hello fredco: but at leats you know /me :-) *least I am trying to grab simultaneous frames from two separate usb cameras. I'm currently using gstreamer on a raspberry pi (or beaglebone black, edison, etc.). My only concern is the real time difference between ostensible simultaneous frames from the two cameras. Is there a way to know the real time difference? If I point at a clock the time difference varies. I am OK with waiting until two frames are closer than some threshold before I accept them. I'm about a 1/10 skill level with v4l, linux drivers, etc. (obviously) headless: at least my first reply was not scolding for breaking the rules. :) I'm not wedded to gstreamer, I believe my issue is endemic to usb camera streaming mode.