services: add a generic mechanism to produce TTSStoppedFrames

src/pipecat/services/ai_services.py

@@ -8,7 +8,8 @@ import io
 import wave
 
 from abc import abstractmethod
-from typing import AsyncGenerator
+from asyncio import Task, sleep
+from typing import AsyncGenerator, Optional
 
 from pipecat.frames.frames import (
     AudioRawFrame,
@@ -20,6 +21,8 @@ from pipecat.frames.frames import (
     StartFrame,
     StartInterruptionFrame,
     TTSSpeakFrame,
+    TTSStartedFrame,
+    TTSStoppedFrame,
     TTSVoiceUpdateFrame,
     TextFrame,
     UserImageRequestFrame,
@@ -156,10 +159,17 @@ class TTSService(AIService):
             aggregate_sentences: bool = True,
             # if True, subclass is responsible for pushing TextFrames and LLMFullResponseEndFrames
             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 = 0.8,
             **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._stop_frame_task: Optional[Task] = None
         self._current_sentence: str = ""
 
     @abstractmethod
@@ -227,6 +237,22 @@ class TTSService(AIService):
         else:
             await self.push_frame(frame, direction)
 
+    async def push_frame(self, frame: Frame, direction: FrameDirection = FrameDirection.DOWNSTREAM):
+        await super().push_frame(frame, direction)
+
+        if isinstance(frame, AudioRawFrame) and self._stop_frame_task is not None:
+            # Reschedule timeout task if it was already running
+            self._stop_frame_task.cancel()
+            self._stop_frame_task = self.get_event_loop().create_task(self._stop_frame_handler())
+        elif isinstance(frame, TTSStartedFrame) and self._push_stop_frames:
+            # Start timeout task if necessary
+            self._stop_frame_task = self.get_event_loop().create_task(self._stop_frame_handler())
+
+    async def _stop_frame_handler(self):
+        await sleep(self._stop_frame_timeout_s)
+        await self.push_frame(TTSStoppedFrame())
+        self._stop_frame_task = None
+
 
 class STTService(AIService):
     """STTService is a base class for speech-to-text services."""

src/pipecat/services/lmnt.py

@@ -49,6 +49,10 @@ class LmntTTSService(TTSService):
             **kwargs):
         super().__init__(**kwargs)
 
+        # Let TTSService produce TTSStoppedFrames after a short delay of
+        # no activity.
+        self._push_stop_frames = True
+
         self._api_key = api_key
         self._voice_id = voice_id
         self._output_format = {