AWS Polly Text to Speech (tts)

Overview

Property	Details
Description	Convert text to natural-sounding speech using AWS Polly's neural and standard TTS engines
Provider Route on LiteLLM	aws_polly/
Supported Operations	/audio/speech
Link to Provider Doc	AWS Polly SynthesizeSpeech ↗

Quick Start

LiteLLM SDK

SDK Usage

import litellm
from pathlib import Path
import os

# Set environment variables
os.environ["AWS_ACCESS_KEY_ID"] = ""
os.environ["AWS_SECRET_ACCESS_KEY"] = ""
os.environ["AWS_REGION_NAME"] = "us-east-1"

# AWS Polly call
speech_file_path = Path(__file__).parent / "speech.mp3"
response = litellm.speech(
    model="aws_polly/neural",
    voice="Joanna",
    input="the quick brown fox jumped over the lazy dogs",
)
response.stream_to_file(speech_file_path)

LiteLLM PROXY

proxy_config.yaml

model_list:
  - model_name: polly-neural
    litellm_params:
      model: aws_polly/neural
      aws_access_key_id: "os.environ/AWS_ACCESS_KEY_ID"
      aws_secret_access_key: "os.environ/AWS_SECRET_ACCESS_KEY"
      aws_region_name: "us-east-1"

Polly Engines

AWS Polly supports different speech synthesis engines. Specify the engine in the model name:

Model	Engine	Cost (per 1M chars)	Description
aws_polly/standard	Standard	$4.00	Original Polly voices, faster and lowest cost
aws_polly/neural	Neural	$16.00	More natural, human-like speech (recommended)
aws_polly/generative	Generative	$30.00	Most expressive, highest quality (limited voices)
aws_polly/long-form	Long-form	$100.00	Optimized for long content like articles

LiteLLM SDK

Using Different Engines

import litellm

# Neural engine (recommended)
response = litellm.speech(
    model="aws_polly/neural",
    voice="Joanna",
    input="Hello world",
)

# Standard engine (lower cost)
response = litellm.speech(
    model="aws_polly/standard",
    voice="Joanna",
    input="Hello world",
)

# Generative engine (highest quality)
response = litellm.speech(
    model="aws_polly/generative",
    voice="Matthew",
    input="Hello world",
)

LiteLLM PROXY

proxy_config.yaml

model_list:
  - model_name: polly-neural
    litellm_params:
      model: aws_polly/neural
      aws_region_name: "us-east-1"
  - model_name: polly-standard
    litellm_params:
      model: aws_polly/standard
      aws_region_name: "us-east-1"
  - model_name: polly-generative
    litellm_params:
      model: aws_polly/generative
      aws_region_name: "us-east-1"

Available Voices

Native Polly Voices

AWS Polly has many voices across different languages. Here are popular US English voices:

Voice	Gender	Engine Support
Joanna	Female	Neural, Standard
Matthew	Male	Neural, Standard, Generative
Ivy	Female (child)	Neural, Standard
Kendra	Female	Neural, Standard
Amy	Female (British)	Neural, Standard
Brian	Male (British)	Neural, Standard

LiteLLM SDK

Using Native Polly Voices

import litellm

# US English female
response = litellm.speech(
    model="aws_polly/neural",
    voice="Joanna",
    input="Hello from Joanna",
)

# US English male
response = litellm.speech(
    model="aws_polly/neural",
    voice="Matthew",
    input="Hello from Matthew",
)

# British English female
response = litellm.speech(
    model="aws_polly/neural",
    voice="Amy",
    input="Hello from Amy",
)

LiteLLM PROXY

proxy_config.yaml

model_list:
  - model_name: polly-joanna
    litellm_params:
      model: aws_polly/neural
      voice: "Joanna"
      aws_region_name: "us-east-1"
  - model_name: polly-matthew
    litellm_params:
      model: aws_polly/neural
      voice: "Matthew"
      aws_region_name: "us-east-1"

OpenAI Voice Mappings

LiteLLM also supports OpenAI voice names, which are automatically mapped to Polly voices:

OpenAI Voice	Maps to Polly Voice
alloy	Joanna
echo	Matthew
fable	Amy
onyx	Brian
nova	Ivy
shimmer	Kendra

LiteLLM SDK

Using OpenAI Voice Names

import litellm

# These are equivalent
response = litellm.speech(
    model="aws_polly/neural",
    voice="alloy",  # Maps to Joanna
    input="Hello world",
)

response = litellm.speech(
    model="aws_polly/neural",
    voice="Joanna",  # Native Polly voice
    input="Hello world",
)

SSML Support

AWS Polly supports SSML (Speech Synthesis Markup Language) for advanced control over speech output. LiteLLM automatically detects SSML input.

LiteLLM SDK

SSML Example

import litellm

ssml_input = """
<speak>
    Hello, <break time="500ms"/> 
    this is a test with <emphasis level="strong">emphasis</emphasis> 
    and <prosody rate="slow">slower speech</prosody>.
</speak>
"""

response = litellm.speech(
    model="aws_polly/neural",
    voice="Joanna",
    input=ssml_input,
)

LiteLLM PROXY

cURL Request with SSML

curl -X POST http://localhost:4000/v1/audio/speech \
  -H "Authorization: Bearer sk-1234" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "polly-neural",
    "voice": "Joanna",
    "input": "<speak>Hello <break time=\"500ms\"/> world</speak>"
  }' \
  --output speech.mp3

Supported Parameters

All Parameters

response = litellm.speech(
    model="aws_polly/neural",
    voice="Joanna",                    # Required: Voice selection
    input="text to convert",           # Required: Input text (or SSML)
    response_format="mp3",             # Optional: mp3, ogg_vorbis, pcm
    
    # AWS-specific parameters
    language_code="en-US",             # Optional: Language code
    sample_rate="22050",               # Optional: Sample rate in Hz
)

Response Formats

Format	Description
mp3	MP3 audio (default)
ogg_vorbis	Ogg Vorbis audio
pcm	Raw PCM audio

LiteLLM SDK

Different Response Formats

import litellm

# MP3 (default)
response = litellm.speech(
    model="aws_polly/neural",
    voice="Joanna",
    input="Hello",
    response_format="mp3",
)

# Ogg Vorbis
response = litellm.speech(
    model="aws_polly/neural",
    voice="Joanna",
    input="Hello",
    response_format="ogg_vorbis",
)

AWS Authentication

LiteLLM supports multiple AWS authentication methods.

LiteLLM SDK

Authentication Options

import litellm
import os

# Option 1: Environment variables (recommended)
os.environ["AWS_ACCESS_KEY_ID"] = "your-access-key"
os.environ["AWS_SECRET_ACCESS_KEY"] = "your-secret-key"
os.environ["AWS_REGION_NAME"] = "us-east-1"

response = litellm.speech(model="aws_polly/neural", voice="Joanna", input="Hello")

# Option 2: Pass credentials directly
response = litellm.speech(
    model="aws_polly/neural",
    voice="Joanna",
    input="Hello",
    aws_access_key_id="your-access-key",
    aws_secret_access_key="your-secret-key",
    aws_region_name="us-east-1",
)

# Option 3: IAM Role (when running on AWS)
response = litellm.speech(
    model="aws_polly/neural",
    voice="Joanna",
    input="Hello",
    aws_region_name="us-east-1",
)

# Option 4: AWS Profile
response = litellm.speech(
    model="aws_polly/neural",
    voice="Joanna",
    input="Hello",
    aws_profile_name="my-profile",
)

LiteLLM PROXY

proxy_config.yaml

model_list:
  # Using environment variables
  - model_name: polly-neural
    litellm_params:
      model: aws_polly/neural
      aws_access_key_id: "os.environ/AWS_ACCESS_KEY_ID"
      aws_secret_access_key: "os.environ/AWS_SECRET_ACCESS_KEY"
      aws_region_name: "us-east-1"
  
  # Using IAM Role (when proxy runs on AWS)
  - model_name: polly-neural-iam
    litellm_params:
      model: aws_polly/neural
      aws_region_name: "us-east-1"
  
  # Using AWS Profile
  - model_name: polly-neural-profile
    litellm_params:
      model: aws_polly/neural
      aws_profile_name: "my-profile"

Async Support

Async Usage

import litellm
import asyncio

async def main():
    response = await litellm.aspeech(
        model="aws_polly/neural",
        voice="Joanna",
        input="Hello from async AWS Polly",
        aws_region_name="us-east-1",
    )
    
    with open("output.mp3", "wb") as f:
        f.write(response.content)

asyncio.run(main())