Flux 3 Video Extend Draft

bfl/flux-3/video-extend/draft

Flux 3 Extend Video Draft is BFL's video-to-video AI model. Transform, enhance, and edit video content using text prompts - from style changes to object manipulation and scene modification.

Use in agent Get API key

Base price: $0.60USD / run
Execution: async
Model type: video
Input fields: 5

Production route

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Playground

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Input

Prompt(string)

The text prompt describing the draft video.

Aspect Ratio(string)

Output aspect ratio. Follows the input when omitted. Allowed values: 21:9, 2:1, 16:9, 4:3, 1:1, 3:4, 9:16.

Video URL(string)

URL or data URI of the source MP4, at most 50 MiB.

Duration(integer)

Seconds of new footage to add after the source video (5-20). Allowed values: 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20.

Generate Audio(boolean)

Whether to generate audio for the draft video.

OutputReady

Your output will appear here

Complete the inputs, then click Run.

Model card

Specifications

Pricing

Base price: $0.60 / run

Context & modalities

Input: Schema-defined
Output: video

Capabilities

Chat: Not supported
Vision: Not supported
Reasoning: Not supported
Structured output: Not supported
Function calling: Not supported
Audio input: Not supported

Access

Provider: BFL
Model ID: bfl/flux-3/video-extend/draft
Execution: async
API: Unified Run API
Endpoint: /v1/run

API README

Flux 3 Video Extend Draft

Flux 3 Extend Video Draft belongs at the low-cost exploration of clip continuation stage of a visual workflow. Rather than treating the model as an isolated demonstration, teams can place it inside briefing, review, selection, and handoff practices where editors can audition several possible next beats before deciding which continuation deserves a full-quality pass. This positioning clarifies why the model earns a place in a real creative pipeline and what kind of decision it helps people make.

A practical use of Flux 3 Extend Video Draft is previsualization, alternate endings, pacing experiments, and rough editorial choices built around the final frame of an existing clip. Begin by agreeing on the creative objective and review criteria, prepare only the source material needed for that objective, and compare results against audience, brand, editorial, and production needs. Technical request choices remain documented below so the prose can stay focused on planning and creative value.

Highlights

Seamless audiovisual continuation. Carries movement, camera direction, dialogue, effects, and ambience across the join with the source clip.

Causal scene development. Predicts a plausible next event while preserving the physical and narrative logic already established.

Character and setting continuity. Maintains recognizable subjects, locations, and visual language as the sequence advances.

Synchronized sound evolution. Extends spoken performance and environmental audio together with the generated frames. The preview configuration favors inexpensive, fast exploration while preserving the approved subjects, composition, and action for a later full render.

Pricing

Option	Price
720p draft per second	$0.12
5 seconds	$0.60

Billed per requested second of new footage. The source video is not billed. Drafts also return draft_cache_url; pass it to Flux 3 Draft Enhance for a full-quality 1080p render.

When to Use

✅ Good fit	❌ Consider alternatives
The model's named workflow matches the source material and intended output	A different input modality or model route is required
A managed asynchronous result is suitable for the production pipeline	A synchronous, interactive editor is essential
The documented controls cover the required duration, framing, or format	The project needs controls outside this endpoint's schema
Creative iteration benefits from a repeatable request structure	Exact deterministic pixels, frames, geometry, or samples are mandatory
A finished downloadable media asset is the desired deliverable	Editable source layers or a native project file are required

Prompt Guide

For generation, state the intended result first, then add the subject or source treatment, progression, style, and delivery constraints. Keep one creative variable per phrase, use the documented field names for controls, and change one setting at a time when comparing results.

{
  "aspect_ratio": "21:9",
  "duration": 5,
  "prompt": "A red panda walks along a mossy log in a sunlit forest, one continuous unbroken shot.",
  "video": "https://example.com/source.mp4"
}

Technical Specs

Spec	Value
Model ID	`bfl/flux-3/extend-video/draft`
Inputs	aspect_ratio, duration, generate_audio, prompt, video
Required inputs	prompt
Output fields	content_type, url
Execution	Async (submit, then poll for result)
Duration	5 / 6 / 7 / 8 / 9 / 10 / 11 / 12 / 13 / 14 / 15 / 16 / 17 / 18 / 19 / 20
Aspect Ratio	21:9 / 16:9 / 3:2 / 4:3 / 5:4 / 1:1 / 4:5 / 3:4 / 2:3 / 9:16

Related Models

bfl/flux-3/extend-video — Compare this concrete local family route.
bfl/flux-3/draft-enhance — Compare this concrete local family route.
bfl/flux-3/first-last-frame-to-video — Compare this concrete local family route.

Start building

Send your first request

OpenAI-compatible endpoint with unified authentication and usage tracking.

Production API

Unified Run API endpoint

https://api.sandbase.ai/v1/run

Model ID

bfl/flux-3/video-extend/draft

# The quoted heredoc keeps Unicode and shell metacharacters unchanged.
result=$(curl --fail-with-body --silent \
  -X POST "https://api.sandbase.ai/v1/run" \
  -H "Authorization: Bearer $SANDBASE_API_KEY" \
  -H "Content-Type: application/json" \
  --data-binary @- <<'SANDBASE_JSON'
{
  "model": "bfl/flux-3/video-extend/draft",
  "video": "https://storage.googleapis.com/falserverless/example_inputs/flux-3-red-panda.mp4",
  "prompt": "A red panda walks along a mossy log in a sunlit forest, one continuous unbroken shot.",
  "duration": 5,
  "generate_audio": true
}
SANDBASE_JSON
)
run_id=$(printf '%s' "$result" | jq -r .id)
for attempt in $(seq 1 120); do
  status=$(printf '%s' "$result" | jq -r .status)
  case "$status" in completed|failed|timeout) break ;; esac
  sleep 2
  result=$(curl --fail-with-body --silent \
    -H "Authorization: Bearer $SANDBASE_API_KEY" \
    "https://api.sandbase.ai/v1/run/$run_id")
done
status=$(printf '%s' "$result" | jq -r .status)
[ "$status" = completed ] || { echo "Generation ended: $status" >&2; exit 1; }
printf '%s\n' "$result"

Choose your model

Compare models

All image & video models

Model	Type	Default price	Released
Flux 3 Video Extend DraftThis model `BFL`	Video	$0.60 / run	Aug 4, 2026
Flux 3 Text to Video `BFL`	Video	$0.85 / run	Aug 4, 2026
Flux 3 Image to Video `BFL`	Video	$0.85 / run	Aug 4, 2026
Flux 3 First-Last Frame to Video `BFL`	Video	$0.85 / run	Aug 4, 2026
Flux 3 Keyframes to Video `BFL`	Video	$0.85 / run	Aug 4, 2026
Flux 3 Video Extend `BFL`	Video	$2.05 / run	Aug 4, 2026

Questions

FAQ

How do I call BFL Flux 3 Video Extend Draft through SandBase?

Create a SandBase API key, then send requests with the model ID "bfl/flux-3/video-extend/draft" to Unified Run API (/v1/run) at https://api.sandbase.ai. The request examples on this page show the exact payload.

Do I need a separate BFL account?

No. One SandBase API key and balance gives you access to BFL Flux 3 Video Extend Draft and the other models in the catalog; you do not need to sign up with BFL separately.