A mode of synchronizer operation that used information derived from SMPTE Time Code and, after initial synchronization, ignores specific frame addresses. Basically this works by looking at and comparing the leading edge of the SMPTE waveforms and keeping them lined up. It’s a commonly used sync technique because it is very precise as long as the waveforms stay intact. There are, however, several possible anomalies that can cause it to jump off by a few frames and because the actual addresses are ignored, the only way to recover is to stop playback and restart, which causes the synchronizer to reacquire the SMPTE address.