seeking in a bag file
I am going to work with large bag files, offline. I am going to have to seek back and forth in the bag to find the data I need, i.e. some sort of random access. Before I start working on a hack of my own, I'd like to know if there is any standard approach implemented out there. Let say the goal is to be able to retrieve a message on topic X, at or near time T.
Note: this question is related: http://answers.ros.org/question/10852/playing-back-large-files-with-rosbag/
I am thinking that I could open a new View with the proper query (X,T). But I am wondering how long will it take. i.e. when opening a view, is it reading an index to open it in a constant time, or is it going to scan through the bag until it finds it?
Did you finally found a solution ? Because I could be very interesting (for me, but also for everyone) if you could share what you found/did :-) Thanks !
It's still on my todo list. Once done i'll post my solution here (probably a couple of months)