# rostopic, rosbag and rxbag slow with large messages [closed]

Hi

I am using ROS fuerte with a velodyne, which is indeed spitting large amount of data. I noticed that there are some problems with some of tools, I think the python tools mostly.

For instance the following command hogs the CPU:

rostopic echo /velodyne_data --noarr


it also skips messages as seen by the seq field in the header skipping counts.

Also doing a rosbag filter on a large bag is terribly slow. I once tried to filter out the velodyne data from a 10 minutes long bag and it took hours. I rewrote my own version in c++ and it took 5 minutes.

Finally, with rxbag, I wanted to check the header of the velodyne data in raw view and moving from one message to the next is so slow that it makes the GUI gray out (unresponsive). It takes several seconds (maybe 10) to move to the next message.