Merge pull request #4245 from kollaikal-rupesh/fix/mixer-cancel-cleanup

Stop audio mixer on pipeline cancellation

src/pipecat/transports/base_output.py

@@ -512,6 +512,10 @@ class BaseOutputTransport(FrameProcessor):
             await self._cancel_clock_task()
             await self._cancel_video_task()
 
+            # Stop audio mixer so it doesn't keep generating frames after cancellation.
+            if self._mixer:
+                await self._mixer.stop()
+
         async def handle_interruptions(self, _: InterruptionFrame):
             """Handle interruption events by restarting tasks and clearing buffers.