Hook, body and CTA from three video models in one 30-second Short

You can spend the expensive model only where the viewer is deciding to stay. A 30-second Short with a 4-second Seedance 2.5 hook at 1080p, a 20-second Wan 3.0 body at 720p and a 6-second Omni Flash call to action at 1080p costs $9.31 in generation and $9.41 after the $0.10 Timeline render.

The same 30 seconds as one Wan 3.0 720p job is $3.75; the mix pays about $5.56 extra for a sharper opening. All three models list 9:16, and Shorts are vertical (YouTube Help, read 2026-10-09).

The mix, line by line

Seedance 2.5 has a 4-second minimum, which is exactly a hook length. Wan 3.0 covers 2 to 30 seconds. Omni Flash 1.1 covers 3 to 10 seconds.

Join with soft cuts

Request all three as 9:16 so the shapes match, import the outputs, then render one file. Timeline's fit defaults to cover, which fills the frame; the output defaults to 1080x1920 so the 720p body is scaled to the same canvas as the 1080p ends.

curl -X POST https://api.sume.com/v1/timeline-1.0/render \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: short-mixed-001" \
  -d '{"audio":{"mode":"silence","duration_seconds":30},
   "video":[
    {"source_url":"https://media.sume.com/artifacts/artf_demo/clip1.mp4","start":0,"duration":4},
    {"source_url":"https://media.sume.com/artifacts/artf_demo/clip2.mp4","start":4,"duration":20,"transition":{"type":"fade","duration":0.25}},
    {"source_url":"https://media.sume.com/artifacts/artf_demo/clip3.mp4","start":24,"duration":6,"transition":{"type":"fade","duration":0.25}}],
   "output":{"width":1080,"height":1920}}'

Limits

• Different models render different looks; keep the style line and any reference image identical across all three prompts.
• Omni Flash takes no audio reference, while Seedance 2.5 and Wan 3.0 do; if one narration file must drive the clips, use it as the Timeline audio spine instead.
• A transition must be on slot 2 or later and no longer than half the shorter neighbor.
• Totals use list rates read 2026-10-09; confirm pricing_skus in GET /v1/videos/models.