Exit Pegasus-Frontend. Note that the brightness issue remains after exiting the application. Temporary Workaround: The only known way to restore normal brightness is to manually turn HDR off and then back on again in Windows settings. This is not an ideal solution, especially for users who frequently use Pegasus-Frontend alongside other HDR-dependent applications. Expected Behavior: Pegasus-Frontend should respect Windows HDR settings and not trigger any system-wide display changes. Upon exiting the application, the display should return to its original HDR state automatically and without side effects. Questions and Request for Resolution: Is this a known issue with Pegasus-Frontend's rendering pipeline or display handling in fullscreen mode? Could this be addressed in a future update to ensure proper HDR compatibility? Are there any recommended settings or startup flags that might help avoid this behavior? Environment: Windows 10/11 with HDR enabled Latest version of Pegasus-Frontend (please specify version if needed) HDR-capable display/monitor We would appreciate any guidance on whether a permanent fix or workaround is possible. — Reply to this email directly, view it on GitHub <#1159>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AX24DCOINO27K67JBOWJX4T3HYPGFAVCNFSM6AAAAACBGJBRJSVHI2DSMVQWIX3LMV43ASLTON2WKOZTGIYTQMZYGM2DMMI> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[Lokito23]

Correction: AI writtten duplicate of issue #767.

[mmatyas]

(Well, even if it's AI, it's still an issue of a human, so…)

Hi! Unfortunately I don't have any HDR supporting display, so I cannot test this. Pegasus itself does not touch any HDR settings, so the issue either comes from Windows, or a graphical library Pegasus uses, such as Qt.

Currently, Pegasus uses Qt 5 for compatibility reasons. It is possible that this bug is fixed in Qt 6. If you are a programmer, or know some programmers, you could try to compile Pegasus with Qt 6.

Alternatively, as mentioned in #767, you could try changing the color settings, so Windows does not change the brightness of the screen.

[Lokito23]

(Well, even if it's AI, it's still an issue of a human, so…)

Fair enough.

Currently, Pegasus uses Qt 5 for compatibility reasons. It is possible that this bug is fixed in Qt 6. If you are a programmer, or know some programmers, you could try to compile Pegasus with Qt 6.

From what I could find, seems like QT 5 doesn't support HDR, or at the very least, it's video player doesn't support it. QT 6 does have support.

Alternatively, as mentioned in #767, you could try changing the color settings, so Windows does not change the brightness of the screen.

I do wonder how it would be fixed in non-Nvidia systems, but I can't test it (I'm not on Windows and I do not have an HDR screen).

[Dreamvoe]

Okay, so given that this issue is caused by qt5, do the developers have plans to recompile it using qt6?

[mmatyas]

It is not 100% certain that the issue is caused by Qt 5, but that is the graphical part of Pegasus. As I don't have HDR display, unfortunately I cannot test if upgrading to Qt 6 fixes the problem.

Porting to Qt 6 is a long term goal, but requires some significant changes to the code, which is why it's going slowly.