Smallest AI

Text-to-speech service using Smallest AI’s WebSocket streaming API

Overview

Smallest AI provides real-time text-to-speech synthesis through a WebSocket-based integration with their Waves API. The service supports configurable voice parameters, multiple languages, and handles interruptions by reconnecting the WebSocket.

Smallest AI TTS API Reference

Complete API reference for all parameters and methods

Example Implementation

Complete example with WebSocket streaming

Installation

uv add "pipecat-ai[smallest]"

Prerequisites

1. Smallest AI Account: Sign up at Smallest AI
2. API Key: Generate an API key from your account dashboard

Set the following environment variable:

export SMALLEST_API_KEY=your_api_key

Configuration

api_key · str · required

Smallest AI API key for authentication.

base_url · str · default: "wss://api.smallest.ai"

Base WebSocket URL for the Smallest API. Override for custom or proxied deployments.

sample_rate · int · default: "None"

Output audio sample rate in Hz. When None, uses the pipeline’s configured sample rate.

output_format · str · default: "pcm"

Audio format returned by the API. One of pcm, mp3, wav, ulaw, alaw. Defaults to pcm, which is what Pipecat expects internally. Fixed at init time.

settings · SmallestTTSService.Settings · default: "None"

Runtime-configurable settings. See Settings below.

Settings

Runtime-configurable settings passed via the settings constructor argument using SmallestTTSService.Settings(...). These can be updated mid-conversation with TTSUpdateSettingsFrame. See Service Settings for details.

Parameter	Type	Default	Description
model	str	lightning_v3.1_pro	Model identifier: lightning_v3.1 or lightning_v3.1_pro.
voice	str	meher	Voice identifier. Default is meher for lightning_v3.1_pro.
language	Language | str	Language.EN	Language code for synthesis.
speed	float	None	Speech speed multiplier (0.5–2.0). When None, uses API defaults.

Usage

Basic Setup

from pipecat.services.smallest import SmallestTTSService

tts = SmallestTTSService(
    api_key=os.getenv("SMALLEST_API_KEY"),
    settings=SmallestTTSService.Settings(
        voice="sophia",
    ),
)

With Voice Customization

from pipecat.transcriptions.language import Language

tts = SmallestTTSService(
    api_key=os.getenv("SMALLEST_API_KEY"),
    settings=SmallestTTSService.Settings(
        voice="sophia",
        language=Language.ES,
        speed=1.2,
    ),
)

Updating Settings at Runtime

Voice settings can be changed mid-conversation using TTSUpdateSettingsFrame:

from pipecat.frames.frames import TTSUpdateSettingsFrame
from pipecat.services.smallest.tts import SmallestTTSSettings

await task.queue_frame(
    TTSUpdateSettingsFrame(
        delta=SmallestTTSSettings(
            voice="new_voice",
            speed=1.1,
        )
    )
)

Notes

• WebSocket streaming: The service uses WebSocket connections for real-time streaming. The connection is automatically managed and will reconnect if interrupted.
• Keepalive: The service sends periodic keepalive messages (every 30 seconds) to prevent idle timeouts on the WebSocket connection.
• Language support: Supports multiple languages including Arabic, Bengali, German, English, Spanish, French, Gujarati, Hebrew, Hindi, Italian, Kannada, Marathi, Dutch, Polish, Russian, and Tamil.

Event Handlers

Smallest AI TTS supports the standard service connection events:

Event	Description
on_connected	Connected to Smallest AI WebSocket
on_disconnected	Disconnected from Smallest WebSocket
on_connection_error	WebSocket connection error occurred

@tts.event_handler("on_connected")
async def on_connected(service):
    print("Connected to Smallest AI")