MOTU micro express-USB, Руководство пользователя

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A P P E N D I X B : S M P T E S Y N C H R O N I Z A T I O N B A S I C S
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elapsed time, such as when preparing a television
broadcast. Otherwise, we suggest that you use 30
Non-drop time code because of the slight
inaccuracy mentioned above, as well as the
confusion that drop frame can cause.
HOW DOES SMPTE SYNCHRONIZATION
WORK?
The syncing process is straightforward. It involves
one device following another. As you play back a
tape with SMPTE time code on it, the SMPTE feeds
into a hardware device called a
SMPTE-to-MIDI
converter . The converter translates the SMPTE
audio signal into MIDI Time Code and sends the
MIDI Time Code to a MIDI device such as a
sequencer. The MIDI device receives the time code
and adjusts its playback position to match the time
code. All of this happens very quickly, around 30
times per second, which is fast enough so that the
MIDI device follows the tape smoothly.
Certain phrases are often used to describe
synchronization. The tape deck to which the MIDI
device is synchronized is called the synchroni-
zation
master ; the MIDI device, which follows, is
called the slave . The MIDI device is slaved to the
master . The converter, which reads the time code
on tape, is locked to tape , or when using SMPTE
time code, locked to SMPTE .
HOW DOES A MOTU SYNCHRONIZER
WORK?
All MOTU MIDI interface/synchronizers function
as a SMPTE-to-MIDI converter. When they receive
SMPTE time code, they convert that signal into
MIDI Time Code, which is then sent to MIDI
devices connected to the network. These devices,
in turn, slave to the MIDI Time Code.
WHAT IS MIDI TIME CODE?
MIDI Time Code is time code in the form of MIDI
data that matches the format of SMPTE time code:
time is expressed in hours, minutes, seconds, and
frames. A MOTU interface/synchronizer can send
MIDI Time Code over MIDI to a sequencer, which
follows the MIDI Time Code.
LOCKING A MOTU INTERFACE TO SMPTE
In order to sync your MIDI device to tape, you
must first successfully lock your MOTU interface/
synchronizer to the SMPTE on the tape. To do so,
you need to:
1. Stripe a tape with SMPTE
2. Connect the MOTU interface/synchronizer to
the tape deck
3. Prepare the MOTU interface/synchronizer to
convert SMPTE
4. Roll the tape to see if successful SMPTE lockup
has been achieved
These steps are discussed in chapter 8, “SMPTE
Synchronization” (page 71). Once lockup has been
achieved, you can stop the tape, set up your MIDI
hardware or software, and then slave it to your
MOTU interface/synchronizer.
!USB Interfaces Manual Book Page 148 Tuesday, October 10, 2000 12:43 PM