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Extend video with audio using LTX-2
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Extend a video with a text prompt.
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-2-19b/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);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-2-19b/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",
});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-2-19b/extend-video", {
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-2-19b/extend-video", {
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 generate the video from.
video_url string* requiredThe URL of the video to extend.
end_image_url stringThe URL of the image to use as the end of the extended video.
num_frames integerThe number of frames to generate. Default value: 121
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 booleanWhether to generate audio for the video. Default value: true
use_multiscale booleanWhether 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 booleanWhen true, match the output FPS to the input video's FPS instead of using the default target FPS. Default value: true
fps floatThe frames per second of the generated video. Default value: 25
guidance_scale floatThe guidance scale to use. Default value: 3
num_inference_steps integerThe number of inference steps to use. Default value: 40
acceleration AccelerationEnumThe acceleration level to use. Default value: "regular"
Possible enum values: none, regular, high, full
camera_lora CameraLoRAEnumThe 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 floatThe 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 stringThe negative prompt to generate the video from. Default value: "blurry, out of focus, overexposed, underexposed, low contrast, washed out colors, excessive noise, grainy texture, poor lighting, flickering, motion blur, distorted proportions, unnatural skin tones, deformed facial features, asymmetrical face, missing facial features, extra limbs, disfigured hands, wrong hand count, artifacts around text, inconsistent perspective, camera shake, incorrect depth of field, background too sharp, background clutter, distracting reflections, harsh shadows, inconsistent lighting direction, color banding, cartoonish rendering, 3D CGI look, unrealistic materials, uncanny valley effect, incorrect ethnicity, wrong gender, exaggerated expressions, wrong gaze direction, mismatched lip sync, silent or muted audio, distorted voice, robotic voice, echo, background noise, off-sync audio,incorrect dialogue, added dialogue, repetitive speech, jittery movement, awkward pauses, incorrect timing, unnatural transitions, inconsistent framing, tilted camera, flat lighting, inconsistent tone, cinematic oversaturation, stylized filters, or AI artifacts."
seed integerThe seed for the random number generator.
enable_prompt_expansion booleanWhether to enable prompt expansion. Default value: true
enable_safety_checker booleanWhether to enable the safety checker. Default value: true
video_output_type VideoOutputTypeEnumThe output type of the generated video. Default value: "X264 (.mp4)"
Possible enum values: X264 (.mp4), VP9 (.webm), PRORES4444 (.mov), GIF (.gif)
video_quality VideoQualityEnumThe quality 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 will be returned as a data URI and the output data won't be available in the request history.
extend_direction ExtendDirectionEnumDirection 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 integerThe number of frames to use as context for the extension. Default value: 25
video_strength floatVideo conditioning strength. Lower values represent more freedom given to the model to change the video content. Default value: 1
audio_strength floatAudio conditioning strength. Lower values represent more freedom given to the model to change the audio content. Default value: 1
end_image_strength floatThe 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": 25,
"guidance_scale": 3,
"num_inference_steps": 40,
"acceleration": "regular",
"camera_lora": "none",
"camera_lora_scale": 1,
"negative_prompt": "blurry, out of focus, overexposed, underexposed, low contrast, washed out colors, excessive noise, grainy texture, poor lighting, flickering, motion blur, distorted proportions, unnatural skin tones, deformed facial features, asymmetrical face, missing facial features, extra limbs, disfigured hands, wrong hand count, artifacts around text, inconsistent perspective, camera shake, incorrect depth of field, background too sharp, background clutter, distracting reflections, harsh shadows, inconsistent lighting direction, color banding, cartoonish rendering, 3D CGI look, unrealistic materials, uncanny valley effect, incorrect ethnicity, wrong gender, exaggerated expressions, wrong gaze direction, mismatched lip sync, silent or muted audio, distorted voice, robotic voice, echo, background noise, off-sync audio,incorrect dialogue, added dialogue, repetitive speech, jittery movement, awkward pauses, incorrect timing, unnatural transitions, inconsistent framing, tilted camera, flat lighting, inconsistent tone, cinematic oversaturation, stylized filters, or AI artifacts.",
"enable_prompt_expansion": true,
"enable_safety_checker": true,
"video_output_type": "X264 (.mp4)",
"video_quality": "high",
"video_write_mode": "balanced",
"extend_direction": "forward",
"num_context_frames": 25,
"video_strength": 1,
"audio_strength": 1,
"end_image_strength": 1
}The generated video.
seed integer* requiredThe seed used for the random number generator.
prompt string* requiredThe prompt used for the generation.
{
"video": {
"fps": 25,
"url": "https://v3b.fal.media/files/b/0a894013/N9lnMTq7W3uMC0lOQg845_BknRPV8I.mp4",
"num_frames": 161,
"content_type": "video/mp4",
"width": 1248,
"duration": 6.44,
"file_name": "CJcQGDrxOSRg2YFl5GNDt_glXPMoji.mp4",
"height": 704
},
"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."
}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.
width integerThe width of the video
height integerThe height of the video
fps floatThe FPS of the video
duration floatThe duration of the video
num_frames integerThe number of frames in the video
width integerThe width of the generated image. Default value: 512
height integerThe height of the generated image. Default value: 512