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Overview

MistralTTSService provides text-to-speech synthesis using Mistral’s Voxtral TTS API. It uses HTTP streaming with Server-Sent Events to generate PCM-encoded audio at 24kHz. Key features include:
  • Streaming TTS with real-time audio generation
  • Automatic resampling to pipeline sample rate
  • Built-in metrics support
  • Multiple voice options

Mistral TTS API Reference

Pipecat’s API methods for Mistral TTS

Example Implementation

Complete example with Mistral STT and TTS

Mistral Documentation

Official Mistral API documentation

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Installation

To use Mistral TTS service, install the required dependencies: 
uv add "pipecat-ai[mistral]"

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Prerequisites

Before using MistralTTSService, you need:
  1. Mistral Account: Sign up at Mistral AI
  2. API Key: Generate an API key from your account dashboard
  3. Model Access: Ensure you have access to the Voxtral TTS API

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Required Environment Variables

  • MISTRAL_API_KEY: Your Mistral API key for authentication

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Configuration

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api_key
str
Mistral API key for authentication.
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sample_rate
int
default:"None"
Output audio sample rate in Hz. Audio is resampled from Mistral’s native 24kHz when a different rate is requested. When None, uses the pipeline’s configured sample rate.
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settings
MistralTTSService.Settings
default:"None"
Runtime-configurable settings for the TTS service. See Settings below.

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Settings

Runtime-configurable settings passed via the settings constructor argument using MistralTTSService.Settings(...). These can be updated mid-conversation with TTSUpdateSettingsFrame. See Service Settings for details.
ParameterTypeDefaultDescription
modelstr"voxtral-mini-tts-2603"Mistral TTS model to use. (Inherited.)
voicestrNoneVoice identifier. (Inherited.)
languageLanguage | strNoneLanguage for synthesis. (Inherited.)

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Available Voices

Mistral provides built-in voices grouped by language. The voice setting accepts either the slug (e.g. fr_marie_neutral) or the UUID. You can always retrieve the latest list of voices via the Mistral API: 
curl "https://api.mistral.ai/v1/audio/voices?limit=200&offset=0" \
  -H "Authorization: Bearer $MISTRAL_API_KEY"
You will have to extract the ‘slug’ or ‘id’ field from the response for each voice to use in the voice setting, for example: 
{
  "name": "Marie - Neutral",
  "slug": "fr_marie_neutral",
  "languages": ["fr_fr"],
  "gender": "female",
  "age": 30,
  "tags": ["composed", "steady", "neutral"],
  "color": "#77778B",
  "description": null,
  "appearance": null,
  "retention_notice": 30,
  "id": "5a271406-039d-46fe-835b-fbbb00eaf08d",
  "created_at": "2026-03-12T09:46:53.411124Z",
  "user_id": null,
  "trimmed_seconds": null
}
Slug example: fr_marie_neutral and UUID example: 5a271406-039d-46fe-835b-fbbb00eaf08d can both be used as the voice identifier in the service settings.

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Usage

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Basic Setup

import os
from pipecat.services.mistral import MistralTTSService

tts = MistralTTSService(
    api_key=os.getenv("MISTRAL_API_KEY"),
)

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With a Built-in Voice

tts = MistralTTSService(
    api_key=os.getenv("MISTRAL_API_KEY"),
    settings=MistralTTSService.Settings(
        model="voxtral-mini-tts-2603",
        voice="fr_marie_neutral",  # see Available Voices section for all slugs
        language="fr",
    ),
)

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With a Custom Voice

If you have created a custom voice in your Mistral account, use its UUID as the voice identifier: 
import os
from pipecat.services.mistral import MistralTTSService

tts = MistralTTSService(
    api_key=os.getenv("MISTRAL_API_KEY"),
    settings=MistralTTSService.Settings(
        voice="your-custom-voice-uuid",  # UUID from your Mistral account dashboard
    ),
)

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With Custom Sample Rate

import os
from pipecat.services.mistral import MistralTTSService

tts = MistralTTSService(
    api_key=os.getenv("MISTRAL_API_KEY"),
    sample_rate=16000,  # Resample from 24kHz to 16kHz
)

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Notes

  • Audio format conversion: The Mistral API returns base64-encoded float32 PCM chunks via Server-Sent Events. The service automatically converts these to int16 PCM for the Pipecat pipeline.
  • Native sample rate: Mistral’s TTS API outputs audio at 24kHz. When a different sample rate is specified, the service automatically resamples the audio.
  • Streaming: The service uses HTTP streaming with Server-Sent Events for real-time audio generation, allowing for low-latency synthesis.
  • Voice identifiers: Both slugs (e.g. fr_marie_neutral) and UUIDs are accepted. Built-in voice slugs are listed in the Available Voices section. Custom voices created in your Mistral account dashboard are referenced by their UUID.

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Event Handlers

This service does not currently expose connection event handlers, as it uses HTTP streaming rather than persistent WebSocket connections.