Omni scene extension on Sume: chain clips with a 3-second tail

Can you chain Gemini Omni clips on Sume to approximate a long scene? Partly. Google's extension reads up to 10 seconds of prior context, but Sume's gemini-omni-flash-1.1 row accepts reference videos of at most 3 seconds each, up to 3 of them. So you cut the last 3 seconds of clip N with video-trim, pass it as a video reference to clip N+1, and join the full clips afterward.

The numbers on each side

Google's launch post says prior context grew from 1 second to up to 10 seconds, with extension in 10 second increments up to 40 seconds. The Gemini API docs give video references as up to 3 clips of up to 3 seconds.

The chain

Take a finished clip that lives on media.sume.com. Send POST /v1/video-trim with video_url, a start three seconds before the end, and a duration of 3, plus an Idempotency-Key. The video-trim docs list precision: exact as the default, a frame-accurate re-encode, and a rate of $0.02 per job. Poll the job until its result gives a new video_url.

Then submit the next generation with that URL as a video entry in input_references, and describe in the prompt what happens next. Repeat for each segment.

Where it is weaker than real extension

Three seconds of context carries motion direction and look, but not a 10 second memory of the scene, so characters and props can drift over several links. Keep each prompt specific about who is in frame. Also, Sume does not expose previous_interaction_id for Omni, so there is no server-side conversation state; each clip is a fresh request.

To assemble the pieces, render all the full clips in order on a timeline, not the trimmed tails, which only serve as references. Check the seam between clips at full speed before you accept the chain.

A worked plan for 30 seconds

Three 10 second Omni clips make a 30 second piece. Generate clip one from your prompt and a first frame. Trim its last 3 seconds and use them as the reference for clip two. Repeat for clip three. Total cost is three generations plus two trims at $0.02 each, plus the final timeline render. At the 720p catalog rate, each 10 second clip bills $1.25 on Sume, so the generations come to $3.75 before trims.

Compare that against a single Seedance 2.5 or Wan 3.0 request, which can reach 30 seconds in one pass, and decide whether you need Omni's native audio or look enough to justify the chain.