OpenAI Realtime Beta

OpenAIRealtimeBetaLLMService provides real-time, multimodal conversation capabilities using OpenAI’s Realtime Beta API. It supports speech-to-speech interactions with integrated LLM processing, function calling, and advanced conversation management.

Real-time Interaction

Stream audio in real-time with minimal latency response times

Speech Processing

Built-in speech-to-text and text-to-speech capabilities with voice options

Advanced Turn Detection

Multiple voice activity detection options including semantic turn detection

Powerful Function Calling

Seamless support for calling external functions and APIs

Installation

To use OpenAIRealtimeBetaLLMService, install the required dependencies:

pip install "pipecat-ai[openai]"

You’ll also need to set up your OpenAI API key as an environment variable: OPENAI_API_KEY.

Configuration

Constructor Parameters

api_key

str

required

Your OpenAI API key

model

str

default:"gpt-4o-realtime-preview-2025-06-03"

The speech-to-speech model used for processing

base_url

str

default:"wss://api.openai.com/v1/realtime"

WebSocket endpoint URL

session_properties

SessionProperties

Configuration for the realtime session

start_audio_paused

bool

default:"False"

Whether to start with audio input paused

send_transcription_frames

bool

default:"True"

Whether to emit transcription frames

Session Properties

The SessionProperties object configures the behavior of the realtime session:

modalities

List[Literal['text', 'audio']]

The modalities to enable (default includes both text and audio)

instructions

str

System instructions that guide the model’s behavior

service = OpenAIRealtimeBetaLLMService(
    api_key=os.getenv("OPENAI_API_KEY"),
    session_properties=SessionProperties(
        instructions="You are a helpful assistant. Be concise and friendly."
    )
)

voice

str

Voice ID for text-to-speech (options: alloy, echo, fable, onyx, nova, shimmer)

input_audio_format

Literal['pcm16', 'g711_ulaw', 'g711_alaw']

Format of the input audio

output_audio_format

Literal['pcm16', 'g711_ulaw', 'g711_alaw']

Format of the output audio

input_audio_transcription

InputAudioTranscription

Configuration for audio transcription

from pipecat.services.openai_realtime_beta.events import InputAudioTranscription

service = OpenAIRealtimeBetaLLMService(
    api_key=os.getenv("OPENAI_API_KEY"),
    session_properties=SessionProperties(
        input_audio_transcription=InputAudioTranscription(
            model="gpt-4o-transcribe",
            language="en",
            prompt="This is a technical conversation about programming"
        )
    )
)

input_audio_noise_reduction

InputAudioNoiseReduction

Configuration for audio noise reduction

turn_detection

Union[TurnDetection, SemanticTurnDetection, bool]

Configuration for turn detection (set to False to disable)

tools

List[Dict]

List of function definitions for tool/function calling

tool_choice

Literal['auto', 'none', 'required']

Controls when the model calls functions

temperature

float

Controls randomness in responses (0.0 to 2.0)

max_response_output_tokens

Union[int, Literal['inf']]

Maximum number of tokens to generate

Input Frames

Audio Input

InputAudioRawFrame

Frame

Raw audio data for speech input

Control Input

StartInterruptionFrame

Frame

Signals start of user interruption

UserStartedSpeakingFrame

Frame

Signals user started speaking

UserStoppedSpeakingFrame

Frame

Signals user stopped speaking

Context Input

OpenAILLMContextFrame

Frame

Contains conversation context

LLMMessagesAppendFrame

Frame

Appends messages to conversation

Output Frames

Audio Output

TTSAudioRawFrame

Frame

Generated speech audio

Control Output

TTSStartedFrame

Frame

Signals start of speech synthesis

TTSStoppedFrame

Frame

Signals end of speech synthesis

Text Output

TextFrame

Frame

Generated text responses

TranscriptionFrame

Frame

Speech transcriptions

Events

on_conversation_item_created

event

Emitted when a conversation item on the server is created. Handler receives:

item_id: str
item: ConversationItem

on_conversation_item_updated

event

Emitted when a conversation item on the server is updated. Handler receives:

item_id: str
item: Optional[ConversationItem] (may not exist for some updates)

Methods

retrieve_conversation_item

method

Retrieves a conversation item’s details from the server.

async def retrieve_conversation_item(self, item_id: str) -> ConversationItem

Usage Example

from pipecat.services.openai_realtime_beta import OpenAIRealtimeBetaLLMService
from pipecat.services.openai_realtime_beta.events import SessionProperties, TurnDetection

# Configure service
service = OpenAIRealtimeBetaLLMService(
    api_key="your-api-key",
    session_properties=SessionProperties(
        modalities=["audio", "text"],
        voice="alloy",
        turn_detection=TurnDetection(
            threshold=0.5,
            silence_duration_ms=800
        ),
        temperature=0.7
    )
)

# Use in pipeline
pipeline = Pipeline([
    audio_input,       # Produces InputAudioRawFrame
    service,           # Processes speech/generates responses
    audio_output       # Handles TTSAudioRawFrame
])

Function Calling

The service supports function calling with automatic response handling:

from pipecat.adapters.schemas.function_schema import FunctionSchema
from pipecat.adapters.schemas.tools_schema import ToolsSchema
from pipecat.services.openai_realtime_beta import SessionProperties

# Define weather function using standardized schema
weather_function = FunctionSchema(
    name="get_weather",
    description="Get weather information",
    properties={
        "location": {"type": "string"}
    },
    required=["location"]
)

# Create tools schema
tools = ToolsSchema(standard_tools=[weather_function])

# Configure service with tools
llm = OpenAIRealtimeBetaLLMService(
    api_key="your-api-key",
    session_properties=SessionProperties(
        tools=tools,
        tool_choice="auto"
    )
)

llm.register_function("get_weather", fetch_weather_from_api)

See the Function Calling guide for:

Detailed implementation instructions
Provider-specific function definitions
Handler registration examples
Control over function call behavior
Complete usage examples

Frame Flow

Metrics Support

The service collects comprehensive metrics:

Token usage (prompt and completion)
Processing duration
Time to First Byte (TTFB)
Audio processing metrics
Function call metrics

Advanced Features

Turn Detection

# Server-side basic VAD
turn_detection = TurnDetection(
    type="server_vad",
    threshold=0.5,
    prefix_padding_ms=300,
    silence_duration_ms=800
)

# Server-side semantic VAD
turn_detection = SemanticTurnDetection(
  type="semantic_vad",
  eagerness="auto", # default. could also be "low" | "medium" | "high"
  create_response=True # default
  interrupt_response=True # default
)

# Disable turn detection
turn_detection = False

Context Management

# Create context
context = OpenAIRealtimeLLMContext(
    messages=[],
    tools=[],
    system="You are a helpful assistant"
)

# Create aggregators
aggregators = service.create_context_aggregator(context)

Foundational Examples