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FLUX 3 Start-End-to-Video Draft quickly generates a transition between required start and end images, with prompt-guided motion, optional synchronized audio, and flexible 5-20 second duration for rapid keyframe iteration.

image-to-video
Input

Idle

$0.3per run·~33 / $10

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FLUX 3 Draft - Start-End-to-Video

FLUX 3 Draft Start-End-to-Video quickly generates a transition between a required starting image and a required ending image. Use the prompt to test the action, transformation, camera movement, pacing, and visual style that connect the two keyframes before moving to a final-quality workflow.

Key Capabilities

  • Create quick transition previews between a start image and an end image.
  • Test subject movement, transformations, camera paths, environment changes, and pacing.
  • Optionally generate synchronized audio for early transition and sound tests.
  • Choose a duration from 5 to 20 seconds.
  • Support landscape, portrait, square, and cinematic aspect ratios.

Parameters

ParameterRequiredDescription
promptYesDescribe the action or transformation connecting the start and end images, including camera movement, timing, mood, lighting, and style.
start_imageYesImage used as the first visual keyframe.
end_imageYesImage used as the final visual keyframe.
aspect_ratioNoOutput aspect ratio. Options: 21:9, 2:1, 16:9, 4:3, 1:1, 3:4, or 9:16.
durationNoDraft video duration in seconds. Choose an integer from 5 to 20. Default: 5.
generate_audioNoGenerate synchronized audio for the draft transition. Default: true.

How to Use

  1. Provide the image that should appear at the beginning of the transition.
  2. Provide the image that should appear at the end of the transition.
  3. Describe the movement, transformation, camera path, and pacing between the keyframes.
  4. Choose the aspect ratio and duration for the draft preview.
  5. Enable generate_audio when you want to test matching ambience, effects, music, or dialogue.

Prompting Tips

  • Describe the visual path from the start image to the end image rather than listing unrelated scenes.
  • Explain what moves, transforms, appears, disappears, or changes between the keyframes.
  • Use camera directions such as dolly-in, pull-back, orbit, tracking shot, or crane movement.
  • Start with a simple transition, then refine the prompt after reviewing the first draft.

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

  • Product reveals, logo transitions, and before-and-after concepts.
  • Character transformations and outfit or environment changes.
  • Keyframe-based story moments and social-media transitions.
  • Quickly comparing different motion paths between two defined states.

Notes

  • Prompt, start_image, and end_image are required.
  • Use visually compatible start and end images when you want a smoother transition.
  • 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 Start End To Video Draft API — Quick start

Grab a WaveSpeedAI API key, then call POST https://api.wavespeed.ai/api/v3/black-forest-labs/flux-3/start-end-to-video-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 Start End To Video 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",
    "start_image": "https://interactive-examples.mdn.mozilla.net/media/cc0-images/painted-hand-298-332.jpg",
    "end_image": "https://interactive-examples.mdn.mozilla.net/media/cc0-images/painted-hand-298-332.jpg",
    "aspect_ratio": "21:9",
    "resolution": "720p",
    "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/start-end-to-video-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/start-end-to-video-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 ${apiKey}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
        "prompt": "A cinematic shot of a city at sunset, soft golden light",
        "start_image": "https://interactive-examples.mdn.mozilla.net/media/cc0-images/painted-hand-298-332.jpg",
        "end_image": "https://interactive-examples.mdn.mozilla.net/media/cc0-images/painted-hand-298-332.jpg",
        "aspect_ratio": "21:9",
        "resolution": "720p",
        "duration": 5,
        "generate_audio": true
}),
});
const task = body.data ?? body;
if (!task.id) throw new Error("Submission response did not contain a prediction id");
const resultUrl = task.urls?.get ||
  `https://api.wavespeed.ai/api/v3/predictions/${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",
    "start_image": "https://interactive-examples.mdn.mozilla.net/media/cc0-images/painted-hand-298-332.jpg",
    "end_image": "https://interactive-examples.mdn.mozilla.net/media/cc0-images/painted-hand-298-332.jpg",
    "aspect_ratio": "21:9",
    "resolution": "720p",
    "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/start-end-to-video-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 Start End To Video Draft API — Frequently asked questions

What is the Flux 3 Start End To Video Draft API?

Flux 3 Start End To Video Draft is a Black Forest Labs model for video generation from images, exposed as a REST API on WaveSpeedAI. FLUX 3 Start-End-to-Video Draft quickly generates a transition between required start and end images, with prompt-guided motion, optional synchronized audio, and flexible 5-20 second duration for rapid keyframe iteration. You can call it programmatically or try it from the playground above.

How do I call the Flux 3 Start End To Video 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-start-end-to-video-draft.

How much does Flux 3 Start End To Video Draft cost per run?

Flux 3 Start End To Video Draft starts at $0.30 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 Start End To Video Draft accept?

Key inputs: `prompt`, `aspect_ratio`, `resolution`, `duration`, `end_image`, `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-start-end-to-video-draft.

How do I get started with the Flux 3 Start End To Video 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 Start End To Video 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.