Since I have been out of the loop now for almost 2 years, I don't know if they are still using the same company or not.  BUT, the Michigan State Police were using the same camera system as their radars. . . . .KUSTOM.  They were just getting to around to using the digital camera systems when I left so I assume that they were slowly transferring to the digital systems, yet they did not get all of the whistle and bells.  Some of those whistle and bells were somehow connecting the speedometer and/or the radar unit to the camera system so the speeds could be displayed in the window.  There are also systems that have mapping systems (GPS involved) with the recording so when the Sergeant plays it back he can see directly where the incident took place.  There are some other whistle and bells I'm sure, but that will take some investigation on your part.  ALSO. . . . who is going to warranty their product in the best way for your specific application should also be a consideration.  Good Luck.

Most of them use a company by the name MPH in Owensboro, KY