Subtitle Timing Shifter
Shift subtitles earlier or later, rescale for a frame rate change, and repair overlapping or too short cues.
Shift subtitles earlier or later, rescale for a different frame rate, and fix overlaps and short cues.
Before and after
This line arrives too early.
And this one overlaps the last.
Too short to read.
- Shifted every cue by +2.5s.
- Stretched 1 cue to at least 1s.
- Trimmed 1 overlapping cue.
Use a plain shift when subtitles are consistently early or late. Use the frame rate rescale when they start correct and drift further out as the video runs, which is what a 23.976 to 25 conversion does.
Generating...About the subtitle timing shifter
Out of sync subtitles have two different causes and two different fixes, and using the wrong one makes it worse. If everything is off by the same amount, a plain shift corrects it. If they start right and drift further out as the video runs, the frame rate is wrong and the timings need rescaling, not shifting.
The classic case is a 23.976 fps film paired with a 25 fps subtitle file, where the drift reaches several seconds by the end. Rescaling by the ratio between the two rates fixes the whole file at once.
It also repairs the two faults that make subtitles hard to read: cues that overlap the next one, and cues too short to finish reading.
How to use it
- 1Paste your subtitle file.
- 2If everything is uniformly late or early, set a shift in seconds.
- 3If the error grows through the video, turn on the frame rate rescale instead.
- 4Set a minimum cue length and let overlaps be trimmed.
- 5Copy the corrected file.
Questions
Should I shift or rescale?
Check the end of the video. If the offset there is the same as at the start, shift. If it has grown, the frame rate is wrong and you need to rescale, because a shift would only move the drift around.
Which frame rates cause this?
23.976 against 25 is the common pair, from film converted for PAL television. Over two hours that difference accumulates to several minutes.
How long should a subtitle stay on screen?
At least one second for anything, and closer to one and a half for a full line. Anything shorter is gone before most people finish reading it.
What does fixing overlaps do?
When one cue starts before the previous ends, the earlier one is trimmed to end just before the next begins. Overlapping cues either stack on top of each other or flicker, depending on the player.