Add subtitles to a video

How burning subtitles works

Upload a video and its subtitles: either an SRT or WebVTT file, or text pasted straight into the box. The tool checks the subtitles, shows how many cues it found, and once started renders them directly into the picture. The result is a plain MP4 in which everyone sees the subtitles, whatever player they use and without switching on closed captions.

The rendering is done by the libass library inside ffmpeg compiled to WebAssembly, which means it runs in your browser. Neither the video nor the subtitles are sent anywhere. The DejaVu Sans font covers all of Latin, Cyrillic and Greek with accents, so no character drops out.

• Three font sizes, always proportional to the height of the video.
• Placement at the bottom or the top, for when graphics or other text sit at the bottom.
• White or yellow text with a black outline, or on a dark box.
• A bold weight for short phone videos that are read from a small screen.
• An SRT file from the audio transcription tool can be uploaded without changes.

Frequently asked questions

What should the subtitles look like?

SRT is the simplest format: a sequence number, a time range written as 00:00:01,000 --> 00:00:03,500, the subtitle text and a blank line before the next block. WebVTT looks almost the same, but starts with a WEBVTT line and uses dots instead of commas in the times. The tool accepts both and converts the file itself.

Can the subtitles be switched off after burning?

No, they become part of the picture. If you need subtitles a viewer can turn on and off, ship the SRT file alongside the video or upload it to a platform that supports subtitle tracks. Burned-in subtitles are the right choice for social networks, where videos play muted and nobody uploads subtitle files.

Why do the subtitles appear at the wrong moment?

Subtitle times count from the start of the video. If you trimmed the video or added an intro beforehand, the subtitles shift. Adjust the times in the file, or burn the subtitles first and cut the video afterwards.

Does the tool handle long subtitles?

Yes, long cues wrap onto several lines according to the width of the video. Still, two short lines read better than three long ones, especially in portrait videos.

How long does burning take?

The picture is re-encoded, and in the browser on a single thread that takes roughly as long as the video lasts. The audio is only converted to AAC and does not affect the processing time.