How to add captions to an MP4 video
There are three ways to pair captions with an MP4: upload a separate caption file, embed a selectable track, or burn the words into the picture. The right choice depends on where the video will be watched.
Choose how the captions should behave
Keep the MP4 and SRT/VTT separate. Viewers can turn captions on or off. This is usually best for video platforms.
Package a selectable caption track inside the MP4. Useful for files distributed directly, but player support varies.
Render text into every frame. It works everywhere but cannot be hidden, restyled, or easily corrected later.
1. Create and review the caption file
Generate an SRT or VTT with CaptionKite. Review names and timing, then save a clean master copy before taking it into an editor or platform. If you are unsure which export to use, start with SRT.
2. For most platforms, upload a sidecar file
Upload the MP4 normally, then find the destination's captions, subtitles, accessibility, or language area and attach the SRT/VTT. Select the correct language and label it accurately. Preview with captions both on and off.
Selectable captions improve accessibility without forcing a visual style, can be indexed or translated by some platforms, and can be corrected without re-encoding the video.
3. Burn captions in only when needed
Import the MP4 and caption file into a video editor, inspect the caption track, choose a high-contrast style, and export a new MP4. Keep text away from controls and important visual details. Test the result on a phone as well as a desktop screen.
Burned-in captions are useful for silent autoplay feeds or players that do not support caption tracks, but they are not a full replacement for selectable accessibility captions.
A five-point quality check
- Captions match the spoken words and intended language.
- No caption appears before the matching speech.
- Text remains readable against changing backgrounds.
- Important names, numbers, and sound cues are correct.
- The final delivery includes the caption file, not only a preview.
Common mistakes to avoid
Do not rename a TXT transcript to .srt; it lacks timings. Do not assume captions are enabled just because a file was uploaded. And do not delete the editable SRT after burning captions into a video—you will need it for corrections, translations, and other platforms.