Video Extension

Seedance 2.5 generates new footage that continues an existing video (forward) or leads into it (backward). The result is only the newly generated part, without the video you send: to get the whole video, join the two yourself.

Create a task

Use the shared create endpoint with model: "seedance-2.5". It usually responds in under 1 second and the cost is frozen within a few seconds; the video usually takes several minutes. Get the result once the task has finished.

Headers

Body

aspect_ratio isn't accepted (the new part follows the video you extend), and neither are image_urls, video_urls and audio_urls: sending any of them returns 400 invalid_request with param set to it (for example aspect_ratio is not allowed for mode video_extension; the output follows the source video).

Continue a video for 5 more seconds, 720p:

curl https://api.nanoapi.ai/v1/tasks \
  -H "Authorization: Bearer $NANOAPI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "seedance-2.5",
    "mode": "video_extension",
    "video_url": "https://example.com/source.mp4",
    "extension_mode": "forward",
    "prompt": "Continue the scene smoothly",
    "resolution": "720p",
    "duration": 5
  }'

Response: 200 OK. data is the newly created task, with only these fields; each one is described in Create a task: Response. Keep data.id to get the result: once the task succeeds, the new part is at data.outputs[0].url of the retrieved task or the webhook. The task can still fail after it's created (for example the video can't be downloaded), so go by what retrieving the task or the webhook tells you.

{
  "code": 200,
  "message": "success",
  "data": {
    "object": "task",
    "id": "tk_01jbd2s8x4c6v9b3n5m7q1w4e8",
    "model": "seedance-2.5",
    "status": "queued",
    "error": null,
    "created_at": "2026-10-31T08:30:00Z"
  }
}

Pricing

cost = duration × price per second of the resolution

Loading the current prices…

Example: the request above (720p, 5 seconds) costs 5 × the 720p price per second.

Billed seconds are the duration of the new part, however long the video you extend is. Prices change, so read the current ones from GET /v1/products (the prices rows whose mode is this mode) instead of hard-coding them; billing.frozen on the retrieved task is what counts. All Seedance 2.5 prices: Seedance 2.5 → Pricing.

Errors

Create request errors: the request fails with an HTTP error and no task is created. Specific to this mode:

Other errors of the create endpoint (401, 402, 429 and so on): Create a task → Errors.

Task failures: the create request succeeded (200) and the task later turned failed. There's no HTTP status: the reason is the task's error.type, from retrieving the task or the webhook.

Failure reasons shared by every mode (such as a balance too low for the task): Seedance 2.5 → Errors; all of them: Failure reasons.