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OpenCaptions

Your first captions

This page follows one video through the web app, from the first click to the saved file. It assumes the quick start is done and you are signed in at http://localhost:5173.

1. Add a video

Section titled “1. Add a video”

Select New project on the home page. Give the project a title, then either:

  • Upload file: choose a video from your computer, or
  • From URL: paste an http:// or https:// link to a video file. The server downloads it, and refuses addresses on your private network (see Security).

A video can be up to 2 GB and an hour long by default. Configuration shows how to change that.

Select Next.

2. Choose how to transcribe

Section titled “2. Choose how to transcribe”

The second step has two parts.

Transcription provider and speech model. The default, a model on your own machine, needs no account and uploads nothing. Pick a model from the list: bigger ones are more accurate and slower. If you are not sure, keep the default, or choose Whisper Small for a quick try. The other providers send the audio to the OpenAI API, or to another OpenCaptions server of yours, and the page says so whenever one of them is selected. See Transcription.

Spoken language. Search the list and pick the language the video is spoken in. The list follows the model: a model that handles fewer languages shows fewer. Your last choice, or your browser’s language, is selected to start with.

Select Create project. The video is uploaded and transcribed, and a progress bar shows the stage: loading the model (downloading it, the first time), then transcribing.

3. The editor

Section titled “3. The editor”

When the transcript is ready, the editor opens:

  • the preview on the left, the video with the captions drawn over it,
  • the style panel beside it, in tabs,
  • the timeline underneath, with a track for the video and one for the captions.

Press Space to play. Everything you change is saved by itself a moment after the last edit: there is no Save button.

Pick a look

Section titled “Pick a look”

The Presets tab holds thirteen looks. Select one and the preview changes at once. The other tabs adjust it: Text (font, size, case, colours), Background, Animation, Outline and Timing. See Styling.

Fix a word

Section titled “Fix a word”

Pause the video and double-click a word in the preview. Type the correction and press Enter (Esc cancels). See Editing.

Move the captions

Section titled “Move the captions”

While the video is paused, drag the caption block in the preview. It is pulled towards the centre lines of the picture, and a guide shows when it is centred.

Retime a caption

Section titled “Retime a caption”

Select a caption block on the timeline and drag one of its edges. If it touches the next caption, that caption’s edge is pushed along.

4. Save the result

Section titled “4. Save the result”

Select Download and choose a format (MP4 with H.264 or H.265, WebM, or ProRes), a size, a frame rate and a background: the video itself, or a green screen with only the captions, to key out in your video editor. The file is made on your server and kept, so asking for the same thing twice is instant.

Subtitle files (SRT, VTT and JSON) come from the separate Download subtitles button next to it, and need no processing. See Exporting.

What next

Section titled “What next”