How to fix subtitles that are out of sync
Work out whether your subtitles are early, late or drifting, then fix them with a time shift, a frame-rate change or a two-point sync.
Updated · Free Subtitle Converter
First, find out what kind of problem it is
Play the video at the start and note whether the words appear before or after people speak. Then jump to a scene near the end and check again. If the gap is the same in both places, the whole file is shifted by a fixed amount. If the gap grows from start to end, the timing is stretched: the subtitles were made for a version of the video that runs at a different speed.
A third case is a gap that jumps suddenly in the middle, often after an ad break or a cut scene. That happens when the subtitles were made for a different edit of the video, and it needs a fix for each part rather than one change for the whole file.
Same gap everywhere: shift the timing
Measure how early or late one line is, for example 2.5 seconds late, and move every caption by that amount. In the subtitle time shifter, choose Move everything, pick Earlier when the words come too late, enter the seconds and download the file. Many players also have a subtitle delay setting that does the same thing for one viewing without changing the file.
Growing gap: change the frame rate
Films are usually shot at 24 frames per second, or 23.976 for video releases. European TV and DVD releases historically played them at 25, which makes the film about 4 percent faster: a two-hour film becomes almost five minutes shorter. Subtitles timed for one version drift steadily against the other.
Choose Change frame rate and enter the rate the subtitles were made for and the rate of your video. If you do not know them, try 25 and 23.976 first, then the other way around. Other common pairs are 24 and 23.976, or 30 and 29.97.
Not sure? Match two captions
The most reliable method is to tell the tool when two lines should appear. Find the exact moment the first spoken line starts in your video, then the moment the last one starts, and type both times. The tool calculates the shift and the stretch together, so it fixes either kind of problem without you knowing which one you have.
Pick lines that are clearly spoken and far apart. After downloading, spot-check a few scenes in the middle. If one part is still off, the video was probably edited differently from the one the subtitles were made for.