Hello,

I am using multiple USB cameras for a project and am facing problems with time synchronization. I am currently using imagetransport library's subscribeCamera function to subscribe to camerainfo and imagerectcolor published by imageproc. While one of my cameras is working fine, the second camera is dropping frames due to camerainfo being published at a lower rate than the image messages. The following is the warning I am receiving:

    [ WARN] [1467164006.770029982]: [image_transport] Topics '/usb_cam_2/image_rect_color' and '/usb_cam_2/camera_info' do not appear to be synchronized. In the last 10s:
   Image messages received:      120
   CameraInfo messages received: 94
   Synchronized pairs:           6

I have seen a few related answers such as this one link: http://answers.ros.org/question/69925/sync-problem-on-image-and-camera_info-over-wireless/ but in my case one of the cameras is working fine with just subscribeCamera. I was wondering what the reason could be specially for the camera_info being published at a lower rate than the image messages and whether this is something that I can rectify without ApproximateTime message filters as suggested in the answer in the link.

Thanks in advance!