Fix subtitles that are out of sync

How to find the right number

1. Play the video with the subtitles on and pick a line that's easy to hear.
2. Note the time the line is spoken, then the time its subtitle appears.
3. Subtract: if the subtitle shows at 0:12.5 and the line is spoken at 0:14.0, the subtitles are 1.5 seconds early, so move them by +1.5.
4. Enter the number, check the preview of the first captions, and download.

Use the nudge buttons to try small corrections: 0.1 seconds is about three frames at 30 fps. Negative numbers move captions earlier. A caption that would end before 0:00 is dropped, and one that crosses 0:00 starts at 0:00.

When shifting won't fix it

A shift only helps when every caption is off by the same amount. If the subtitles are right at the start and further off towards the end, the drift comes from a frame-rate mismatch or from a cut in the video. Shifting by one number can't fix that, because the error grows over time.

For drifting subtitles, the reliable fix is to make them again from the video you're actually publishing. Cuecaps finds every word and times it to that file's own audio, so nothing drifts, and the export gives you SRT and VTT in one go.

Same format in, same format out

The fixed file is saved in the format you gave it, with -shifted added to the name, so the original stays untouched. If you need the other format too, the second button converts while it shifts: an SRT comes back as VTT and the other way round.

Questions