processors: introduce input queues

Frame processors can now decide if they should continue processing frames or
not, and if so also decide when to continue processing frames. For example,
asynchronous TTS services will stop processing frames until they have generated
all the audio for an LLM response.

src/pipecat/services/ai_services.py

@@ -15,6 +15,7 @@ from loguru import logger
 from pipecat.audio.utils import calculate_audio_volume, exp_smoothing
 from pipecat.frames.frames import (
     AudioRawFrame,
+    BotStoppedSpeakingFrame,
     CancelFrame,
     EndFrame,
     ErrorFrame,
@@ -297,6 +298,8 @@ class TTSService(AIService):
             await self._process_text_frame(frame)
         elif isinstance(frame, StartInterruptionFrame):
             await self._handle_interruption(frame, direction)
+        elif isinstance(frame, BotStoppedSpeakingFrame):
+            await self.resume_processing_frames()
         elif isinstance(frame, (LLMFullResponseEndFrame, EndFrame)):
             sentence = self._current_sentence
             self._current_sentence = ""