Lab demo video to worksheet stills: video frames at up to 24 times

To turn a recorded science demo into a worksheet, call POST /v1/video-frames with an at list of the seconds where each step is clear. It takes 1 to 24 values per call from a clip of 300 seconds or less and returns each still as a durable image artifact. Omit max_edge and the stills keep the source frame size, which suits print.

Source: Video frames, read 2026-10-04.

Two tools, two jobs

Pick the instants by looking at a sampled grid first. Video inspect returns eight mid-bin stills by default, or 1 to 24 at times you name, and each call is billed by its Modal compute.

Extract the steps

Every at value must fall inside the clip: 0 <= t < duration, or the worker fails with frame_time_out_of_range and names the probed duration. Use png for lossless stills, jpeg is the default.

curl -X POST https://api.sume.com/v1/video-frames \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: lab-demo-frames-001" \
  -d '{
    "video_url": "https://media.sume.com/artifacts/artf_demo/lab-demo.mp4",
    "at": [3.0, 14.5, 31.2, 58.0, 82.4, 119.0],
    "format": "png"
  }\

Read the result

The submit returns 202, so poll GET /v1/video-frames/:id until resource_status is ready. The response lists frames[{t,url,width,height}]. One instant that failed to extract comes back with a null url and does not fail the whole job, so check each entry before you build the worksheet.

Long recordings

Clips over 300 seconds need cutting first with video trim, which takes a source of up to 1800 seconds and writes up to 900 seconds. Trim to the part you want, then extract from the new MP4.