> ## Documentation Index
> Fetch the complete documentation index at: https://visionagents.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Decart

[Decart](https://decart.ai/) 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.

<Info>
  Vision Agents requires a [Stream](https://getstream.io/try-for-free/) account
  for real-time transport. Most providers offer free tiers to get started.
</Info>

## Installation

```sh theme={null}
uv add "vision-agents[decart]"
```

## Quick start

```python theme={null}
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],
)
```

<Warning>
  Set `DECART_API_KEY` in your environment or pass `api_key` directly.
</Warning>

## 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:

```python theme={null}
@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`:

```python theme={null}
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

<CardGroup cols={2}>
  <Card title="Build a Voice Agent" icon="microphone" href="/introduction/voice-agents">
    Get started with voice
  </Card>

  <Card title="Build a Video Agent" icon="video" href="/introduction/video-agents">
    Add video processing
  </Card>
</CardGroup>