# LTX-2.5 API

> LTX-2.5 as a hosted realtime API. Video on main_video and the audio generated with it on main_audio, aligned per window. $0.0040 per billable second.

Source: https://windflow.online/models/ltx-2-5 · Realtime video generation · Windflow Labs

## What it is

LTX-2.5 is Lightricks' 22-billion-parameter joint audio-and-video diffusion model. On Windflow it generates a stream window by window from a text prompt and an optional reference still, delivering video on main_video and the audio generated with it on main_audio, aligned per window.

## Specifications

- **Architecture:** 22B joint audio+video DiT, two-stage, generated one window at a time
- **Resolution:** 832 × 448 measured; the canvas is configurable in multiples of 64
- **Playout:** 24
- **Chunk:** 241 frames per window (10.04 s)
- **Control latency:** A whole window: the pipeline does not yield progressively, so time-to-first-frame equals one window's generation time. The reference still is published while it runs.
- **Inputs:** A text prompt and an optional reference still
- **Outputs:** Video on main_video and the audio generated with it on main_audio, aligned per window
- **Delivery:** WebRTC
- **Session protocol:** sdk.realtime.v2
- **Price:** $0.0040 per billable second

## Pricing

$0.0040 per billable session-second ($14.40/hr of billable time). Billing starts at the session's first generation_started event and stops when the session is released or ends. Queueing, worker startup, time before generation starts and the documented reconnect grace are not billed. After generation starts, paused or unwatched time remains billable; release the owner session to stop the meter.

## Use cases

- Audio-visual scenes where sound is generated with the picture rather than dubbed after.
- Continuous AI television or channel formats built from successive windows.
- Reference-still-anchored characters and settings across windows.
- Comparing a joint audio-video model with video-only alternatives on one protocol.

## Where it comes from

- [Lightricks/LTX-2 on GitHub](https://github.com/Lightricks/LTX-2) — LTX-2 Community License
- [Lightricks/LTX-2.5 on Hugging Face](https://huggingface.co/Lightricks/LTX-2.5)

## FAQ

### Is the audio generated or dubbed?

Generated. The model produces audio with the picture, and it follows the scene. Plan a fallback sound bed for content that needs continuous audio.

### Which licence covers LTX-2.5?

The LTX-2 Community License, as published by Lightricks. Read it before building a product on the model.

### How much does LTX-2.5 cost on Windflow?

LTX-2.5 costs $0.0040 per billable session-second ($14.40/hr of billable time). Billing starts at the session's first generation_started event and stops when the session is released or ends. Queueing, worker startup, time before generation starts and the documented reconnect grace are not billed. After generation starts, paused or unwatched time remains billable; release the owner session to stop the meter. There is no subscription.

### How do I get access to LTX-2.5?

Windflow is in private beta. Request access from the sign-up page, or ask for a live demo of LTX-2.5. Approved accounts start with $5 and four concurrent sessions.

### Is LTX-2.5 always running?

No. Model capacity is brought up on demand rather than kept standing. Live readiness for each model is published at api.windflow.online/v1/status, and a live demo can be arranged on request.

## Related guides

- [Choosing a realtime video model: a decision guide for 12 hosted models](https://windflow.online/guides/choosing-a-realtime-video-model)
- [How per-second pricing works for realtime video, with worked examples](https://windflow.online/guides/how-per-second-pricing-works)
- [How to measure realtime video API latency and responsiveness](https://windflow.online/guides/measure-realtime-video-latency)
- [Realtime video API: generate, edit and control live AI video](https://windflow.online/guides/realtime-video-api)
- [How to use the LTX-2.5 API](https://windflow.online/guides/ltx-2-5-api)
- [LTX-2.5 prompting guide: scenes, sound and dialogue](https://windflow.online/guides/ltx-2-5-prompting-guide)