Set `smart: true` to select strong preview images with AI instead of taking frames only at regular intervals. The Robot scores candidate frames for clarity, brightness, composition, faces, expressions, action, and visual interest, then returns the best `count` frames in chronological order. Smart results include `file.meta.smart_score` and `file.meta.smart_reasons`. If AI scoring is unavailable, the Assembly continues with the candidate frames in fallback order. No AI credentials are required.

## AI pricing

Regular `/video/thumbs` processing charges still apply. AI frame analysis is billed separately at the underlying provider cost plus a 50% Transloadit markup. The exact AI charge varies with the number of candidate frames, the internally selected model and provider pricing, and the image payload size.

`smart_max_candidates` is the main cost and latency control. The Robot analyzes up to three candidates per requested thumbnail, capped by `smart_max_candidates`, but never fewer than `count`. With the defaults of `count: 8` and `smart_max_candidates: 20`, it analyzes 20 frames and returns the best 8. Lower the candidate limit to reduce AI cost and latency; raise it to give the AI more frames to choose from.

###### Note

Use `count` with smart selection. The `offsets` parameter is for extracting exact timestamps and should not be combined with `smart`.