LTX-2.5 Fast

LTX-2.5 Fast is the speed-focused variant in the LTX 2.5 video family, built for high-throughput text-to-video and image-to-video generation. It supports output from 720p through 4K, longer durations at HD resolutions, optional native audio generation, and first-to-last-frame image guidance for more directed motion and shot planning. It is well suited to rapid creative iteration, storyboard development, social and advertising content, and other video workflows that need faster turnaround without dropping to low-end resolutions.

Complete technical specification for integration
Ready-to-use code snippets for common workflows
API Options
Platform-level options for task execution and delivery.
taskType
stringrequiredvalue: videoInferenceIdentifier for the type of task being performed
taskUUID
stringrequiredUUID v4UUID v4 identifier for tracking tasks and matching async responses. Must be unique per task.
outputType
stringdefault: URLVideo output type.
Allowed values1 value
outputFormat
stringdefault: MP4Specifies the file format of the generated output. The available values depend on the task type and the specific model's capabilities.
- `MP4`: Widely supported video container (H.264), recommended for general use.
- `WEBM`: Optimized for web delivery.
- `MOV`: QuickTime format, common in professional workflows (Apple ecosystem).
Allowed values3 values
outputQuality
integermin: 20max: 99default: 95Compression quality of the output. Higher values preserve quality but increase file size.
webhookURL
stringuriSpecifies a webhook URL where JSON responses will be sent via HTTP POST when generation tasks complete. For batch requests with multiple results, each completed item triggers a separate webhook call as it becomes available.
Learn more1 resource
- WebhooksPLATFORM
- Webhooks
deliveryMethod
stringdefault: asyncDetermines how the API delivers task results.
Allowed values1 value
- Returns an immediate acknowledgment with the task UUID. Poll for results using getResponse. Required for long-running tasks like video generation.
Learn more1 resource
- Task PollingPLATFORM
uploadEndpoint
stringuriSpecifies a URL where the generated content will be automatically uploaded using the HTTP PUT method. The raw binary data of the media file is sent directly as the request body. For secure uploads to cloud storage, use presigned URLs that include temporary authentication credentials.
Common use cases:
- Cloud storage: Upload directly to S3 buckets, Google Cloud Storage, or Azure Blob Storage using presigned URLs.
- CDN integration: Upload to content delivery networks for immediate distribution.
// S3 presigned URL for secure upload https://your-bucket.s3.amazonaws.com/generated/content.mp4?X-Amz-Signature=abc123&X-Amz-Expires=3600 // Google Cloud Storage presigned URL https://storage.googleapis.com/your-bucket/content.jpg?X-Goog-Signature=xyz789 // Custom storage endpoint https://storage.example.com/uploads/generated-image.jpgThe content data will be sent as the request body to the specified URL when generation is complete.
safety
objectContent safety checking configuration for video generation.
Properties2 properties
safety»checkContentcheckContent
booleanEnable or disable content safety checking. Increases total generation time.
safety»modemode
stringdefault: fastSafety checking mode for video generation.
Allowed values2 values
- Checks key frames.
- Checks all frames.
ttl
integermin: 60Time-to-live (TTL) in seconds for generated content. Only applies when
outputTypeisURL.
includeCost
booleanInclude task cost in the response.
numberResults
integermin: 1max: 4default: 1Number of results to generate. Each result uses a different seed, producing variations of the same parameters.
Inputs
Input resources for the task (images, audio, etc). These must be nested inside the inputs object.
inputs object.inputs»referenceImagesreferenceImages
array of stringsitems: 1List of reference images (UUID, URL, Data URI, or Base64).
inputs»frameImagesframeImages
array of strings or objectsmin items: 1max items: 2An array of frame-specific image inputs to guide video generation. Each item can be either a plain image input (UUID, URL, Data URI, or Base64) or an object that pairs an image with a target position in the video.
The
frameImagesparameter allows you to constrain specific frames within the video sequence, ensuring that particular visual content appears at designated points. Position can be specified usingframe(named positions or frame indices) ortimestamp(seconds), depending on model support. This is different fromreferenceImages, which provide overall visual guidance without constraining specific timeline positions.When the
frameparameter is omitted, automatic distribution rules apply:- 1 image: Used as the first frame.
- 2 images: First and last frames.
Examples3 examples
Shorthand format: When you don't need to specify a frame position, you can pass a plain image input directly.
"frameImages": [ "aac49721-1964-481a-ae78-8a4e29b91402" ]Object format: When you need to specify a position, use an object with
imageand eitherframeortimestamp(model-dependent).First and last frames: With two images, they automatically become the first and last frames of the video sequence. You can mix shorthand and object formats."frameImages": [ { "image": "aac49721-1964-481a-ae78-8a4e29b91402", "frame": "first" } ]"frameImages": [ "aac49721-1964-481a-ae78-8a4e29b91402", { "image": "3ad204c3-a9de-4963-8a1a-c3911e3afafe", "frame": "last" } ]Format 1: string[]
Image input (UUID, URL, Data URI, or Base64).
Format 2: object[]2 properties
inputs»frameImages»imageimage
stringrequiredImage input (UUID, URL, Data URI, or Base64).
inputs»frameImages»frameframe
objectTarget frame position for the image. Supports first and last frame.
Allowed values4 values
- First frame of the video.
- Last frame of the video.
- Frame index 0 (first frame).
- Frame index -1 (last frame).
inputs»audioaudio
string1 limitAudio input (UUID or URL). Drives the generated video, whose length follows the audio.
Core Parameters
Primary parameters that define the task output.
model
stringrequiredvalue: lightricks:ltx@2.5-fastIdentifier of the model to use for generation.
Learn more3 resources
positivePrompt
stringrequiredmin: 2max: 5000Text prompt describing elements to include in the generated output.
Learn more1 resource
- PromptsLEARN
- Prompts
Width of the generated media in pixels.
Learn more2 resources
Height of the generated media in pixels.
Learn more2 resources
duration
integer | stringdefault: 6Length of the generated video in seconds. The total number of frames produced is determined by duration multiplied by the model's frame rate (fps).
Allowed values13 values
fps
integerFrames per second for video generation. Higher values create smoother motion but require more processing time.
Allowed values4 values
Settings
Technical parameters to fine-tune the inference process. These must be nested inside the settings object.
settings object.settings»audioaudio
booleanGenerate synchronized audio.
settings»cameraMovementcameraMovement
stringCinematic camera movement.
Allowed values8 values
- Camera moves toward the subject.
- Camera moves away from the subject.
- Camera tracks to the left.
- Camera tracks to the right.
- Camera rises on a jib.
- Camera lowers on a jib.
- Fixed camera with no movement.
- Focus racks between subjects.