Burn subtitles into WebM video — browser-based, free
WebCodecs VP9 / H.264 encoder · supports VP9 + AV1 input · output WebM or MP4
WebM is the open, royalty-free video container used widely on the open web (YouTube, Wikipedia, many CDNs). Browser tools rarely support burning subtitles directly into WebM because the codecs (VP9, AV1) are less common in legacy software. BurnSub uses WebCodecs, which natively understands VP9 and AV1 — so you can hardcode captions into WebM without losing the format or converting to MP4 first.
How to burn subtitles into webm video
- 1
Open BurnSub
Go to burnsub.com — works in Chrome, Edge, Firefox 147+, and Safari 17+.
- 2
Drop your WebM file
BurnSub decodes the VP9 or AV1 track using the browser's native codec.
- 3
Import or auto-generate captions
Use Whisper-Turbo for local transcription or import your existing SRT/VTT.
- 4
Pick a style
Choose one of 30+ named presets or build your own. Live preview reflects every setting.
- 5
Burn and export
Choose output: keep WebM (VP9) for the open web, or export MP4 (H.264) for maximum platform compatibility.
Frequently asked
Why is WebM subtitle-burning rare in browser tools?
Most browser tools rely on ffmpeg.wasm, which is slow for VP9 and AV1. BurnSub uses native WebCodecs, which is hardware-accelerated for these codecs in modern browsers.
Can I output to WebM or MP4?
Both. Pick WebM if you want the same open-format container as your input, or MP4 for broader compatibility (TikTok, Reels, etc.).
Does AV1 input work?
Yes in browsers that support AV1 decoding (Chrome, Edge, Firefox). Output remains H.264 MP4 or VP9 WebM — AV1 encoding from the browser is not yet broadly supported.
Will the WebM stay the same quality?
BurnSub re-encodes at your chosen settings. Match the original bitrate to keep quality near-identical.
Is anything uploaded?
No. Everything happens in your browser. Verify in DevTools → Network tab.
Ready to burn srt / vtt into webm / mp4?
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