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.
Idle
$0.6per run·~16 / $10
Continue seamlessly as the employee and the cleaning robot race toward the end of the aisle. The robot takes a shortcut around a display while the employee quickly turns into the next aisle. A customer watches them in confusion. They reach the checkout area almost at the same time, and the employee raises his mop in playful victory while the robot slowly bumps into his shoe. The camera follows smoothly and ends on their funny standoff. Preserve the same employee, store, robot, lighting, and movement direction.
FLUX 3 Draft Video Extend quickly continues a required input video into a draft extension guided by your prompt. Use it to test what should happen next, how the camera should move, and how the visual style should continue before moving to a final-quality workflow.
Video extension draft generation
Continue an existing video with a prompt-guided draft extension.
Fast continuation testing
Test next-scene action, visual continuity, subject behavior, camera movement, pacing, and atmosphere.
Prompt-guided scene development
Describe how the video should continue after the source clip ends.
Optional synchronized audio
Generate matching audio for early ambience, effects, music, or dialogue tests.
Flexible duration
Choose a draft extension duration from 5 to 20 seconds.
Multiple aspect ratios
Supports landscape, portrait, square, and cinematic formats.
| Parameter | Required | Description |
|---|---|---|
| prompt | Yes | Describe the next action, scene development, camera movement, mood, lighting, and visual continuity. |
| video | Yes | Input MP4 video used as the starting point. The source must be under 50 MB and under 15 seconds. |
| aspect_ratio | No | Output aspect ratio. Options: 21:9, 2:1, 16:9, 4:3, 1:1, 3:4, or 9:16. |
| duration | No | Duration of the draft extension in seconds. Range: 5–20. Default: 5. |
| generate_audio | No | Generate synchronized audio for the draft extension. Default: true. |
5 to 20 seconds.generate_audio when you want to test ambience, effects, music, or dialogue.Pricing is based on billed extension duration.
Billed duration is rounded up to the next whole second and capped at 20 seconds. Audio generation does not add a separate charge.
| Billing Unit | Price |
|---|---|
| Per 5s | $0.60 |
| Per second | $0.12 |
| Duration | Billed Duration | Cost |
|---|---|---|
| 5s | 5s | $0.60 |
| 10s | 10s | $1.20 |
| 15s | 15s | $1.80 |
| 20s | 20s | $2.40 |
Grab a WaveSpeedAI API key, then call POST https://api.wavespeed.ai/api/v3/black-forest-labs/flux-3/video-extend-draft with your input as JSON. The endpoint returns a prediction id. Start polling the result endpoint around every 2 seconds, increase the interval for long-running tasks, and stop on any terminal status. On completed, read output values from data.outputs. Examples for Flux 3 Video Extend Draft below.
set -euo pipefail
: "${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="https://api.wavespeed.ai/api/v3/predictions/$PREDICTION_ID/result"
# 2. Poll until the prediction finishes.
while true; do
RESPONSE=$(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' "$RESULT" | jq '.outputs'; break ;;
failed|cancelled|timeout|deleted) printf '%s\n' "$RESULT" | jq . >&2; exit 1 ;;
*) sleep 2 ;;
esac
doneconst 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 ${apiKey}`,
"Content-Type": "application/json",
},
body: JSON.stringify({
"prompt": "A cinematic shot of a city at sunset, soft golden light",
"video": "https://interactive-examples.mdn.mozilla.net/media/cc0-videos/flower.mp4",
"aspect_ratio": "21:9",
"duration": 5,
"generate_audio": true
}),
});
const task = body.data ?? body;
if (!task.id) throw new Error("Submission response did not contain a prediction id");
const resultUrl = `https://api.wavespeed.ai/api/v3/predictions/${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", "deleted"].includes(result.status)) throw new Error(JSON.stringify(result));
await new Promise(resolve => setTimeout(resolve, 2000));
}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 = 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", "deleted"}:
raise RuntimeError(result)
time.sleep(2)Flux 3 Video Extend Draft is a Black Forest Labs model for video extension, 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.
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 Python, JavaScript, and cURL examples for submitting requests and polling results. Full request/response shape is documented at https://wavespeed.ai/docs/docs-api/black-forest-labs/black-forest-labs-flux-3-video-extend-draft.
Flux 3 Video Extend Draft starts at $0.6 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.
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.
Reported generation time on WaveSpeedAI is around 83 seconds per request. This is an estimate, not a latency guarantee; queue time and input settings can change the total wait. live status is visible in the prediction record.
Commercial usage rights depend on the model's license, set by its provider (Black Forest Labs). Check the provider's applicable terms and WaveSpeedAI's Terms of Service before commercial use.