Apple Studio Display XDR: Reproducible HDR video stutter on Mac Studio M4 Max, but not M1 mini
I’ve spent the last few days trying to isolate a reproducible HDR playback issue involving my Apple Studio Display and Mac Studio M4 Max. At first I thought it was an issue with an iPhone recording, but after a lot of testing I’m now convinced it’s something much more specific.
Symptoms
Random micro-stutters during playback of 4K HDR videos. It looks like a frame is held slightly too long, followed by a visible jump. With some HDR videos, I also see brief localized flashing on the XDR display (looks like the HDR/local dimming changes momentarily).
Test setup
Display
Apple Studio Display XDR (same monitor throughout)
Macs
Mac Studio M4 Max (stutters) - Tahoe 26.5.1
Mac mini M1 (plays smoothly) - Sequoia 15.3.2
Content tested
Multiple iPhone 4K60 HDR HEVC recordings
Multiple YouTube HDR videos
Results
Mac Studio M4 Max + Apple Studio Display XDR
❌ Random frame stutters on almost every HDR iPhone clip
❌ Same behavior with YouTube HDR
❌ Occasional localized HDR flashing
Mac mini M1 + Apple Studio Display XDR
✅ Same videos play smoothly
✅ No noticeable stuttering
Mac Studio M4 Max + different monitor
✅ YouTube HDR plays smoothly
✅ No obvious stutter
So the issue only appears with the combination of:
M4 Max
Apple Studio Display
HDR playback
What I investigated
Initially I suspected the iPhone recording itself.
I analyzed the original file using ffprobe and ffmpeg showinfo. I found:
Mostly constant 60 fps timestamps with only 21 tiny timestamp corrections (~1.67 ms over a 67-second clip).
I then:
Transcoded to H.264 using software (libx264)
Removed B-frames
Generated CFR versions
Verified there were no decoder frame drops in VLC
Performed frame-by-frame motion analysis using OpenCV phase correlation
The motion analysis did not reveal corresponding image-motion discontinuities that explain the visible frame holds.
Important to note that the original file also plays perfectly smoothly on both my iPhone and iPad.
Current conclusion
At this point I no longer think this is an issue with the iPhone recording itself. The evidence points much more strongly toward an issue somewhere in the HDR playback/rendering pipeline specific to the combination of the M4 Max and the Apple Studio Display. Whether that’s a macOS regression, a GPU/display engine issue, or something else in Apple’s HDR presentation path, I can’t say.
Has anyone else with an Apple Studio Display and an M4-series Mac noticed similar HDR playback stutter or flashing?
I also recorded a short demonstration documenting the stutter and flashing behavior if anyone is interested: