# Extend Video

Extend video with audio using LTX-2.3

## Table of contents

### 1. Calling the API

#### Install the client

The client provides a convenient way to interact with the model API.

```bash
npm install --save @fal-ai/client
```

#### Setup your API Key

Set `FAL_KEY` as an environment variable in your runtime.

```bash
export FAL_KEY="YOUR_API_KEY"
```

#### Submit a request

The client API handles the API submit protocol. It will handle the request status updates and return the result when the request is completed.

```javascript
import { fal } from "@fal-ai/client";

const result = await fal.subscribe("fal-ai/ltx-2.3-22b/extend-video", {
  input: {
    prompt: "Continue the scene naturally, maintaining the same style and motion.",
    video_url: "https://v3b.fal.media/files/b/0a8824b1/sdm0KfmenrlywesfzY1Y1_if6euPp1.mp4"
  },
  logs: true,
  onQueueUpdate: (update) => {
    if (update.status === "IN_PROGRESS") {
      update.logs.map((log) => log.message).forEach(console.log);
    }
  },
});
console.log(result.data);
console.log(result.requestId);
```

## 2. Authentication

The API uses an API Key for authentication. It is recommended you set the `FAL_KEY` environment variable in your runtime when possible.

### API Key

In case your app is running in an environment where you cannot set environment variables, you can set the API Key manually as a client configuration.

```javascript
import { fal } from "@fal-ai/client";

fal.config({
  credentials: "YOUR_FAL_KEY"
});
```

##### Protect your API Key

When running code on the client-side (e.g. in a browser, mobile app or GUI applications), make sure to not expose your `FAL_KEY`. Instead, **use a server-side proxy** to make requests to the API.

## 3. Queue

### Submit a request

The client API provides a convenient way to submit requests to the model.

```javascript
import { fal } from "@fal-ai/client";

const { request_id } = await fal.queue.submit("fal-ai/ltx-2.3-22b/extend-video", {
  input: {
    prompt: "Continue the scene naturally, maintaining the same style and motion.",
    video_url: "https://v3b.fal.media/files/b/0a8824b1/sdm0KfmenrlywesfzY1Y1_if6euPp1.mp4"
  },
  webhookUrl: "https://optional.webhook.url/for/results",
});
```

### Fetch request status

You can fetch the status of a request to check if it is completed or still in progress.

```javascript
import { fal } from "@fal-ai/client";

const status = await fal.queue.status("fal-ai/ltx-2.3-22b/extend-video", {
  requestId: "764cabcf-b745-4b3e-ae38-1200304cf45b",
  logs: true,
});
```

### Get the result

Once the request is completed, you can fetch the result.

```javascript
import { fal } from "@fal-ai/client";

const result = await fal.queue.result("fal-ai/ltx-2.3-22b/extend-video", {
  requestId: "764cabcf-b745-4b3e-ae38-1200304cf45b"
});
console.log(result.data);
console.log(result.requestId);
```

## 4. Files

Some attributes in the API accept file URLs as input. Whenever that's the case you can pass your own URL or a Base64 data URI.

### Data URI (base64)

You can pass a Base64 data URI as a file input. The API will handle the file decoding for you. Keep in mind that for large files, this alternative although convenient can impact the request performance.

### Hosted files (URL)

You can also pass your own URLs as long as they are publicly accessible. Be aware that some hosts might block cross-site requests, rate-limit, or consider the request as a bot.

### Uploading files

We provide a convenient file storage that allows you to upload files and use them in your requests.

```javascript
import { fal } from "@fal-ai/client";

const file = new File(["Hello, World!"], "hello.txt", { type: "text/plain" });
const url = await fal.storage.upload(file);
```

## 5. Schema

### Input

`prompt``string`\* required

The prompt to generate the video from.

`video_url``string`\* required

The URL of the video to extend.

**Example Input:**
```json
{
  "prompt": "Continue the scene naturally, maintaining the same style and motion.",
  "video_url": "https://v3b.fal.media/files/b/0a8824b1/sdm0KfmenrlywesfzY1Y1_if6euPp1.mp4",
  "num_frames": 121,
  "video_size": "auto",
  "generate_audio": true,
  "use_multiscale": true,
  "match_input_fps": true,
  "fps": 24,
  "num_inference_steps": 40,
  "video_cfg_scale": 3,
  "video_rescaling_scale": 0.7,
  "video_modality_scale": 3,
  "audio_cfg_scale": 7,
  "audio_rescaling_scale": 0.7,
  "audio_modality_scale": 3,
  "gradient_estimation_gamma": 2,
  "scheduler": "ltx2",
  "acceleration": "regular",
  "camera_lora": "none",
  "camera_lora_scale": 1,
  "negative_prompt": "news broadcast, 3d animation, computer graphics, pc game, console game, video game, cartoon, childish, watermark, logo, text, on screen text, subtitles, titles, signature, slowmo, static",
  "enable_prompt_expansion": true,
  "enable_safety_checker": true,
  "video_output_type": "X264 (.mp4)",
  "video_quality": "high",
  "video_write_mode": "balanced",
  "distill_lora_first_pass_scale": 0.2,
  "distill_lora_second_pass_scale": 0.5,
  "extend_direction": "forward",
  "num_context_frames": 25,
  "video_strength": 1,
  "audio_strength": 1,
  "end_image_strength": 1
}
```

### Output

**Example Output:**
```json
{
  "video": {
    "content_type": "video/mp4",
    "height": 704,
    "num_frames": 161,
    "file_name": "CJcQGDrxOSRg2YFl5GNDt_glXPMoji.mp4",
    "width": 1248,
    "duration": 6.44,
    "url": "https://v3b.fal.media/files/b/0a894013/N9lnMTq7W3uMC0lOQg845_BknRPV8I.mp4",
    "fps": 25
  },
  "seed": 2078003885,
  "prompt": "A woman stands still amid a busy neon-lit street at night. The camera slowly dollies in toward her face as people blur past, their motion emphasizing her calm presence. City lights flicker and reflections shift across her denim jacket."
}
```