Video frames fps on Sume: mid-bin sampling and the 24-frame cap

With fps: 0.5, Sume video frames samples mid-bin instants, 0.5/fps, 1.5/fps and so on, so the stills land at 1, 3, 5 seconds, not at 0. The call returns at most 24 frames, fps must be above 0 and no more than 2, and the clip must be 300 seconds or shorter. For exact instants send at[] instead. Source: Video frames, read 2026-10-06.

How do at[] and fps differ?

Send only one of them.

When do I use video frames and not video inspect?

Video inspect samples 8 mid-bin stills with a default max_edge of 768. Video frames does not clamp unless you send max_edge, so use it when you need the source size, such as an OCR pass or a check of a first frame. A submit always returns 202, because the job is pinned to async, and you read GET /v1/video-frames/:id until resource_status is ready.

• A failed instant has url: null and does not fail the job.
• Over 90 seconds, warnings[] can carry low_confidence_long_video.
• Billing is by the job's Modal compute, never more than the reserved hold.