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Overview

AWSTTSService provides text-to-speech capabilities using Amazon’s Polly service. It supports multiple voices, languages, and speech customization options through SSML.

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Installation

To use AWSTTSService, install the required dependencies:

pip install pipecat-ai[aws]

You’ll also need to set up your AWS credentials as environment variables:

  • AWS_SECRET_ACCESS_KEY
  • AWS_ACCESS_KEY_ID
  • AWS_REGION

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Configuration

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Constructor Parameters

api_key
str
required

AWS secret access key

aws_access_key_id
str
required

AWS access key ID

region
str
required

AWS region name

voice_id
str
default: "Joanna"

AWS Polly voice identifier

sample_rate
int
default: "24000"

Output audio sample rate in Hz

text_filter
BaseTextFilter
default: "None"

Modifies text provided to the TTS. Learn more about the available filters.

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Input Parameters

class InputParams(BaseModel):
    engine: Optional[str] = None      # Polly engine type
    language: Optional[Language] = Language.EN
    pitch: Optional[str] = None       # SSML pitch adjustment
    rate: Optional[str] = None        # SSML rate adjustment
    volume: Optional[str] = None      # SSML volume adjustment

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Output Frames

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Control Frames

TTSStartedFrame
Frame

Signals start of speech synthesis

TTSStoppedFrame
Frame

Signals completion of speech synthesis

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Audio Frames

TTSAudioRawFrame
Frame

Contains generated audio data with: - PCM audio format - Specified sample rate

  • Single channel (mono)

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Error Frames

ErrorFrame
Frame

Contains AWS Polly error information

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Methods

See the TTS base class methods for additional functionality.

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Language Support

Supports multiple languages and regional variants:

Language CodeDescriptionService Code
Language.CACatalanca-ES
Language.ZHChinese (Mandarin)cmn-CN
Language.DADanishda-DK
Language.NLDutchnl-NL
Language.NL_BEDutch (Belgium)nl-BE
Language.ENEnglish (US)en-US
Language.EN_AUEnglish (Australia)en-AU
Language.EN_GBEnglish (UK)en-GB
Language.EN_INEnglish (India)en-IN
Language.EN_NZEnglish (New Zealand)en-NZ
Language.FRFrenchfr-FR
Language.FR_CAFrench (Canada)fr-CA
Language.DEGermande-DE
Language.HIHindihi-IN
Language.ITItalianit-IT
Language.JAJapaneseja-JP
Language.KOKoreanko-KR
Language.NONorwegiannb-NO
Language.PLPolishpl-PL
Language.PTPortuguesept-PT
Language.PT_BRPortuguese (Brazil)pt-BR
Language.RORomanianro-RO
Language.RURussianru-RU
Language.ESSpanishes-ES
Language.SVSwedishsv-SE
Language.TRTurkishtr-TR

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Usage Example

from pipecat.services.aws import AWSTTSService
from pipecat.transcriptions.language import Language

# Configure service
tts_service = AWSTTSService(
    api_key="your-aws-secret-key",
    aws_access_key_id="your-aws-access-key",
    region="us-east-1",
    voice_id="Joanna",
    params=AWSTTSService.InputParams(
        engine="neural",
        language=Language.EN,
        rate="medium",
        pitch="high"
    )
)

# Use in pipeline
pipeline = Pipeline([
    text_input,         # Produces text
    tts_service,        # Converts text to speech
    audio_output        # Plays audio
])

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SSML Support

The service automatically constructs SSML tags for advanced speech control:

# Example with SSML controls
service = AWSTTSService(
    # ... other params ...
    params=AWSTTSService.InputParams(
        rate="+20%",      # Increase speed
        pitch="low",      # Lower pitch
        volume="loud"     # Increase volume
    )
)

Note: Prosody tags (rate, pitch, volume) are only supported for standard and neural engines, not the generative engine.

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Frame Flow

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Metrics Support

The service collects processing metrics:

  • Time to First Byte (TTFB)
  • Processing duration
  • Character usage
  • API calls

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Notes

  • Supports multiple AWS Polly engines (standard, neural, generative)
  • Automatic audio resampling
  • SSML-based speech customization
  • Chunked audio delivery
  • Thread-safe processing
  • Automatic error handling
  • Manages AWS client lifecycle
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