RunwayMediumUltra

Gen-4.5

Runway's Gen-4.5 model, offering state-of-the-art video motion quality, prompt adherence, and visual fidelity for text-to-video and image-to-video generation.

1400 credits

per 5s video (default) — billed per second (279/s, 5-10s)

State-of-the-art motion quality and prompt adherence

Flat per-second pricing regardless of aspect ratio

Text-to-video or image-to-video from an optional first frame

5 or 10 second duration options

Wide range of aspect ratios including 21:9 cinematic

Run it right now

Test this model instantly in the Console Playground — no code required

Use with AI Assistant

Copy usage instructions for Claude, ChatGPT, or other AI

llms.txtllms.txt ↗

Quick Start

curl -X POST "https://api.core.today/v1/predictions" \
  -H "Content-Type: application/json" \
  -H "X-API-Key: cdt_your_api_key" \
  -d '{
  "model": "runwayml/gen-4.5",
  "input": {
    "prompt": "A dense, verdant jungle world made up of small lego-like pieces. We see a rainbow chameleon running through the 3D world, the camera in and out of focus.",
    "duration": 10,
    "aspect_ratio": "16:9"
  }
}'

Parameters

Parameter	Type	Required	Default	Description
`prompt`	string	Yes	-	Text prompt for video generation
`image`	string	No	-	Optional initial image (first frame). If omitted, video is generated from text only
`duration`	integer	No	5	Duration of the output video in seconds 510
`aspect_ratio`	string	No	16:9	Video aspect ratio 16:99:164:33:41:121:9
`seed`	integer	No	-	Random seed for reproducible generation

How to Provide File Input

There are 3 ways to provide files for the image parameter:

Recommended

Direct Upload (Multipart)

Attach files directly to POST /v1/predictions/upload. No separate upload step needed.

curl -X POST "https://api.core.today/v1/predictions/upload" \
  -H "X-API-Key: cdt_your_api_key" \
  -F "model=runwayml/gen-4.5" \
  -F 'input={"prompt":"your prompt here"}' \
  -F "file:image=@your_file.png"

Image URL

Pass a publicly accessible URL directly. You can also use file_url from the Storage API.

{
  "model": "runwayml/gen-4.5",
  "input": {
    "prompt": "your prompt here",
    "image": "https://example.com/image.jpg"
  }
}

See the File Upload docs for more upload methods including Presigned URLs.

Common Parameters

Common parameters used when calling POST /v1/predictions.

Parameter	Type	Required	Default	Description
`model`	string	Yes	-	Model identifier
`input`	object	Yes	-	Object containing the model-specific parameters from the table above
`output_folder`	string	No	-	Folder path for output files (max 256 chars, '..' not allowed)
`webhook_url`	string	No	-	Webhook URL to call on completion
`is_public`	boolean	No	false	If true, output files are also available via permanent public URLs

Examples

Text-to-Video (10s)

A fully text-driven scene at the maximum 10-second duration

curl -X POST "https://api.core.today/v1/predictions" \
  -H "Content-Type: application/json" \
  -H "X-API-Key: cdt_your_api_key" \
  -d '{
  "model": "runwayml/gen-4.5",
  "input": {
    "prompt": "A dense, verdant jungle world made up of small lego-like pieces. We see a rainbow chameleon running through the 3D world, the camera in and out of focus.",
    "duration": 10,
    "aspect_ratio": "16:9"
  }
}'

Cinematic 21:9 Clip (5s)

A shorter, cheaper clip in a wide cinematic aspect ratio

curl -X POST "https://api.core.today/v1/predictions" \
  -H "Content-Type: application/json" \
  -H "X-API-Key: cdt_your_api_key" \
  -d '{
  "model": "runwayml/gen-4.5",
  "input": {
    "prompt": "A vintage train winding through snow-capped mountains at golden hour",
    "duration": 5,
    "aspect_ratio": "21:9"
  }
}'