Black Forest Labs Flux 3 Video Extend Draft

Black Forest Labs Flux 3 Video Extend Draft

Playground

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.

Features

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

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 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.

Authentication

For authentication details, please refer to the Authentication Guide.

API Endpoints

Submit Task & Query Result

set -euo pipefail

export WAVESPEED_API_KEY="your-api-key"

REQUEST_BODY=$(cat <<'JSON'
{
  "prompt": "A cinematic ocean wave at sunrise, highly detailed",
  "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 "Authorization: Bearer ${WAVESPEED_API_KEY}" \
  -H "Content-Type: application/json" \
  -d "${REQUEST_BODY}")

TASK=$(printf '%s' "${SUBMIT_RESPONSE}" | jq 'if type == "object" and has("data") then .data else . end')
PREDICTION_ID=$(printf '%s' "${TASK}" | jq -r '.id // empty')
if [ -z "${PREDICTION_ID}" ]; then
  printf 'Submission response did not contain a prediction id
' >&2
  exit 1
fi
RESULT_URL=$(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' "${RESPONSE}" | jq 'if type == "object" and has("data") then .data else . end')
  STATUS=$(printf '%s' "${RESULT}" | jq -r '.status // empty')

  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

Parameters

Task Submission Parameters

Request Parameters

Response Parameters

Result Request Parameters

Result Response Parameters