StillreelHow to add subtitles to a video on a Mac
There are two kinds of subtitles, and which one you need decides the tool. Here is how to make either kind on your own Mac, without uploading the video anywhere.
Burned in, or a subtitle file?
Burned-in (open) captions are drawn into the picture. They show everywhere, including feeds that autoplay with the sound off, and nobody can switch them off. Subtitle files (closed captions) such as SRT and VTT travel next to the video: players and sites like YouTube let viewers turn them on and off, and you can fix a typo without exporting the video again.
For Reels, TikTok and Shorts, burned-in captions are the usual choice. For YouTube, long videos or accessibility requirements, upload an SRT or VTT file as well.
Free: when you already have an SRT file
HandBrake, a free open-source video converter, can burn an existing SRT file into an MP4 or MOV. Open the video, go to the Subtitles tab, import the SRT, tick Burn In and start the encode. You still need to write or generate the SRT first, and you can't see the captions on the picture until the encode has finished.
QuickTime Player and VLC can show a subtitle track while you watch, but that doesn't change the video file. iMovie has no subtitle import, so there you would type each line as a separate title.
With Stillreel
- Drag an MP4, MOV or M4V file into Stillreel.
- Choose the language and click Transcribe. Speech is turned into text on your Mac by whisper.cpp, an open-source engine for OpenAI's Whisper speech model. On our test Mac (Apple silicon Mac mini), 11 to 15 seconds of speech took under a second.
- Read the captions through and fix any word by editing its text. If a caption starts a little early or late, nudge it by one or five frames, or move just its start or end.
- Pick a style (Clean, Bold Pop, Karaoke, Boxed or Minimal) and place it at the top, middle or bottom.
- Click Export H.264 MP4 for a video with the captions burned in, and Export SRT + VTT for the subtitle files.
Cutting the video later doesn't break the captions: they are rebuilt from each word's timing after every edit. In our tests, captions on an edited export (a split and a clip moved to the front) still appeared on the right frames, checked by reading every caption back out of the exported video with text recognition.
Which format should you use?
| Format | What it is | Use it for |
|---|---|---|
| Burned in | Text drawn into every frame | Reels, TikTok, Shorts, anywhere you can't upload a subtitle file |
| SRT | Plain text: numbered cues with start and end times | YouTube, Vimeo, Final Cut Pro, Premiere, VLC |
| VTT (WebVTT) | The web's caption format, close to SRT | Video players on websites |
Tips for readable subtitles
- Keep each caption to two short lines. Stillreel's default is at most 2 lines of about 32 characters.
- Proofread names, numbers and brand words. Speech recognition gets those wrong most often.
- On vertical video, keep captions clear of the app buttons that TikTok and Instagram draw along the right edge and the bottom; the middle position is the safest.
- Watch the export once with the sound off before you post it.
Is anything uploaded?
No. Transcription, preview and export all run on your Mac, and the app works offline. The only network request Stillreel makes is to check your licence key.
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