Create a Runway video-to-video task
Use CometAPI Runway POST /runwayml/v1/video_to_video to start video-to-video generation tasks, set X-Runway-Version, and transform source clips.
Before you call it
- Prepare a source video that matches the provider’s input requirements
- Include the required
X-Runway-Versionheader for the feature set you want - Start with one short prompt that describes the change, not a full storyboard
Output ratio
ratio values. Use 1280:720 for 1280x720 output and 720:1280 for 720x1280; 1280x720 is not accepted on every Runway video-to-video route.
Task flow
Submit the source clip and prompt
Poll task details
Store the transformed result
Authorizations
Bearer token authentication. Use your CometAPI key.
Headers
Runway API version header, for example 2024-11-06.
Body
HTTPS URL of the source video, or a base64 data URI containing the video.
Text prompt describing the desired output. Maximum 1000 characters.
Random seed for reproducible results. Range: 0–4294967295.
Model variant to use.
Optional reference images to guide generation. Each item must include type (e.g. image) and uri (HTTPS URL).
Requested output frame shape. Use colon-separated values such as 1280:720 or 720:1280; read them as 1280x720 and 720x1280 targets. Do not assume every Runway video-to-video route accepts 1280x720 with an x separator.
Response
success
The ID of the task that was created. Use this to retrieve the task later.