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pipecat/examples/foundational/57-parallel-content-filter.py
2026-03-05 11:17:02 +08:00

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#
# Copyright (c) 20242026, Daily
#
# SPDX-License-Identifier: BSD 2-Clause License
#
import os
from dataclasses import dataclass
from dotenv import load_dotenv
from loguru import logger
from pipecat.audio.turn.smart_turn.base_smart_turn import SmartTurnParams
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 (
ControlFrame,
Frame,
LLMContextFrame,
LLMFullResponseEndFrame,
LLMRunFrame,
SystemFrame,
TTSSpeakFrame,
)
from pipecat.pipeline.parallel_pipeline import ParallelPipeline
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
from pipecat.processors.frame_processor import FrameDirection, FrameProcessor
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
load_dotenv(override=True)
@dataclass
class ContentApprovedFrame(ControlFrame):
"""Signal frame indicating content passed the filter."""
pass
@dataclass
class ContentRejectedFrame(ControlFrame):
"""Signal frame indicating content was rejected by the filter."""
pass
FILTERED_WORDS = ["apple", "banana", "car"]
class ContentFilterProcessor(FrameProcessor):
"""Checks LLMContextFrames for filtered words and emits signal frames.
Runs in one branch of a ParallelPipeline. Emits ContentApprovedFrame or
ContentRejectedFrame so that a downstream ContentFilterGate can decide
whether to let the LLM's output through.
"""
def _contains_filtered_words(self, context: "LLMContext") -> bool:
"""Check if the last message in the context contains any filtered words."""
messages = context.messages
if messages:
last_message = messages[-1]
content = last_message.get("content", "") if isinstance(last_message, dict) else ""
if isinstance(content, str):
content_lower = content.lower()
if any(word in content_lower for word in FILTERED_WORDS):
logger.info(f"Filtered content detected: {content}")
return True
return False
async def process_frame(self, frame: Frame, direction: FrameDirection):
await super().process_frame(frame, direction)
if isinstance(frame, LLMContextFrame):
if self._contains_filtered_words(frame.context):
await self.push_frame(ContentRejectedFrame(), direction)
else:
await self.push_frame(ContentApprovedFrame(), direction)
return
await self.push_frame(frame, direction)
class ContentFilterGate(FrameProcessor):
"""Gates LLM output until the content filter signals approval or rejection.
Placed after a ParallelPipeline that runs a ContentFilterProcessor alongside
an LLM. Because the content filter (a fast regex check) completes before the
LLM's first token arrives, the signal frame always reaches this gate first.
- On ContentApprovedFrame: subsequent LLM output passes through normally.
- On ContentRejectedFrame: LLM output is discarded and a canned rejection
message is spoken instead via TTSSpeakFrame.
Note: For a production implementation with a slow content filter (e.g. an
external moderation API), you would add frame buffering so that LLM output
arriving before the filter decision is held rather than passed through.
"""
def __init__(self, **kwargs):
super().__init__(**kwargs)
self._rejecting = False
async def process_frame(self, frame: Frame, direction: FrameDirection):
await super().process_frame(frame, direction)
# System frames always pass through.
if isinstance(frame, SystemFrame):
await self.push_frame(frame, direction)
return
# Content filter approved — LLM output will pass through normally.
if isinstance(frame, ContentApprovedFrame):
return
# Content filter rejected — suppress LLM output and speak a rejection.
if isinstance(frame, ContentRejectedFrame):
self._rejecting = True
await self.push_frame(
TTSSpeakFrame(text="I'm sorry, I can't respond to that."), direction
)
return
# LLMFullResponseEndFrame marks the end of the LLM's response.
# When rejecting, consume it to finish suppression.
if isinstance(frame, LLMFullResponseEndFrame) and self._rejecting:
self._rejecting = False
return
# While rejecting, discard all other frames (LLM text, etc.).
if self._rejecting:
return
await self.push_frame(frame, direction)
# 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)),
turn_analyzer=LocalSmartTurnAnalyzerV3(params=SmartTurnParams()),
),
"twilio": lambda: FastAPIWebsocketParams(
audio_in_enabled=True,
audio_out_enabled=True,
vad_analyzer=SileroVADAnalyzer(params=VADParams(stop_secs=0.2)),
turn_analyzer=LocalSmartTurnAnalyzerV3(params=SmartTurnParams()),
),
"webrtc": lambda: TransportParams(
audio_in_enabled=True,
audio_out_enabled=True,
vad_analyzer=SileroVADAnalyzer(params=VADParams(stop_secs=0.2)),
turn_analyzer=LocalSmartTurnAnalyzerV3(params=SmartTurnParams()),
),
}
async def run_bot(transport: BaseTransport, runner_args: RunnerArguments):
logger.info(f"Starting bot")
stt = DeepgramSTTService(api_key=os.getenv("DEEPGRAM_API_KEY", ""))
tts = CartesiaTTSService(
api_key=os.getenv("CARTESIA_API_KEY", ""),
voice_id="71a7ad14-091c-4e8e-a314-022ece01c121", # British Reading Lady
)
llm = OpenAILLMService(api_key=os.getenv("OPENAI_API_KEY"))
messages = [
{
"role": "system",
"content": "You are a helpful LLM in a WebRTC call. Your goal is to demonstrate your capabilities in a succinct way. Your output will be spoken aloud, so avoid special characters that can't easily be spoken, such as emojis or bullet points. Respond to what the user said in a creative and helpful way.",
},
]
context = LLMContext(messages)
context_aggregator = LLMContextAggregatorPair(context)
content_filter = ContentFilterProcessor()
content_gate = ContentFilterGate()
# The content filter and LLM run in parallel. The content filter emits
# a signal frame (approved/rejected) while the LLM generates text
# concurrently. The gate after the ParallelPipeline blocks output until
# the content filter decides. TTS is placed after the gate so rejected
# content never reaches it.
pipeline = Pipeline(
[
transport.input(), # Transport user input
stt,
context_aggregator.user(), # User responses
ParallelPipeline(
[content_filter], # Branch 1: content filter (emits signal frames)
[llm], # Branch 2: LLM text generation
),
content_gate, # Gates output until content filter approves
tts, # TTS (only processes approved text)
transport.output(), # Transport bot output
context_aggregator.assistant(), # Assistant spoken responses
]
)
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")
# Kick off the conversation.
messages.append({"role": "system", "content": "Please introduce yourself to the user."})
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()