When I have a datalogger and I want to sync a video-file to the recording, what would be an easy method? The logger and the camera both have an internal clock, but they may not be set exactly to the same time, so I cannot use those timestamps to sync the start, and during long recordings they may drift apart.
The solution seems to be to let the datalogger record an extra sync-signal, but what should this channel contain (no. of frames?) and how do I get this information from a regular camera?