[Bug]: Recorded footage renders shrunk into a corner inside a solid black frame instead of the selected background

[adambossy]

Search existing issues

• I have searched the existing issues

Describe the bug

In the Edit tab, the preview canvas shows the footage rendered small and pushed into one corner (bottom-left, in my case), with the rest of the frame filled solid black. This reproduces immediately in the editor preview, not just on export.

Expected behavior

The footage should render at the size and position that matches the solid black area, instead of having a solid black area with the footage shrunk into one corner.

To Reproduce

1. Record a screen capture on macOS (built-in Retina display in my case; see Additional context for full display setup).
2. Open the recording in the Edit tab.
3. Observe the preview canvas: the footage appears as a small rectangle anchored to the bottom-left, with the rest of the frame black instead of showing the background.

Screenshots

Attached: Edit-tab preview showing the footage confined to a small rectangle in the bottom-left corner of the frame, with a solid black area filling the rest.

OS

macOS

OS Version

macOS 26.6 (build 25G72)

Other OS

No response

Browser

Other

Browser Version

1.160.0 (85122)

Other Browser

Arc

Device Type

Desktop

Other Device

No response

Additional context

Hardware/display setup (verified via system_profiler SPDisplaysDataType -detailLevel full):

• MacBook Pro (Mac16,8, Apple M4 Pro, 48 GB RAM)
• Built-in display: "Color LCD" — Built-in Liquid Retina XDR, 3024 x 1964, HiDPI/Retina, main display
• External display: LC49G95T, 5120 x 1440, standard (non-Retina) scaling
• The recording in question was made on the built-in Retina display, not the external one.

Recording file verification (verified via mdls on the actual .mp4 in ~/Library/Application Support/openscreen/recordings/):

• kMDItemPixelWidth = 3024, kMDItemPixelHeight = 1898 (matches the built-in display's native panel resolution, modulo menu-bar/notch cropping)
• kMDItemDurationSeconds = 18.46 (matches the ~18.5s duration shown in the editor timeline)
• Content type: public.mpeg-4

This confirms the source recording itself is captured at full native resolution for the display it was recorded from, so the capture step looks correct — the bug appears to be in how the editor renders/composites that footage against the frame and background.

[github-actions]

Fixed by #423 and merged into main.

This change is assigned to the Next Release release milestone and is not necessarily available in the latest downloadable desktop release yet. It is currently marked as status: pending release until a packaged release containing it is published.

[EtienneLescot]

Fixed in #423.

It wasn't the editor. On a Retina display the macOS capture helper was sizing the ScreenCaptureKit buffer wrong, so your desktop got drawn at half size in one corner with black around it, and that's baked into the mp4. It's why the file measured 3024 × 1898 correctly but was wrong inside. On a non-Retina display the two sizes happen to match, which is how it slipped through.

One thing that isn't a bug: the reason you see no background at all is the 1.80× zoom at the playhead. A zoom scales the screen past the padding and covers the wallpaper. You'd see it again anywhere on the timeline without a zoom.

Sorry, existing recordings can't be salvaged. The pixels were never captured. New ones will be fine.

Thanks for the report, the mdls output and the display details are what made it findable.