Veo 3.1 Video Extend

POST/v1/run

Veo3.1 Extend Video is Google's video-to-video AI model. Transform, enhance, and edit video content using text prompts - from style changes to object manipulation and scene modification.

Request body

Submit an async generation request. The model field selects the model; other fields are model-specific input parameters.

stringmodelrequired

Model identifier. Set to google/veo3.1/video-extend.

Default: google/veo3.1/video-extend

stringpromptrequired

The text prompt describing how the video should be extended

stringvideorequired

Video to extend: MP4 at 24 fps, 720p (for example a Veo output). Veo appends the requested duration to it.

Optional<integer>duration

Length of the generated extension in seconds.

Allowed values: 7

Default: 7

Optional<string>resolution

Output resolution. Extensions are generated at 720p.

Allowed values: 720p

Default: 720p

Optional<string>aspect_ratio

Output aspect ratio. Omit to match the input video.

Allowed values: 16:9, 9:16

Optional<boolean>generate_audio

Generate synchronized audio. Videos without audio are cheaper.

Default: true

Optional<string>negative_prompt

What to avoid in the video.

Optional<integer>seed

Random seed for more reproducible results.

Range: 0 to 4294967295

Response Schema

The submit endpoint returns a run response. If its status is pending or running, poll GET /v1/run/{id} with the returned opaque ID until it reaches a terminal state.

stringidrequired

Opaque SandBase run identifier. Use it exactly as returned; no prefix is guaranteed.

stringstatusrequired

Current public run status.

Allowed values: pending, running, completed, failed, timeout

Optional<string>model

Public SandBase model name used for this run.

Optional<array<object>>outputs

Present only for completed runs. Each object is capability-specific; inspect the selected model schema for its fields.

Optional<object>error

Present only for failed or timeout runs. Contains a public error type and sanitized message.

Optional<string>error.type

Stable public error category.

Optional<string>error.message

Sanitized error message safe to show to clients.

Optional<object>usage

Usage details when available.

Model capabilities

array<string>capability_tagsrequired

Capabilities declared by the model registry.

Default: video-to-video

stringexecution_moderequired

Execution mode declared by the model registry.

Default: async

# 1. Submit a generation request
curl -X POST https://api.sandbase.ai/v1/run \
  -H "Authorization: Bearer $SANDBASE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "model": "google/veo3.1/video-extend",
  "prompt": "Continue the scene naturally, maintaining the same style and motion.",
  "video": "https://static.sandbase.ai/examples/input.mp4",
  "duration": 7,
  "aspect_ratio": "16:9"
}'

# 2. If the response is still running, poll the returned id
curl https://api.sandbase.ai/v1/run/f3d2e8a1-7c4b-4a12-9d2e-123456789abc \
  -H "Authorization: Bearer $SANDBASE_API_KEY"

Response202 Accepted

{
  "id": "f3d2e8a1-7c4b-4a12-9d2e-123456789abc",
  "model": "google/veo3.1/video-extend",
  "status": "running"
}