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FLUX 3 Start-End to Video: Image-to-Video

Generate a video transition between a start and end keyframe with native audio using FLUX 3. Try free — pay per generation, no subscription. FLUX 3 Start-End to Video generates a video transition between a start and end keyframe, with optional native synchronized audio, using Black Forest Labs' unified image/video/audio architecture.

Interactive model controls

FLUX 3 Start-End to Video generates a video transition between a start and end keyframe, with optional native synchronized audio, using Black Forest Labs' unified image/video/audio architecture.

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Overview

About this model

FLUX 3 Start-End to Video generates a video transition between a start and end keyframe, with optional native synchronized audio, using Black Forest Labs' unified image/video/audio architecture. Describe how the two frames should connect and FLUX 3 fills in physically plausible motion between them — useful for precise camera moves, lighting transitions, and object transformations that FLUX 3 Image to Video alone can't pin down.

1Transitions: Morph between a before-and-after pair with controlled motion.
2Product Reveals: Transition a product from packaged to unboxed states.
3Time-of-Day Shifts: Move a scene from day to night with matching lighting cues.
4Storyboarding: Lock down both the opening and closing frame of a planned shot.
5Style Bridges: Transition between two distinct visual styles or scenes.
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Pricing & Value

Cost analysis

muapiapp$0.25/sec (720p), $0.42/sec (1080p)

Pay-per-generation pricing, no subscription required. Audio generation included at no extra charge.

Fal.aiNot available

FLUX 3 Start-End to Video is not yet listed on Fal.ai.

ReplicateNot available

FLUX 3 Start-End to Video is not yet listed on Replicate.

** Competitor pricing is estimated based on similar model architectures and usage tiers.

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Technical Details

Configuration schema

Promptstring

Describe the action or transformation connecting the start and end images.

Default ValueThe scene morphs from a busy daytime street to the same street quiet at night, streetlights turning on.
Start Image URLstring

Initial visual keyframe for the transition.

Default Valuehttps://d3adwkbyhxyrtq.cloudfront.net/ai-images/186/712345784292/4a8c5c70-abcc-4920-873e-b0e219986453.jpg
End Image URLstring

Final visual keyframe for the transition.

Default Valuehttps://d3adwkbyhxyrtq.cloudfront.net/ai-images/186/712345784292/4a8c5c70-abcc-4920-873e-b0e219986453.jpg
Aspect RatioEnum (6 options)

Aspect ratio of the output video.

Default Value16:9
Durationint

Video duration in seconds.

Default Value5
ResolutionEnum (2 options)

Output video resolution.

Default Value720p
Generate Audioboolean

Whether to generate synchronized native audio for the video.

Default Valuetrue
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Implementation Guide

Developer documentation

How to Use FLUX 3 Start-End to Video

  1. Upload a start image via image_url and an end image via end_image_url.

  2. Write a transition prompt — describe the action or transformation connecting the two frames.

  3. Configure output — set resolution (720p or 1080p) and duration (5–20 seconds); aspect_ratio is optional.

  4. Toggle generate_audio for synchronized native audio at no extra charge.

  5. Submit the request:

curl -X POST https://api.muapi.ai/api/v1/flux-3-start-end-to-video \
  -H "x-api-key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"prompt": "The scene morphs from a busy daytime street to the same street quiet at night", "image_url": "https://example.com/start.jpg", "end_image_url": "https://example.com/end.jpg", "resolution": "1080p", "duration": 5, "generate_audio": true}'
  1. Poll /api/v1/predictions/{request_id}/result until completed.
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Common Questions

Frequently asked

What is FLUX 3 Start-End to Video?

It generates a video transition between two keyframes you supply — a start image and an end image — with optional native synchronized audio.

How is this different from FLUX 3 Image to Video?

FLUX 3 Image to Video animates from a single starting frame with open-ended motion. Start-End to Video locks down both the first and last frame, giving precise control over where the clip ends up.

Does it generate audio?

Yes, native synchronized audio can be toggled with the `generate_audio` parameter at no extra charge.

What resolutions and durations are supported?

720p and 1080p resolution, with durations from 5 to 20 seconds, billed rounded up to the next whole second.

How much does FLUX 3 Start-End to Video cost?

Muapi bills $0.25/second at 720p and $0.42/second at 1080p, rounded up to the next whole second, capped at 20 seconds.