fix(livekit): prevent memory leak when video_in_enabled is False

src/pipecat/transports/livekit/transport.py

@@ -539,11 +539,14 @@ class LiveKitTransportClient:
         elif track.kind == rtc.TrackKind.KIND_VIDEO:
             logger.info(f"Video track subscribed: {track.sid} from participant {participant.sid}")
             self._video_tracks[participant.sid] = track
-            video_stream = rtc.VideoStream(track)
-            self._task_manager.create_task(
-                self._process_video_stream(video_stream, participant.sid),
-                f"{self}::_process_video_stream",
-            )
+            # Only process video stream if video input is enabled to prevent
+            # unbounded queue growth when there is no consumer for video frames.
+            if self._params.video_in_enabled:
+                video_stream = rtc.VideoStream(track)
+                self._task_manager.create_task(
+                    self._process_video_stream(video_stream, participant.sid),
+                    f"{self}::_process_video_stream",
+                )
             await self._callbacks.on_video_track_subscribed(participant.sid)
 
     async def _async_on_track_unsubscribed(

tests/test_livekit_transport.py

@@ -0,0 +1,133 @@
+#
+# Copyright (c) 2024-2026, Daily
+#
+# SPDX-License-Identifier: BSD 2-Clause License
+#
+
+"""Tests for LiveKit transport video stream handling.
+
+Regression tests for issue #3116: Memory leak when video_in_enabled=False
+but video tracks are subscribed.
+"""
+
+import asyncio
+import unittest
+from unittest.mock import AsyncMock, MagicMock
+
+from livekit import rtc
+
+from pipecat.transports.livekit.transport import (
+    LiveKitCallbacks,
+    LiveKitParams,
+    LiveKitTransportClient,
+)
+
+
+class TestLiveKitTransportClient(unittest.IsolatedAsyncioTestCase):
+    """Tests for LiveKitTransportClient video stream handling."""
+
+    def _create_client(self, video_in_enabled: bool) -> LiveKitTransportClient:
+        """Create a LiveKitTransportClient with the specified video_in_enabled setting."""
+        params = LiveKitParams(video_in_enabled=video_in_enabled)
+
+        callbacks = LiveKitCallbacks(
+            on_connected=AsyncMock(),
+            on_disconnected=AsyncMock(),
+            on_before_disconnect=AsyncMock(),
+            on_participant_connected=AsyncMock(),
+            on_participant_disconnected=AsyncMock(),
+            on_audio_track_subscribed=AsyncMock(),
+            on_audio_track_unsubscribed=AsyncMock(),
+            on_video_track_subscribed=AsyncMock(),
+            on_video_track_unsubscribed=AsyncMock(),
+            on_data_received=AsyncMock(),
+            on_first_participant_joined=AsyncMock(),
+        )
+
+        client = LiveKitTransportClient(
+            url="wss://test.livekit.cloud",
+            token="test-token",
+            room_name="test-room",
+            params=params,
+            callbacks=callbacks,
+            transport_name="test-transport",
+        )
+
+        # Mock the task manager
+        client._task_manager = MagicMock()
+        client._task_manager.create_task = MagicMock()
+
+        return client
+
+    def _create_mock_video_track(self) -> tuple:
+        """Create mock video track, publication, and participant."""
+        mock_track = MagicMock()
+        mock_track.kind = rtc.TrackKind.KIND_VIDEO
+        mock_track.sid = "test-track-sid"
+
+        mock_publication = MagicMock()
+
+        mock_participant = MagicMock()
+        mock_participant.sid = "test-participant-sid"
+
+        return mock_track, mock_publication, mock_participant
+
+    def _was_video_stream_task_created(self, client: LiveKitTransportClient) -> bool:
+        """Check if _process_video_stream task was created."""
+        for call in client._task_manager.create_task.call_args_list:
+            task_name = call[0][1] if len(call[0]) > 1 else call[1].get("name", "")
+            if "_process_video_stream" in task_name:
+                return True
+        return False
+
+    async def test_video_stream_not_started_when_video_in_disabled(self):
+        """Test that _process_video_stream is NOT started when video_in_enabled=False.
+
+        This prevents unbounded queue growth when there is no consumer for video frames.
+        Regression test for issue #3116.
+        """
+        client = self._create_client(video_in_enabled=False)
+        mock_track, mock_publication, mock_participant = self._create_mock_video_track()
+
+        # Call the track subscribed handler
+        await client._async_on_track_subscribed(mock_track, mock_publication, mock_participant)
+
+        # Verify that create_task was NOT called for video stream processing
+        self.assertFalse(
+            self._was_video_stream_task_created(client),
+            "Video stream processing should NOT be started when video_in_enabled=False",
+        )
+
+        # Verify that the callback was still called
+        client._callbacks.on_video_track_subscribed.assert_called_once_with(mock_participant.sid)
+
+        # Verify that the track was still added to _video_tracks
+        self.assertIn(mock_participant.sid, client._video_tracks)
+
+    async def test_video_stream_started_when_video_in_enabled(self):
+        """Test that _process_video_stream IS started when video_in_enabled=True."""
+        from unittest.mock import patch
+
+        client = self._create_client(video_in_enabled=True)
+        mock_track, mock_publication, mock_participant = self._create_mock_video_track()
+
+        # Mock rtc.VideoStream to avoid needing a real LiveKit connection
+        with patch("pipecat.transports.livekit.transport.rtc.VideoStream"):
+            # Call the track subscribed handler
+            await client._async_on_track_subscribed(mock_track, mock_publication, mock_participant)
+
+        # Verify that create_task WAS called for video stream processing
+        self.assertTrue(
+            self._was_video_stream_task_created(client),
+            "Video stream processing SHOULD be started when video_in_enabled=True",
+        )
+
+        # Verify that the callback was called
+        client._callbacks.on_video_track_subscribed.assert_called_once_with(mock_participant.sid)
+
+        # Verify that the track was added to _video_tracks
+        self.assertIn(mock_participant.sid, client._video_tracks)
+
+
+if __name__ == "__main__":
+    unittest.main()