Longcat Multi Avatar | Audio to Video

fal-ai/longcat-multi-avatar/image-audio-to-video

LongCat-Video-Avatar is an audio-driven video generation model that can generates super-realistic, lip-synchronized long video generation with natural dynamics and consistent identity.

Inference

Commercial use

Schema

LLMs

Playground API

About

Generate a multi-speaker talking avatar video from an image and two audio files.

Each speaker can have their own audio track, and their lip movements will be synchronized independently based on their bounding box regions.

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. Please check the migration guide for more information.

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/longcat-multi-avatar/image-audio-to-video", {
  input: {
    image_url: "https://raw.githubusercontent.com/meituan-longcat/LongCat-Video/refs/heads/main/assets/avatar/multi/sing.png"
  },
  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.

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/longcat-multi-avatar/image-audio-to-video", {
  input: {
    image_url: "https://raw.githubusercontent.com/meituan-longcat/LongCat-Video/refs/heads/main/assets/avatar/multi/sing.png"
  },
  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/longcat-multi-avatar/image-audio-to-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/longcat-multi-avatar/image-audio-to-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#

image_url string* required

The URL of the image containing two speakers.

audio_url_person1 string

The URL of the audio file for person 1 (left side). Default value: "https://raw.githubusercontent.com/meituan-longcat/LongCat-Video/refs/heads/main/assets/avatar/multi/sing_man.WAV"

audio_url_person2 string

The URL of the audio file for person 2 (right side). Default value: "https://raw.githubusercontent.com/meituan-longcat/LongCat-Video/refs/heads/main/assets/avatar/multi/sing_woman.WAV"

prompt string

The prompt to guide the video generation. Default value: "Two people are having a conversation with natural expressions and movements."

negative_prompt string

The negative prompt to avoid in the video generation. Default value: "Close-up, Bright tones, overexposed, static, blurred details, subtitles, style, works, paintings, images, static, overall gray, worst quality, low quality, JPEG compression residue, ugly, incomplete, extra fingers, poorly drawn hands, poorly drawn faces, deformed, disfigured, misshapen limbs, fused fingers, still picture, messy background, three legs, many people in the background, walking backwards"

bbox_person1 BoundingBox

Bounding box for person 1. If not provided, defaults to left half of image.

bbox_person2 BoundingBox

Bounding box for person 2. If not provided, defaults to right half of image.

audio_type AudioTypeEnum

How to combine the two audio tracks. 'para' (parallel) plays both simultaneously, 'add' (sequential) plays person 1 first then person 2. Default value: "para"

Possible enum values: para, add

num_inference_steps integer

The number of inference steps to use. Default value: 30

text_guidance_scale float

The text guidance scale for classifier-free guidance. Default value: 4

audio_guidance_scale float

The audio guidance scale. Higher values may lead to exaggerated mouth movements. Default value: 4

resolution ResolutionEnum

Resolution of the generated video (480p or 720p). Billing is per video-second (16 frames): 480p is 1 unit per second and 720p is 4 units per second. Default value: "480p"

Possible enum values: 480p, 720p

num_segments integer

Number of video segments to generate. Each segment adds ~5 seconds of video. First segment is ~5.8s, additional segments are 5s each. Default value: 1

seed integer

The seed for the random number generator.

enable_safety_checker boolean

Whether to enable safety checker. Default value: true

{
  "image_url": "https://raw.githubusercontent.com/meituan-longcat/LongCat-Video/refs/heads/main/assets/avatar/multi/sing.png",
  "audio_url_person1": "https://raw.githubusercontent.com/meituan-longcat/LongCat-Video/refs/heads/main/assets/avatar/multi/sing_man.WAV",
  "audio_url_person2": "https://raw.githubusercontent.com/meituan-longcat/LongCat-Video/refs/heads/main/assets/avatar/multi/sing_woman.WAV",
  "prompt": "Static camera, In a professional recording studio, two people stand facing each other, both wearing large headphones. They are speaking clearly into a large condenser microphone suspended between them. They looked at each other affectionately and occasionally shook their heads according to the rhythm. The soundproofed walls and visible recording equipment create an atmosphere focused on capturing high-quality audio as they interact and communicate.",
  "negative_prompt": "Close-up, Bright tones, overexposed, static, blurred details, subtitles, style, works, paintings, images, static, overall gray, worst quality, low quality, JPEG compression residue, ugly, incomplete, extra fingers, poorly drawn hands, poorly drawn faces, deformed, disfigured, misshapen limbs, fused fingers, still picture, messy background, three legs, many people in the background, walking backwards",
  "audio_type": "para",
  "num_inference_steps": 30,
  "text_guidance_scale": 4,
  "audio_guidance_scale": 4,
  "resolution": "480p",
  "num_segments": 1,
  "enable_safety_checker": true
}

Output#

video File* required

The generated video file.

seed integer* required

The seed used for generation.

{
  "video": {
    "content_type": "video/mp4",
    "url": "https://v3b.fal.media/files/b/0a87a882/k7N4EBTQnVM9nCW9ylN8i_output_87614f102ba94cc0b101d058a815c81f.mp4"
  },
  "seed": 424911732
}

Other types#

BoundingBox#

x float* required

X-coordinate of the top-left corner

y float* required

Y-coordinate of the top-left corner

w float* required

Width of the bounding box

h float* required

Height of the bounding box

label string* required

Label of the bounding box

File#

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.

file_data string

File data

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#

BoundingBox#

File#

Related Models

Longcat Multi Avatar Audio to 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#

BoundingBox#

File#

Related Models