Align Ultravox Realtime service with OpenAI/Gemini patterns

- Add InterruptionFrame handling with stop_all_metrics()
- Add processing metrics (start/stop) at response boundaries
- Fix agent transcript handling for voice and text modalities:
  - Voice mode: push LLMTextFrame (append_to_context=False) and
    TTSTextFrame for deltas, skip duplicated final text
  - Text mode: push LLMTextFrame with proper response lifecycle,
    no TTSTextFrame (downstream TTS handles audio)
- Add output_medium parameter to AgentInputParams and OneShotInputParams
- Improve TTFB measurement using VAD speech end time
- Update example with user turn strategies and transcript events
- Add text-only output example (50a-ultravox-realtime-text.py)

examples/foundational/50-ultravox-realtime.py

@@ -12,11 +12,18 @@ from loguru import logger
 
 from pipecat.adapters.schemas.function_schema import FunctionSchema
 from pipecat.adapters.schemas.tools_schema import ToolsSchema
+from pipecat.audio.vad.silero import SileroVADAnalyzer
+from pipecat.audio.vad.vad_analyzer import VADParams
 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.aggregators.llm_response_universal import (
+    AssistantTurnStoppedMessage,
+    LLMContextAggregatorPair,
+    LLMUserAggregatorParams,
+    UserTurnStoppedMessage,
+)
 from pipecat.runner.types import RunnerArguments
 from pipecat.runner.utils import create_transport
 from pipecat.services.llm_service import FunctionCallParams
@@ -24,6 +31,8 @@ from pipecat.services.ultravox.llm import OneShotInputParams, UltravoxRealtimeLL
 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 SpeechTimeoutUserTurnStopStrategy
+from pipecat.turns.user_turn_strategies import UserTurnStrategies
 
 # Load environment variables
 load_dotenv(override=True)
@@ -168,8 +177,21 @@ There is also a secret menu that changes daily. If the user asks about it, use t
 
     llm.register_function("get_secret_menu", get_secret_menu)
 
-    # Necessary to complete the function call lifecycle in Pipecat.
-    user_aggregator, assistant_aggregator = LLMContextAggregatorPair(LLMContext([]))
+    context = LLMContext([])
+
+    # Necessary to complete the function call lifecycle in Pipecat and
+    # to produce user and assistant turn stopped events.
+    user_aggregator, assistant_aggregator = LLMContextAggregatorPair(
+        context,
+        user_params=LLMUserAggregatorParams(
+            user_turn_strategies=UserTurnStrategies(
+                stop=[SpeechTimeoutUserTurnStopStrategy()],
+            ),
+            # Set the VAD analyzer to create reliable TTFB measurements and
+            # user stop events.
+            vad_analyzer=SileroVADAnalyzer(),
+        ),
+    )
 
     # Build the pipeline
     pipeline = Pipeline(
@@ -177,8 +199,8 @@ There is also a secret menu that changes daily. If the user asks about it, use t
             transport.input(),
             user_aggregator,
             llm,
-            assistant_aggregator,
             transport.output(),
+            assistant_aggregator,
         ]
     )
 
@@ -203,6 +225,18 @@ There is also a secret menu that changes daily. If the user asks about it, use t
         logger.info(f"Client disconnected")
         await task.cancel()
 
+    @user_aggregator.event_handler("on_user_turn_stopped")
+    async def on_user_turn_stopped(aggregator, strategy, message: UserTurnStoppedMessage):
+        timestamp = f"[{message.timestamp}] " if message.timestamp else ""
+        line = f"{timestamp}user: {message.content}"
+        logger.info(f"Transcript: {line}")
+
+    @assistant_aggregator.event_handler("on_assistant_turn_stopped")
+    async def on_assistant_turn_stopped(aggregator, message: AssistantTurnStoppedMessage):
+        timestamp = f"[{message.timestamp}] " if message.timestamp else ""
+        line = f"{timestamp}assistant: {message.content}"
+        logger.info(f"Transcript: {line}")
+
     # Run the pipeline
     runner = PipelineRunner(handle_sigint=runner_args.handle_sigint)
     await runner.run(task)