Product launch · Xiaohu Explains

Decart ships Lucy 2.5: edit video while it's live, with sub-40ms latency claimed

Add objects, swap backgrounds, apply effects in real time; the product page claims sub-40ms latency and 100FPS continuous generation. Try it at lucy.decart.ai.

TL;DR

Decart has released Lucy 2.5, built around real-time video editing: add, swap, or remove content while the video is still playing, plus scene changes and effects.
Version 2.5 focuses on two things: more realistic frames and better prompt adherence.
Product-page performance numbers: sub-40ms latency, 100FPS continuous generation, and 4x faster real-time inference.
Use cases include virtual try-ons and live shopping, interactive streams, ad variations, and real-time product placement.
Try it: lucy.decart.ai; product page: decart.ai/lucy

⚑ A note on sourcing: the capabilities, speed numbers, and use cases below come from Decart's official posts and product page. They're the company's claims, not third-party benchmarks.

1The launch

Decart announces Lucy 2.5

On July 17, 2026, AI company Decart announced Lucy 2.5 on X, calling it the most advanced realtime model it has shipped.

The pitch in one line: Lucy can edit the video while it's still playing and being generated. No waiting for a full render before opening a timeline to start cutting.

◎

Most AI video tools have been generate first, export later. Lucy's differentiator is doing the edit at the live frame level: by the time viewers see the frame, the outfit, background, or effect has already changed.

Hero demo from the official site. Source: decart.ai/lucy

First demo in the launch thread. Source: Decart official X

2Capabilities

What you can actually change on screen

Four core operations: add, swap, remove, and apply effects.

What Lucy 2.5 improves over the previous version

Higher realism and visual fidelity, plus better prompt adherence — it understands what you ask it to change more reliably.

Objects & characters

Add, swap, remove

Swap characters, add people, replace or remove objects, change attributes like color or appearance.

Scenes

Background & style

Change the background, shift the whole visual style, "restyle" the scene into something else.

Effects

Real-time VFX

Generate visual effects while the video plays, no need to spend a night in an effects app first.

Positioning

Programmable video

Treats video as a programmable medium: people, products, environments, and effects can all be changed on the fly.

The stream is still running while the edit is applied to the current frame.

Second thread demo: adding, replacing, removing, and real-time VFX. Source: Decart official X

How this differs from traditional editing

Traditional workflow: record → import into software → edit frame by frame → export and publish. Lucy's aim is: while the livestream is still happening, the prompt or command has already changed the current frame. It's like swapping props on set in the middle of a live show, not finishing the recording and heading into the edit bay.

3Speed

What "realtime" actually means here

Realtime runs on Decart's own inference infrastructure, DOS. The numbers below come from the product page, not from our own testing.

<40ms

Latency: edits appear before the frame finishes rendering

100FPS

Continuous generation frame rate

Real-time inference speed

30x

More frames per second vs. comparable systems

The FAQ also mentions "within 200ms, 22FPS (512×768)" — a separate set of numbers from the headline sub-40ms / 100FPS claims. The public page doesn't spell out the test conditions for either set. Keep this in mind: the headline numbers are sub-40ms and 100FPS; your own end-to-end experience will depend on your machine.

Lucy runs on Decart's DOS, which the company describes as its own inference and training infrastructure built for realtime workloads, designed to hit the latency and frame rates above.

4Use cases

What you can do with it

Three main buckets: e-commerce, livestreaming, and ads — plus social and gaming demos on the side.

E-commerce

Virtual try-on, live shopping

While the host is talking, the outfit, shelf, or background can change instantly.

Livestreaming

Interactive streams, instant viewer control

Viewer votes or commands can affect the visuals, not just fill the chat.

Ads

Ad variations, real-time product placement

One piece of footage becomes multiple versions on the fly; drop products into a live stream as it airs.

Social, gaming

Extensions aimed at creators and digital worlds, with demos in social and gaming.

E-commerce / shopping demo. Source: decart.ai

Streaming / live demo. Source: decart.ai

Advertising demo. Source: decart.ai

Third thread demo: industry roundup. Source: Decart official X

LOOOK.AI founder Dmytro Kornilov's take, roughly: Decart's SDK enables realtime consumer experiences in retail settings without sacrificing quality. That's a partner endorsement, not an independent lab report.

5Trying it out

How to try it

Decart calls Lucy the only realtime video model and points to a try-it page. That's the company's own positioning.

🧰 Quick start · Lucy 2.5

Try itlucy.decart.ai

Overviewdecart.ai/lucy

AccessOpen the try-it page and start experimenting; enterprise onboarding goes through the official contact page

The company also says pricing will keep trending down, but no concrete plan was announced with this launch. Check the try-it page and sales conversations for actual numbers.

Meet Lucy 2.5, our most advanced realtime model yet. Lucy edits video in real time, now with more power and control. Decart official X, 2026-07-17

Primary sources: Decart launch thread (2026-07-17); product page decart.ai/lucy; try-it page lucy.decart.ai. Capabilities, latency, frame rates, and industry claims all come from vendor materials. The FAQ also lists 200ms / 22FPS, which isn't clearly defined as being under the same test conditions as the headline sub-40ms / 100FPS numbers.

One-Pager · This page ≈ the whole article · best.xiaohu.ai

Decart drops Lucy 2.5: the video's still playing, and the frame's already been edited

Decart's Lucy 2.5 edits live video: add objects, swap backgrounds, remove items, all while it plays. This page walks through how it works and where the numbers come from.

↓ Read this page and you've got the gist · with one animated diagram

Launch · the problem it solves

On July 17, 2026, Decart announced Lucy 2.5 on X, centered on real-time video editing: while the video is still playing, the AI can add, swap, and remove elements, change scenes, or apply effects.

✔ AI can already generate and edit video
✘ But you had to wait for the video to finish generating and export before you could edit it — nothing could be changed mid-stream
Most AI video tools used to be generate-then-export. Lucy moves the edit into the same moment the video is playing or being generated.

What's new · what it's for

Before, getting this kind of effect meant recording the whole video, exporting it, then opening an editor and adjusting frame by frame. Now that step happens in the same instant the video is playing.

Before

Record → import → edit frame by frame → export and publish. Viewers only ever saw the finished cut.

Now

The video is still playing and generating. A prompt comes in, the frame changes immediately, and viewers see the new result.

Decart points to two improvements over the previous version: more realistic frames and better adherence to prompt instructions.

How it works · one diagram

Lucy doesn't process the whole video — it works on the frame that's being generated or played right now. The camera is recording, Lucy edits the content in sync, and viewers see the altered frame on the other end.

Xiaohu is live-selling clothes. While viewers are still watching, Lucy has already swapped the outfit, background, or effect — the frame on the viewer's side is the edited one.

Speed · results and caveats

These numbers come from Decart's product page. Lucy runs on the company's self-built inference system, DOS.

<40ms

Latency: the edit appears before the frame finishes

100FPS

Continuous generation rate

Real-time inference speed

30x

More frames/sec than comparable systems

⚠️

The product-page FAQ also lists 200ms and 22FPS (at 512×768 resolution). It's not clear whether those were measured the same way as the headline numbers. All figures come from Decart's own product page; no third party has reproduced them yet.

Decart's listed scenarios focus on e-commerce live shopping, interactive streaming, ad variations, and real-time product placement, with additional social and gaming demos. The try-it page is at lucy.decart.ai and the product overview at decart.ai/lucy; enterprise inquiries go through the official contact page. Pricing hasn't been announced yet.

Takeaway: Lucy 2.5 moves video editing from "record first, edit later" to "edit while it's playing." The latency and frame-rate numbers come from Decart's own product page and haven't been independently reproduced.

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