Know the True Frame Rate on Your Media

If you get your media from a production company instead of recording them yourself, be absolutely sure that they indicate the SMPTE frame rate used on the tape correctly. Several timecode formats use the same frame count (such as 23.976 fps and 24 fps) yet they run at slightly different frame rates per second.

A Synchronization peripheral (and some third-party products) can be used to help determine frame rate.