Decart

Decart provides real-time AI video transformation with style transfer and virtual try-on. Transform video streams into animated styles, apply reference-image costumes, or any custom prompt-based visual effect using models like Lucy.

Vision Agents uses Stream Video for real-time WebRTC transport by default. External WebRTC transports are supported as well. Most AI providers offer free tiers to get started.

Installation

uv add "vision-agents[decart]"

Quick start

from vision_agents.core import Agent, User
from vision_agents.plugins import decart, gemini, deepgram, elevenlabs, getstream

processor = decart.RestylingProcessor(
    initial_prompt="Studio Ghibli animation style",
    model="lucy_2_rt",
)

agent = Agent(
    edge=getstream.Edge(),
    agent_user=User(name="Styled AI"),
    instructions="Be helpful",
    llm=gemini.Realtime(),
    stt=deepgram.STT(),
    tts=elevenlabs.TTS(),
    processors=[processor],
)

Set DECART_API_KEY in your environment or pass api_key directly.

Parameters

Name	Type	Default	Description
model	str	"lucy_2_rt"	Decart model
initial_prompt	str	"Cyberpunk city"	Style prompt for visual transformation
initial_image	bytes | str | Path	None	Optional reference image for first connect (bytes, file path, http(s) URL, data URI, or raw base64)
enhance	bool	True	Whether to enhance the prompt
mirror	bool	True	Mirror mode for front-facing cameras
width	int	1280	Output video width
height	int	720	Output video height
api_key	str	None	API key (defaults to DECART_API_KEY env var)

Dynamic style changes

Update the video style during a call via function calling:

@llm.register_function(description="Changes the video style")
async def change_style(prompt: str) -> str:
    await processor.update_prompt(prompt)
    return f"Style changed to: {prompt}"

Reference images

For models like Lucy that accept a reference image, pass it at construction time and/or swap it atomically with a prompt using update_state:

processor = decart.RestylingProcessor(
    model="lucy_2_rt",
    initial_prompt="A person wearing a superhero costume",
    initial_image="./costumes/superhero.png",
)

# Atomically change prompt + reference image
await processor.update_state(
    prompt="A person wearing a wizard robe",
    image="./costumes/wizard.png",
)

# Image-only update
await processor.update_state(image=b"<raw image bytes>")

initial_image and update_state(image=...) accept bytes, a local file path, an http(s) URL, a data: URI, or a raw base64 string.

Next steps

Build a Voice Agent

Get started with voice

Build a Video Agent

Add video processing