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CLOCKWORKS

Frame lock

The Frame lock check box is only available when your

MOTU interface is locking to external SMPTE time code

(in any form — MTC or LTC). It is not available when your

MOTU interface is in Internal sync mode.

To understand the Frame lock option, you ﬁrst need to

know that your MOTU interface continuously monitors

incoming time code to detect any possible discontinuity in

the frame times as they advance. If your MOTU interface

detects more than ﬁve frames in a row that are not

continuous with respect to previous frames received, then

it does one of two things, depending on whether the Frame

lock option is turned on (checked) or off (unchecked).

If the Frame lock option is turned on (checked), and your

MOTU interface detects more than ﬁve frames in a row

that are not continuous with respect to previous frames

received, then it will stop converting altogether.

If the Frame lock option is turned off (unchecked), and

your MOTU interface detects more than ﬁve frames in a

row that are not continuous with respect to previous

frames received, then it begins to perform a kind of

“pseudo jam sync”. In this mode, it continues to convert

an uninterrupted stream of continuous time code, while at

the same time clocking off of the incoming time code.

Even though the frames it is generating no longer match

the frames it is reading, it will continue to remain in sync

with the incoming time code.

In other words, when the Frame lock option is off, your

MOTU interface ignores discontinuous jumps in

incoming time code by continuing to clock itself off of the

incoming time code without stopping (or pausing). In

doing so, it continues to convert a continuous,

uninterrupted stream of frame times based on the time

code to which it ﬁrst locked.

Turn on Frame lock when you want your MOTU

interface’s frame times to match incoming frame times,

and you want it to stop converting altogether if there are

jumps in incoming time code.

!USB Interfaces Manual Book Page 43 Tuesday, August 16, 2011 11:21 AM