Fix missing topics validation

rosbags2video/bag2video.py

@@ -32,6 +32,7 @@ def write_frames(
     convert = {topics[i]: i for i in range(len(topics))}
     frame_duration = 1.0 / fps
 
+    # Initialize with 3 channels, will be adjusted if needed
     images = [
         np.zeros((sizes[i][1], sizes[i][0], 3), np.uint8) for i in range(len(topics))
     ]
@@ -64,7 +65,26 @@ def write_frames(
             time = stamp_to_sec(msg.header.stamp)
 
         if init:
-            image = message_to_cvimage(msg, encoding)
+            # Try to convert with the specified encoding first
+            try:
+                image = message_to_cvimage(msg, encoding)
+            except Exception as e:
+                # If conversion fails and it's likely a grayscale image, try mono8
+                if "8UC1" in str(e) or "mono" in str(e).lower():
+                    logging.info(
+                        f"Detected grayscale image, switching to mono8 encoding for topic {topic}"
+                    )
+                    encoding = "mono8"
+                    image = message_to_cvimage(msg, encoding)
+                    # Convert grayscale to 3-channel for consistency
+                    if len(image.shape) == 2:
+                        image = cv2.cvtColor(image, cv2.COLOR_GRAY2BGR)
+                else:
+                    raise e
+
+            # Ensure all images are 3-channel for consistency
+            if len(image.shape) == 2:
+                image = cv2.cvtColor(image, cv2.COLOR_GRAY2BGR)
 
             if timestamp_all:
                 image = embed_timestamp(image, time, add_timestamp, add_raw_timestamp)
@@ -104,7 +124,26 @@ def write_frames(
                 frame_num = frame_num_next
                 num_msgs += 1
 
-            image = message_to_cvimage(msg, encoding)
+            # Try to convert with the current encoding
+            try:
+                image = message_to_cvimage(msg, encoding)
+            except Exception as e:
+                # If conversion fails and it's likely a grayscale image, try mono8
+                if "8UC1" in str(e) or "mono" in str(e).lower():
+                    logging.info(
+                        f"Detected grayscale image, switching to mono8 encoding for topic {topic}"
+                    )
+                    encoding = "mono8"
+                    image = message_to_cvimage(msg, encoding)
+                    # Convert grayscale to 3-channel for consistency
+                    if len(image.shape) == 2:
+                        image = cv2.cvtColor(image, cv2.COLOR_GRAY2BGR)
+                else:
+                    raise e
+
+            # Ensure all images are 3-channel for consistency
+            if len(image.shape) == 2:
+                image = cv2.cvtColor(image, cv2.COLOR_GRAY2BGR)
 
             if timestamp_all:
                 image = embed_timestamp(image, time, add_timestamp, add_raw_timestamp)

rosbags2video/utils.py

@@ -30,6 +30,29 @@ def get_sizes(bag_reader, topics=None, index=0, scale=1.0):
     for topic in topics:
         try:
             connections = [x for x in bag_reader.connections if x.topic == topic]
+
+            # Check if topic exists in the bag
+            if not connections:
+                logging.critical(f"Topic '{topic}' not found in bag file.")
+                logging.critical("Available topics:")
+                for conn in bag_reader.connections:
+                    logging.critical(f"  {conn.topic}: {conn.msgtype}")
+                sys.exit(1)
+
+            # Check if the topic is an image type
+            connection = connections[0]
+            if not (
+                connection.msgtype.endswith("/Image")
+                or connection.msgtype.endswith("/CompressedImage")
+            ):
+                logging.critical(
+                    f"Topic '{topic}' is not an image topic (type: {connection.msgtype})."
+                )
+                logging.critical(
+                    "Only sensor_msgs/Image and sensor_msgs/CompressedImage topics are supported."
+                )
+                sys.exit(1)
+
             for connection, timestamp, rawdata in bag_reader.messages(
                 connections=connections
             ):