tts_engine.py

"""
tts_engine.py — ElevenLabs TTS engine.
Returns raw MP3 bytes for a spoken line given a voice_id.
"""

import os
import requests


class TTSEngine:
    """Wraps the ElevenLabs REST API for text-to-speech synthesis."""

    _BASE_URL = "https://api.elevenlabs.io/v1/text-to-speech/{voice_id}"
    _MODEL = "eleven_multilingual_v2"

    def __init__(self, api_key: str):
        self.api_key = api_key
        if not self.api_key:
            print("[TTSEngine] WARNING: api_key is empty — TTS will be skipped.")

    def speak(self, text: str, voice_id: str) -> bytes:
        """
        Synthesize `text` with `voice_id`.

        Returns raw MP3 bytes on success.
        Raises RuntimeError on API failure.
        Falls through to raise so callers can catch and skip audio gracefully.
        """
        if not self.api_key:
            raise RuntimeError("ElevenLabs API key not configured.")

        text = text.strip()
        if not text:
            raise ValueError("speak() called with empty text.")

        url = self._BASE_URL.format(voice_id=voice_id)
        headers = {
            "xi-api-key": self.api_key,
            "Content-Type": "application/json",
            "Accept": "audio/mpeg",
        }
        payload = {
            "text": text,
            "model_id": self._MODEL,
            "voice_settings": {
                "stability": 0.35,
                "similarity_boost": 0.75,
                "style": 0.65,
                "use_speaker_boost": True
            },
        }

        response = requests.post(url, json=payload, headers=headers, timeout=30)

        if response.status_code == 200:
            return response.content
        else:
            raise RuntimeError(
                f"ElevenLabs API error {response.status_code}: {response.text[:300]}"
            )