Give every Seedance 2.5 reference a role in the prompt

In a Seedance 2.5 reference-to-video request, tell the model what each reference is for: an image for identity, another for place, a video for motion or camera, an audio file for voice or music. Sume does not define a tag syntax for Seedance in the docs read on 2026-10-04, so write the roles in plain words in the prompt and keep the reference list short.

Why roles matter

A bag of references is ambiguous. Three photos might be three characters, three views of one character, or three locations. ByteDance describes references as a way to control performance, lighting, shadow and camera movement (ByteDance Seed: Seedance 2.0), which are different jobs for different inputs. Naming the job reduces the ways the model can misread your input.

A role table

The fields below are the Sume Video Router fields. The "role" column is a prompt-writing convention, not an API setting.

Say it in the prompt

Refer to inputs by what they are, and keep the order of the arrays predictable. The Sume docs define positional tags such as <IMAGE_REF_0> only for Gemini Omni Flash 1.1 in the Video Router docs; do not assume the same syntax works for Seedance. Describe it in words instead.

curl -X POST https://api.sume.com/v1/video-router/generate \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: roles-001" \
  -d '{
    "model": "seedance-2.5",
    "prompt": "The woman in the first image is the lead. The second image is the cafe where the scene takes place. Follow the slow dolly-in of the reference video. Pace the cuts to the reference music.",
    "reference_image_urls": ["https://example.com/lead.png","https://example.com/cafe.png"],
    "reference_video_urls": ["https://example.com/dolly.mp4"],
    "reference_audio_urls": ["https://example.com/theme.mp3"],
    "resolution": "480p",
    "duration": 10,
    "mode": "async"
  }'

Mind the price of video references

A reference video changes the bill. In Sume's pricing code a request with a reference video is priced on the output length plus an assumed 15 seconds of input, at 0.6 of the base, so short outputs cost more and 30-second outputs cost less than the no-video price. At 720p, a 10-second output goes from $5.78 to about $8.67, and a 30-second output goes from $17.33 to about $15.60. Confirm in the live catalog before relying on this.

Test with one image role at a time first. If the identity is wrong with images alone, adding a video will not fix it.