/speech-build

Text-to-Speech (TTS)

Overview

Google Cloud and Vertex AI offer multiple TTS solutions:

1. Gemini-TTS: Advanced, controllable speech generation using Gemini 2.5 models.
2. Chirp 3 HD: High-fidelity, natural-sounding voices.
3. Instant Custom Voice (Chirp 3): Create custom voices from short audio samples (allowlist required).

Gemini-TTS (Preview)

Use gemini-2.5-flash-preview-tts for controllable speech.

Single Speaker

from google import genai
from google.genai import types

client = genai.Client()
response = client.models.generate_content(
    model="gemini-2.5-flash-preview-tts",
    contents="Say cheerfully: Have a wonderful day!",
    config=types.GenerateContentConfig(
        response_modalities=["AUDIO"],
        speech_config=types.SpeechConfig(
            voice_config=types.VoiceConfig(
                prebuilt_voice_config=types.PrebuiltVoiceConfig(voice_name='Kore')
            )
        ),
    )
)
# Save response.candidates[0].content.parts[0].inline_data.data to .wav

Multi-Speaker

config = types.GenerateContentConfig(
    response_modalities=["AUDIO"],
    speech_config=types.SpeechConfig(
        multi_speaker_voice_config=types.MultiSpeakerVoiceConfig(
            speaker_voice_configs=[
                types.SpeakerVoiceConfig(
                    speaker='Joe',
                    voice_config=types.VoiceConfig(
                        prebuilt_voice_config=types.PrebuiltVoiceConfig(voice_name='Kore')
                    )
                ),
                types.SpeakerVoiceConfig(
                    speaker='Jane',
                    voice_config=types.VoiceConfig(
                        prebuilt_voice_config=types.PrebuiltVoiceConfig(voice_name='Puck')
                    )
                ),
            ]
        )
    )
)

Chirp 3 HD (Vertex AI)

High-fidelity voices for general use.

response = client.models.generate_content(
    model="gemini-2.5-flash-tts", # or chirp-3-hd via speech client
    contents="Hello world",
    config=types.GenerateContentConfig(
        speech_config=types.SpeechConfig(
            language_code="en-US",
            voice_config=types.VoiceConfig(
                prebuilt_voice_config=types.PrebuiltVoiceConfig(voice_name="Aoede")
            )
        )
    )
)

Instant Custom Voice (Chirp 3)

Requires Allowlist. Uses voices:generateVoiceCloningKey to create a key, then gemini-2.5-flash-tts to synthesize.

1. Create Cloning Key (REST API)

The SDK does not yet support key generation directly. Use the REST API.

Endpoint: POST https://texttospeech.googleapis.com/v1beta1/voices:generateVoiceCloningKey

Body:

{
  "reference_audio": {
    "content": "BASE64_ENCODED_WAV",
    "audio_config": {"audio_encoding": "LINEAR16", "sample_rate_hertz": 24000}
  },
  "voice_talent_consent": {
    "content": "BASE64_ENCODED_WAV",
    "audio_config": {"audio_encoding": "LINEAR16", "sample_rate_hertz": 24000}
  },
  "consent_script": "I am the owner of this voice and I consent to Google using this voice to create a synthetic voice model.",
  "language_code": "en-US"
}

2. Synthesize (SDK)

Use the key in VoiceConfig.

response = client.models.generate_content(
    model="gemini-2.5-flash-tts",
    contents="This is my cloned voice.",
    config=types.GenerateContentConfig(
        response_modalities=["AUDIO"],
        speech_config=types.SpeechConfig(
            voice_config=types.VoiceConfig(
                voice_clone=types.VoiceClone(
                    voice_cloning_key="YOUR_GENERATED_KEY"
                )
            )
        )
    )
)