fix(realsense): ignore invalid frames for disabled streams

src/lerobot/cameras/realsense/camera_realsense.py

@@ -749,11 +749,11 @@ def _build_frame_snapshot(self, frames: Any) -> _FrameSnapshot:
         depth = None
 
         color_frame = frames.get_color_frame()
-        if color_frame is not None:
+        if color_frame:
             color = np.ascontiguousarray(_decode_color_frame_to_rgb(color_frame))
 
         depth_frame = frames.get_depth_frame()
-        if depth_frame is not None:
+        if depth_frame:
             depth = np.ascontiguousarray(np.asanyarray(depth_frame.get_data()).copy())
 
         return _FrameSnapshot(color=color, depth=depth)

tests/cameras/test_realsense_frame_snapshot.py

@@ -0,0 +1,82 @@
+#!/usr/bin/env python
+
+# Copyright 2024 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import unittest
+from unittest.mock import MagicMock, patch
+
+import numpy as np
+
+from lerobot.cameras.realsense import D405_MODEL_TRAITS, SharedRealSenseManager
+
+
+class TestBuildFrameSnapshot(unittest.TestCase):
+    """Regression tests for falsey pyrealsense2 frames returned by disabled streams."""
+
+    def setUp(self):
+        self.manager = SharedRealSenseManager(serial_number="042", model_traits=D405_MODEL_TRAITS)
+
+    def test_ignores_invalid_color_frame(self):
+        invalid_color_frame = MagicMock()
+        invalid_color_frame.__bool__.return_value = False
+        frames = MagicMock()
+        frames.get_color_frame.return_value = invalid_color_frame
+        frames.get_depth_frame.return_value = None
+
+        with patch(
+            "lerobot.cameras.realsense.camera_realsense._decode_color_frame_to_rgb"
+        ) as decode_color_frame:
+            snapshot = self.manager._build_frame_snapshot(frames)
+
+        decode_color_frame.assert_not_called()
+        invalid_color_frame.get_data.assert_not_called()
+        self.assertIsNone(snapshot.color)
+        self.assertIsNone(snapshot.depth)
+
+    def test_ignores_invalid_depth_frame(self):
+        invalid_depth_frame = MagicMock()
+        invalid_depth_frame.__bool__.return_value = False
+        frames = MagicMock()
+        frames.get_color_frame.return_value = None
+        frames.get_depth_frame.return_value = invalid_depth_frame
+
+        snapshot = self.manager._build_frame_snapshot(frames)
+
+        invalid_depth_frame.get_data.assert_not_called()
+        self.assertIsNone(snapshot.color)
+        self.assertIsNone(snapshot.depth)
+
+    def test_decodes_valid_frames(self):
+        color_frame = MagicMock()
+        color_frame.__bool__.return_value = True
+        depth_frame = MagicMock()
+        depth_frame.__bool__.return_value = True
+        depth_data = np.arange(4, dtype=np.uint16).reshape(2, 2)
+        depth_frame.get_data.return_value = depth_data
+        frames = MagicMock()
+        frames.get_color_frame.return_value = color_frame
+        frames.get_depth_frame.return_value = depth_frame
+        expected_color = np.arange(12, dtype=np.uint8).reshape(2, 2, 3)
+
+        with patch(
+            "lerobot.cameras.realsense.camera_realsense._decode_color_frame_to_rgb",
+            return_value=expected_color,
+        ) as decode_color_frame:
+            snapshot = self.manager._build_frame_snapshot(frames)
+
+        decode_color_frame.assert_called_once_with(color_frame)
+        depth_frame.get_data.assert_called_once_with()
+        np.testing.assert_array_equal(snapshot.color, expected_color)
+        np.testing.assert_array_equal(snapshot.depth, depth_data)