Open captions are burned into the picture and always visible; closed captions are a separate file the viewer can turn on or off. Default to closed captions (SRT or VTT) for anything going to YouTube, a streaming platform, a learning system or a broadcast pipeline, because those platforms expect a sidecar file and viewers expect control. Choose open captions only when you cannot rely on the player to show a caption track — social feeds with autoplay sound off, kiosk and event screens, embedded clips on sites you do not control, or anywhere the caption must survive a re-encode.
Either way, the captions start as a transcript of the speech. Auto Subtitles transcribes the audio in your video on your own device, lets you fix the text and timing, then either burns the result into the picture or hands you a subtitle file to ship alongside it.
When to use Open captions
Open captions (also called burned-in, hardcoded or hardsubs) are part of the video frames themselves. Once rendered, they are pixels, not a track.
Use them when:
- Sound-off autoplay is the norm. Instagram, TikTok, Facebook and X autoplay muted. A closed caption track on those feeds is often ignored or unavailable, so a burned-in line is the only caption most viewers will ever see.
- The player is not yours. A clip embedded in a client's CMS, a slide deck, a trade-show loop or a hotel TV may have no caption button at all.
- You need guaranteed styling. Burned text keeps your font, size, position and color exactly. A caption track renders however the player decides, and viewers can restyle it.
- The file must be self-contained. One MP4 that travels through email, USB drives or a chat app carries its captions with it. No sidecar to lose.
- Accuracy is legally or editorially fixed. A burned caption cannot be turned off or edited by a downstream viewer.
The cost is permanence. Open captions cannot be switched off, cannot be translated on the fly, cannot be searched as text, and will sit on top of any lower-third graphics you add later. They also add nothing to the file size worth worrying about, but they do mean re-rendering the whole video if one word is wrong.
When to use Closed captions
Closed captions are a timed text file — usually SRT or WebVTT — delivered next to the video or attached as a separate track. The viewer toggles them.
Use them when:
- The platform supports them. YouTube, Vimeo, Netflix-style players, most LMS platforms and broadcast workflows all accept a caption file and expose a CC button.
- Accessibility compliance matters. WCAG and most accessibility regimes expect captions that can be turned on by people who need them and off by people who do not.
- You want searchable, indexable text. Caption files give search engines and platform search real text tied to timestamps, which helps discovery.
- Translation is coming. One transcript can become a dozen caption files. Burned text would mean a dozen re-renders.
- You may need to correct something. Fixing a typo in a sidecar file takes seconds. Fixing it in burned-in text means re-exporting the video.
- Multiple languages or multiple audiences. A single video plus several caption tracks serves everyone.
The trade-off: closed captions only exist if the player honors them. On a muted social feed or a bare <video> tag with no track configured, the viewer sees nothing.
A common production pattern is both: ship the video with a closed caption track for the platforms that honor it, and also export a burned-in version for social cuts and embeds.
Open captions vs closed captions compared
The table above covers the deciding dimensions. The short version: open captions win on guaranteed visibility and portability of a single file; closed captions win on flexibility, cost of correction, compliance and search.
Why doing this locally in the browser beats upload-based caption sites
Most caption services ask you to upload the video, wait in a queue, then download a file. That means your footage — client work, internal meetings, footage of identifiable people — sits on someone else's server, often for a retention window you did not choose.
Alvseike's Auto Subtitles runs the transcription and the burn-in on your machine. Nothing is uploaded. There is no file-size cap, so a long recording does not hit a paywall or a 500 MB ceiling halfway through. There are no watermarks on the output.
On the free plan you get 5 exports a day without an account, or 15 a day with a free account. A run is one export, however many files it contains. Pro is $12.99/month and covers all 50 Alvseike tools — image compression and format conversion, video and audio editors, recorders, PDF tools and export packs — not just this one, and it removes the daily cap. Offline use, by installing the site as an app, is a Pro feature. If you need more than the free daily allowance, see /pricing.
If the finished video is too large for the platform you are publishing to, Video Compressor shrinks it locally without a cloud service. If you need to reframe vertical for social before burning captions in, Video Cropper crops and trims in the browser. And if the source clip has a station logo or watermark you need gone first, Video Logo Remover handles that on your device too.
Common mistakes
- Burning captions in, then needing an edit. Burned text is final. Get the transcript right before you commit, or keep the caption file as well.
- Shipping only a sidecar to a muted feed. If the clip autoplays silent, a caption file nobody can see is the same as no captions.
- Assuming the platform will generate them. Auto-generated platform captions are fast but frequently wrong on names, jargon and accents, and on many platforms you cannot correct them without uploading your own file.
- Captioning the wrong element. Captions cover dialogue and meaningful sound. On-screen text, speaker labels and sound effects have their own conventions — do not dump everything into one line.
- Ignoring line length and reading speed. Long unbroken lines are unreadable at speed. Keep lines short and let each caption sit long enough to read.
- Forgetting the safe area. Burned captions placed too low get cut off by player controls or a mobile crop.
- Mixing formats. SRT and VTT are not interchangeable everywhere. Check what your destination accepts before exporting.