Most likely you were being videotaped during most of your encounter.
Most police cars are equipped with a dash camera and were running prior to the officer turning on his lights and pulling you over. Some of the larger police agencies are starting to use body worn cameras in addition to their dash cameras. There is often a back seat camera when the officer is transporting you from the scene, to the jail or hospital. At the police station most of the rooms and holding cells are being recorded. Therefore, any more field sobriety tests done at the station, any breath test, or any blood draw is being recorded.