Add Subtitles to a Movie Permanently

First, whose film is it?

This page assumes a film you have the right to use: your own short, a family film, a public-domain classic, or footage your licence lets you modify for personal viewing. Copyright, private-copying and fair-dealing rules differ by country and by the terms you bought the film under, so check what applies to you; nothing here is legal advice. Films bought from online stores or downloaded inside streaming apps are usually copy-protected, and a protected file won't open in a browser editor. Getting around that protection is itself unlawful in many countries. Using someone else's video discusses the rights questions in more depth.

Why burn subtitles into a film

A separate SRT works well in a player that looks for it, as subtitles in VLC shows. Elsewhere it often goes missing: a TV's USB player may ignore it or show it in a font you can't change, phones play the video without it, and a copy sent to a relative arrives without the second file. Burned-in subtitles are part of every frame, so they show wherever the film plays.

The trade-offs are real, though. Nobody can switch them off or pick another language, the film is re-encoded to draw them in, and the new file is often larger than the source. Keep the original film and the SRT as well, so you can make a different version later. Permanent subtitles weighs those trade-offs for any video.

Finding a subtitle file that matches your copy

The same film exists in several cuts, and a subtitle file only fits the one it was timed for. Theatrical and extended editions differ by whole scenes; releases differ by a studio logo or a longer opening; some European TV and DVD releases run at 25 frames per second where the cinema version runs at 23.976. Subtitle sites usually label files with the release they match, so compare that label with your copy's running time.

Before styling anything, test three points: the first spoken line, a line around the middle and one near the end. If all three are right, the file fits. If all three are wrong by the same amount, you have a simple offset. If the error grows from start to finish, the file was made for a different frame rate.

Hardcoding an SRT into a film

1. Open the editor with "Write the subtitles automatically with AI" switched off and choose the film: MP4, MOV, M4V, WebM or MKV.
2. Click Import SRT / VTT and pick the subtitle file. A note reports how many lines were imported and how many unreadable blocks were skipped.
3. Press the Down arrow to select the first line, which also moves the playhead to it, and play. Check that the words appear with the voice, then repeat around the middle and near the end of the film.
4. If every line is early or late by the same amount, type the difference in seconds into "Shift all by" and click Apply. A negative number moves the lines earlier.
5. Open Style and choose the Cinema preset, then adjust the size and the distance from the bottom edge.
6. Click Render video and read the summary: resolution kept, the audio plan and the estimated file size. Start the render, leave the tab open, then click Download video.

Offset, drift or a jump?

Constant offset

Every line is early or late by the same amount, typically because one release has a longer intro. "Shift all by" fixes it in one move.

Drift

Correct at the start, a second off by the middle, several seconds off by the end. This is the frame-rate mismatch, and a constant shift cannot fix it because the timings need stretching by a ratio. The editor doesn't stretch timings; desktop tools such as Subtitle Edit have a frame-rate conversion feature, and open-source sync tools such as ffsubsync or alass realign a file against the soundtrack. Retime there, then import the result.

A sudden jump

Fine until one scene, then off by a fixed amount: your cut adds or removes footage at that point. "Shift all by" moves every line, so look for a file made for your cut, or retime the section after the jump in a desktop subtitle tool.

Shifting subtitle timing goes further into offsets, and frame rates explained covers why 23.976 and 25 don't mix.

Subtitles that live inside an MKV

Many films arrive as MKV files with one or more subtitle tracks inside. The editor opens the MKV's picture and sound but doesn't read those tracks; it renders only the lines you import or type. Extract the track you want first:

• MKVToolNix, free for Windows, macOS and Linux, lists a file's tracks with their numbers (mkvmerge --identify film.mkv) and writes one out with a command such as mkvextract film.mkv tracks 2:film.srt. Its graphical tools do the same without a terminal.
• FFmpeg writes the first subtitle track as an SRT with ffmpeg -i film.mkv -map 0:s:0 film.srt. That works for text tracks, including ASS, whose styling is dropped in the conversion.
• Picture-based tracks, PGS from Blu-ray discs and VobSub from DVDs, are images rather than text. They need optical character recognition, which Subtitle Edit offers, before they become an SRT.

Then load the file with Import SRT / VTT. Subtitling MKV files covers the container in more detail.

What changes on import

The editor draws every line in one style, so it strips the formatting tags that subtitle files sometimes carry. Italics marking an off-screen voice or a song lose their slant; you can make the whole style italic, but not single lines. Older subtitle files saved in a regional encoding rather than UTF-8 can show accented letters as nonsense; re-save the file as UTF-8 in a text editor before importing, as strange characters in subtitles explains.

The Cinema look and a film-length render

Cinema sets an elegant serif with a soft shadow at the bottom of the frame, closer to a release print than to a social-media caption. For a letterboxed film, nudging the subtitles down into the black bar keeps them off the picture; cinematic subtitles shows how. Keep lines to two at most and watch the reading-speed warnings during fast dialogue.

The output is an MP4 at the source's resolution and frame rate, in H.264 whenever your browser can encode it at that size, which most TVs and phones play. The soundtrack is copied unchanged when MP4 can carry it and converted to AAC or Opus otherwise. If the browser can't decode the soundtrack at all, as can happen with surround formats common on film releases, the summary says so and rendering stays blocked; convert the audio with HandBrake or FFmpeg first. A feature film is a long render, so read subtitling a long video for disk space, progress and cancelling.

No subtitle file at all?

For a home movie or your own film up to 2 hours, AI subtitles can write the file. A 104-minute film costs 104 credits (10.4¢), and the result can be translated into any of 21 languages. Music and sound effects make speech harder to recognise, so plan a full review before rendering. If you only want the subtitle file, the AI subtitle generator produces SRT and VTT downloads, and translated subtitles does the same in another language.

About the subtitle editor on this page

Opens

MP4, MOV, M4V, WebM, MKV videos your browser can decode

Subtitles from

AI (from the speech, optionally translated into one of 21 languages), an SRT or VTT file, or typing them in

You download

An MP4 with the subtitles drawn into the picture at the original resolution and frame rate, plus SRT and VTT files

Cost

Editing, styling, rendering and SRT/VTT export are free, with no account and no watermark. AI subtitles cost 1 credit per minute (5-credit minimum per video); signing in with Google gives 100 free credits and accounts get 10 free credits a day

Privacy

The video never leaves your device and is rendered in your browser. Only for AI subtitles is the audio sent, over HTTPS, and it is deleted within 30 minutes of delivery

Rendering needs

Chrome or Edge 94+, Safari 16.4+, or Firefox 130+ on a computer. Editing and SRT/VTT export work in any current browser