Subtitles early, late or in the wrong format? How to fix, convert and translate SRT, VTT and ASS

By Marcelo Amantino · published October 21, 2026 · 3 min read · who we are

The speech ends and the subtitle is still on the previous sentence. Or the subtitle appears two seconds before the actor opens their mouth. Or your site only accepts VTT and the file you have is SRT. These problems are very common for people who make videos, classes and social media content, and all of them have a quick fix once you know what is going on inside a subtitle file.

What a subtitle looks like on the inside

A subtitle is a text file with lines of speech and two times for each one: when it appears and when it disappears. SRT is the simplest and most universal format. VTT is the standard for video on the web. ASS and SSA accept advanced styles (colors, position, effects). Converting to a simpler format may lose those styles, and converting to a richer one does not create a style that did not exist.

Subtitles early or late: how to fix them

When all the lines are shifted by the same amount of time, the fix is just one: move everything. In the Subtitles converter you shift all the lines, in seconds, forward or backward. To check, listen to a line from the beginning and one from the end: if both are right, the sync is good. If the offset grows over the video (the subtitle starts right and drifts away), the problem is different, for example a subtitle made for a version of the video with a different speed or cuts, and it needs line-by-line adjustment.

Fix it while watching the video

The most reliable way to review is to see the video next to the text. The tool loads the video in the browser itself and lets you adjust each line (the text, the start and the end), as well as add, split, merge and delete lines. It also warns you when a line is too long or appears and disappears too fast to be read, using 42 characters per line and 20 per second as a reference (adjustable values). The video stays on your device.

Converting between formats

The tool converts between SRT, VTT, ASS, SSA, JSON, clean TXT, Markdown and script, detecting the input format by itself. If you are unsure which format to use, SRT is the most widely accepted. When the text comes without times (TXT or Markdown), you set the duration of each block during the conversion.

The video has subtitles, but you don’t have the file

Some videos carry the subtitles embedded. The tool opens MP4, MOV, MKV and WebM videos (up to 2 GB) and ZIP packages (up to 256 MB) and looks for the subtitles inside them. One important limit: subtitles stored as images (bitmap), common on some DVDs and discs, are not text and cannot be extracted as such. And if the video has no subtitles at all, Transcription can generate the text of the speech, which you then refine here.

Translating with AI, with review

Optional AI translation covers nine languages and preserves the timing and the division of the lines. Two things to know: only the text of the lines is sent to the translation service, and only when you click translate (videos and ZIPs are not sent), and the result must be reviewed. Names, slang, jokes and technical terms are where machine translation fails most.

Checklist before publishing

Listen to the beginning, the middle and the end to check the sync.
Resolve the warnings about long lines and reading speed.
Review proper names and numbers.
Export in the format required by the player or the network where you will publish.