How to Fix Subtitles That Keep Drifting Out of Sync
If your subtitles keep drifting out of sync, the timing codes in the file no longer match the audio — usually because of a frame-rate mismatch or a file that was edited after the video was trimmed. CaptionIt reads the existing SRT or WebVTT file, pulls the drifting timings back into line with the audio, and gives you a corrected file to download, all processed locally in your browser.
Why Subtitles Drift Out of Sync
Drift usually happens when a video is cut, re-encoded, or exported at a different frame rate than the one the subtitle file was built for. Small timing offsets at the start of a file tend to grow larger as the video plays, which is why captions that look fine early on fall further behind or ahead later.
Re-syncing an Existing File
Upload your SRT or WebVTT file into CaptionIt and it will detect and adjust the out-of-sync timings so the captions line up with the audio again. The file is processed in your own browser — nothing is uploaded to a server.
Switching Between SRT and WebVTT
If your drift problem started because you converted formats and the timing codes got mangled in the process, CaptionIt also converts cleanly between SRT and WebVTT so you can re-export in whichever format your player needs.
No Transcript Yet? Start From Audio
If you don't have a transcript or subtitle file at all, CaptionIt can generate one directly from the audio and build the timing from scratch, rather than trying to patch an already-drifting file. This is charged by the minute, with the first 30 seconds free so you can check the result before committing.
Turning a Plain Transcript Into Timed Captions
If you already have a plain-text transcript but no timing information, CaptionIt can turn it into a properly timed caption file, which avoids drift issues entirely since the timing is built fresh against the audio rather than inherited from an old, misaligned file.
Why Nothing Gets Uploaded
All conversion and re-syncing happens in your browser. Your subtitle file, transcript, and audio stay on your own device during processing — we care about not handling more of your content than necessary, and local processing is simply the more private way to do this kind of file work.
Frequently asked questions
How do I fix subtitles that keep drifting out of sync?
Run the SRT or WebVTT file through CaptionIt, which detects the timing offset and re-syncs the captions to the audio, processed locally in your browser.
Why do my subtitles drift out of sync the longer the video plays?
This pattern points to a frame-rate mismatch between the subtitle file and the video — a small early offset compounds over time, which is why the drift gets worse later in the file.
Can I fix subtitle sync without uploading my video anywhere?
Yes. CaptionIt processes the subtitle file in your browser and nothing is uploaded, so your file stays on your device.
Does converting between SRT and WebVTT fix drifting subtitles?
Converting formats alone won't fix drift, but CaptionIt handles the format conversion and the re-sync in the same step if both are needed.
What if I don't have a subtitle file at all, just the video?
CaptionIt can generate a transcript from the audio and build properly timed captions from scratch, charged by the minute with the first 30 seconds free.