Generate digital twin videos using HeyGen Avatar V.
Avatar V is HeyGen's newest avatar rendering engine. It uses
cross-reference-driven animation for more natural motion and
lip-sync than Avatar IV, especially for complex expressions and
longer scripts. Avatar V is only available through HeyGen's v3
API — this endpoint sets engine={"type": "avatar_v"}
automatically.
Supports the v3 Avatar V feature set: fit, remove_background,
background, watermark, caption, and webm output.
Billed per second of output video ($0.1500/s).
The client provides a convenient way to interact with the model API.
npm install --save @fal-ai/clientThe @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.
Set FAL_KEY as an environment variable in your runtime.
export FAL_KEY="YOUR_API_KEY"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/heygen/avatar5/digital-twin", {
input: {},
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);The API uses an API Key for authentication. It is recommended you set the FAL_KEY environment variable in your runtime when possible.
import { fal } from "@fal-ai/client";
fal.config({
credentials: "YOUR_FAL_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.
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/heygen/avatar5/digital-twin", {
input: {},
webhookUrl: "https://optional.webhook.url/for/results",
});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/heygen/avatar5/digital-twin", {
requestId: "764cabcf-b745-4b3e-ae38-1200304cf45b",
logs: true,
});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/heygen/avatar5/digital-twin", {
requestId: "764cabcf-b745-4b3e-ae38-1200304cf45b"
});
console.log(result.data);
console.log(result.requestId);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.
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.
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.
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);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.
avatar stringName of the Avatar V-eligible avatar to use. Default value: "Abigail Sofa Front"
prompt stringText the avatar will speak. Required when audio_url is not provided.
voice stringName of the text-to-speech voice to use for the avatar when audio_url is not provided. Default value: "Warm Pro Narrator"
audio_url stringHTTP(S) URL of an audio file for the avatar to lip-sync to. When provided, the avatar uses this audio instead of text-to-speech and prompt/voice are ignored.
fit FitEnumHow the avatar fits within the output frame. 'contain' keeps the full avatar in view (may letterbox); 'cover' fills the frame (may crop). Default value: "cover"
Possible enum values: contain, cover
remove_background booleanRemove the avatar's background. Requires a matting-enabled avatar.
Optional background to composite behind the avatar. Ignored when output_format='webm' (webm output is transparent).
Optional watermark image to overlay on the output video.
caption booleanGenerate a sidecar SRT caption file alongside the video.
output_format OutputFormatEnumOutput container format. 'webm' produces a transparent video (automatically removes the background) and ignores the background field. Default value: "mp4"
Possible enum values: mp4, webm
resolution ResolutionEnumOutput resolution preset. Default value: "720p"
Possible enum values: 720p, 1080p, 4k
aspect_ratio AspectRatioEnumAspect ratio of the output video. Supported values: '16:9', '9:16', '4:5', '5:4', '1:1', and 'auto'. 'auto' preserves the source aspect ratio when HeyGen can read it, falling back to '16:9' otherwise. Default value: "16:9"
Possible enum values: 16:9, 9:16, 4:5, 5:4, 1:1, auto
enable_safety_checker booleanAuthorized callers may set false to request relaxed screening. Default value: true
{
"avatar": "Abigail Office Front",
"prompt": "Hello and welcome to this demonstration of HeyGen Avatar V.",
"voice": "Warm Pro Narrator",
"fit": "cover",
"output_format": "mp4",
"resolution": "720p",
"aspect_ratio": "16:9",
"enable_safety_checker": true
}The generated Avatar V video file.
Generated caption file (SRT) when caption=True and HeyGen returns one.
{
"video": {
"url": "https://v3b.fal.media/files/b/0a900636/DUES0_z4i7FWnife02ieH_output.mp4"
}
}url string* requiredThe URL where the file can be downloaded from.
content_type stringThe mime type of the file.
file_name stringThe name of the file. It will be auto-generated if not provided.
file_size integerThe size of the file in bytes.
image_url string* requiredHTTP(S) URL of the watermark image to overlay on the video.
scale floatWatermark scale relative to the video (0.0 exclusive–2.0).
opacity floatWatermark opacity (0.0 = transparent, 1.0 = opaque).
placement EnumWhere to place the watermark on the video.
Possible enum values: top-left, top-right, bottom-left, bottom-right
type TypeEnumType of background. 'color' for a solid hex color, 'image' for an image URL. Default value: "color"
Possible enum values: color, image
value stringBackground value — hex color for 'color' type, or HTTP(S) URL for 'image' type. Default value: "#FFFFFF"