How burning works here
“Burning” or “hardcoding” means drawing the text into the video frames, so it becomes part of the picture. SubtitleWave plays your video in a hidden player, draws each frame plus the current subtitle onto a canvas, and records the result together with the original audio using your browser's built-in encoder. Because it plays through the video once, rendering takes about as long as the video lasts. Keep the tab in front while it runs: browsers slow down background tabs.
When a desktop tool is better
For feature-length films, 4K masters or exact frame-rate preservation, FFmpeg is the professional route and also runs locally: ffmpeg -i in.mp4 -vf subtitles=subs.srt -c:a copy out.mp4. The browser renderer is ideal for social clips, tutorials and anything under about 15 minutes.
Legibility checklist
- Size around 5% of the frame height for landscape video, 6 to 7% for vertical.
- Use the broadcast box over busy or bright footage; outline over plain, darker shots.
- Keep lines under 42 characters and at most two lines, so the eye does not travel far.
- Check the reading-speed tags in the Edit tab first: amber and red lines are hard to read in time.
Questions people ask
How do I hardcode subtitles into an MP4?
Load the SRT or VTT file and the MP4 above, choose a style, then press “Render captioned video” in the Export tab. When it finishes, press Save to download the MP4.
Why does rendering take as long as the video?
Browsers encode video in real time while it plays. That keeps everything on your device and works in any modern browser, at the cost of speed.
Why did I get a WebM file instead of MP4?
Firefox and some older browsers only record WebM. YouTube, CapCut, Premiere and most platforms accept it; convert it to MP4 with any video converter if needed.
Can I burn in ASS subtitles with their styling?
The text and timing of ASS files are imported, but their own fonts and positions are replaced by the style you choose here.