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FLUX 3 Video Extend Draft quickly continues a required input video into a draft clip with prompt-guided next-scene motion, optional synchronized audio, and flexible 5-20 second duration for rapid iteration.

video-to-video
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Idle

$0.6per run·~16 / $10

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README

FLUX 3 Draft - Video Extend

FLUX 3 Draft Video Extend quickly continues a required input video into a draft extension guided by your prompt. Test what should happen next, how the camera should move, and how the visual style should continue before producing a final-quality result.

Key Capabilities

  • Continue an existing video with prompt-guided next-scene action.
  • Test visual continuity, subject behavior, camera movement, pacing, and atmosphere.
  • Optionally generate synchronized audio for early continuation and sound tests.
  • Choose a draft duration from 5 to 20 seconds.
  • Support landscape, portrait, square, and cinematic aspect ratios.

Parameters

ParameterRequiredDescription
promptYesDescribe the next action, scene development, camera movement, mood, lighting, and visual continuity.
videoYesInput MP4 video used as the starting point. The source must be under 50 MB and under 15 seconds.
aspect_ratioNoOutput aspect ratio. Options: 21:9, 2:1, 16:9, 4:3, 1:1, 3:4, or 9:16.
durationNoDuration of the draft extension in seconds. Choose an integer from 5 to 20. Default: 5.
generate_audioNoGenerate synchronized audio for the draft extension. Default: true.

How to Use

  1. Upload an MP4 source video under 50 MB and under 15 seconds.
  2. Describe the next event or movement and explain how the scene should continue.
  3. Choose the aspect ratio and extension duration for the draft.
  4. Enable generate_audio when you want to test matching ambience, effects, music, or dialogue.
  5. Compare different continuation prompts and refine the strongest direction for production.

Prompting Tips

  • Begin with the next action rather than repeating the entire source video.
  • State continuity requirements such as keeping the same lighting, subject appearance, environment, or camera movement.
  • Describe the first visible action immediately after the source video ends.
  • Keep the draft prompt focused on one clear continuation event.

Pricing

Billing UnitPrice
Per second$0.06

Billing Rules

  • The billed duration is rounded up to the next whole second.
  • The minimum billed duration is 5 seconds.
  • The maximum billed duration is 20 seconds.
  • Audio generation does not add a separate charge in the current pricing formula.
  • Example: a 5-second draft costs $0.30.
  • Example: a 10-second draft costs $0.60.

Best Use Cases

  • Testing alternative next scenes and endings.
  • Extending product demonstrations and character actions.
  • Exploring camera and pacing continuity.
  • Building social-video and advertising concepts from existing footage.

Notes

  • An input video and prompt are both required.
  • The source video must be MP4, under 50 MB, and under 15 seconds.
  • Draft outputs are intended for exploration and iteration.
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.

Flux 3 Video Extend Draft API — Quick start

Grab a WaveSpeedAI API key, then call POST https://api.wavespeed.ai/api/v3/black-forest-labs/flux-3/video-extend-draft 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 Flux 3 Video Extend Draft 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",
    "aspect_ratio": "21:9",
    "duration": 5,
    "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/black-forest-labs/flux-3/video-extend-draft" \
  -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/black-forest-labs/flux-3/video-extend-draft";
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 ${apiKey}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
        "prompt": "A cinematic shot of a city at sunset, soft golden light",
        "video": "https://interactive-examples.mdn.mozilla.net/media/cc0-videos/flower.mp4",
        "aspect_ratio": "21:9",
        "duration": 5,
        "generate_audio": true
}),
});
const task = body.data ?? body;
if (!task.id) throw new Error("Submission response did not contain a prediction id");
const resultUrl = task.urls?.get ||
  `https://api.wavespeed.ai/api/v3/predictions/${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",
    "aspect_ratio": "21:9",
    "duration": 5,
    "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/black-forest-labs/flux-3/video-extend-draft", 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)

Flux 3 Video Extend Draft API — Frequently asked questions

What is the Flux 3 Video Extend Draft API?

Flux 3 Video Extend Draft is a Black Forest Labs model for video editing, exposed as a REST API on WaveSpeedAI. FLUX 3 Video Extend Draft quickly continues a required input video into a draft clip with prompt-guided next-scene motion, optional synchronized audio, and flexible 5-20 second duration for rapid iteration. You can call it programmatically or try it from the playground above.

How do I call the Flux 3 Video Extend Draft 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/black-forest-labs/black-forest-labs-flux-3-video-extend-draft.

How much does Flux 3 Video Extend Draft cost per run?

Flux 3 Video Extend Draft starts at $0.60 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 Flux 3 Video Extend Draft accept?

Key inputs: `prompt`, `video`, `aspect_ratio`, `duration`, `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/black-forest-labs/black-forest-labs-flux-3-video-extend-draft.

How do I get started with the Flux 3 Video Extend Draft 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 Flux 3 Video Extend Draft outputs commercially?

Commercial usage rights depend on the model's license, set by its provider (Black Forest Labs). The license summary appears on the model card above; see WaveSpeedAI's Terms of Service for platform-level conditions.