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Seedance 2.0 Fast Video Extend

bytedance /

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.

video-extend
入力

待機中

$0.51回あたり·~20 / $10

サンプルすべて表示

Continue the video naturally from the last frame. The woman finishes getting into the vintage convertible, gently closes the car door, then places both hands on the steering wheel and starts driving forward. She looks ahead with a confident relaxed expression, the car smoothly pulls away from the gas station and moves onto the desert road. Natural body movement, realistic hand interaction with the door and steering wheel, subtle wind moving her hair. Keep the exact same woman, car, outfit, lighting, and camera angle. Minimal movement, fixed cinematic shot, realistic driving physics, smooth 5-second continuation.

関連モデル

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_image to 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

ParameterRequiredDescription
promptYesDescribe the cinematic continuation.
videoYesInput video URL. Generation continues from the last frame.
last_imageNoOptional target last-frame URL. Interpolates from the input's last frame to this image.
durationNoLength in seconds of the new segment (4-15, default 5).
resolutionNo480p, 720p (default), 1080p, or 4k.
enable_web_searchNoEnable web search for real-time context.

How to Use

  1. Upload the input video. The new segment will be appended to it.
  2. Write the prompt. Describe the continuation in cinematic detail.
  3. (Optional) Upload a target last frame. The new segment will interpolate to this image.
  4. Pick a duration and resolution.
  5. 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.

ResolutionPer second
480p$0.10
720p$0.20
1080p$0.50
4k$1.00

Examples (5s extension):

ResolutionCost
480p$0.50
720p$1.00
1080p$2.50
4k$5.00

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

注記:本サイトは第三者が提供するAIモデルを使用しています。

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. Start polling the result endpoint around every 2 seconds, increase the interval for long-running tasks, and stop on any terminal status. On completed, read output values from data.outputs. Examples for Seedance 2.0 Fast Video Extend below.

HTTP example
set -euo pipefail

: "${WAVESPEED_API_KEY:?Set WAVESPEED_API_KEY}"

REQUEST_BODY=$(cat <<'JSON'
{
    "prompt": "A cinematic shot of a city at sunset, soft golden light",
    "video": "https://interactive-examples.mdn.mozilla.net/media/cc0-videos/flower.mp4",
    "resolution": "720p",
    "duration": 5,
    "enable_web_search": false,
    "generate_audio": true
}
JSON
)

# 1. Submit the prediction.
SUBMIT_RESPONSE=$(curl --silent --show-error --fail-with-body \
  -X POST "https://api.wavespeed.ai/api/v3/bytedance/seedance-2.0-fast/video-extend" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $WAVESPEED_API_KEY" \
  -d "$REQUEST_BODY")

TASK=$(printf '%s' "$SUBMIT_RESPONSE" | jq 'if has("data") then .data else . end')
PREDICTION_ID=$(printf '%s' "$TASK" | jq -r '.id')
if [ -z "$PREDICTION_ID" ] || [ "$PREDICTION_ID" = "null" ]; then
  printf 'Submission response did not contain a prediction id
' >&2
  exit 1
fi
RESULT_URL=$(printf '%s' "$TASK" | jq -r '.urls.get // empty')
if [ -z "$RESULT_URL" ]; then
  RESULT_URL="https://api.wavespeed.ai/api/v3/predictions/$PREDICTION_ID/result"
fi

# 2. Poll until the prediction finishes.
while true; do
  RESPONSE=$(curl --silent --show-error --fail-with-body "$RESULT_URL" \
    -H "Authorization: Bearer $WAVESPEED_API_KEY")
  RESULT=$(printf '%s' "$RESPONSE" | jq 'if has("data") then .data else . end')
  STATUS=$(printf '%s' "$RESULT" | jq -r '.status')
  case "$STATUS" in
    completed) printf '%s\n' "$RESULT" | jq '.outputs'; break ;;
    failed|cancelled|timeout) printf '%s\n' "$RESULT" | jq . >&2; exit 1 ;;
    created|processing) sleep 2 ;;
    *) printf 'Unexpected status: %s
' "$STATUS" >&2; exit 1 ;;
  esac
done
Node.js example
const submitUrl = "https://api.wavespeed.ai/api/v3/bytedance/seedance-2.0-fast/video-extend";
const apiKey = process.env.WAVESPEED_API_KEY;
if (!apiKey) throw new Error('Set WAVESPEED_API_KEY');

async function requestJson(url, options = {}) {
  const response = await fetch(url, options);
  if (!response.ok) throw new Error(await response.text());
  return response.json();
}

// 1. Submit the prediction.
const body = await requestJson(submitUrl, {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${apiKey}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
        "prompt": "A cinematic shot of a city at sunset, soft golden light",
        "video": "https://interactive-examples.mdn.mozilla.net/media/cc0-videos/flower.mp4",
        "resolution": "720p",
        "duration": 5,
        "enable_web_search": false,
        "generate_audio": true
}),
});
const task = body.data ?? body;
if (!task.id) throw new Error("Submission response did not contain a prediction id");
const resultUrl = task.urls?.get ||
  `https://api.wavespeed.ai/api/v3/predictions/${task.id}/result`;

// 2. Poll until the prediction finishes.
while (true) {
  const resultBody = await requestJson(resultUrl, {
    headers: { "Authorization": `Bearer ${apiKey}` },
  });
  const result = resultBody.data ?? resultBody;
  if (result.status === "completed") {
    console.log(result.outputs);
    break;
  }
  if (["failed", "cancelled", "timeout"].includes(result.status)) throw new Error(JSON.stringify(result));
  if (!["created", "processing"].includes(result.status)) throw new Error("Unexpected status: " + result.status);
  await new Promise(resolve => setTimeout(resolve, 2000));
}
Python example
import json
import os
import time
from urllib.request import Request, urlopen

api_key = os.environ["WAVESPEED_API_KEY"]
headers = {"Authorization": f"Bearer {api_key}", "Content-Type": "application/json"}
payload = {
    "prompt": "A cinematic shot of a city at sunset, soft golden light",
    "video": "https://interactive-examples.mdn.mozilla.net/media/cc0-videos/flower.mp4",
    "resolution": "720p",
    "duration": 5,
    "enable_web_search": False,
    "generate_audio": True
}

def request_json(url, data=None):
    request = Request(url, data=data, headers=headers, method="POST" if data else "GET")
    with urlopen(request) as response:
        return json.load(response)

# 1. Submit the prediction.
body = request_json("https://api.wavespeed.ai/api/v3/bytedance/seedance-2.0-fast/video-extend", json.dumps(payload).encode())
task = body.get("data", body)
if not task.get("id"):
    raise RuntimeError("Submission response did not contain a prediction id")
result_url = task.get("urls", {}).get("get") or f"https://api.wavespeed.ai/api/v3/predictions/{task['id']}/result"

# 2. Poll until the prediction finishes.
while True:
    result_body = request_json(result_url)
    result = result_body.get("data", result_body)
    status = result.get("status")
    if status == "completed":
        print(result.get("outputs", []))
        break
    if status in {"failed", "cancelled", "timeout"}:
        raise RuntimeError(result)
    if status not in {"created", "processing"}:
        raise RuntimeError(f"Unexpected status: {status}")
    time.sleep(2)

Seedance 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 result endpoint starting around every 2 seconds, increase the interval for long-running tasks, and stop on any terminal status. The playground generates production-oriented Python, JavaScript, and cURL examples with timeouts, transient-error handling, and safe GET retries. 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 long does Seedance 2.0 Fast Video Extend take to generate?

Median end-to-end generation time on WaveSpeedAI is around 217 seconds per request, based on recent successful runs. Queue time varies with global demand; live status is visible in the prediction record.

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.

Seedance 2.0 Fast Video Extend | AI Video Extension API | WaveSpeedAI