Reference Video To Video Lora
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/ltx-2.3-quality/reference-video-to-video/lora", {
input: {
prompt: "A dancer in a flowing red dress against a black backdrop, studio lighting, cinematic.",
video_url: "https://v3b.fal.media/files/b/0a8824b1/sdm0KfmenrlywesfzY1Y1_if6euPp1.mp4",
loras: [{
path: "https://example.com/path/to/lora.safetensors",
scale: 1,
transformer: "both"
}]
},
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/ltx-2.3-quality/reference-video-to-video/lora", {
input: {
prompt: "A dancer in a flowing red dress against a black backdrop, studio lighting, cinematic.",
video_url: "https://v3b.fal.media/files/b/0a8824b1/sdm0KfmenrlywesfzY1Y1_if6euPp1.mp4",
loras: [{
path: "https://example.com/path/to/lora.safetensors",
scale: 1,
transformer: "both"
}]
},
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/ltx-2.3-quality/reference-video-to-video/lora", {
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/ltx-2.3-quality/reference-video-to-video/lora", {
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.
prompt string* requiredThe prompt to guide generation.
video_url string* requiredThe URL of the reference video that supplies motion/structure.
control_video_url stringOptional pre-computed control video (e.g. an already-rendered depth / edge / pose composite). When provided together with skip_control_preprocess, the built-in control estimation is skipped and this video is used directly as the control signal, resampled to the output resolution and frame count.
skip_control_preprocess booleanSkip the built-in control estimation (depth / edge / pose) and use control_video_url directly as the control signal. Requires control_video_url; ignored if it is not set. With resolution='auto', the output follows the source video size/aspect up to the LTX limits. Explicit resolutions are honored and 64-aligned so the RGB video and control video stay matched.
preserve_original_video booleanTrue video-to-video: the base video_url is used as the generation's starting point, while control_video_url still drives the structure. The amount of the original preserved is controlled by strength (denoise): lower strength keeps more of the original video's pixels. Requires skip_control_preprocess, video_url and control_video_url. Default off leaves the standard control path unchanged.
image_url stringOptional reference image for style/character anchoring. This is the FIRST-frame keyframe.
mid_image_url stringOptional middle-frame keyframe image. When set, the look/appearance is anchored to this image around the middle of the clip (in addition to image_url at the start), so the appearance follows a moving camera instead of drifting. Requires image_url.
end_image_url stringOptional last-frame keyframe image. When set, the look/appearance is anchored to this image at the end of the clip. Useful for shots where the camera travels to a different place than the start image. Requires image_url.
video_strength floatVideo conditioning strength. Lower values give the model more freedom to change the reference video motion/structure. Default value: 0.6
strength floatSampler denoise strength for reference-video-to-video. With preserve_original_video on, this is the video-to-video amount: lower values keep more of the original video's pixels (e.g. 0.5 = keep ~50%), 1.0 fully regenerates. Without preserve_original_video it only trims the denoise schedule. Default value: 1
num_frames integerThe number of output frames to generate. This IC-LoRA endpoint caps the resolution x frames volume for stability (~150 frames at 720p-class; more at smaller sizes). A request above the budget returns a 422 — reduce num_frames or use a smaller resolution. Default value: 121
The size of the generated video. In direct-control mode (skip_control_preprocess with control_video_url), 'auto' follows the source video size/aspect up to the LTX limits and explicit sizes are honored with 64px alignment. In the built-in control estimation mode, the output stays near the official control workflow size. Higher resolutions reduce the maximum stable frame count; lower resolutions can run longer. 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
}frames_per_second floatFrames per second of the generated video. Default value: 24
num_inference_steps integerNumber of inference steps. Defaults to 15 and can be increased up to 30. Default value: 15
guidance_scale floatClassifier-free guidance scale. The default is tuned for fast, high-quality generation. Default value: 1
generate_audio booleanWhether to include audio in the returned video. When disabled, the final MP4 is returned without an audio track. Default value: true
negative_prompt stringThe negative prompt to steer generation away from. Default value: "color distortion, overexposure, static, blurry details, subtitles, style, artwork, painting, frame, still, dim overall tone, worst quality, low quality, JPEG compression artifacts, ugly, mutilated, extra fingers, poorly drawn hands, poorly drawn face, deformed, disfigured, malformed limbs, fused fingers, motionless frame, cluttered background, three legs, crowded background, walking backwards"
seed integerRandom seed for reproducibility. If None, a random seed is chosen.
enable_prompt_expansion booleanWhether to enable prompt expansion. Default value: true
enable_safety_checker booleanWhether to enable the safety checker. Default value: true
video_quality VideoQualityEnumThe quality preset of the generated video. Default value: "high"
Possible enum values: low, medium, high, maximum
video_write_mode VideoWriteModeEnumThe write mode of the generated video. Default value: "balanced"
Possible enum values: fast, balanced, small
sync_mode booleanIf True, the media is returned as a data URI inline in the response. Useful for short-lived requests and tests.
Up to 3 LoRAs to apply on top of LTX-2.3. Each path is downloaded through the registry SSRF-safe downloader before it is loaded. Max size: 3 GB per LoRA.
{
"prompt": "A dancer in a flowing red dress against a black backdrop, studio lighting, cinematic.",
"video_url": "https://v3b.fal.media/files/b/0a8824b1/sdm0KfmenrlywesfzY1Y1_if6euPp1.mp4",
"video_strength": 0.6,
"strength": 1,
"num_frames": 121,
"resolution": "auto",
"frames_per_second": 24,
"num_inference_steps": 15,
"guidance_scale": 1,
"generate_audio": true,
"negative_prompt": "color distortion, overexposure, static, blurry details, subtitles, style, artwork, painting, frame, still, dim overall tone, worst quality, low quality, JPEG compression artifacts, ugly, mutilated, extra fingers, poorly drawn hands, poorly drawn face, deformed, disfigured, malformed limbs, fused fingers, motionless frame, cluttered background, three legs, crowded background, walking backwards",
"enable_prompt_expansion": true,
"enable_safety_checker": true,
"video_quality": "high",
"video_write_mode": "balanced",
"loras": [
{
"path": "https://example.com/path/to/lora.safetensors",
"scale": 1,
"transformer": "both"
}
]
}The generated video.
seed integer* requiredThe seed actually used for generation.
prompt string* requiredThe prompt used for generation (after any expansion).
{
"video": {
"url": "",
"content_type": "image/png",
"file_name": "z9RV14K95DvU.png",
"file_size": 4404019
},
"prompt": ""
}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.
path string* requiredDirect HTTP(S) download URL of the LoRA file (.safetensors). The file is downloaded through an SSRF-safe downloader before it is loaded. Max size: 3 GB.
scale floatStrength of the LoRA application (0.0 to 2.0). Higher values = stronger effect on the generated video. Default value: 1
transformer TransformerEnumForward-compatibility flag for multi-transformer architectures. LTX-2.3 has a single transformer, so 'both' is the right choice for almost all users. Default value: "both"
Possible enum values: high, low, both
width integerThe width of the generated image. Default value: 512
height integerThe height of the generated image. Default value: 512