feat(mistral): add voxtral TTS support

[jeanprbt]

Summary

• Add TTS support to the livekit-plugins-mistralai plugin using Mistral's new voxtral-mini-tts-2603 model

Details

TTS implementation (tts.py)

• ChunkedStream-based synthesis via client.audio.speech.complete_async() with streamed output
• Supports configurable model, voice (28 voice presets across 4 speakers), and response format (mp3, wav, pcm, opus, flac)
• Base64-decodes audio_data from the API response
• Maps SDK errors to LiveKit's APITimeoutError, APIStatusError, and APIConnectionError
• pcm audio format is default as it's fastest, requires additional float32 -> float16 conversion

Models & voices (models.py)

• Added TTSModels literal: voxtral-mini-tts-2603, voxtral-mini-tts-latest
• Added TTSVoices literal with 28 voice presets (Jane, Marie, Oliver, Paul)

This would solve issue #5247.

[CLAassistant]

All committers have signed the CLA.

[jeanprbt]

It's worth mentioning that both livekit-plugins/livekit-plugins-aws/livekit/plugins/aws/experimental/realtime/realtime_model.py & livekit-plugins/livekit-plugins-aws/livekit/plugins/aws/experimental/realtime/turn_tracker.py were only changed by make fix which called ruff format --fix. This was necessary to have all checks passing, even though this PR has nothing to do with these files.

[fabitokki]

Hello @jeanprbt

I just realized I did the same PR as you did 2 hours ago, sorry for that. Just wondering where you found the labels for the TTS ? I just found this one on the doc: "voxtral-tts-2603"

https://docs.mistral.ai/models/voxtral-tts-26-03

[jeanprbt]

Hi @fabitokki,

I just realized I did the same PR as you did 2 hours ago, sorry for that. Just wondering where you found the labels for the TTS ? I just found this one on the doc: "voxtral-tts-2603"

I found the labels here. You can rely on this PR for official Mistral support of Voxtral TTS, no worries!

[lasryaric]

Would really love to have that. This might be some real competition for 11labs. When can we expect to have that available on the pip repository?

[jeanprbt]

Would really love to have that. This might be some real competition for 11labs. When can we expect to have that available on the pip repository?

As soon as this PR is merged I guess! Looking forward too ;)

[fabitokki]

I made a feature request @jeanprbt so you can link this PR to the request: #5247. You can upvote it as well so there is more chance for it to be noticed (we are quite a lot of people to want this actually).

They are usually quite fast to review PRs.

[jeanprbt]

@fabitokki Done, I just edited the description. Thank you!

[fabitokki]

@jeanprbt Cool, I closed my PR to avoid duplication. Have a good day!

[theomonnom]

Lgtm! Thanks!