Subtitle Editor, Converter & Resync

About Subtitle Editor, Converter & Resync

Subtitle Editor, Converter & Resync (Subtitle Studio) is a free, browser-based caption workbench that parses SRT, VTT, SBV, ASS/SSA and LRC files, lets you edit cue text and timings, and exports to SRT, VTT, SBV, ASS, LRC or plain text. It fixes out-of-sync captions with a global offset, frame-rate rescale, two-point anchor sync, and stretch-to-duration, plus a reading-speed QC check against Netflix, BBC or Relaxed presets. The optional auto-caption feature transcribes audio or video into timed cues using on-device Whisper. Everything runs locally in your browser with nothing uploaded and no signup.

How to use Subtitle Editor, Converter & Resync

1. Paste subtitles, or click File or drag-and-drop a .srt, .vtt, .sbv, .ass, .ssa or .lrc file; the format is auto-detected. You can also click Sample, or Choose media to auto-caption audio/video with on-device Whisper.
2. In the QC panel, pick a reading-speed preset (Netflix, BBC or Relaxed) to flag cues that break the CPS, line-length, duration or gap limits, and click Balance lines to re-wrap.
3. Fix timing in the Resync panel: Global shift like +1.5s or -500ms, Rescale FPS between rates such as 23.976 and 25, Stretch to a target total duration, or Two-point sync to pin two cues to correct times.
4. Edit individual cues below: change start/end times in mm:ss.mmm, rewrite text, add or delete cues; each cue shows its live CPS reading speed.
5. Use Find and replace across all cues, with optional Regex and Ignore-case toggles.
6. In the Export panel choose SRT, VTT, SBV, ASS, LRC or Text, then click Copy or Download to save.

Frequently asked questions

Are my subtitle or media files uploaded to a server?

No. Parsing, editing, resync, conversion and even Whisper auto-captioning all run entirely in your browser; your files never leave your device, and nothing is uploaded.

Is it free and do I need an account?

Yes, it is completely free with no signup, account or watermark.

Which subtitle formats can it read and write?

It reads SRT, VTT, SBV, ASS/SSA and LRC with auto-detection, and exports to SRT, VTT, SBV, ASS, LRC or plain text. ASS override tags are stripped on import.

How do I fix captions that drift further out of sync over time?

A single Global shift only fixes a constant offset. For progressive drift, use Two-point sync to pin two cues to their correct times, or Rescale FPS if the cause was a frame-rate mismatch like 25 to 29.97.

What do the Netflix, BBC and Relaxed QC presets check?

They validate reading speed and layout. Netflix is 17 CPS, 42 chars per line, 2 lines; BBC is stricter at 16 CPS, 37 chars; Relaxed allows up to 21 CPS. The panel flags cues that are too fast, too long, too short, or too close together.

How does auto-caption work and are there size limits?

Drop an audio or video file and an on-device Whisper model transcribes speech into timed SRT cues; you can hint the spoken language. Subtitle files are capped at 10 MB and media files at 500 MB.

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