Different applications benefit from different levels of video/data synchronicity. The exact method deployed will depend on any one of a number of aspects of the system solution. Where the data and video sources are distributed, the comms methods used to connect them can sometimes present a challenge – there may be no sync signal available, and / or there may be non-deterministic delays introduced by the protocol stack or operating system itself.
Sometimes the system contains an internal master clock of questionable quality, in other cases there may be a reliable external timing source which may not easily map to all system elements. Cost, as always, is another factor to consider.
By means of an example, Fen has successfully synchronised a multi-video and telemetry source system over ethernet and USB, where the timing source was an external GPS module and system elements were both embedded Linux controlled and state-machine controlled. The high-level requirement was to be able to align 3D imaging and measurement parameters to sub-microsecond accuracy.
In another case Fen used the common timing source within an embedded system to graphically overlay system time on the video stream, and enabled video-editing-like manipulation of the video stream as a recorded experiment review function.
