Replaces cv2.imshow with Pygame to avoid hanging on Ubuntu (🐛 Bug)

lerobot/common/robot_devices/control_utils.py

@@ -24,7 +24,20 @@
 from lerobot.common.robot_devices.utils import busy_wait
 from lerobot.common.utils.utils import get_safe_torch_device, init_hydra_config, set_global_seed
 from lerobot.scripts.eval import get_pretrained_policy_path
+import platform
+import os
+import pygame
+import numpy as np
 
+def init_pygame_display():
+    """Initialize pygame display for showing camera feeds."""
+    pygame.init()
+    pygame.font.init()  # Initialize the font module
+    return None  # Will create windows as needed
+
+def cleanup_pygame():
+    """Cleanup pygame resources."""
+    pygame.quit()
 
 def log_control_info(robot: Robot, dt_s, episode_index=None, frame_index=None, fps=None):
     log_items = []
@@ -255,6 +268,9 @@ def control_loop(
 
     timestamp = 0
     start_episode_t = time.perf_counter()
+    init_pygame_display()
+    main_window = None
+
     while timestamp < control_time_s:
         start_loop_t = time.perf_counter()
 
@@ -276,9 +292,43 @@ def control_loop(
 
         if display_cameras and not is_headless():
             image_keys = [key for key in observation if "image" in key]
+
+            # Calculate total width and maximum height for the window
+            total_width = sum(observation[key].shape[1] for key in image_keys) + (len(image_keys) - 1) * 10
+            max_height = max(observation[key].shape[0] for key in image_keys)
+
+            # Create or get main window
+            if main_window is None:
+                main_window = pygame.display.set_mode((total_width, max_height + 30))  # Add 30 pixels for text
+                pygame.display.set_caption("Camera Feeds (Press 'q' to quit)")
+
+            # Clear the window
+            main_window.fill((0, 0, 0))
+
+            # Draw images side by side
+            x_offset = 0
             for key in image_keys:
-                cv2.imshow(key, cv2.cvtColor(observation[key].numpy(), cv2.COLOR_RGB2BGR))
-            cv2.waitKey(1)
+                img = observation[key].numpy()
+                img_rgb = cv2.cvtColor(img, cv2.COLOR_RGB2BGR)
+                surface = pygame.surfarray.make_surface(np.transpose(img_rgb, (1, 0, 2)))
+                main_window.blit(surface, (x_offset, 0))
+                # Draw camera name above each image
+                font = pygame.font.Font(None, 24)
+                text = font.render(key, True, (255, 255, 255))
+                main_window.blit(text, (x_offset, max_height + 5))
+                x_offset += img.shape[1] + 10  # Add 10 pixels gap
+
+            pygame.display.flip()
+
+            # Handle pygame events
+            for event in pygame.event.get():
+                if event.type == pygame.QUIT:
+                    cleanup_pygame()
+                    events["exit_early"] = True
+                elif event.type == pygame.KEYDOWN:
+                    if event.key == pygame.K_q:
+                        cleanup_pygame()
+                        events["exit_early"] = True
 
         if fps is not None:
             dt_s = time.perf_counter() - start_loop_t
@@ -314,14 +364,14 @@ def reset_environment(robot, events, reset_time_s):
 
 
 def stop_recording(robot, listener, display_cameras):
+    """Stop recording and cleanup resources."""
     robot.disconnect()
 
     if not is_headless():
         if listener is not None:
             listener.stop()
-
         if display_cameras:
-            cv2.destroyAllWindows()
+            cleanup_pygame()
 
 
 def sanity_check_dataset_name(repo_id, policy):

pyproject.toml

@@ -40,6 +40,7 @@ zarr = ">=2.17.0"
 numba = ">=0.59.0"
 torch = ">=2.2.1"
 opencv-python = ">=4.9.0"
+pygame = ">=2.5.2"
 diffusers = ">=0.27.2"
 torchvision = ">=0.17.1"
 h5py = ">=3.10.0"