Video and audio corrupted after recording with multiple segments

[josiahsrc]

Description

Hey, love the software. Just purchased a license for it, but running into some errors.

I was recording a 20 minute video, and pressing the pause button occasionally. When I finished the recording, several of the "segments" where corrupted and I lost them. When I play back and reach those corrupted segments, they either have audio corrupted, or the clips are straight up missing. They look like some segments are duplicated.

Reproduction

Record a long video on a mac M4, press the pause button. Experience is unpleasant.

Additional Context

• Cap version: Latest 0.4.3
• Operating system, version: MacOS Tahoe 26.2
• Device (optional): MacBook Air Latest

cap-desktop.log

[linear]

CAP-629

[tembo]

Thanks for the detailed report and for attaching the log file. This is a known problem area that the team has been actively working on.

Related Work

There's an open PR #1514 that addresses a critical bug in multi-segment recording recovery where segments could be processed in the wrong order (alphabetical sorting caused segment-10 to be processed before segment-2). This could explain why some segments appear duplicated or missing. The fix implements natural numeric sorting for segment directories.

PR #1478 (merged late December) added drift correction for audio/video timestamps to prevent sync issues during long recordings. If you're on 0.4.3, this should be included, but the corruption symptoms you describe (audio corruption, missing/duplicated clips at segment boundaries) suggest there may be edge cases not fully covered.

Relevant Code

The pause/resume logic lives in crates/recording/src/studio_recording.rs (lines 168-230). Each pause creates a new segment directory (segment-0, segment-1, etc.) with independent audio/video files. The segment synchronization uses a 30ms drift threshold to align audio and video timestamps when resuming.

Similar issues have been reported:

• #382 - Export audio not sync to video
• #593 - Audio not sync with video
• #1341 - Recording failed (also on macOS with pause)

Potential Causes

Based on the codebase, a few things could cause the symptoms you're seeing:

1. Segment ordering during recovery/export - The fix in PR Fix multi-segment recording data loss during recovery #1514 addresses this but isn't merged yet
2. Audio drift accumulation - Long recordings with multiple pauses may accumulate timing drift that exceeds the 30ms correction threshold
3. M4S fragment boundaries - macOS uses fragmented MP4 muxing with 3-second segments; pause points that don't align cleanly with fragment boundaries could cause issues

The log file you attached would be helpful for the maintainers to identify the specific failure point in the pipeline.

[richiemcilroy]

Hey! Will be fixed in 0.4.5. Thanks for reporting :)