MOTU Digital Timepiece Instruction Manual download pdf (Page 74)

SMPTE SYNCHRONIZATION

steadily as well. For the micro express, the lights on the front panel

are arranged slightly differently than what is show here on the XT, but

they perform in an identical fashion.

If the LOCK and TACH lights do not behave as

described, your Express interface is not

successfully locking to the SMPTE time code. This

could be a problem with the audio connections

between the tape deck and your Express interface.

It could also be that the SMPTE level is not high

enough. See Appendix C, “Troubleshooting and

Customer Support” page (149).

The SMPTE display in the Express XT Console

Toolbar

When the Express XT is shipped from the factory,

it is set up so that the MIDI Express XT Console

Toolbar SMPTE display will provide a running

update of the SMPTE time code being generated or

converted by the MIDI Express XT.

Routing MIDI Time Code

At times, you may need to route MIDI Time Code

to a device connected to one of the Express

interface’s MIDI OUTs. To route time code to a

MIDI OUT cable, use the MIDI Routing window in

the Express Console as described in “The Sync In

and Sync Out icons” on page 38 (for micro express

users) and “The Sync In and Sync Out icons” on

page 58 (for Express XT users). Connect the Sync

icon in the left-hand column of sources to the

desired MIDI output(s) in the right-hand column.

SMPTE Offset

When reading time code, there may be times when

you need to offset your Express interface a certain

amount from the time code you are feeding it. See

“Offset/start time” on page 43 (for micro express

users) or “Offset/start time” on page 63 (for

Express XT users) for details.

Freewheeling to avoid time code dropouts

When your Express interface encounters a drop-

out —a series of missing or unreadable frames—in

the SMPTE time code, it “freewheels” past them,

pretending that they were not missing by brieﬂy

generating its own code to make up for the missing

frames. The default freewheel value is 4 frames.

This means that your Express interface will

continue to generate time code for four more

frames after it stops receiving time code. If it does

not receive any more time code after four frames, it

will stop converting.

The factory default base setups have the

freewheeling feature set to 4 frames for fastest

response when you stop the tape deck. The

Freewheel amount can be adjusted up to 32 frames.

This allows your Express interface to maintain

lockup even over lengthy SMPTE drop outs.

If you encounter a time code drop out that causes

your Express interface to stop converting for a

moment, try increasing the “Jam for” amount in

the Sync window. Try adding just a few frames at a

time when adjusting the amount. (For details on

the “one time jam sync” option, see “Regenerating

fresh time code (‘jam syncing’)” on page 74.)

your Express interface freewheels at the frame rate

it is reading at the time it begins freewheeling —

except for 29.97 drop and non-drop. If you intend

on reading 29.97 SMPTE, be sure to manually set

the SMPTE format to 29.97 so that freewheeling

will occur at the proper rate.

When you increase the “Jam for” amount, you also

increase the amount of time that your Express

interface keeps converting when you stop tape. To

make your Express interface as responsive as

possible, only raise the “Jam for” amount as high as

necessary to overcome the drop-out(s) you are

encountering.

Synchronizing to discontinuous time code

Your Express interface has the ability to stay in sync

with discontinuous time code — that is, time code

that has no gaps in it but does have jumps in its

frame locations. For details about how to do this,

!USB Interfaces Manual Book Page 72 Tuesday, October 10, 2000 12:43 PM

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MOTU Digital Timepiece Instruction Manual Page 74

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