Seedance V1.5 Pro Video Extend | AI Video Extension API

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

Parameter	Description
video*	Input video (public URL or uploaded file reference, depending on client).
prompt*	Describe what should happen next and what must remain consistent.
duration	Output duration in seconds (commonly used values: 4–12s; exact allowed values depend on endpoint validation).
resolution	Output resolution: 720p or 480p.
generate_audio	Whether to generate audio for the output video (true/false).
camera_fixed	Whether to fix the camera position (true/false).
seed	Random 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)

Resolution	Price per second	Example (5s)	Example (10s)
720p	$0.052	$0.26	$0.52
480p	$0.024	$0.12	$0.24

Reference pricing (generate_audio = false)

Resolution	Price per second	Example (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

Seedance V1.5 Pro Video Extend Fast — Faster processing with higher-resolution options for rapid iteration and production outputs.
Seedance V1.5 Pro (Text-to-Video) — Generate new videos from text prompts for end-to-end creation.
Seedance V1.5 Pro (Image-to-Video) — Animate still images into videos with guided motion and stable aesthetics.

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; poll the prediction endpoint until status flips to completed, then read the output URL from data.outputs[0]. Examples for Seedance v1.5 Pro Video Extend below.

HTTP example

# Submit the prediction
curl -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 '{
    "prompt": "A cinematic shot of a city at sunset, soft golden light",
    "video": "https://example.com/your-input.mp4",
    "duration": 5,
    "resolution": "720p",
    "generate_audio": true,
    "camera_fixed": false,
    "seed": -1
}'

# 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-v1.5-pro/video-extend", {
        "prompt": "A cinematic shot of a city at sunset, soft golden light",
        "video": "https://example.com/your-input.mp4",
        "duration": 5,
        "resolution": "720p",
        "generate_audio": true,
        "camera_fixed": false,
        "seed": -1
});

console.log(result.outputs[0]); // → URL of the generated output

Python example

# pip install wavespeed
import wavespeed

output = wavespeed.run(
    "bytedance/seedance-v1.5-pro/video-extend",
    {
    "prompt": "A cinematic shot of a city at sunset, soft golden light",
    "video": "https://example.com/your-input.mp4",
    "duration": 5,
    "resolution": "720p",
    "generate_audio": true,
    "camera_fixed": false,
    "seed": -1
}
)

print(output["outputs"][0])  # → URL of the generated output

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 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-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?

Average end-to-end generation time on WaveSpeedAI is around 185 seconds per request — measured across recent runs. Queue time scales 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.

ExamplesView all

Related Models

README

Seedance V1.5 Pro — Video Extend

Why it stands out

Key Capabilities

Parametrs

Prompt Tips

Pricing

Reference pricing (generate_audio = true)

Reference pricing (generate_audio = false)

Best Practices

Use Cases

Notes

Related Models

Seedance v1.5 Pro Video Extend API — Quick start

Seedance v1.5 Pro Video Extend API — Frequently asked questions