Caption video
Add animated captions (and optional B-roll) to an existing video.
Requires
source.urlmedia: moving-imagevoice-over: off by defaultmusic: on by defaultcaptions: on by defaultratio: 9:16 by default
Build your request
Only the parameters that apply to caption-video are shown. Set values on the left, copy the payload on the right.
source.urlrequiredThe source content URL: audio file, video file, YouTube link, Spotify track, article page, or PDF depending on the workflow. http(s) is enforced; bare domains get https:// prepended.
{
"workflow": "caption-video",
"source": {
"url": "https://cdn.revid.ai/uploads/1771944925512-video.mp4"
}
}Free, no API key needed.
Good to know
- →captions.autoCrop = true reframes the video for vertical formats (face tracking).
- →PDF URLs are also accepted as source.url: each page becomes a narrated section.
- →metadata.duration (seconds) speeds up processing.
Recipes
PDF to video
Turn a PDF (carousel, report) into a narrated video, one section per page.
{
"webhookUrl": "https://your-server.com/revid/webhook",
"workflow": "caption-video",
"source": {
"url": "https://cdn.revid.ai/uploads/1772035824673-application.pdf"
},
"media": {
"type": "moving-image",
"density": "medium",
"animation": "dynamic",
"imageModel": "cheap",
"videoModel": "base"
},
"voice": {
"enabled": true,
"voiceId": "nPczCjzI2devNBz1zQrb",
"speed": 1
},
"captions": {
"enabled": true,
"position": "bottom"
},
"aspectRatio": "9:16"
}