LinkedIn carousel from a video: up to 10 square cards with Sume

A LinkedIn carousel takes 2 to 10 cards, recommends 1080 x 1080 and allows JPG, PNG or non-animated GIF at up to 10 MB per card. You can build the cards from a video: crop a 9:16 clip to a square with Sume video filter ($0.02), then pull up to 24 stills per call with video frames and keep the best 10.

The carousel rules

Values from the LinkedIn page, read on 2026-10-08.

Crop to a square

Video filter's crop op takes a rectangle as fractions of the source frame: x and y from 0 to 1, width and height from 0.05 to 1, with x + width and y + height at most 1. For a 9:16 source, a square keeps the full width and a height of 9/16 = 0.5625. To centre it, y = (1 - 0.5625) / 2 = 0.21875. The source can be up to 300 seconds, and the job is $0.02.

For a 16:9 source, swap the axes: height 1, width 0.5625, x 0.21875.

curl -X POST https://api.sume.com/v1/video-filter \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: square-crop-001" \
  -d '{"video_url":"https://media.sume.com/artifacts/artf_demo/vertical.mp4","ops":[{"op":"crop","x":0,"y":0.21875,"width":1,"height":0.5625}]}'

Pull the cards

Run video frames on the cropped file. Send at with up to 24 times, or fps up to 2, and set format to png if you want lossless cards. max_edge clamps the long side between 16 and 2160, so max_edge 1080 on a square gives 1080 x 1080. Frames come back as durable images; a frame that cannot be extracted has no url and does not fail the job.

Choose the stills that read as a sequence. Ten cards from a 30 second clip is one every three seconds, so at = [1, 4, 7, 10, 13, 16, 19, 22, 25, 28].

• Crop: $0.02 per job.
• Frames: Modal compute, no fixed price.
• Check each file against the 10 MB per card limit.

Limits of the method

Stills from a video have no headline or text; add that in your design tool or burn it into the clip first with video captions, which is $0.20 per job. Motion blur can ruin a still, so pick times where the picture is steady. And the carousel needs at least 2 cards, so a very short video may not yield enough distinct frames. If the first crop cuts off a face or product, adjust y and run the filter again; a new Idempotency-Key makes a new $0.02 job, while the same key returns the old one. The crop compiler rounds to even values for yuv420p, so the output may differ from a perfect square by a pixel. Set max_edge in the frames call and check the result before you build the carousel.