AI avatar video length limit: 4 to 60 seconds per job

An avatar video job on Sume has to fit an estimated 4 to 60 seconds, inclusive. The rule is about Sume's estimate of the target duration, not a word or character count, and it applies to a plain script, to ordered video_inputs, to previews and to inline captions. Outside the window, shorten the script or split it into multiple jobs.

Where does the 4 to 60 second window apply?

Is the limit a word count?

No. The docs say Sume estimates the target video duration, and they publish no formula, so do not treat any words-per-minute figure as a guarantee. For a rule of thumb and a worked example, see script length for an AI avatar video; this post only covers where the window applies.

In a multi-scene plan you set each scene's voice.duration yourself. The docs example uses scenes of 3, 4 and 5 seconds, which adds up to 12 seconds and sits inside the window.

Is there a minimum too?

Yes. The window is 4 to 60 seconds inclusive, so a one-word script whose estimate falls under 4 seconds is outside it as well. Silence beats count for this, because a scene with voice.type of silence carries its own duration.

The same window is what the preview route uses, so you can test a borderline script there before spending on a render.

What happens when my script is too long?

The docs tell you to shorten longer scripts or split them into multiple jobs. Each job is its own request with its own Idempotency-Key, and each returns a clip you join afterwards; the joining steps are in AI avatar video longer than 60 seconds.

Captions are the second place a long video bites. Inline captions reject an estimated duration above 60 seconds, but the standalone Video captions route takes an existing public video URL, so it is the route for a clip you have already joined. See captions on a long video.

How do I stay inside the window?

• Write the script first and cut it until it reads comfortably in under a minute.
• Prefer several short clips over one clip that sits near 60 seconds; a single estimate near the edge is the easiest to overshoot.
• Use a preview first: it applies the same window, so a script that is too long fails before you pay for the full render.
• For a scene that should stay quiet, use a silence beat with its own duration rather than padding the script.