Seedance 2.0 Fast API

Seedance 2.0 Fast image-to-video starts the clip on a picture you supply and animates it for up to 15 seconds. Add a closing still and the shot has to arrive there, which is what makes transitions and before-and-after pairs repeatable.

Seedance 2.0 Fast is the speed tier of ByteDance's Seedance 2.0 line. Its three endpoints return 4 to 15 second clips at 480p or 720p, with audio generated alongside the picture.

Choose a Seedance 2.0 Fast mode by starting material

One field set, three sources

All three endpoints take the same core fields: prompt, duration_seconds from 4 to 15 (or -1 to let the model choose), resolution at 480p or 720p, aspect_ratio, generate_audio and seed. What changes is the source that anchors the picture: nothing, an opening frame, or a set of references. A request built for one mode moves to another by adding or removing that source.

Picture and sound in one pass

generate_audio is on by default and renders ambience, movement effects and voice locked to the frames. Switching it off does not lower the rate in this tier, so turn it off only for silent loops or for material you will score in post.

Adaptive framing by default

aspect_ratio defaults to adaptive: image-to-video keeps the proportions of the opening frame, reference-to-video follows the primary reference, and text-to-video lets the model pick the shape the prompt suggests. The six fixed ratios, 16:9, 9:16, 4:3, 3:4, 1:1 and 21:9, are there when a placement dictates the shape.

Literal results from your own frame

Whatever the opening frame shows is already in the clip, so the prompt only has to describe motion and does not have to argue for content. This is the dependable path when Seedance's own filter refuses the same beat written as text.

Before-and-after and transition pairs

Send last_image_url with image_url and the shot has to land on the closing still. The published example fills a bare room with a rug, a sofa and lamps over ten seconds with the camera locked, which is the shape of a renovation reveal or a product transformation.

Draft at 480p, deliver at 720p

Sweep cheap 480p passes until the action and the framing read, then re-run the same request at 720p for the take you keep. Resolution changes the delivered format only; it adds no detail the first frame does not already have.

# Generate the idempotency key once; reuse it when retrying after a lost response.
export SPICY_IDEMPOTENCY_KEY="${SPICY_IDEMPOTENCY_KEY:-$(uuidgen)}"
curl -X POST https://api.spicyapi.ai/api/v1/jobs/createTask \
  -H "Authorization: Bearer $SPICY_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: $SPICY_IDEMPOTENCY_KEY" \
  -d '{
  "model": "bytedance/seedance-2.0-fast/image-to-video",
  "input": {
    "aspect_ratio": "adaptive",
    "bitrate_mode": "standard",
    "duration_seconds": 5,
    "generate_audio": true,
    "image_url": "https://example.com/reference.png",
    "prompt": "A slow aerial shot drifting over a misty pine forest at sunrise"
  }
}'

# Copy data.taskId from the response into TASK_ID, then poll the status.
TASK_ID="TASK_ID_FROM_RESPONSE"
curl "https://api.spicyapi.ai/api/v1/jobs/recordInfo?taskId=$TASK_ID" \
  -H "Authorization: Bearer $SPICY_API_KEY"

See the API reference for authentication, the complete schema, polling, and error handling.