Cartesia STT

Cartesia provides low-latency speech-to-text with the Ink model. STT streams PCM audio to Cartesia Ink and emits transcript and turn events that Vision Agents uses for interruption and eager turn handling.

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.

Cartesia also provides low-latency text-to-speech. You can use both in the same agent.

Installation

uv add "vision-agents[cartesia]"

Quick Start

from vision_agents.core import Agent, User
from vision_agents.plugins import cartesia, gemini, getstream

agent = Agent(
    edge=getstream.Edge(),
    agent_user=User(name="Assistant", id="agent"),
    instructions="You are a helpful assistant.",
    llm=gemini.LLM("gemini-3-flash-preview"),
    stt=cartesia.STT(),
    tts=cartesia.TTS(),
)

Set CARTESIA_API_KEY in your environment or pass api_key directly.

Parameters

Name	Type	Default	Description
api_key	str	None	API key (defaults to CARTESIA_API_KEY env var)
model	str	"ink-2"	Cartesia STT model
sample_rate	int	16000	PCM sample rate (Hz) sent to Cartesia. One of 8000, 16000, 22050, 24000, 44100, 48000
encoding	str	"pcm_s16le"	PCM encoding sent to Cartesia
cartesia_version	str	"2026-03-01"	Cartesia API version used for the turn-detection websocket
websocket_url	str	"wss://api.cartesia.ai/stt/turns/websocket"	WebSocket endpoint (mainly useful for tests)
audio_chunk_duration_ms	int	100	Maximum duration per WebSocket audio frame (ms)

Next Steps

Cartesia TTS

Low-latency text-to-speech

Build a Voice Agent

Get started with voice