2029122 - [Win] YouTube videos on 4k60 with HDR have massive stutters and frame drops

Status: NEW

(Core :: Audio/Video: Playback, defect, P3)

Description

[Catalin Sasca, Desktop Test Engineering [:csasca]]

Attachment: about support.txt

Found in

• Firefox 151.0a1 (2026-04-02)

Affected versions

• Firefox 150.0b4
• Firefox 151.0a1 (2026-04-02)

Tested platforms

• Affected platforms: Windows 11

Preconditions

• HDR capable display and HDR enabled in Windows settings -> Nightly opened on the HDR monitor.

Steps to reproduce

1. Load and play one of these videos: Example 1 or Example 2

Expected result

• The video is correctly rendered, the performance is good.

Actual result

• The video has large stutters and multiple frame drops

Additional Notes

• The issue can be seen in the following attachment.
• The video performance is good on a non-hdr display (internal) still on 4k60 on the same laptop.
• I've attached the about:support as well for system info.
• Playback is much better on other browsers (Chrome, Edge) for the same videos.

Comment 1

[Ashley Hale [:ahale]]

My theory is that this may just be doing too many copies and other work that could be skipped, we have not tackled 'ZeroCopy' support for HDR video yet, and could potentially also skip the YUV to RGB conversion being done in VideoProcessor in some cases if YUV overlays are directly supported (at least for PQ transfer function video which is the majority of HDR video, this wouldn't be possible for HLG transfer function used more commonly for TV broadcasts as that can't be directly sent to the desktop compositor and needs VideoProcessor to perform the conversion).