ROS Programming: Building Powerful Robots

What is a bag file?

A bag file is a container of messages sent by topics that were recorded during a session using a robot or nodes. In brief, they are the log files for the messages transferred during the execution of our system, and they allow us to play back everything, even with time delays, since all messages are recorded with a timestamp-not only the timestamp in the header, but also for the packets contained within the bag file. The difference between the timestamp used to record and the one in the header is that the first one is set once the message is recorded, while the other is set by the producer/publisher of the message.

The data stored in a bag file is in the binary format. The particular structure of this container allows for ...