Subtitle Sync Delay Shifter
A subtitle file that’s out of sync — dialogue appearing a beat too early or too late compared to the audio — is one of the most common small annoyances in video playback, and it usually just needs every timestamp shifted by the same fixed amount rather than a full resync. This tool takes a subtitle file (SRT, VTT, or similar formats) and shifts every timestamp forward or backward by a set delay, either as a flat offset across the whole file or with a gradual adjustment if the drift changes over the video’s runtime.
Set the delay amount in seconds or milliseconds, and specify direction — shifting subtitles later if dialogue is appearing too early relative to the audio, or earlier if it’s lagging behind. For files where the drift isn’t constant (subtitles that start in sync but gradually fall behind as the video plays, which happens with some frame-rate mismatches between the subtitle source and the video), the tool supports a linear stretch that gradually adjusts the offset across the file rather than applying one fixed shift throughout.
FAQ
How do I figure out exactly how much delay to apply?
Play the video with the subtitles loaded and note the timestamp where a specific line appears versus when it’s actually spoken — the difference between those two points is your delay amount, and it’s often easier to spot this on a clearly-timed line (like the very first spoken line) rather than partway through.
Why does the sync drift get worse the longer the video plays?
This usually indicates a frame rate mismatch between the subtitle file’s original source and the video file you’re using — the subtitle was likely timed against a slightly different frame rate version of the same content, and a flat delay shift won’t fully correct for progressive drift, which is why the linear stretch option exists specifically for this case.
Does this work with subtitle files that include multiple languages in one file?
Yes — the shift applies to every timestamp in the file regardless of how many language tracks or subtitle streams it contains, since the adjustment operates on timing data rather than the text content itself.
If the subtitle text itself needs cleanup — formatting artifacts, timing codes mixed into the readable text — rather than just a timing shift, Subtitle → Clean Script Text handles turning a subtitle file into readable plain text separately from the sync adjustment.