Logo on a Seedance 2.5 clip: reference image or an exact overlay

If your logo must be pixel-exact in a Seedance 2.5 clip, do not rely on the model to draw it. Generate the clip without the mark, then place the real logo file over it with Sume's timeline compose overlay operation, a flat $0.02 job. If you want the logo to exist inside the scene, such as on a product or a wall, send it as a reference image and check the frames.

Two different jobs

A logo can be part of the scene or part of the frame. Part of the scene means a bottle label or a shop sign; the model has to render it in perspective and may alter letters. Part of the frame means a watermark or an end card, and a deterministic overlay is the safer tool.

Route 1: logo as a reference image

Send the logo on a plain background as one of the reference_image_urls, and mention where it belongs in the prompt. Sume allows up to 9 reference images on Seedance models. Then extract stills with video frames (the clip must already be stored on media.sume.com, so import a downloaded MP4 first) at the moments the mark is visible. Reject takes where letters change; ByteDance does not publish a text-fidelity guarantee on the pages read on 2026-10-04.

Route 2: exact overlay with timeline compose

The timeline compose docs say overlay puts one still on top of one video and returns one MP4. Both files must already be media hosted by your workspace, so import the logo and the clip first. layout accepts position (top, center, bottom), width_ratio and margin_ratio for overlay.

curl -X POST https://api.sume.com/v1/timeline-1.0/compose \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: logo-overlay-001" \
  -d '{
    "operation": "overlay",
    "image": { "url": "https://media.sume.com/artifacts/artf_demo/logo.png" },
    "video": { "url": "https://media.sume.com/artifacts/artf_demo/clip.mp4" },
    "layout": { "position": "bottom", "width_ratio": 0.3, "margin_ratio": 0.05 }
  }'

Cost and caveats

The overlay is a flat $0.02 per job per the compose docs, with no model inference. Output defaults to 1080x1920, so set output.width and output.height to your delivery size to avoid rescaling twice. The still is held for the whole clip, which suits a persistent watermark but not a logo that animates in.

A 30-second Seedance 2.5 clip at 720p costs about $17.33 on Sume's rate card, so one wasted take dwarfs the overlay fee. Fix the logo step in the pipeline, not in the prompt.