# # Copyright (c) 2024–2025, Daily # # SPDX-License-Identifier: BSD 2-Clause License # """Pattern Pair Voice Switching Example with Pipecat. This example demonstrates how to use the PatternPairAggregator to dynamically switch between different voices in a storytelling application. It showcases how pattern matching can be used to control TTS behavior in streaming text from an LLM. The example: 1. Sets up a storytelling bot with three distinct voices (narrator, male, female) 2. Uses pattern pairs (name) to trigger voice switching 3. Processes the patterns in real-time as text streams from the LLM 4. Removes the pattern tags before sending text to TTS The PatternPairAggregator: - Buffers text until complete patterns are detected - Identifies content between start/end pattern pairs - Triggers callbacks when patterns are matched - Processes patterns that may span across multiple text chunks - Returns processed text at sentence boundaries Requirements: - OpenAI API key (for GPT-4o) - Cartesia API key (for text-to-speech) - Daily API key (for video/audio transport) Environment variables (.env file): OPENAI_API_KEY=your_openai_key CARTESIA_API_KEY=your_cartesia_key DAILY_API_KEY=your_daily_key Note: This example shows one application of PatternPairAggregator (voice switching), but the same approach can be used for various pattern-based text processing needs, such as formatting instructions, command recognition, or structured data extraction. """ import os from dotenv import load_dotenv from loguru import logger from pipecat.audio.turn.smart_turn.local_smart_turn_v3 import LocalSmartTurnAnalyzerV3 from pipecat.audio.vad.silero import SileroVADAnalyzer from pipecat.audio.vad.vad_analyzer import VADParams from pipecat.frames.frames import LLMRunFrame 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.cartesia.tts import CartesiaTTSService from pipecat.services.deepgram.stt import DeepgramSTTService from pipecat.services.openai.llm import OpenAILLMService from pipecat.transports.base_transport import BaseTransport, TransportParams from pipecat.transports.daily.transport import DailyParams from pipecat.transports.websocket.fastapi import FastAPIWebsocketParams from pipecat.turns.user_stop import TurnAnalyzerUserTurnStopStrategy from pipecat.turns.user_turn_strategies import UserTurnStrategies from pipecat.utils.text.pattern_pair_aggregator import ( MatchAction, PatternMatch, PatternPairAggregator, ) load_dotenv(override=True) # Define voice IDs VOICE_IDS = { "narrator": "c45bc5ec-dc68-4feb-8829-6e6b2748095d", # Narrator voice "female": "71a7ad14-091c-4e8e-a314-022ece01c121", # Female character voice "male": "7cf0e2b1-8daf-4fe4-89ad-f6039398f359", # Male character voice } # We store functions so objects (e.g. SileroVADAnalyzer) don't get # instantiated. The function will be called when the desired transport gets # selected. transport_params = { "daily": lambda: DailyParams( audio_in_enabled=True, audio_out_enabled=True, vad_analyzer=SileroVADAnalyzer(params=VADParams(stop_secs=0.2)), ), "twilio": lambda: FastAPIWebsocketParams( audio_in_enabled=True, audio_out_enabled=True, vad_analyzer=SileroVADAnalyzer(params=VADParams(stop_secs=0.2)), ), "webrtc": lambda: TransportParams( audio_in_enabled=True, audio_out_enabled=True, vad_analyzer=SileroVADAnalyzer(params=VADParams(stop_secs=0.2)), ), } async def run_bot(transport: BaseTransport, runner_args: RunnerArguments): logger.info(f"Starting bot") # Create pattern pair aggregator for voice switching pattern_aggregator = PatternPairAggregator() # Add pattern for voice switching pattern_aggregator.add_pattern( type="voice", start_pattern="", end_pattern="", action=MatchAction.REMOVE, # Remove tags from final text ) # Register handler for voice switching async def on_voice_tag(match: PatternMatch): voice_name = match.text.strip().lower() if voice_name in VOICE_IDS: # First flush any existing audio to finish the current context await tts.flush_audio() # Then set the new voice tts.set_voice(VOICE_IDS[voice_name]) logger.info(f"Switched to {voice_name} voice") else: logger.warning(f"Unknown voice: {voice_name}") pattern_aggregator.on_pattern_match("voice", on_voice_tag) stt = DeepgramSTTService(api_key=os.getenv("DEEPGRAM_API_KEY")) # Initialize TTS with narrator voice as default tts = CartesiaTTSService( api_key=os.getenv("CARTESIA_API_KEY"), voice_id=VOICE_IDS["narrator"], text_aggregator=pattern_aggregator, ) # Initialize LLM llm = OpenAILLMService(api_key=os.getenv("OPENAI_API_KEY")) # System prompt for storytelling with voice switching system_prompt = """You are an engaging storyteller that uses different voices to bring stories to life. You have three voices to use, but each has a specific purpose: narrator This is the default narrator voice. Use this for all narration, descriptions, and non-dialogue text. female Use this ONLY for direct speech by female characters (just the quoted text). male Use this ONLY for direct speech by male characters (just the quoted text). IMPORTANT: Switch back to narrator voice immediately after character dialogue. Here's an EXAMPLE of correct voice usage: narrator Sarah spotted her old friend across the café. She couldn't believe her eyes. female "Jacob! It's been so long!" narrator Sarah exclaimed, jumping up from her seat with a radiant smile. male "Sarah, is it really you? I can't believe it!" narrator Jacob replied, grinning widely as he walked over to her. The two friends embraced warmly, as if trying to make up for all the years spent apart. female "What are you doing in town? Last I heard you were in Seattle." narrator She asked, gesturing for him to join her at the table. FOLLOW THESE RULES: 1. Always begin with the narrator voice 2. Only use character voices for the EXACT words they speak (in quotes) 3. SWITCH BACK to narrator voice for speech tags and all other text 4. Begin by asking what kind of story the user would like to hear 5. Create engaging dialogue with distinct characters Remember: Use narrator voice for EVERYTHING except the actual quoted dialogue.""" # Set up LLM context messages = [ { "role": "system", "content": system_prompt, }, ] context = LLMContext(messages) context_aggregator = LLMContextAggregatorPair( context, user_params=LLMUserAggregatorParams( user_turn_strategies=UserTurnStrategies( stop=[TurnAnalyzerUserTurnStopStrategy(turn_analyzer=LocalSmartTurnAnalyzerV3())] ), ), ) # Create pipeline pipeline = Pipeline( [ transport.input(), stt, context_aggregator.user(), llm, tts, # TTS with pattern aggregator transport.output(), context_aggregator.assistant(), ] ) task = PipelineTask( pipeline, params=PipelineParams( enable_metrics=True, enable_usage_metrics=True, ), idle_timeout_secs=runner_args.pipeline_idle_timeout_secs, ) @transport.event_handler("on_client_connected") async def on_client_connected(transport, client): logger.info(f"Client connected") # Start conversation - empty prompt to let LLM follow system instructions await task.queue_frames([LLMRunFrame()]) @transport.event_handler("on_client_disconnected") async def on_client_disconnected(transport, client): logger.info(f"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()