# # Copyright (c) 2024-2026, Daily # # SPDX-License-Identifier: BSD 2-Clause License # """TTSSpeakFrame timing and transcript ordering example. Demonstrates two common patterns for injecting hardcoded speech into a voice agent without breaking the LLM context / transcript ordering: 1. Intro / pre-roll. Say something before the agent speaks, and make sure it shows up in the LLM context in the right place. 2. Tool-call filler. Say something while a function call is in flight, without the filler audio overlapping the post-tool LLM response and without the filler text landing on the wrong turn in the transcript. Key techniques shown: - ``TTSSpeakFrame(text, append_to_context=True)`` — the TTS service commits the spoken text to the assistant aggregator after the audio drains, so turn ordering in the transcript matches the audio. - ``pause_frame_processing=True`` on the TTS service — stops the TTS from processing the next LLM response while the filler is still speaking, which is what keeps the audio and the transcript aligned during tool calls. - A system-prompt nudge asking the LLM not to acknowledge before a tool call, so you don't get double acknowledgements (one from the LLM, one from ``on_function_calls_started``). Notes: - Do NOT call ``asyncio.sleep`` to add pauses around TTS. Use ``FrameProcessorPauseFrame`` / ``FrameProcessorResumeUrgentFrame`` if you need a synthetic gap. ``asyncio.sleep`` does not interact with the frame-processing system and will desync audio and transcript. - The base ``TTSService`` defaults ``pause_frame_processing`` to ``False``. Many wrappers (ElevenLabs, Rime, Deepgram, Groq, Azure, ...) hardcode it to ``True`` in their ``super().__init__()`` calls, so you don't need to opt in. ``OpenAITTSService`` inherits the base default (``False``), so we pass it explicitly below. - ``CartesiaTTSService`` is the odd one: it hardcodes ``pause_frame_processing=False`` AND does not accept the kwarg via the constructor (you'll get ``TypeError: got multiple values for keyword argument 'pause_frame_processing'``). If you're on Cartesia, set it after construction: ``tts._pause_frame_processing = True``. Requirements: - OpenAI API key Environment variables (.env): OPENAI_API_KEY=... """ import os from dotenv import load_dotenv from loguru import logger from pipecat.adapters.schemas.function_schema import FunctionSchema from pipecat.adapters.schemas.tools_schema import ToolsSchema from pipecat.audio.vad.silero import SileroVADAnalyzer from pipecat.frames.frames import LLMRunFrame, TTSSpeakFrame from pipecat.pipeline.pipeline import Pipeline from pipecat.pipeline.runner import PipelineRunner from pipecat.pipeline.task import PipelineParams, PipelineTask from pipecat.processors.aggregators.llm_context import LLMContext from pipecat.processors.aggregators.llm_response_universal import ( LLMContextAggregatorPair, LLMUserAggregatorParams, ) from pipecat.runner.types import RunnerArguments from pipecat.runner.utils import create_transport from pipecat.services.llm_service import FunctionCallParams from pipecat.services.openai.llm import OpenAILLMService from pipecat.services.openai.stt import OpenAISTTService from pipecat.services.openai.tts import OpenAITTSService from pipecat.transports.base_transport import BaseTransport, TransportParams from pipecat.transports.daily.transport import DailyParams from pipecat.transports.websocket.fastapi import FastAPIWebsocketParams load_dotenv(override=True) SYSTEM_INSTRUCTION = """You are a helpful assistant in a voice conversation. Your \ responses will be spoken aloud, so avoid emojis, bullet points, or other formatting \ that can't be spoken. Keep responses brief. IMPORTANT: When you are about to call a tool, do NOT say an acknowledgement like \ "Let me check on that" or "One moment" before the call. The system plays its own \ filler audio while the tool runs, so if you also acknowledge you will be heard twice.""" async def fetch_weather_from_api(params: FunctionCallParams): await params.result_callback({"conditions": "sunny", "temperature": "75"}) transport_params = { "daily": lambda: DailyParams(audio_in_enabled=True, audio_out_enabled=True), "twilio": lambda: FastAPIWebsocketParams(audio_in_enabled=True, audio_out_enabled=True), "webrtc": lambda: TransportParams(audio_in_enabled=True, audio_out_enabled=True), } async def run_bot(transport: BaseTransport, runner_args: RunnerArguments): logger.info("Starting TTSSpeakFrame timing demo") stt = OpenAISTTService(api_key=os.getenv("OPENAI_API_KEY")) # pause_frame_processing=True keeps filler audio and the post-tool LLM # response from overlapping. OpenAI TTS inherits the base default of False, # so we opt in explicitly here. tts = OpenAITTSService( api_key=os.getenv("OPENAI_API_KEY"), settings=OpenAITTSService.Settings(voice="ballad"), pause_frame_processing=True, ) llm = OpenAILLMService( api_key=os.getenv("OPENAI_API_KEY"), settings=OpenAILLMService.Settings(system_instruction=SYSTEM_INSTRUCTION), ) llm.register_function("get_current_weather", fetch_weather_from_api) # Tool-call filler. Fires once per function-call batch. append_to_context=True # makes the filler text show up in the transcript in the correct turn order, # because the TTS service commits it only after the audio drains. @llm.event_handler("on_function_calls_started") async def on_function_calls_started(service, function_calls): await tts.queue_frame(TTSSpeakFrame("Gotcha, one sec.", append_to_context=True)) weather_function = FunctionSchema( name="get_current_weather", description="Get the current weather for a location", properties={ "location": { "type": "string", "description": "The city and state, e.g. San Francisco, CA", }, }, required=["location"], ) tools = ToolsSchema(standard_tools=[weather_function]) context = LLMContext(tools=tools) user_aggregator, assistant_aggregator = LLMContextAggregatorPair( context, user_params=LLMUserAggregatorParams(vad_analyzer=SileroVADAnalyzer()), ) pipeline = Pipeline( [ transport.input(), stt, user_aggregator, llm, tts, transport.output(), assistant_aggregator, ] ) task = PipelineTask( pipeline, params=PipelineParams(enable_metrics=True, enable_usage_metrics=True), ) @transport.event_handler("on_client_connected") async def on_client_connected(transport, client): logger.info("Client connected") # Intro / pre-roll. append_to_context=True makes this line land in the # LLM context before the first user message, in the correct turn order. # No LLMFullResponseStart/End wrap needed. await tts.queue_frame( TTSSpeakFrame( "Hi, I'm Paul, your virtual agent. Ask me about the weather anywhere.", append_to_context=True, ) ) # Kick off the LLM so it's ready to respond to the first user turn. await task.queue_frames([LLMRunFrame()]) @transport.event_handler("on_client_disconnected") async def on_client_disconnected(transport, client): logger.info("Client disconnected") await task.cancel() runner = PipelineRunner(handle_sigint=runner_args.handle_sigint) await runner.run(task) async def bot(runner_args: RunnerArguments): """Main bot entry point compatible with Pipecat Cloud.""" transport = await create_transport(runner_args, transport_params) await run_bot(transport, runner_args) if __name__ == "__main__": from pipecat.runner.run import main main()