Nick Shirokov 5acb586bbf fix(web-test): fix audio-video sync drift in narration ...

Screencast frame duplication (Math.round) causes video to be ~5% longer
than wall-clock time. Caption timestamps are wall-clock based, so the
audio track drifted ahead by ~8s at the midpoint of a 5-minute video.

Fix:
- stopRecording() saves recordingDuration in captions.json
- addNarration() reads actual video duration via ffprobe and scales
  caption timestamps by videoDuration/recordingDuration ratio
- Phase 2 timeline now tracks actual cumulative position instead of
  computing gaps from previous caption data (prevents MP3 frame
  quantization drift)
- Also fixed findFfmpeg() → resolveFfmpeg() call in addNarration

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

2026-03-03 00:45:30 +03:00

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skills

fix(web-test): fix audio-video sync drift in narration

2026-03-03 00:45:30 +03:00