Technical note: Calibration of frame intervals of video recorders using Global Positioning System (GPS) signal as time reference

Abstract

A method has been developed for calibrating the time intervals of video recorders using a LED panel known as “SEXTA”, which utilizes Global Positioning System (GPS) signal as time reference. This method directly measures the frame intervals frame by frame down to a time resolution of 2 ms of the recordings by video recorders equipped with CCD or CMOS sensors in global shutter or rolling shutter modes respectively. The method has been validated by using a Digital Single Lens Reflex (DSLR) camera and a previous studied dashboard camera. Frame by frame analysis of the calibrated video recording of SEXTA can reveal characteristics of sensors, such as type of sensors (CMOS vs CCD), exposure time, the direction and speed of rolling shutter for CMOS sensors as well as the common characteristics of dashboard cameras such as frame skipping.

Keywords

• Frame interval
• Video recorders
• Global Positioning System (GPS)
• Rolling shutter
• Global shutter
• CMOS