Syncing subtitles to audio
When downloaded or generated subtitles drift out of sync — starting too early, too late, or drifting progressively due to a framerate mismatch — Auto-Sync realigns every cue automatically by analyzing the audio, powered by the offline ffsubsync engine.
Two sync modes
- Sync with Video Audio — analyzes speech in the video itself to align subtitles. Takes roughly 20–30 seconds. Unavailable for subtitle-only files with no video.
- Sync with Reference Subtitle — uses another subtitle track that's already correctly timed as a reference. Near-instant. A dropdown lets you pick which detected track to use (the currently loaded one is excluded from the list).
Advanced options
Collapsed by default, behind a chevron:
- Skip framerate correction — disables ffsubsync's automatic correction for framerate-drift errors.
- Use golden-section search (slower, more accurate) — a more precise but slower alignment algorithm.
- Use auditok VAD (for low-quality audio) — an alternative voice-activity-detection engine, only shown in video-sync mode.
- Max offset — caps how far ffsubsync will shift subtitles, in seconds (1–3600, default 60).
Running a sync
Click Sync with Video or Sync with Reference (the button label matches your selected mode). A progress modal appears — "This may take 20–60 seconds depending on video length…" — and the current subtitles are replaced with the re-timed result once it completes. Like any edit, this can be undone with ⌘Z.
Syncing many files at once
From the file list view (not the editor), select multiple files and click Sync Selected to open a bulk version of this same dialog. It applies your chosen options to every selected file that has a video track, automatically loading each file's first subtitle track if needed, and writes each synced result to disk immediately. Files without a video (subtitle-only) are skipped and reported in a summary dialog once the batch finishes, alongside how many succeeded.