Burn Subtitles into Video

How the Subtitle Burner works

Subtitles come in two forms. Closed captions are a separate track that the player draws on top and the viewer can switch off. Open captions, also called burned-in or hard-coded subtitles, are part of the picture itself. They cannot be turned off, but they also cannot go missing.

When to burn subtitles into video

• Social feeds: most people scroll with the sound off, and many feeds autoplay muted. Captions in the picture carry the message without sound.
• Platforms with no caption upload: many chat apps, some ad networks and most messaging tools accept a video file but have nowhere to put an SRT.
• Sharing a file directly: a caption file sent alongside a video is easy to lose or forget.
• Translations for one audience: a clip with burned-in Spanish subtitles is ready to post on a Spanish-language page with no setup.

Keep a clean copy of the original. Burned-in captions cannot be edited or removed later, so a typo means rendering again from the source.

How the subtitle burner works

The tool reads your subtitle file and pulls out every cue: a start time, an end time and the text. It understands both SRT, with comma decimals like 00:01:02,500, and WebVTT, with dots and an optional hours field. Formatting tags such as <i> and SSA-style {\an8} codes are stripped.

The video then plays through once. For each frame the tool finds the cue whose span covers the current time and draws its text centred near the top or bottom, wrapped to 90% of the frame width. The canvas is recorded with MediaRecorder along with the original audio, so the render takes as long as the clip.

Text size and style

Size scales with the frame height, so captions look the same on a 720p and a 4K source.

Outline draws white text with a thick black edge. It suits most footage and hides little of the picture. Box puts each line on a 75% black band, which reads best over busy or bright scenes like snow, sky or white walls. Use Top when the bottom of the frame holds something that matters, such as on-screen lower thirds, or when a platform's buttons cover the bottom of vertical video.

Tips and pitfalls

Times out of sync? If every line is early or late by the same amount, shift the whole file with an SRT timestamp shifter before burning. Drift that grows over time usually means the subtitles were made for a version at a different frame rate.

Line length. Aim for no more than about 42 characters per line and two lines per cue, the limit most broadcasters use. Longer cues are wrapped onto extra lines and may cover more of the picture.

Wrong characters? Save the subtitle file as UTF-8. Files saved in an older code page show accented letters as symbols.

Vertical video: choose Medium or Large and Top or a raised bottom. TikTok and Reels put captions, buttons and the username over the lower fifth of the frame.

How to read the result

The stats show how many cues were found, when the first one starts and the new file size. Play the result and jump to a few points to check the timing, then Download.

For a single title or caption without an SRT file, use add text to video.

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