How to Fix Subtitles That Are Out of Sync
If captions are early or late by the same amount throughout the video, shift every cue by that offset. Positive seconds move subtitles later; negative seconds move them earlier. If the mismatch grows during playback, a single offset will not solve it.
By SceneDub · Published · Editorial methodology
Open Subtitle shifterMeasure two or three reference points
Choose a short, unmistakable spoken word near the start. Compare its audible onset with the subtitle cue, then repeat near the end. A stable half-second difference suggests an offset. A small early difference and a much larger late difference suggests drift or a different cut. Check the middle too: an abrupt change may indicate an inserted or removed scene.
Calculate the sign before applying it
Suppose a caption starts at 10.0 seconds but the matching speech begins at 10.8. Apply +0.8 seconds to delay the caption. If the speech begins at 9.2, apply -0.8. SceneDub's input is in seconds, so 500 milliseconds means 0.5, not 500. Shifting past the start clamps a cue to zero; review the earliest cues after a negative adjustment.
Recognize problems an offset cannot repair
A subtitle file for a different edit may need several local adjustments. Playback-speed mismatches need retiming or stretching in an editor. A timing shifter also cannot fix a wrong transcription or captions that are too dense to read. Download to a new filename, keep the original, and test the output in the player where the problem occurred.
The workflow
- Measure the mismatch near the beginning and end.
- Apply the matching positive or negative seconds if the mismatch is constant.
- Download a copy and verify several points against the final video.
Delay every subtitle by half a second
Input / starting point
1
00:00:01,250 --> 00:00:03,500
Welcome to the recording.Output / result
1
00:00:01,750 --> 00:00:04,000
Welcome to the recording.An offset of +0.5 moves this cue from 1.250 seconds to 1.750 seconds. Its text and duration are preserved unless an earlier shift reaches time zero.
