Extend video with audio using LTX-2.3

fal-ai/ltx-2.3-22b/extend-video

Extend video with audio using LTX-2.3

Inference

Commercial use

Schema

LLMs

Playground API

About

Extend a video with a text prompt.

1. Calling the API#

Install the client#

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

npm install --save @fal-ai/client

Migrate to @fal-ai/client

The @fal-ai/serverless-client package has been deprecated in favor of @fal-ai/client. Install the new package and update your imports — see client setup.

Setup your API Key#

Set FAL_KEY as an environment variable in your runtime.

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.

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 an environment where you cannot set environment variables, you can configure the API key manually on the client.

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. For more information, check out our server-side integration guide.

3. Queue#

Long-running requests

For long-running requests, such as training jobs or models with slower inference times, it is recommended to check the Queue status and rely on Webhooks instead of blocking while waiting for the result.

Submit a request#

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

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.

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. See the Output Schema for the expected result format.

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. You can upload files using the client API and use the returned URL in your requests.

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

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

Auto uploads

The client will auto-upload the file for you if you pass a binary object (e.g. File, Data).

Read more about file handling in our file upload guide.

5. Schema#

Input#

prompt string* required

The prompt to generate the video from.

video_url string* required

The URL of the video to extend.

end_image_url string

The URL of the image to use as the end of the extended video.

num_frames integer

The number of frames to generate. Default value: 121

video_size ImageSize | Enum

The size of the generated video. Default value: auto

Possible enum values: auto, square_hd, square, portrait_4_3, portrait_16_9, landscape_4_3, landscape_16_9

Note: For custom image sizes, you can pass the width and height as an object:

"image_size": {
  "width": 1280,
  "height": 720
}

generate_audio boolean

Whether to generate audio for the video. Default value: true

use_multiscale boolean

Whether to use multi-scale generation. If True, the model will generate the video at a smaller scale first, then use the smaller video to guide the generation of a video at or above your requested size. This results in better coherence and details. Default value: true

match_input_fps boolean

When true, match the output FPS to the input video's FPS instead of using the default target FPS. Default value: true

fps float

The frames per second of the generated video. Default value: 24

num_inference_steps integer

The number of inference steps to use. Default value: 40

video_cfg_scale float

The Classifier-Free Guidance (CFG) scale for the video. Higher values result in more consistent and focused video content. Default value: 3

video_stg_scale float

The Spatiotemporal Guidance (STG) scale for the video. Higher values result in more consistent and focused video content.

video_rescaling_scale float

The rescaling scale for the video. Controls the ratio between classifier-free guidance and spatiotemporal guidance. Default value: 0.7

video_modality_scale float

The modality scale for the video. Controls the ratio between video and audio modalities. Default value: 3

audio_cfg_scale float

The Classifier-Free Guidance (CFG) scale for the audio. Higher values result in more consistent and focused audio content. Default value: 7

audio_stg_scale float

The Spatiotemporal Guidance (STG) scale for the audio. Higher values result in more consistent and focused audio content.

audio_rescaling_scale float

The rescaling scale for the audio. Controls the ratio between classifier-free guidance and spatiotemporal guidance. Default value: 0.7

audio_modality_scale float

The modality scale for the audio. Controls the ratio between video and audio modalities. Default value: 3

gradient_estimation_gamma float

The gamma of gradient estimation during denoising. Set to 0 to disable. Default value: 2

use_restart_sampling boolean

Whether to use restart sampling. This will inject a small amount of noise during each denoising step, which can help improve the quality of the generated video.

scheduler SchedulerEnum

The scheduler to use. Default value: "ltx2"

Possible enum values: ltx2, linear_quadratic, beta

acceleration AccelerationEnum

The acceleration level to use. Default value: "regular"

Possible enum values: none, regular, high, full

camera_lora CameraLoRAEnum

The camera LoRA to use. This allows you to control the camera movement of the generated video more accurately than just prompting the model to move the camera. Default value: "none"

Possible enum values: dolly_in, dolly_out, dolly_left, dolly_right, jib_up, jib_down, static, none

camera_lora_scale float

The scale of the camera LoRA to use. This allows you to control the camera movement of the generated video more accurately than just prompting the model to move the camera. Default value: 1

negative_prompt string

The negative prompt to generate the video from. Default value: "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"

seed integer

The seed for the random number generator.

enable_prompt_expansion boolean

Whether to enable prompt expansion. Default value: true

enable_safety_checker boolean

Whether to enable the safety checker. Default value: true

video_output_type VideoOutputTypeEnum

The output type of the generated video. Default value: "X264 (.mp4)"

Possible enum values: X264 (.mp4), VP9 (.webm), PRORES4444 (.mov), GIF (.gif)

video_quality VideoQualityEnum

The quality of the generated video. Default value: "high"

Possible enum values: low, medium, high, maximum

video_write_mode VideoWriteModeEnum

The write mode of the generated video. Default value: "balanced"

Possible enum values: fast, balanced, small

sync_mode boolean

If True, the media will be returned as a data URI and the output data won't be available in the request history.

distill_lora_first_pass_scale float

The scale of the distill LoRA to use for the first pass. Set to 0 to disable. Default value: 0.2

distill_lora_second_pass_scale float

The scale of the distill LoRA to use for the second and subsequent passes. Default value: 0.5

extend_direction ExtendDirectionEnum

Direction to extend the video. 'forward' extends from the end of the video, 'backward' extends from the beginning. Default value: "forward"

Possible enum values: forward, backward

num_context_frames integer

The number of frames to use as context for the extension. Default value: 25

video_strength float

Video conditioning strength. Lower values represent more freedom given to the model to change the video content. Default value: 1

audio_strength float

Audio conditioning strength. Lower values represent more freedom given to the model to change the audio content. Default value: 1

end_image_strength float

The strength of the end image to use for the video generation. Default value: 1

{
  "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#

video VideoFile* required

The generated video.

seed integer* required

The seed used for the random number generator.

prompt string* required

The prompt used for the generation.

{
  "video": {
    "fps": 25,
    "num_frames": 161,
    "height": 704,
    "width": 1248,
    "duration": 6.44,
    "content_type": "video/mp4",
    "file_name": "CJcQGDrxOSRg2YFl5GNDt_glXPMoji.mp4",
    "url": "https://v3b.fal.media/files/b/0a894013/N9lnMTq7W3uMC0lOQg845_BknRPV8I.mp4"
  },
  "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."
}

Other types#

VideoFile#

url string* required

The URL where the file can be downloaded from.

content_type string

The mime type of the file.

file_name string

The name of the file. It will be auto-generated if not provided.

file_size integer

The size of the file in bytes.

width integer

The width of the video

height integer

The height of the video

fps float

The FPS of the video

duration float

The duration of the video

num_frames integer

The number of frames in the video

ImageSize#

width integer

The width of the generated image. Default value: 512

height integer

The height of the generated image. Default value: 512

Related Models

Loading API documentation…

1. Calling the API

2. Authentication

API Key

3. Queue

4. Files

5. Schema

About

Extend a video with a text prompt.

1. Calling the API#

Install the client#

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

npm install --save @fal-ai/client

Migrate to @fal-ai/client

The @fal-ai/serverless-client package has been deprecated in favor of @fal-ai/client. Install the new package and update your imports — see client setup.

Setup your API Key#

Set FAL_KEY as an environment variable in your runtime.

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.

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 an environment where you cannot set environment variables, you can configure the API key manually on the client.

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

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

Protect your API Key

3. Queue#

Long-running requests

Submit a request#

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

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.

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. See the Output Schema for the expected result format.

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)#

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. You can upload files using the client API and use the returned URL in your requests.

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

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

Auto uploads

The client will auto-upload the file for you if you pass a binary object (e.g. File, Data).

Read more about file handling in our file upload guide.

5. Schema#

Input#

prompt string* required

The prompt to generate the video from.

video_url string* required

The URL of the video to extend.

end_image_url string

The URL of the image to use as the end of the extended video.

num_frames integer

The number of frames to generate. Default value: 121

video_size ImageSize | Enum

The size of the generated video. Default value: auto

Possible enum values: auto, square_hd, square, portrait_4_3, portrait_16_9, landscape_4_3, landscape_16_9

Note: For custom image sizes, you can pass the width and height as an object:

"image_size": {
  "width": 1280,
  "height": 720
}

generate_audio boolean

Whether to generate audio for the video. Default value: true

use_multiscale boolean

match_input_fps boolean

When true, match the output FPS to the input video's FPS instead of using the default target FPS. Default value: true

fps float

The frames per second of the generated video. Default value: 24

num_inference_steps integer

The number of inference steps to use. Default value: 40

video_cfg_scale float

The Classifier-Free Guidance (CFG) scale for the video. Higher values result in more consistent and focused video content. Default value: 3

video_stg_scale float

The Spatiotemporal Guidance (STG) scale for the video. Higher values result in more consistent and focused video content.

video_rescaling_scale float

The rescaling scale for the video. Controls the ratio between classifier-free guidance and spatiotemporal guidance. Default value: 0.7

video_modality_scale float

The modality scale for the video. Controls the ratio between video and audio modalities. Default value: 3

audio_cfg_scale float

The Classifier-Free Guidance (CFG) scale for the audio. Higher values result in more consistent and focused audio content. Default value: 7

audio_stg_scale float

The Spatiotemporal Guidance (STG) scale for the audio. Higher values result in more consistent and focused audio content.

audio_rescaling_scale float

The rescaling scale for the audio. Controls the ratio between classifier-free guidance and spatiotemporal guidance. Default value: 0.7

audio_modality_scale float

The modality scale for the audio. Controls the ratio between video and audio modalities. Default value: 3

gradient_estimation_gamma float

The gamma of gradient estimation during denoising. Set to 0 to disable. Default value: 2

use_restart_sampling boolean

Whether to use restart sampling. This will inject a small amount of noise during each denoising step, which can help improve the quality of the generated video.

scheduler SchedulerEnum

The scheduler to use. Default value: "ltx2"

Possible enum values: ltx2, linear_quadratic, beta

acceleration AccelerationEnum

The acceleration level to use. Default value: "regular"

Possible enum values: none, regular, high, full

camera_lora CameraLoRAEnum

The camera LoRA to use. This allows you to control the camera movement of the generated video more accurately than just prompting the model to move the camera. Default value: "none"

Possible enum values: dolly_in, dolly_out, dolly_left, dolly_right, jib_up, jib_down, static, none

camera_lora_scale float

The scale of the camera LoRA to use. This allows you to control the camera movement of the generated video more accurately than just prompting the model to move the camera. Default value: 1

negative_prompt string

seed integer

The seed for the random number generator.

enable_prompt_expansion boolean

Whether to enable prompt expansion. Default value: true

enable_safety_checker boolean

Whether to enable the safety checker. Default value: true

video_output_type VideoOutputTypeEnum

The output type of the generated video. Default value: "X264 (.mp4)"

Possible enum values: X264 (.mp4), VP9 (.webm), PRORES4444 (.mov), GIF (.gif)

video_quality VideoQualityEnum

The quality of the generated video. Default value: "high"

Possible enum values: low, medium, high, maximum

video_write_mode VideoWriteModeEnum

The write mode of the generated video. Default value: "balanced"

Possible enum values: fast, balanced, small

sync_mode boolean

If True, the media will be returned as a data URI and the output data won't be available in the request history.

distill_lora_first_pass_scale float

The scale of the distill LoRA to use for the first pass. Set to 0 to disable. Default value: 0.2

distill_lora_second_pass_scale float

The scale of the distill LoRA to use for the second and subsequent passes. Default value: 0.5

extend_direction ExtendDirectionEnum

Direction to extend the video. 'forward' extends from the end of the video, 'backward' extends from the beginning. Default value: "forward"

Possible enum values: forward, backward

num_context_frames integer

The number of frames to use as context for the extension. Default value: 25

video_strength float

Video conditioning strength. Lower values represent more freedom given to the model to change the video content. Default value: 1

audio_strength float

Audio conditioning strength. Lower values represent more freedom given to the model to change the audio content. Default value: 1

end_image_strength float

The strength of the end image to use for the video generation. Default value: 1

{
  "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#

video VideoFile* required

The generated video.

seed integer* required

The seed used for the random number generator.

prompt string* required

The prompt used for the generation.

{
  "video": {
    "fps": 25,
    "num_frames": 161,
    "height": 704,
    "width": 1248,
    "duration": 6.44,
    "content_type": "video/mp4",
    "file_name": "CJcQGDrxOSRg2YFl5GNDt_glXPMoji.mp4",
    "url": "https://v3b.fal.media/files/b/0a894013/N9lnMTq7W3uMC0lOQg845_BknRPV8I.mp4"
  },
  "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."
}

Other types#

VideoFile#

url string* required

The URL where the file can be downloaded from.

content_type string

The mime type of the file.

file_name string

The name of the file. It will be auto-generated if not provided.

file_size integer

The size of the file in bytes.

width integer

The width of the video

height integer

The height of the video

fps float

The FPS of the video

duration float

The duration of the video

num_frames integer

The number of frames in the video

ImageSize#

width integer

The width of the generated image. Default value: 512

height integer

The height of the generated image. Default value: 512

Related Models

LTX-2.3 22B Video to Video API Docs | fal

fal-ai/ltx-2.3-22b/extend-video

fal-ai/ltx-2.3-22b/extend-video

fal-ai/ltx-2.3-22b/extend-video

Table of contents

1. Calling the API

2. Authentication

3. Queue

4. Files

5. Schema

About

1. Calling the API#

Install the client#

Migrate to @fal-ai/client

Setup your API Key#

Submit a request#

2. Authentication#

API Key#

Protect your API Key

3. Queue#

Long-running requests

Submit a request#

Fetch request status#

Get the result#

4. Files#

Data URI (base64)#

Hosted files (URL)#

Uploading files#

Auto uploads

5. Schema#

Input#

Output#

Other types#

VideoFile#

ImageSize#

Related Models

Table of contents

1. Calling the API

2. Authentication

3. Queue

4. Files

5. Schema

About

1. Calling the API#

Install the client#

Migrate to @fal-ai/client

Setup your API Key#

Submit a request#

2. Authentication#

API Key#

Protect your API Key

3. Queue#

Long-running requests

Submit a request#

Fetch request status#

Get the result#

4. Files#

Data URI (base64)#

Hosted files (URL)#

Uploading files#

Auto uploads

5. Schema#

Input#

Output#

Other types#

VideoFile#

ImageSize#

Related Models