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Recording (macOS): size the video bitrate from the actual capture, not the 4K ceiling #924
Description
Part of #920 (rank 15). Effort S, risk low.
Problem
- macOS always asks ScreenCaptureKit's writer for 76.5 Mbit/s, whatever the capture size:
useScreenRecorder.tssendscomputeBitrate(TARGET_WIDTH, TARGET_HEIGHT), the app's 4K ceiling with the high-frame-rate boost. - That is 4.25× the Windows budget for a 1080p capture.
- Linux had the same bug and fixed it: its request sends no bitrate, and the helper derives it from the size it actually got (see the comment in
buildNativeLinuxRequest).
Proposal
- Same fix as Linux: derive the bitrate in the Swift helper from the real output size (same tiers as
computeBitrate), and stop sending the ceiling's bitrate.
Verify
- Swift unit test for the size → bitrate tiers (runs in the
swift-macos-helperCI job). - On a Mac:
ffprobebitrate of a 1080p take, before and after. Expected 2 to 4× smaller files below 4K.
Activity
github-actions commentedon Sep 30, 2026
Fixed by #930 and merged into
main.This change is assigned to the
Next Releaserelease milestone and is not necessarily available in the latest downloadable desktop release yet. It is currently marked asstatus: pending releaseuntil a packaged release containing it is published.EtienneLescot commentedon Sep 30, 2026
Moved into
v2.0.0as part of the pre-release cut.fix(macos): size the video bitrate from the actual capture, not the 4…