My goal is to subscribe to pointclouds in my .bag file, grab their width, height, and density boolean, and use that data in another program. I followed this tutorial on ros.org so that I can use other tutorials on the pcl.org website.. but when I run the program as is, nothing happens.

I saw another question on ros answers whose program worked once he changed the input from 'input:=/narrowstereotextured/points2' to 'input:=/camera/depthregistered/points'. However, my input should be coming from a .bag file saved in my package. I tried to do 'input:=/sr/pointcloud2raw' (to get the pointcloud data from my .bag file) but that didn't work.

I thought the purpose of using a publisher/subscriber was so that I didn't have to manually convert my .bag pointclouds to .pcd files saved on my machine. That is what I want to do- just grab and pass the pointcloud data into another program.