Subtitle Drift Fix — When Subtitles Go Out of Sync Progressively
If your subtitles match at minute one and are three seconds late by minute forty, you do not have a sync offset — you have drift, almost always because the subtitle file was timed for a different frame rate (23.976 vs 25 fps is the classic). Shifting everything by a constant just moves the problem from one end of the video to the other.
- ✓A constant +2000 ms shift fixes the opening and makes the ending worse — the signature of drift.
- ✓The real fix is linear: pin one sync point near the start and one near the end, then stretch every cue between them.
- ✓Most subtitle tools only offer the constant shift; two-point calibration is the missing feature.
- ✓Our fixer shows the computed scale and drift, previews the first cues before/after, and downloads a corrected .srt.
FAQ
What causes subtitle drift?
Usually a frame-rate mismatch: subtitles timed for a 23.976 fps release played against a 25 fps video (or vice versa) drift by about 0.1% — roughly 4 seconds per hour. Rips and re-encodes can drift for similar reasons.
How do I pick the two sync points?
Find a line in the first minute whose timing you can verify, and note file-time vs real-time. Do the same in the last minutes of the video. The tool computes the stretch from those two pairs.
My subtitles are off by the same amount everywhere. Is that drift?
No — that is a constant offset. Use the Simple shift tab instead: one number, whole file moved.