> ## Documentation Index > Fetch the complete documentation index at: https://docs.vidgo.ai/llms.txt > Use this file to discover all available pages before exploring further. # FLUX 3 Extend Video > Continue an existing video with FLUX 3, using a text prompt to guide the next part of the scene with optional sound. 1. Submit the request with `VIDGO_API_KEY`. A `task_id` is returned immediately. Keep it until the task reaches `finished` or `failed`. 2. Use [Query Task Status](/api-manual/task-management/status) to retrieve the result. If you provide a `callback_url`, Vidgo sends the result to your [webhook](/api-manual/task-management/webhooks) when the task finishes or fails. # FLUX 3 Extend Video Continue an existing video with FLUX 3, using a text prompt to guide the next part of the scene with optional sound. ## Available Models * **blackforestlabs/flux-3/extend-video** - Continue an existing video with a prompt describing the next part of the scene. ## Duration Options * **5-20 seconds** - Set `duration` as an integer. Default: **5 seconds**. * `duration` specifies the newly generated extension, not the length of the source video. ## Key Features * Continue an existing video with a prompt describing the next part of the scene. * Choose from `720p`, `1080p` output resolutions. * Control audio generation with `sound`; it defaults to `true`. ## Advanced Parameters Set `model` and optional `callback_url` at the request root. Place the parameters below inside `input`. Send only the input fields supported by this workflow. Unsupported `input` fields are rejected before credits are deducted. Input URLs must use HTTP(S), include a hostname, and contain no embedded credentials. ### Prompt * `prompt`: Required. Describe the scene and desired motion. * The prompt must not be blank when supplied. ### Source Video * `video_url`: Required. Provide one publicly accessible source video URL. ### Resolution * `resolution`: `720p`, `1080p`. Default: `720p`. ### Aspect Ratio * `aspect_ratio`: `auto`, `21:9`, `2:1`, `16:9`, `4:3`, `1:1`, `3:4`, `9:16`. Default: `auto`. ### Audio * `sound`: Set to `true` to enable generated audio, or `false` to disable it. Default: `true`. ## Pricing Pricing depends on the selected model and applicable output settings. Check the Vidgo dashboard for the current rate. Credits are deducted on submission and refunded if the task fails. ## OpenAPI ````yaml api-manual/video-series/blackforestlabs-flux-3-extend-video.json POST /api/generate/submit openapi: 3.0.0 info: title: Vidgo API - FLUX 3 Extend Video description: >- Continue an existing video with FLUX 3, using a text prompt to guide the next part of the scene with optional sound. version: 1.0.0 servers: - url: https://api.vidgo.ai security: - BearerAuth: [] paths: /api/generate/submit: post: tags: - Video Series summary: FLUX 3 Extend Video description: >- Send only the fields shown for this workflow. Parameters from other workflows are rejected before credits are deducted. When supplied, prompt and text must not be blank. Input URL fields require HTTP(S) URLs with a hostname and no embedded credentials. Provide a publicly accessible HTTP(S) source video URL. The duration field specifies newly generated output, from five to twenty seconds. operationId: submit_blackforestlabs_flux_3_extend_video requestBody: required: true content: application/json: schema: type: object required: - model - input additionalProperties: true properties: model: type: string enum: - blackforestlabs/flux-3/extend-video example: blackforestlabs/flux-3/extend-video description: >- Vidgo public model ID. Must be `blackforestlabs/flux-3/extend-video`. input: type: object required: - prompt - video_url properties: prompt: type: string minLength: 1 description: Prompt. duration: type: integer minimum: 5 maximum: 20 default: 5 description: Duration. resolution: type: string enum: - 720p - 1080p default: 720p description: Resolution. aspect_ratio: type: string enum: - auto - '21:9' - '2:1' - '16:9' - '4:3' - '1:1' - '3:4' - '9:16' default: auto description: Aspect ratio. sound: type: boolean default: true description: Sound. video_url: type: string format: uri description: >- Source video URL (flux-3/extend-video only, required). Provide a publicly accessible HTTP(S) video URL. additionalProperties: false callback_url: type: string nullable: true description: >- Optional public HTTP(S) endpoint for task completion notifications. HTTPS is recommended. Omit, use null, or use an empty string to disable callbacks. description: >- Keep model and callback_url at the root. Unknown root fields are ignored; unsupported input fields are rejected. examples: basic: summary: Basic workflow value: model: blackforestlabs/flux-3/extend-video input: prompt: >- A quiet forest under soft morning light, with natural detail. video_url: https://example.com/video.mp4 duration: 5 resolution: 720p aspect_ratio: auto sound: true callback: summary: Receive a completion callback value: model: blackforestlabs/flux-3/extend-video input: prompt: >- A quiet forest under soft morning light, with natural detail. video_url: https://example.com/video.mp4 duration: 5 resolution: 720p aspect_ratio: auto sound: true callback_url: https://your-domain.com/callback responses: '200': description: Task submitted content: application/json: schema: type: object required: - code - data properties: code: type: integer enum: - 200 data: type: object required: - task_id - status - created_time properties: task_id: type: string status: type: string enum: - not_started - running - finished - failed created_time: type: string format: date-time example: code: 200 data: task_id: task-unified-example status: running created_time: '2026-09-10T08:00:00' '400': description: >- Invalid input, unsupported tier, inaccessible media, or insufficient credits content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} '401': description: Invalid credentials content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} '403': description: Access denied content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} '404': description: Unknown or disabled model content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} '408': description: Request timed out content: text/plain: schema: type: string example: Request timeout '422': description: Invalid JSON or non-object request body content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} '429': description: Rate or API key credit limit exceeded content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} '500': description: Internal error content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} '502': description: Unable to create the upstream generation task content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} '503': description: Model configuration or capability is not approved content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} components: securitySchemes: BearerAuth: type: http scheme: bearer description: Use VIDGO_API_KEY. ````