Sync subtitles
Shift every timing in a .srt or .vtt and fix frame rate drift.
Subtitles go wrong in two ways. The first is a constant offset: they always land two seconds late, start to finish. That is fixed by shifting every timing by the same amount.
The second is nastier: they line up at the start and have drifted several seconds by the end. That is almost never a sync error but a frame rate mismatch between the copy the subtitles were made for and the one you are watching: 23.976 fps film against Europe 25 fps PAL, typically. Shifting will not help there; the timings have to be rescaled by the ratio between the two rates.
This tool does both, together or separately, and shows you the first cue before and after so you can check the adjustment before downloading.
How to use it
- 01 Load the subtitle file that is out of sync.
- 02 Put the offset in seconds into the shift field: positive if the subtitles should appear later, negative if they should come earlier.
- 03 If the drift grows through the video, pick the matching frame rate conversion as well.
- 04 Check the before and after of the first cue and download the corrected file.
Frequently asked questions
How do I know how many seconds to shift?
Find the first line you hear clearly. Note the exact moment it is spoken and subtract the moment the subtitle appears. If the subtitle is late, the result is negative and it needs to come earlier.
What if the offset changes through the video?
Then it is a frame rate problem, not a sync one. Use the fps conversion: 23.976 to 25 if the subtitles fall progressively behind, and the other way round if they run ahead.
What happens if a cue goes negative?
It is clamped to 00:00:00,000 and you get a warning. That is what editing software usually does too.
Does it accept VTT?
Yes, and it comes out in the same format you loaded, SRT or VTT.
Related tools
This is what Eco does live.
These utilities work on files you already have. Eco transcribes and translates while the audio is still playing: meetings, classes, videos in another language.
Download Eco free10 free minutes per month · No card required