Seedance 2.0 Fast (Video-Extend) extends an input video with a new cinematic continuation generated from its last frame and a natural-language prompt — at the faster, cheaper Seedance 2.0 Fast tier. Ready-to-use REST API, best performance, no coldstarts, affordable pricing.
Idle
$0.5per run·~20 / $10
ExamplesView all
Seamlessly continue from the previous frame in the same late-night interview studio. Keep all five people in the exact same positions and maintain their identities, clothing, hairstyles, facial features, and proportions. The background LED screen still clearly reads “TONIGHT: STRANGE WORLDS” with stable, readable text. The host leans forward slightly and asks a question, smiling with a relaxed expression. The four guests turn their attention toward the host, with subtle natural reactions: one nods thoughtfully, one smiles, one adjusts their hands on their lap, and one makes brief eye contact with another guest. The camera performs a slow gentle push-in, warm studio lighting remains consistent, audience silhouettes stay softly blurred, realistic motion, stable faces, cinematic TV show atmosphere.
Related Models
README
Seedance 2.0 Fast Video-Extend
Seedance 2.0 Fast Video-Extend is the faster, cheaper tier of Seedance 2.0 Video-Extend. It appends a new cinematic continuation to an existing video by generating a fresh segment from the input video's last frame and a natural-language prompt, then concatenating original and new segment into a single output.
Key Features
- Seamless continuation — Generation starts from the input video's last frame so the join is visually consistent.
- Optional target last frame — Provide
last_imageto steer the new segment toward a specific end frame. - Director-level control — Camera movement, lighting, shadows, and character performance via prompts.
- Native audio synchronization — Audio from both the original video and the new segment are preserved in the final output.
- Faster, cheaper — ~17% cheaper than the standard Seedance 2.0 Video-Extend at every resolution.
Parameters
| Parameter | Required | Description |
|---|---|---|
| prompt | Yes | Describe the cinematic continuation. |
| video | Yes | Input video URL. Generation continues from the last frame. |
| last_image | No | Optional target last-frame URL. Interpolates from the input's last frame to this image. |
| duration | No | Length in seconds of the new segment (4-15, default 5). |
| resolution | No | 480p, 720p (default), or 1080p. |
| enable_web_search | No | Enable web search for real-time context. |
How to Use
- Upload the input video. The new segment will be appended to it.
- Write the prompt. Describe the continuation in cinematic detail.
- (Optional) Upload a target last frame. The new segment will interpolate to this image.
- Pick a duration and resolution.
- Run. Receive the original video plus the new segment concatenated into one output.
Pricing
Billed per second of the new segment only. Resolution multipliers match Seedance 2.0 Fast image-to-video.
| Resolution | Per second |
|---|---|
| 480p | $0.10 |
| 720p | $0.20 |
| 1080p | $0.50 |
Examples (5s extension):
| Resolution | Cost |
|---|---|
| 480p | $0.50 |
| 720p | $1.00 |
| 1080p | $2.50 |
Notes
- Pricing is based on the new segment length only — the input video is not re-billed.
- Aspect ratio of the new segment matches the input video's last frame automatically.
- Native audio generation is included for the new segment; the original video's audio is preserved.
Related Models
- Seedance 2.0 Video-Extend — Standard tier of this model.
- Seedance 2.0 Fast Image-to-Video — Fast image-to-video generation.
- Seedance 2.0 Fast Video-Edit — Fast video-edit at 480p / 720p / 1080p.
Seedance 2.0 Fast Video Extend API — Quick start
Grab a WaveSpeedAI API key, then call POST https://api.wavespeed.ai/api/v3/bytedance/seedance-2.0-fast/video-extend with your input as JSON. The endpoint returns a prediction id; poll the prediction endpoint until status flips to completed, then read the output URL from data.outputs[0]. Examples for Seedance 2.0 Fast Video Extend below.
HTTP example
# Submit the prediction
curl -X POST "https://api.wavespeed.ai/api/v3/bytedance/seedance-2.0-fast/video-extend" \
-H "Content-Type: application/json" \
-H "Authorization: Bearer $WAVESPEED_API_KEY" \
-d '{
"prompt": "A cinematic shot of a city at sunset, soft golden light",
"video": "https://example.com/your-input.mp4",
"resolution": "720p",
"duration": 5,
"enable_web_search": false,
"generate_audio": true
}'
# Response includes a prediction id. Poll for the result:
curl -X GET "https://api.wavespeed.ai/api/v3/predictions/{request_id}/result" \
-H "Authorization: Bearer $WAVESPEED_API_KEY"
# When status is "completed", read the output from data.outputs[0].Node.js example
// npm install wavespeed
const WaveSpeed = require('wavespeed');
const client = new WaveSpeed(); // reads WAVESPEED_API_KEY from env
const result = await client.run("bytedance/seedance-2.0-fast/video-extend", {
"prompt": "A cinematic shot of a city at sunset, soft golden light",
"video": "https://example.com/your-input.mp4",
"resolution": "720p",
"duration": 5,
"enable_web_search": false,
"generate_audio": true
});
console.log(result.outputs[0]); // → URL of the generated outputPython example
# pip install wavespeed
import wavespeed
output = wavespeed.run(
"bytedance/seedance-2.0-fast/video-extend",
{
"prompt": "A cinematic shot of a city at sunset, soft golden light",
"video": "https://example.com/your-input.mp4",
"resolution": "720p",
"duration": 5,
"enable_web_search": false,
"generate_audio": true
}
)
print(output["outputs"][0]) # → URL of the generated outputSeedance 2.0 Fast Video Extend API — Frequently asked questions
What is the Seedance 2.0 Fast Video Extend API?
Seedance 2.0 Fast Video Extend is a ByteDance model for video extension, exposed as a REST API on WaveSpeedAI. Seedance 2.0 Fast (Video-Extend) extends an input video with a new cinematic continuation generated from its last frame and a natural-language prompt — at the faster, cheaper Seedance 2.0 Fast tier. Ready-to-use REST API, best performance, no coldstarts, affordable pricing. You can call it programmatically or try it from the playground above.
How do I call the Seedance 2.0 Fast Video Extend API?
POST your input parameters to the model's REST endpoint (shown in the API tab of this playground) with your WaveSpeedAI API key in the Authorization header. Submission returns a prediction ID; poll the prediction endpoint until status flips to "completed", then read the output URL from the result. The playground generates a ready-to-paste code sample in Python, JavaScript, or cURL for whatever inputs you've set. Full request/response shape is documented at https://wavespeed.ai/docs/docs-api/bytedance/bytedance-seedance-2.0-fast-video-extend.
How much does Seedance 2.0 Fast Video Extend cost per run?
Seedance 2.0 Fast Video Extend starts at $0.50 per run. That figure is the base price — the final charge scales with the parameters you set in the form (output size, length, count, references, or whatever knobs this model exposes), so a higher-quality or larger output costs more than a minimal one. The exact cost for your current input is shown live next to the Generate button before you submit, and the actual per-call charge is recorded on the prediction afterwards.
What inputs does Seedance 2.0 Fast Video Extend accept?
Key inputs: `prompt`, `video`, `resolution`, `duration`, `enable_web_search`, `generate_audio`. The full JSON schema (types, defaults, allowed values) is rendered above the Generate button and mirrored in the API reference at https://wavespeed.ai/docs/docs-api/bytedance/bytedance-seedance-2.0-fast-video-extend.
How do I get started with the Seedance 2.0 Fast Video Extend API?
Sign up for a free WaveSpeedAI account to claim starter credits, copy your API key from /accesskey, then call the endpoint shown in the API tab of the playground. The playground also auto-generates a code sample in Python, JavaScript, or cURL for the parameters you've set.
Can I use Seedance 2.0 Fast Video Extend outputs commercially?
Commercial usage rights depend on the model's license, set by its provider (ByteDance). The license summary appears on the model card above; see WaveSpeedAI's Terms of Service for platform-level conditions.