[EtienneLescot]

Summary

Follow-up to #1351, which did not fix the reporter's case. On KDE Plasma (Wayland), a still window still failed to record ("the screen share delivered no frame within 10 s"). It only started if the user typed in it during the countdown.

Why #1351 missed. It skipped the crop wait when the buffers did not carry SPA_META_VideoCrop. KWin's buffers do carry the block; KWin just never fills it. The 2.1.2 CI build still logged window-crop-missing … 8 frames once the window repainted.

Fix. The crop wait is now bounded by time, not by frame count.

• The latest crop-less window frame is held instead of discarded.
• A frame that brings a crop supersedes it. That is mutter, which sends its crop a few frames late.
• Otherwise, after 500 ms, the held frame starts the recording at the stream's size, replayed through the same FrameReady path.
• The negotiated-meta check from fix(linux): start a KDE window recording on its first frame #1351 is removed.

Related issue

Refs #1351. Reported on Discord by a Debian 13 / KDE Plasma 6 / AMD Renoir user.

Type of change

• Bug fix

Release impact

• Patch

Desktop impact

• Linux

Testing

• Helper tests: cargo test --bin openscreen-pipewire-helper in WSL (rustc 1.98.1): 101 passed, including a_crop_is_awaited_for_a_bounded_time_not_a_frame_count.
• Real KDE run, pending: a CI build of this branch goes to the reporter before merge.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Window recording now waits briefly for crop information before starting. If crop information does not arrive, recording starts with the full stream instead of remaining stalled. When crop information is available, recording proceeds with the cropped view.

[coderabbitai]

No actionable comments were generated in the recent review.

Recent review info

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• Run ID: c425c8b9-78af-4bf1-b81b-5f7d5fa82073

Commits

Reviewing files that changed from the base of the PR and between 8be1b28 and ce32f85.

Files selected for processing: 1

• electron/native/pipewire-capture/src/main.rs

Included review availability: This review used your included allowance. Your plan provides up to 8 included reviews per hour; 6 remain after this review.

Walkthrough

Window crop waiting now uses a 500 ms duration instead of a frame limit or negotiated-metadata check. The capture helper holds crop-less window frames during the wait and replays the latest held frame if the wait expires. Crop-less non-window frames do not wait.

Changes: Window crop wait

Layer / File(s)	Summary
Hold and replay frames electron/native/pipewire-capture/src/main.rs	The helper tracks elapsed wait time and holds a crop-less window frame for up to 500 ms. It replays the held frame when the wait expires, warns when proceeding without a crop, and reports elapsed milliseconds in diagnostics. The test checks the wait duration and verifies that a source not expecting a crop is not held.

Priority: Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Possibly related PRs

• getopenscreen/openscreen#1380: Both changes update crop-less window-frame handling in the PipeWire capture helper. This PR replaces the frame-limit fallback with a 500 ms timeout and replays the latest held frame.

Merge Risk: Minimal · up to ce32f

No actionable issue remains from this review; the change is mergeable after normal checks.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Documentation-only edits and deletions within surv…	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Title check		The title clearly and concisely describes the main Linux fix: replacing the window crop wait frame-count limit with a time limit.
Description check		The description follows the repository template. It explains the bug, root cause, fix, related issue, change type, release impact, platform impact, and testing status. It also clearly identifies that …
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Description check

Explanation

The description follows the repository template. It explains the bug, root cause, fix, related issue, change type, release impact, platform impact, and testing status. It also clearly identifies that real KDE validation is still pending.

Full details: Docstring Coverage

Explanation

Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Documentation-only edits and deletions within surviving functions are included; unchanged diff context and fully deleted functions are excluded. Analyzed 3 functions across 1 files.

Resolution

Write docstrings for the functions missing them to satisfy the coverage threshold.

Finishing Touches: 💡 1

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[EtienneLescot]

Measured on real Linux (Ubuntu 24.04, GNOME 46 Wayland, PipeWire 1.0.5, Vivobook). Helper built from this branch (ce32f85) and from main (5bb1b3f), driven through the real portal picker, 60 fps request, 7 s takes, 3 takes each, interleaved.

cargo test --bin openscreen-pipewire-helper: 104 passed, including the new a_crop_is_awaited_for_a_bounded_time_not_a_frame_count.

Still window (no input at all)

	branch	main
Share → first frame encoded	324 / 335 / 335 ms	322 / 327 / 330 ms
stream-started → capture-started	~19 ms	~19 ms
encoded size	422×322 (crop applied)	422×322
cropWaitMs / window-crop-missing	0 / none	n/a / none
frames in 7.08 s, dropped	406, 406, 406 · 0	406, 407, 407 · 0
transcode of the take (export proxy)	0.240 s	0.237 s

Full screen

	branch	main
Share → first frame encoded	337 / 338 / 335 ms	334 / 328 / 337 ms
frames in ~7.08 s, dropped	405, 406, 406 · 0	407, 406, 407 · 0
transcode of the take (export proxy)	1.757 s	1.765 s

All within ±1.5% of main. On mutter the crop still lands on the first frame, so the window is still recorded at window size, not stream size. No "no frame within 10 s" anywhere.

Not covered: KDE/KWin itself (this machine runs GNOME), so the 500 ms fallback path was not exercised live; the unit test covers it. The diff does not touch the export pipeline, hence the transcode proxy.

🤖 Generated with Claude Code