MOTU Micro Lite [142/166] Frame rates

APPENDIX B: SMPTE SYNCHRONIZATION BASICS

142

SHOULD I USE LTC OR VITC?

Since VITC only works with video, you must use LTC for

synchronizing a multi-track tape deck. But don’t fret: LTC

is affordable and more than adequate for tape synchroni-

zation.

If you compose music for ﬁlm or video, you too can use

LTC. We strongly recommend, however, that you consider

VITC because of the beneﬁts noted above. Contact MOTU

for more information about the Digital Timepiece.

FRAME RATES

In either form (LTC or VITC), SMPTE time code has

several basic formats for counting frames per second (fps):

24, 25, 29.97 non-drop, 29.97 drop-frame, and 30. 24 is the

standard frame rate for ﬁlm in the US; 25 is the European

format for ﬁlm; 30 is the US standard for audio; and 29.97

drop and non-drop are used for video. Drop frame,

explained in detail in the next section, allows SMPTE time

code numbers to precisely match the actual elapsed time.

WHAT IS DROP FRAME?

Drop Frame SMPTE time code counts frames at a rate of

29.97 frames per second but skips two frame numbers at

the beginning of each minute, except every 10th minute.

When the time code display reaches HH:MM:59:29 (59

seconds and 29 frames at the end of each minute), the

frame count skips 00 and 01 and jumps ahead to

HH:MM:00:02. This jump does not happen at minutes 00,

10, 20, 30, 40, and 50.

Thus, frame numbers such as 11:14:00:00 and 11:14:00:01

do not exist in Drop Frame: the display will show a frame

at 11:13:59:29 and the next frame at 11:14:00:02. However,

frame numbers at each tenth minute will not be skipped,

such as from 11:19:59:29 to 11:20:00:00, followed by

11:20:00:01 and 11:20:00:02, etc.

Keep in mind that only numbers are skipped, not actual

frames of the picture. In other words, every picture frame

gets a frame number and the numbers skip every once in a

while.