Thanks Patrick.
It worked.




________________________________
From: Patrick Mihelich <mihelich@willowgarage.com>
To: User discussions <ros-users@code.ros.org>
Sent: Wednesday, October 13, 2010 15:53:42
Subject: Re: [ros-users] rosbag play help

Instead of changing the bag file time stamps, you should use simulated time. See 
http://www.ros.org/wiki/Clock.

Short version:
 - Before launching any nodes, set parameter /use_sim_time to True.
 - Use the --clock option of rosbag play.

Then rosbag will publish the simulated time on the /clock topic. All nodes using 
ROS time will use the simulated time instead of wall-clock time.

Cheers,
Patrick


On Tue, Oct 12, 2010 at 11:41 PM, Peshala Jayasekara <peshala_24@yahoo.com> 
wrote:

Hi all,
>
>I want to know if there is a way to change the time stamp of a bagfile when you 
>play it.
>For example, when you run robot_pose_ekf of navigation stack, it compares 
>current time with sensor time stamps and it will not update the filter for old 
>sensor data.
>
>Thank you in advance.
>Peshala
>
>
>
>
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