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Seedance 1.5 Pro Video-Extend turns short video clips into longer videos with natural motion continuation, stable aesthetics, and upscaled output. It supports 4–12s duration control, multiple aspect ratios/resolutions, and seed-reproducible results—ideal for extending ad creatives and short-drama shots. Built for stable production use with a ready-to-use REST API, no cold starts, and predictable pricing.

video-extend
Input

Idle

$0.26per run·~38 / $10

ExamplesView all

The ball is lighting at the end

A woman kisses a man in the kitchen

A man comes and kisses the woman. The woman stays in the chair.

The woman hugs the dog at the end

The woman in the front is eating a cake

Related Models

README

Seedance V1.5 Pro — Video Extend

Seedance V1.5 Pro (Video Extend) extends an existing video into a longer clip while preserving motion continuity, subject identity, and scene coherence. Use a prompt to guide what happens next, set duration and resolution, and optionally enable audio generation for the extended segment.

Why it stands out

  • Smooth continuation that matches the original clip’s rhythm and aesthetics
  • Prompt-guided extension to steer action, mood, and camera behavior
  • Resolution options with transparent multipliers (480p / 720p)
  • Optional audio generation with clear pricing impact

Key Capabilities

  • Natural motion continuation Extends movement with consistent pacing and visual logic.

  • Scene coherence preservation Maintains lighting, framing, and subject consistency across the extension.

  • Prompt-guided direction Describe the next action and constraints without rebuilding the scene.

  • Optional audio generation Enable or disable audio generation depending on your workflow needs.

Parametrs

ParameterDescription
video*Input video (public URL or uploaded file reference, depending on client).
prompt*Describe what should happen next and what must remain consistent.
durationOutput duration in seconds (commonly used values: 4–12s; exact allowed values depend on endpoint validation).
resolutionOutput resolution: 720p or 480p.
generate_audioWhether to generate audio for the output video (true/false).
camera_fixedWhether to fix the camera position (true/false).
seedRandom seed (-1 for random; set a fixed integer for reproducible results).

Prompt Tips

Write prompts like a continuation brief:

  • Describe what happens next (action + timing)
  • Add motion intensity (subtle / smooth / dynamic)
  • Specify camera behavior if needed (fixed / slow pan / gentle zoom)
  • Add constraints: “keep the same character, outfit, lighting, framing”

Example prompts:

  • Continue the scene with the subject holding the glowing ball, the light intensifies near the end, keep the same camera angle and lighting style.
  • Extend with subtle hand movement and a slow push-in, keep the subject centered and the environment unchanged.

Pricing

Reference pricing (generate_audio = true)

ResolutionPrice per secondExample (5s)Example (10s)
720p$0.052$0.26$0.52
480p$0.024$0.12$0.24

Reference pricing (generate_audio = false)

ResolutionPrice per secondExample (5s)Example (10s)
720p$0.026$0.13$0.26
480p$0.012$0.06$0.12

Best Practices

  • Use clean input videos (clear subject, stable exposure, minimal compression artifacts).
  • Keep prompts specific but short, and explicitly state what must stay the same.
  • Start with 5 seconds to validate motion and framing before extending longer.
  • Use a fixed seed when iterating to compare small prompt changes.

Use Cases

  • Ad creative extension (turn short shots into longer deliverables)
  • Social content variations (longer cuts from a base clip)
  • Storytelling continuity (extend key moments with controlled motion)
  • Marketing edits (extend hero scenes with stable aesthetics)

Notes

  • The input video must be accessible to the runtime (public URL or valid uploaded reference).
  • If motion drifts or the scene changes too much, add stronger constraints: “keep camera fixed”, “same outfit and lighting”, “do not change background”.
  • Supported durations and modes can vary by deployment; rely on the endpoint UI/validator for exact allowed values.

Related Models

Note:This website uses AI models provided by third parties. Documentation prices are for reference and may be outdated. The Generate button shows an estimate; the final task charge prevails.

Seedance v1.5 Pro Video Extend API — Quick start

Grab a WaveSpeedAI API key, then call POST https://api.wavespeed.ai/api/v3/bytedance/seedance-v1.5-pro/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 v1.5 Pro 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",
    "duration": 5,
    "resolution": "720p",
    "generate_audio": true,
    "camera_fixed": false,
    "seed": -1
}
JSON
)

# 1. Submit the prediction.
SUBMIT_RESPONSE=$(curl --silent --show-error --fail-with-body \
  -X POST "https://api.wavespeed.ai/api/v3/bytedance/seedance-v1.5-pro/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-v1.5-pro/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 ${apiKey}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
        "prompt": "A cinematic shot of a city at sunset, soft golden light",
        "video": "https://interactive-examples.mdn.mozilla.net/media/cc0-videos/flower.mp4",
        "duration": 5,
        "resolution": "720p",
        "generate_audio": true,
        "camera_fixed": false,
        "seed": -1
}),
});
const task = body.data ?? body;
if (!task.id) throw new Error("Submission response did not contain a prediction id");
const resultUrl = task.urls?.get ||
  `https://api.wavespeed.ai/api/v3/predictions/${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",
    "duration": 5,
    "resolution": "720p",
    "generate_audio": True,
    "camera_fixed": False,
    "seed": -1
}

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-v1.5-pro/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 v1.5 Pro Video Extend API — Frequently asked questions

What is the Seedance v1.5 Pro Video Extend API?

Seedance v1.5 Pro Video Extend is a ByteDance model for video extension, exposed as a REST API on WaveSpeedAI. Seedance 1.5 Pro Video-Extend turns short video clips into longer videos with natural motion continuation, stable aesthetics, and upscaled output. It supports 4–12s duration control, multiple aspect ratios/resolutions, and seed-reproducible results—ideal for extending ad creatives and short-drama shots. Built for stable production use with a ready-to-use REST API, no cold starts, and predictable pricing. You can call it programmatically or try it from the playground above.

How do I call the Seedance v1.5 Pro 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-v1.5-pro-video-extend.

How much does Seedance v1.5 Pro Video Extend cost per run?

Seedance v1.5 Pro Video Extend starts at $0.26 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 v1.5 Pro Video Extend accept?

Key inputs: `prompt`, `video`, `resolution`, `duration`, `seed`, `camera_fixed`. 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-v1.5-pro-video-extend.

How long does Seedance v1.5 Pro Video Extend take to generate?

Median end-to-end generation time on WaveSpeedAI is around 146 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 v1.5 Pro 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 V1.5 Pro Video Extend | AI Video Extension API on WaveSpeedAI