A timecode track is an additional strip of data recorded in the file alongside the video and audio, noting the exact time of recording for each frame of video. This comes in handy when later editing the video, since you can sync up the time between multiple cameras or even separate audio recorders and cut between cameras and sound sources with perfect precision.
REC allows you to record timecode from the following sources:
Time of Day
Use the iPhone’s built-in clock to set the timecode to the current time of day (“wall clock”).
Tentacle Sync
Connect to a Tentacle Sync device to apply perfectly synchronized timecode.