Motionix / Your workspace
Fix the timing. Keep the words.
A late caption, a broken timestamp, or a file that drifts out of sync: start with the actual problem, preview the changes, and keep your original subtitle file.
Three steps. One result to inspect.
Choose a file or sample
Load an existing subtitle file. Speech transcription and translation are not part of this workflow.
Inspect the proposed change
Use an offset for a constant delay or two reliable timing points for drift. Review malformed cues and intentional overlaps.
Download a separate copy
Check the preview and any conversion warnings. Keep the original and test the new file with your video player.
Subtitle delay or progressive drift: choose the right repair
If captions are equally early or late throughout a video, a constant offset is usually the right timing operation. If the mismatch grows, a uniform shift cannot fix both the beginning and the end. Use two source timestamps and their desired positions to calculate a scale and offset. Choose points you can identify reliably in the actual video. This tool cannot infer the spoken words or discover synchronization points automatically.
Repair invalid SRT timestamps without losing caption text
Inspect warnings before exporting. An end time before a start time, an unreadable timestamp, or an empty cue needs a deliberate decision. Malformed blocks must not simply disappear to produce a clean-looking result. Renumbering or sorting can help a valid file, but does not repair missing words. Preview the affected cues and keep the source file, especially when subtitle identifiers or styling matter to another editor.
Overlapping subtitles are not always errors
Two speakers, multiple caption layers, or positioned WebVTT cues can legitimately overlap. Treat the overlap report as a prompt to inspect, not permission to delete information. Apply only the repairs you understand and compare the exported text. A timing checker does not judge reading speed, translation quality, accessibility compliance, or whether the captions accurately represent the audio. Review those separately with the video.
Convert SRT and VTT with clear format limits
SRT and WebVTT are related text formats, not interchangeable containers for every feature. VTT may contain cue settings, identifiers, notes or styling. An SRT export cannot represent all of them. The tool warns or blocks unsupported transformations rather than claiming a lossless round trip. Files are processed locally; loading the site still makes normal network requests. Download your corrected copy before leaving and try it in the receiving player.
Your files, with explicit choices
File processing does not require an upload. The site and processing assets use the network. Results are not automatically backed up. Download your result and keep the original.
Frequently asked questions
Can this create subtitles from speech?
No. Start with an existing SRT or VTT file. The tool adjusts timing and structure, not speech transcription.
Is a constant delay the same as subtitle drift?
No. An offset shifts every cue equally. Progressive drift needs a scale adjustment based on two reliable timing points.
Should every overlapping subtitle be removed?
No. Overlapping speakers or layers may be intentional. Review warnings and choose repairs explicitly.
Can SRT keep every VTT feature?
No. VTT can carry identifiers, positioning and styling that SRT cannot represent. Review conversion warnings and keep the original.
Are subtitle contents uploaded?
The workflow runs locally without uploading the subtitle file. Ordinary website and asset requests still occur.
Sources and the limits of this page
Sources checked
- MDN WebVTT guide
Cue structure, timestamps, text and positioning.
- W3C WebVTT specification
Format rules; not a certification of subtitle accuracy.
These references explain formats or published requirements. They do not represent a partnership or an inspection of your file. Check the current requirements before using an export.