# Extend Video

> Continue a generated video with a new prompt direction.

## Overview

The Extend Video node continues a video by appending new content guided by a text prompt. VEO and Runway extends require an upstream video generated by the matching node (they need the original provider task ID). LTX 2.3 Pro and Seedance 2 Extend work on **any** video URL — including uploads. Use it to create longer videos from short clips.

## Configuration

| Field | Type | Default | Description |
|-------|------|---------|-------------|
| Provider | Select | veo-extend | Extension provider |
| Prompt | Textarea | — | How the video should continue |

### Provider-Specific Options

| Provider | Extra Fields |
|----------|-------------|
| veo-extend | Model: fast (VEO 3.1 Fast) or quality (VEO 3.1 Quality) |
| runway-extend | Quality: 720p or 1080p |
| ltx-2.3-pro | Extend mode: `start` (prepend before clip) or `end` (append after clip, default); duration: 1–20s of new footage to add |
| seedance-2-extend | Duration: 4–15s of new footage to add (default 8); Resolution: 480p / 720p / 1080p (default 720p); Generate Audio: continue the soundtrack into the extension (default on) |

## Inputs & Outputs

**Inputs:**
- Video (required) — upstream VEO, Runway, or LTX 2.3 Pro generated video. VEO and Runway extends require the original provider task ID (so the source must come from the corresponding generation node). LTX 2.3 Pro and Seedance 2 Extend accept any video URL.

**Outputs:**
- Extended video URL

## Providers

| Provider | Source video must come from | Extend mode | Duration cap | Resolution |
|---|---|---|---|---|
| `veo-extend` | VEO generation node | append-only | provider-fixed | 720p / 1080p |
| `runway-extend` | Runway generation node | append-only | provider-fixed | 720p / 1080p |
| `ltx-2.3-pro` | Any video URL | `start` or `end` | +1–20s of new footage per run (no cumulative cap; chain extends to go further) | 1080p |
| `seedance-2-extend` | Any video URL | append-only | +4–15s of new footage per run (chain to go further) | 480p / 720p / 1080p |

LTX 2.3 Fast does **not** support extend mode — only Pro extends. The `extend_mode` field controls whether the new footage is prepended (`start`) or appended (`end`, default).

### How Seedance 2 Extend works

Seedance 2 generates the continuation natively (it watches the source clip and produces only what happens next, soundtrack included), then the platform **smart-stitches** source + extension into one seamless clip: it PSNR-matches the source's last 8 frames against the extension's first 8, ends the source **on** the most similar frame and starts the extension **right after** its near-identical twin — the duplicated boundary moment plays exactly once and motion continues through the cut. If no genuine match is found (below the 24dB threshold), the stitch falls back to fixed trims (source's last 4 frames + extension's first 3). The join is a hard cut with a short audio blend; the applied cut is reported in the job's `output_data.smartCuts` (frames dropped each side + match PSNR). The extension automatically matches the source's aspect ratio.

### Seedance 2 Extend credits

Pricing is per duration tier × resolution (the same rates as Seedance 2 generation with a video reference, plus a flat 3-credit stitch overhead baked into every row). Off-tier durations snap up to the next tier (e.g. 6s bills as 8s):

| Seconds added | 480p | 720p | 1080p |
|---|---|---|---|
| up to 4s | 15 | 28 | 41 |
| up to 8s | 26 | 53 | 78 |
| up to 12s | 38 | 78 | 116 |
| up to 15s | 47 | 97 | 144 |

## Best Practices

- For VEO / Runway: the source video must come from the matching generation node — this node cannot extend arbitrary uploaded videos for those providers.
- For LTX 2.3 Pro: any video URL works; use `extend_mode: "start"` to add a lead-in, `extend_mode: "end"` (default) to add a continuation.
- For Seedance 2 Extend: describe only what happens next, in plain action language (e.g. "the ball keeps rolling until it hits a cup") — the platform handles the continuation phrasing. Match the source's resolution for the cleanest seam.
- Write prompts that describe the continuation, not the original content.
- Use "fast" mode for iteration, "quality" for final output (VEO).
- Chain multiple Extend Video nodes to create progressively longer content — each LTX extend adds up to 20s, so two chained runs give +40s.

## Common Use Cases

- Extend a 5-second VEO clip into a 15+ second video.
- Continue a scene with a new action or direction change.
- Build longer narratives by chaining extensions.
- Prepend an establishing shot in front of a hero clip (LTX 2.3 Pro with `extend_mode: "start"`).
- Create variations of how a scene continues.

## Tips

- Use "fast" mode for draft iterations and "quality" for final renders (VEO).
- The prompt for extension should describe what happens next (or, for `start` mode, what happens before).
- Each VEO/Runway extension adds roughly the same duration as the original clip; LTX 2.3 Pro extensions add exactly the user-specified duration (up to +20s per run).