How to Resync and Edit Subtitles (SRT and VTT)

You hit play, the dialogue starts, and the captions show up two seconds late the whole way through. Or they race ahead of the voices. This is the most common subtitle problem, and it almost never means the file is broken. The subtitle file and your copy of the video just do not line up at the start, so every line is off by the same amount.

The fix is a single time shift across the entire file, not hours of dragging lines one by one. This guide covers how to find the right offset, when to shift forward versus back, how to fix individual typos, and how to move between SRT and VTT. Everything below works in your browser with the subtitle editor, and your file never leaves your device.

How do I fix subtitles that are ahead of or behind the audio?

Apply one time shift to the whole file. If captions appear too early, shift them later by a few seconds. If they lag behind the spoken words, shift them earlier. Because the same offset moves every timestamp at once, the entire track snaps back into sync in a single step.

The reason this works is that timing drift is usually constant. You downloaded subtitles meant for one release of a film, but your copy was encoded with a slightly different intro length, an extra studio logo, or a different cut point. That moves the zero mark, and from there every line inherits the same gap. You are not correcting hundreds of separate errors. You are correcting one.

To do it, load your file, enter the offset, and apply it to all lines. Play the video again and check a line near the start and a line near the end. If both match the audio now, you are done.

Positive vs negative shift

The direction trips people up, so anchor it to what you see:

• Subtitles appear too early (text shows before the words are spoken): shift positive to push them later.
• Subtitles appear too late (words are spoken, then the text catches up): shift negative to pull them earlier.

A quick mental check: you are trying to move the caption toward where it should be. If the caption is sitting to the left of the audio on an imaginary timeline, add time. If it is sitting to the right, subtract time.

When a single shift is not enough

A constant offset fixes constant drift. It will not fix subtitles that start in sync but slowly fall behind over an hour. That kind of creep usually means the two files run at different frame rates, and the gap grows the longer the video plays. If a single shift lines up the opening but the ending is still off, you are looking at a rate mismatch rather than a fixed offset, and you will need to stretch the timing rather than just slide it.

How do I find the right offset?

Pick one line of dialogue you can hear clearly, note when it actually appears on screen, and note when it should appear. The difference between those two times is your offset. A line that shows at 00:10 but should show at 00:12 needs a positive two-second shift; reverse it if the caption is late.

The trick is choosing a good reference line. Use a short, unmistakable line of speech near the start, ideally the first real sentence after any intro. Avoid music cues or ambient sound, since those are harder to pin to an exact moment.

Here is the workflow:

1. Play until the first clear line of dialogue.
2. Pause the moment the words are spoken and read the player’s current time. That is when the line should appear.
3. Find that same line in the subtitle file and read its timestamp. That is when it does appear.
4. Subtract the “should” time from the “does” time.

Apply that offset, then verify against a second line further into the video. If your reference was good, both ends will line up.

How do I edit individual lines and fix typos?

Open the file in the editor, find the caption you want to change, and edit its text directly. This is for the small stuff: a misspelled name, a missing word, a line broken in an awkward spot. Each caption is an editable block with its own start time, end time, and text, so you change only the one you are fixing.

Common single-line edits worth making:

• Typos and wrong names, especially proper nouns that auto-transcription tends to mangle.
• Awkward line breaks where a sentence splits mid-phrase and reads badly on screen.
• Timing on one stubborn caption that sits a beat too long or vanishes too fast, even though the rest of the file is fine.
• Stray formatting tags left over from another player that show up as visible junk text.

Keep individual captions short enough to read in the time they are on screen. If a line feels cramped, splitting it across two captions reads better than squeezing everything into one.

How do I convert between SRT and VTT?

Load an SRT and save as VTT, or the reverse. The editor reads the timestamps and text from one format and writes them out in the other, so you do not retype anything. Reach for this when a player rejects the file you have: web players usually want VTT, while most desktop players and downloads expect SRT.

The two formats hold the same information in slightly different packaging:

• SRT numbers each caption (1, 2, 3…) and writes times with a comma before the milliseconds, like 00:01:23,456.
• VTT opens with a WEBVTT line, drops the required numbering, and writes times with a period, like 00:01:23.456. It also allows styling and on-screen positioning that SRT does not.

If a subtitle file refuses to load in a browser-based video player, an SRT-to-VTT conversion is often all it needs. Going the other way, save as SRT for the broadest compatibility with media players and TVs.

One thing to watch after converting: text encoding. Subtitles full of accented characters or non-Latin scripts should be saved as UTF-8 so the characters survive. If you open a converted file and see garbled symbols where accents used to be, the encoding is the culprit rather than the conversion itself.

Working safely with your files

Everything here happens on your own machine. The subtitle editor reads your file locally, lets you shift, edit, and convert it, then saves the result back to your computer. Nothing is uploaded, which matters when you are working with screeners, unreleased cuts, or anything you would rather not hand to a server.

It also means your video is never touched. Subtitles live in a separate text file, so resyncing or rewording them leaves the video untouched, with no re-encoding and no quality loss. Keep a copy of the original subtitle file before a big batch of edits, and you can always start over if a shift goes the wrong way.

Once your timing matches and your typos are gone, open the subtitle editor and save the corrected file next to your video. Most players pick up a subtitle file automatically when it shares the video’s name and sits in the same folder.