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Overview

Synthesizers are used to convert text into speech; this guide will show you how to configure and use synthesizers in Vocode.

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Supported Synthesizers

Vocode currently supports the following synthesizers:
  1. Azure (Microsoft)
  2. Google
  3. Eleven Labs
  4. Rime
  5. Play.ht
  6. Coqui TTS
  7. GTTS (Google Text-to-Speech)
  8. Stream Elements
  9. Bark
These synthesizers are defined using their respective configuration classes, which are subclasses of the SynthesizerConfig class.

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Configuring Synthesizers

To use a synthesizer, you need to create a configuration object for the synthesizer you want to use. Here are some examples of how to create configuration objects for different synthesizers:

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Example 1: Using Eleven Labs with a phone call

from vocode.streaming.telephony.hosted.inbound_call_server import InboundCallServer
from vocode.streaming.models.synthesizer import ElevenLabsSynthesizerConfig

server = InboundCallServer(
    ...
    synthesizer_config=ElevenLabsSynthesizerConfig.from_telephone_output_device(
        api_key=os.getenv("ELEVENLABS_API_KEY"),
        voice_id=os.getenv("YOUR VOICE ID")
    )
    ...
)
In this example, the ElevenLabsSynthesizerConfig.from_telephone_output_device() method is used to create a configuration object for the Eleven Labs synthesizer. The method hardcodes some values like the sampling_rate and audio_encoding for compatibility with telephone output devices.

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Example 2: Using Azure in StreamingConversation locally

from vocode.streaming.models.synthesizer import AzureSynthesizerConfig
from vocode.helpers import create_microphone_input_and_speaker_output

microphone_input, speaker_output = create_microphone_input_and_speaker_output(
        streaming=True, use_default_devices=False
)

conversation = StreamingConversation(
    ...
    synthesizer=AzureSynthesizer(
        AzureSynthesizerConfig.from_output_device(speaker_output)
    ),
    ...
)
In this example, the AzureSynthesizerConfig.from_output_device() method is used to create a configuration object for the Azure synthesizer. The method takes a speaker_output object as an argument, and extracts the sampling_rate and audio_encoding from the output device.

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When to Use Configs vs. Synthesizer Objects

  • For everything except StreamingConversation, you must use configuration objects.
  • For StreamingConversation, you can use the actual synthesizer object, but you still need to initialize it with a configuration object.

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Synthesizer Comparisons

ProviderLatencyVoice CloningNatural SoundingNotes
Azure (Microsoft)LowNo
GoogleLowNo
Eleven LabsHighYes
RimeLowNo
Play.htHighYes
Coqui TTSOpen source
GTTS
Stream Elements
Bark