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pipecat/src/pipecat/services/tts_service.py
2025-06-09 07:29:09 -07:00

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#
# Copyright (c) 20242025, Daily
#
# SPDX-License-Identifier: BSD 2-Clause License
#
import asyncio
from abc import abstractmethod
from typing import Any, AsyncGenerator, Dict, List, Mapping, Optional, Sequence, Tuple
from loguru import logger
from pipecat.frames.frames import (
BotStartedSpeakingFrame,
BotStoppedSpeakingFrame,
CancelFrame,
EndFrame,
ErrorFrame,
Frame,
InterimTranscriptionFrame,
LLMFullResponseEndFrame,
LLMFullResponseStartFrame,
StartFrame,
StartInterruptionFrame,
TextFrame,
TranscriptionFrame,
TTSAudioRawFrame,
TTSSpeakFrame,
TTSStartedFrame,
TTSStoppedFrame,
TTSTextFrame,
TTSUpdateSettingsFrame,
)
from pipecat.processors.frame_processor import FrameDirection
from pipecat.services.ai_service import AIService
from pipecat.services.websocket_service import WebsocketService
from pipecat.transcriptions.language import Language
from pipecat.utils.text.base_text_aggregator import BaseTextAggregator
from pipecat.utils.text.base_text_filter import BaseTextFilter
from pipecat.utils.text.simple_text_aggregator import SimpleTextAggregator
from pipecat.utils.time import seconds_to_nanoseconds
class TTSService(AIService):
def __init__(
self,
*,
aggregate_sentences: bool = True,
# if True, TTSService will push TextFrames and LLMFullResponseEndFrames,
# otherwise subclass must do it
push_text_frames: bool = True,
# if True, TTSService will push TTSStoppedFrames, otherwise subclass must do it
push_stop_frames: bool = False,
# if push_stop_frames is True, wait for this idle period before pushing TTSStoppedFrame
stop_frame_timeout_s: float = 2.0,
# if True, TTSService will push silence audio frames after TTSStoppedFrame
push_silence_after_stop: bool = False,
# if push_silence_after_stop is True, send this amount of audio silence
silence_time_s: float = 2.0,
# if True, we will pause processing frames while we are receiving audio
pause_frame_processing: bool = False,
# TTS output sample rate
sample_rate: Optional[int] = None,
# Text aggregator to aggregate incoming tokens and decide when to push to the TTS.
text_aggregator: Optional[BaseTextAggregator] = None,
# Text filter executed after text has been aggregated.
text_filters: Optional[Sequence[BaseTextFilter]] = None,
text_filter: Optional[BaseTextFilter] = None,
# Audio transport destination of the generated frames.
transport_destination: Optional[str] = None,
**kwargs,
):
super().__init__(**kwargs)
self._aggregate_sentences: bool = aggregate_sentences
self._push_text_frames: bool = push_text_frames
self._push_stop_frames: bool = push_stop_frames
self._stop_frame_timeout_s: float = stop_frame_timeout_s
self._push_silence_after_stop: bool = push_silence_after_stop
self._silence_time_s: float = silence_time_s
self._pause_frame_processing: bool = pause_frame_processing
self._init_sample_rate = sample_rate
self._sample_rate = 0
self._voice_id: str = ""
self._settings: Dict[str, Any] = {}
self._text_aggregator: BaseTextAggregator = text_aggregator or SimpleTextAggregator()
self._text_filters: Sequence[BaseTextFilter] = text_filters or []
self._transport_destination: Optional[str] = transport_destination
if text_filter:
import warnings
with warnings.catch_warnings():
warnings.simplefilter("always")
warnings.warn(
"Parameter 'text_filter' is deprecated, use 'text_filters' instead.",
DeprecationWarning,
)
self._text_filters = [text_filter]
self._stop_frame_task: Optional[asyncio.Task] = None
self._stop_frame_queue: asyncio.Queue = asyncio.Queue()
self._processing_text: bool = False
@property
def sample_rate(self) -> int:
return self._sample_rate
@property
def chunk_size(self) -> int:
"""This property indicates how much audio we download (from TTS services
that require chunking) before we start pushing the first audio
frame. This will make sure we download the rest of the audio while audio
is being played without causing audio glitches (specially at the
beginning). Of course, this will also depend on how fast the TTS service
generates bytes.
"""
CHUNK_SECONDS = 0.5
return int(self.sample_rate * CHUNK_SECONDS * 2) # 2 bytes/sample
async def set_model(self, model: str):
self.set_model_name(model)
def set_voice(self, voice: str):
self._voice_id = voice
# Converts the text to audio.
@abstractmethod
async def run_tts(self, text: str) -> AsyncGenerator[Frame, None]:
pass
def language_to_service_language(self, language: Language) -> Optional[str]:
return Language(language)
async def update_setting(self, key: str, value: Any):
pass
async def flush_audio(self):
pass
async def start(self, frame: StartFrame):
await super().start(frame)
self._sample_rate = self._init_sample_rate or frame.audio_out_sample_rate
if self._push_stop_frames and not self._stop_frame_task:
self._stop_frame_task = self.create_task(self._stop_frame_handler())
async def stop(self, frame: EndFrame):
await super().stop(frame)
if self._stop_frame_task:
await self.cancel_task(self._stop_frame_task)
self._stop_frame_task = None
async def cancel(self, frame: CancelFrame):
await super().cancel(frame)
if self._stop_frame_task:
await self.cancel_task(self._stop_frame_task)
self._stop_frame_task = None
async def _update_settings(self, settings: Mapping[str, Any]):
for key, value in settings.items():
if key in self._settings:
logger.info(f"Updating TTS setting {key} to: [{value}]")
self._settings[key] = value
if key == "language":
self._settings[key] = self.language_to_service_language(value)
elif key == "model":
self.set_model_name(value)
elif key == "voice":
self.set_voice(value)
elif key == "text_filter":
for filter in self._text_filters:
await filter.update_settings(value)
else:
logger.warning(f"Unknown setting for TTS service: {key}")
async def say(self, text: str):
await self.queue_frame(TTSSpeakFrame(text))
async def process_frame(self, frame: Frame, direction: FrameDirection):
await super().process_frame(frame, direction)
if (
isinstance(frame, TextFrame)
and not isinstance(frame, InterimTranscriptionFrame)
and not isinstance(frame, TranscriptionFrame)
):
await self._process_text_frame(frame)
elif isinstance(frame, StartInterruptionFrame):
await self._handle_interruption(frame, direction)
await self.push_frame(frame, direction)
elif isinstance(frame, (LLMFullResponseEndFrame, EndFrame)):
# We pause processing incoming frames if the LLM response included
# text (it might be that it's only a function calling response). We
# pause to avoid audio overlapping.
await self._maybe_pause_frame_processing()
sentence = self._text_aggregator.text
await self._text_aggregator.reset()
self._processing_text = False
await self._push_tts_frames(sentence)
if isinstance(frame, LLMFullResponseEndFrame):
if self._push_text_frames:
await self.push_frame(frame, direction)
else:
await self.push_frame(frame, direction)
elif isinstance(frame, TTSSpeakFrame):
# Store if we were processing text or not so we can set it back.
processing_text = self._processing_text
await self._push_tts_frames(frame.text)
# We pause processing incoming frames because we are sending data to
# the TTS. We pause to avoid audio overlapping.
await self._maybe_pause_frame_processing()
await self.flush_audio()
self._processing_text = processing_text
elif isinstance(frame, TTSUpdateSettingsFrame):
await self._update_settings(frame.settings)
elif isinstance(frame, BotStoppedSpeakingFrame):
await self._maybe_resume_frame_processing()
await self.push_frame(frame, direction)
else:
await self.push_frame(frame, direction)
async def push_frame(self, frame: Frame, direction: FrameDirection = FrameDirection.DOWNSTREAM):
if self._push_silence_after_stop and isinstance(frame, TTSStoppedFrame):
silence_num_bytes = int(self._silence_time_s * self.sample_rate * 2) # 16-bit
silence_frame = TTSAudioRawFrame(
audio=b"\x00" * silence_num_bytes,
sample_rate=self.sample_rate,
num_channels=1,
)
silence_frame.transport_destination = self._transport_destination
await self.push_frame(silence_frame)
if isinstance(frame, (TTSStartedFrame, TTSStoppedFrame, TTSAudioRawFrame, TTSTextFrame)):
frame.transport_destination = self._transport_destination
await super().push_frame(frame, direction)
if self._push_stop_frames and (
isinstance(frame, StartInterruptionFrame)
or isinstance(frame, TTSStartedFrame)
or isinstance(frame, TTSAudioRawFrame)
or isinstance(frame, TTSStoppedFrame)
):
await self._stop_frame_queue.put(frame)
async def _handle_interruption(self, frame: StartInterruptionFrame, direction: FrameDirection):
self._processing_text = False
await self._text_aggregator.handle_interruption()
for filter in self._text_filters:
await filter.handle_interruption()
async def _maybe_pause_frame_processing(self):
if self._processing_text and self._pause_frame_processing:
await self.pause_processing_frames()
async def _maybe_resume_frame_processing(self):
if self._pause_frame_processing:
await self.resume_processing_frames()
async def _process_text_frame(self, frame: TextFrame):
text: Optional[str] = None
if not self._aggregate_sentences:
text = frame.text
else:
text = await self._text_aggregator.aggregate(frame.text)
if text:
await self._push_tts_frames(text)
async def _push_tts_frames(self, text: str):
# Remove leading newlines only
text = text.lstrip("\n")
# Don't send only whitespace. This causes problems for some TTS models. But also don't
# strip all whitespace, as whitespace can influence prosody.
if not text.strip():
return
# This is just a flag that indicates if we sent something to the TTS
# service. It will be cleared if we sent text because of a TTSSpeakFrame
# or when we received an LLMFullResponseEndFrame
self._processing_text = True
await self.start_processing_metrics()
# Process all filter.
for filter in self._text_filters:
await filter.reset_interruption()
text = await filter.filter(text)
if text:
await self.process_generator(self.run_tts(text))
await self.stop_processing_metrics()
if self._push_text_frames:
# We send the original text after the audio. This way, if we are
# interrupted, the text is not added to the assistant context.
await self.push_frame(TTSTextFrame(text))
async def _stop_frame_handler(self):
has_started = False
while True:
try:
frame = await asyncio.wait_for(
self._stop_frame_queue.get(), self._stop_frame_timeout_s
)
if isinstance(frame, TTSStartedFrame):
has_started = True
elif isinstance(frame, (TTSStoppedFrame, StartInterruptionFrame)):
has_started = False
except asyncio.TimeoutError:
if has_started:
await self.push_frame(TTSStoppedFrame())
has_started = False
class WordTTSService(TTSService):
"""This is a base class for TTS services that support word timestamps. Word
timestamps are useful to synchronize audio with text of the spoken
words. This way only the spoken words are added to the conversation context.
"""
def __init__(self, **kwargs):
super().__init__(**kwargs)
self._initial_word_timestamp = -1
self._words_queue = asyncio.Queue()
self._words_task = None
self._llm_response_started: bool = False
def start_word_timestamps(self):
if self._initial_word_timestamp == -1:
self._initial_word_timestamp = self.get_clock().get_time()
def reset_word_timestamps(self):
self._initial_word_timestamp = -1
async def add_word_timestamps(self, word_times: List[Tuple[str, float]]):
for word, timestamp in word_times:
await self._words_queue.put((word, seconds_to_nanoseconds(timestamp)))
async def start(self, frame: StartFrame):
await super().start(frame)
self._create_words_task()
async def stop(self, frame: EndFrame):
await super().stop(frame)
await self._stop_words_task()
async def cancel(self, frame: CancelFrame):
await super().cancel(frame)
await self._stop_words_task()
async def process_frame(self, frame: Frame, direction: FrameDirection):
await super().process_frame(frame, direction)
if isinstance(frame, LLMFullResponseStartFrame):
self._llm_response_started = True
elif isinstance(frame, (LLMFullResponseEndFrame, EndFrame)):
await self.flush_audio()
async def _handle_interruption(self, frame: StartInterruptionFrame, direction: FrameDirection):
await super()._handle_interruption(frame, direction)
self._llm_response_started = False
self.reset_word_timestamps()
def _create_words_task(self):
if not self._words_task:
self._words_task = self.create_task(self._words_task_handler())
async def _stop_words_task(self):
if self._words_task:
await self.cancel_task(self._words_task)
self._words_task = None
async def _words_task_handler(self):
last_pts = 0
while True:
frame = None
(word, timestamp) = await self._words_queue.get()
if word == "Reset" and timestamp == 0:
self.reset_word_timestamps()
if self._llm_response_started:
self._llm_response_started = False
frame = LLMFullResponseEndFrame()
frame.pts = last_pts
elif word == "TTSStoppedFrame" and timestamp == 0:
frame = TTSStoppedFrame()
frame.pts = last_pts
else:
frame = TTSTextFrame(word)
frame.pts = self._initial_word_timestamp + timestamp
if frame:
last_pts = frame.pts
await self.push_frame(frame)
self._words_queue.task_done()
class WebsocketTTSService(TTSService, WebsocketService):
"""This is a base class for websocket-based TTS services.
If an error occurs with the websocket, an "on_connection_error" event will
be triggered:
@tts.event_handler("on_connection_error")
async def on_connection_error(tts: TTSService, error: str):
...
"""
def __init__(self, *, reconnect_on_error: bool = True, **kwargs):
TTSService.__init__(self, **kwargs)
WebsocketService.__init__(self, reconnect_on_error=reconnect_on_error, **kwargs)
self._register_event_handler("on_connection_error")
async def _report_error(self, error: ErrorFrame):
await self._call_event_handler("on_connection_error", error.error)
await self.push_error(error)
class InterruptibleTTSService(WebsocketTTSService):
"""This is a base class for websocket-based TTS services that don't support
word timestamps and that don't offer a way to correlate the generated audio
to the requested text.
"""
def __init__(self, **kwargs):
super().__init__(**kwargs)
# Indicates if the bot is speaking. If the bot is not speaking we don't
# need to reconnect when the user speaks. If the bot is speaking and the
# user interrupts we need to reconnect.
self._bot_speaking = False
async def _handle_interruption(self, frame: StartInterruptionFrame, direction: FrameDirection):
await super()._handle_interruption(frame, direction)
if self._bot_speaking:
await self._disconnect()
await self._connect()
async def process_frame(self, frame: Frame, direction: FrameDirection):
await super().process_frame(frame, direction)
if isinstance(frame, BotStartedSpeakingFrame):
self._bot_speaking = True
elif isinstance(frame, BotStoppedSpeakingFrame):
self._bot_speaking = False
class WebsocketWordTTSService(WordTTSService, WebsocketService):
"""This is a base class for websocket-based TTS services that support word
timestamps.
If an error occurs with the websocket a "on_connection_error" event will be
triggered:
@tts.event_handler("on_connection_error")
async def on_connection_error(tts: TTSService, error: str):
...
"""
def __init__(self, *, reconnect_on_error: bool = True, **kwargs):
WordTTSService.__init__(self, **kwargs)
WebsocketService.__init__(self, reconnect_on_error=reconnect_on_error, **kwargs)
self._register_event_handler("on_connection_error")
async def _report_error(self, error: ErrorFrame):
await self._call_event_handler("on_connection_error", error.error)
await self.push_error(error)
class InterruptibleWordTTSService(WebsocketWordTTSService):
"""This is a base class for websocket-based TTS services that support word
timestamps but don't offer a way to correlate the generated audio to the
requested text.
"""
def __init__(self, **kwargs):
super().__init__(**kwargs)
# Indicates if the bot is speaking. If the bot is not speaking we don't
# need to reconnect when the user speaks. If the bot is speaking and the
# user interrupts we need to reconnect.
self._bot_speaking = False
async def _handle_interruption(self, frame: StartInterruptionFrame, direction: FrameDirection):
await super()._handle_interruption(frame, direction)
if self._bot_speaking:
await self._disconnect()
await self._connect()
async def process_frame(self, frame: Frame, direction: FrameDirection):
await super().process_frame(frame, direction)
if isinstance(frame, BotStartedSpeakingFrame):
self._bot_speaking = True
elif isinstance(frame, BotStoppedSpeakingFrame):
self._bot_speaking = False
class AudioContextWordTTSService(WebsocketWordTTSService):
"""This is a base class for websocket-based TTS services that support word
timestamps and also allow correlating the generated audio with the requested
text.
Each request could be multiple sentences long which are grouped by
context. For this to work, the TTS service needs to support handling
multiple requests at once (i.e. multiple simultaneous contexts).
The audio received from the TTS will be played in context order. That is, if
we requested audio for a context "A" and then audio for context "B", the
audio from context ID "A" will be played first.
"""
def __init__(self, **kwargs):
super().__init__(**kwargs)
self._contexts_queue = asyncio.Queue()
self._contexts: Dict[str, asyncio.Queue] = {}
self._audio_context_task = None
async def create_audio_context(self, context_id: str):
"""Create a new audio context."""
await self._contexts_queue.put(context_id)
self._contexts[context_id] = asyncio.Queue()
logger.trace(f"{self} created audio context {context_id}")
async def append_to_audio_context(self, context_id: str, frame: TTSAudioRawFrame):
"""Append audio to an existing context."""
if self.audio_context_available(context_id):
logger.trace(f"{self} appending audio {frame} to audio context {context_id}")
await self._contexts[context_id].put(frame)
else:
logger.warning(f"{self} unable to append audio to context {context_id}")
async def remove_audio_context(self, context_id: str):
"""Remove an existing audio context."""
if self.audio_context_available(context_id):
# We just mark the audio context for deletion by appending
# None. Once we reach None while handling audio we know we can
# safely remove the context.
logger.trace(f"{self} marking audio context {context_id} for deletion")
await self._contexts[context_id].put(None)
else:
logger.warning(f"{self} unable to remove context {context_id}")
def audio_context_available(self, context_id: str) -> bool:
"""Checks whether the given audio context is registered."""
return context_id in self._contexts
async def start(self, frame: StartFrame):
await super().start(frame)
self._create_audio_context_task()
async def stop(self, frame: EndFrame):
await super().stop(frame)
if self._audio_context_task:
# Indicate no more audio contexts are available. this will end the
# task cleanly after all contexts have been processed.
await self._contexts_queue.put(None)
await self.wait_for_task(self._audio_context_task)
self._audio_context_task = None
async def cancel(self, frame: CancelFrame):
await super().cancel(frame)
await self._stop_audio_context_task()
async def _handle_interruption(self, frame: StartInterruptionFrame, direction: FrameDirection):
await super()._handle_interruption(frame, direction)
await self._stop_audio_context_task()
self._create_audio_context_task()
def _create_audio_context_task(self):
if not self._audio_context_task:
self._contexts_queue = asyncio.Queue()
self._contexts: Dict[str, asyncio.Queue] = {}
self._audio_context_task = self.create_task(self._audio_context_task_handler())
async def _stop_audio_context_task(self):
if self._audio_context_task:
await self.cancel_task(self._audio_context_task)
self._audio_context_task = None
async def _audio_context_task_handler(self):
"""In this task we process audio contexts in order."""
running = True
while running:
context_id = await self._contexts_queue.get()
if context_id:
# Process the audio context until the context doesn't have more
# audio available (i.e. we find None).
await self._handle_audio_context(context_id)
# We just finished processing the context, so we can safely remove it.
del self._contexts[context_id]
# Append some silence between sentences.
silence = b"\x00" * self.sample_rate
frame = TTSAudioRawFrame(
audio=silence, sample_rate=self.sample_rate, num_channels=1
)
await self.push_frame(frame)
else:
running = False
self._contexts_queue.task_done()
async def _handle_audio_context(self, context_id: str):
# If we don't receive any audio during this time, we consider the context finished.
AUDIO_CONTEXT_TIMEOUT = 3.0
queue = self._contexts[context_id]
running = True
while running:
try:
frame = await asyncio.wait_for(queue.get(), timeout=AUDIO_CONTEXT_TIMEOUT)
if frame:
await self.push_frame(frame)
running = frame is not None
except asyncio.TimeoutError:
# We didn't get audio, so let's consider this context finished.
logger.trace(f"{self} time out on audio context {context_id}")
break