How to publish topic with old rosbag time? [closed]

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I first set /use_sim_time to true. Then play the ros bag file. My code subscribes the point cloud in the bag. After some processing, my code publishes the processed point cloud. However, the rviz can only display the point cloud in the bag. It can't display the processed point cloud. I guess the processed point cloud use the current time and the rviz use the old time, so the processed point cloud can not be displayed. So, how to publish the processed point cloud using the old bag time?