Subtitle Workbench
A video trimmer changes picture or audio sections; this workbench edits when subtitle text appears. Import the plain-text subset of UTF-8 SRT, WebVTT or basic ASS, add or change cues, shift one cue or the entire track to the millisecond, and rewrap a long line including Korean text. An optional local video plays with a cue overlay for timing checks. The review highlights overlapping cues, high reading speed, and long lines; WebVTT permits overlaps, so the overlap is a warning. Positioning, tags, effects and advanced ASS styles cannot survive a plain-text conversion, so files containing those features are rejected explicitly.
Key features
- Open UTF-8 SRT, WebVTT or basic ASS dialogue and edit up to 300 cues.
- Shift one cue or every cue by a signed offset; invalid or negative times are rejected.
- Rewrap Korean or English text and review overlaps, characters per second, line count and long lines.
- Preview a local video's playback time with a subtitle overlay without sending it to the app server.
- Download SRT, WebVTT or basic ASS. ASS stores time to centiseconds.
How to use
- Load the example or a UTF-8 SRT, VTT or ASS file up to 1MB; optionally select a local video.
- Select a cue to edit its start, end and text, or add another cue.
- Shift all or one cue, rewrap a line, and inspect overlap and reading-speed warnings.
- Preview the video if provided and download the desired subtitle format.
Use cases
- Move a whole subtitle track half a second to match dialogue.
- Split a long Korean caption into shorter lines and review cues that disappear too quickly.
- Convert a plain SRT track to WebVTT or basic ASS for another editor.
Frequently asked questions
Are WebVTT positions or ASS effects preserved?
No. This is a plain-text cue workbench. It rejects WebVTT NOTE, STYLE, REGION, cue settings and tags, and advanced ASS styles, positions, effects and override tags instead of silently discarding them.
Are overlapping cues invalid?
Not necessarily. WebVTT allows overlapping cues. The workbench flags them for review and permits export.
Does ASS export preserve milliseconds?
ASS timestamps use centiseconds, so times are rounded to the nearest hundredth of a second. Save SRT or WebVTT to retain milliseconds.
Does this edit the video or burn captions into it?
No. The optional local video is a timing preview only. Video bytes are neither modified nor downloaded. Only subtitle files are exported.
Can it read every subtitle file?
It supports a UTF-8 plain-text subset: at most 1MB, 300 cues and two hours. Advanced formatting, other encodings and unsupported structures are rejected.
Are files uploaded?
No. Subtitles are read in browser memory, and the video uses a local object URL. Export creates a browser download.
Privacy
Subtitle text and the selected video stay in this browser tab and are not submitted to the app server. The temporary video object URL is revoked when replaced or the page closes.
Comments & questions