Apple Final Cut Pro 7 - Manual (Page 1927)

Timecode on Tape
There are several kinds of timecode recorded on videotape, each stored in a different
part of the video signal. LTC is stored as an audio signal, whereas VITC is stored in a line
of each video frame.
• LTC (longitudinal timecode): Is typically recorded as an audio signal on a dedicated
timecode track. You can add or change LTC on your original tapes even after they’ve
been recorded because it’s recorded on its own independent track. LTC is also used
with professional audio formats, such as DAT and other multitrack audio recorders.
Because LTC is audio, it can be interpreted by a timecode reader even when the tape
is fast-forwarding, but it can’t be read when the tape is paused or moving extremely
slowly.
• VITC (vertical interval timecode): Is recorded as part of the video signal, using several
video lines that are normally masked by consumer televisions. You can see VITC as a
series of white dots at the top of the video frame if you view the video on a professional
monitor in underscan mode. Because VITC is part of the video signal, it can only be
changed on your original tapes if you also replace the video itself, which is rarely
worthwhile. The VITC part of the video signal is not captured as part of a Final Cut Pro
clip’s video frame, but VITC can be captured directly from the device control connection.
Because VITC is part of the video signal, which most decks can show in slow motion
or even when paused, VITC can be read at very slow speeds, but it breaks up when
fast-forwarding or rewinding.
Most timecode readers can automatically switch between LTC and VITC if they are both
available. In Final Cut Pro, you can choose this setting in your device control preset:
LTC+VITC. If you choose this setting, Final Cut Pro looks at both types of timecode so that
accurate timecode can be read no matter what speed the tape is playing (LTC is used for
normal and high-speed playback; VITC is used for slow motion and pause).
LTC is most easily read when a deck is in fast-forward, and VITC is most easily read when
a deck is in slow motion. Most professional video decks can read both signals and
automatically send timecode from the one that’s clearest at any moment. The LTC and
VITC signals on most tapes are almost always identical.
Important: Video decks capable of reading both LTC and VITC usually have a switch that
lets you select whether a deck outputs one or the other, or both. Unless the VITC and LTC
signals on your tape don’t match for some reason, leave this switch set to both.
Unlike DV and professional video formats, analog tape formats don’t always have timecode
written onto them. If you’re using S-VHS or Hi-8, you need to make sure that you’re using
a device-controllable deck and, if your tapes don’t already have timecode on them, that
you post-stripe timecode onto them. For information on how to do this, see the
documentation that came with your video deck.
1927 Appendix C Frame Rate and Timecode