> ## Documentation Index
> Fetch the complete documentation index at: https://docs.comfy.org/llms.txt
> Use this file to discover all available pages before exploring further.

# RunwayFirstLastFrameNode - ComfyUI Built-in Node Documentation

> Complete documentation for the RunwayFirstLastFrameNode node in ComfyUI. Learn its inputs, outputs, parameters and usage.

> This documentation was AI-generated. If you find any errors or have suggestions for improvement, please feel free to contribute! [Edit on GitHub](https://github.com/Comfy-Org/embedded-docs/blob/main/comfyui_embedded_docs/docs/RunwayFirstLastFrameNode/en.md)

The Runway First-Last-Frame to Video node generates videos by uploading first and last keyframes along with a text prompt. It creates smooth transitions between the provided start and end frames using Runway's Gen-3 model. This is particularly useful for complex transitions where the end frame differs significantly from the start frame.

## Inputs

| Parameter     | Data Type | Required | Range                      | Description                                                          |
| ------------- | --------- | -------- | -------------------------- | -------------------------------------------------------------------- |
| `prompt`      | STRING    | Yes      | N/A                        | Text prompt for the generation (default: empty string)               |
| `start_frame` | IMAGE     | Yes      | N/A                        | Start frame to be used for the video                                 |
| `end_frame`   | IMAGE     | Yes      | N/A                        | End frame to be used for the video. Supported for gen3a\_turbo only. |
| `duration`    | COMBO     | Yes      | Multiple options available | Video duration selection from available Duration options             |
| `ratio`       | COMBO     | Yes      | Multiple options available | Aspect ratio selection from available RunwayGen3aAspectRatio options |
| `seed`        | INT       | No       | 0-4294967295               | Random seed for generation (default: 0)                              |

**Parameter Constraints:**

* The `prompt` must contain at least 1 character
* Both `start_frame` and `end_frame` must have maximum dimensions of 7999x7999 pixels
* Both `start_frame` and `end_frame` must have aspect ratios between 0.5 and 2.0
* The `end_frame` parameter is only supported when using the gen3a\_turbo model

## Outputs

| Output Name | Data Type | Description                                                        |
| ----------- | --------- | ------------------------------------------------------------------ |
| `output`    | VIDEO     | The generated video transitioning between the start and end frames |