User guide

USING CLOCKWORKS FOR MAC OS X WITH THE MIDI TIMEPIECE AV 12
If you change the MIDI Timepiece AV device ID for some reason,
make sure that it does not match the ID of another device
connected to it.
Figure 17: MMC ID and other options.
Measured Timebase
This status indicator shows the actual sample rate being generated
by the MIDI Timepiece AV based on the current time base. This
display shows the number of samples being generated per second.
It allows you to measure how accurate external time base sources
are (such as video or LTC). It is also affected by the sample rate
settings in the MIDI Timepiece AV, so it can help you chase down
discrepancies with pull-up and pull-down sample rates.
LTC Ou tput
This slider allows you to adjust the overall gain of the SMPTE time
code from the MIDI Timepiece AV LTC output jack. Move it
towards the left to reduce the level; move it towards the right to
increase it. This level control affects LTC output in all sync modes,
including LTC, MTC, etc.
Still-frame sensitivity
This option lets you control how many frames in a row the MIDI
Timepiece AV needs to receive to consider incoming SMPTE as
being parked on a single frame. While lowering this value makes
the MIDI Timepiece AV more responsive when you pause your
video deck, it is also more likely to misinterpret ordinary
transport shuttling. So make this value as low as you can, but raise
it if you start getting improper frame locations when shuttling
your deck.
Freewheel _ frames
This option lets you set the number of frames the MIDI Timepiece
AV w i l l f r eewheel over when it encounters a time code drop-out.
For a complete explanation of freewheeling, please refer to the
MOTU USB MIDI User’s Guide that accompanies this guide.
Infinite freewheel (zero)
When you choose this option, the MIDI Timepiece AV begins
generating time code on its own indefinitely as soon as it stops
receiving incoming time code. And it will continue to do so until
you stop it with the ENTER button on the front panel. You can
also stop it by changing the master sync mode or by changing the
Freewheel setting in ClockWorks.
Offset external timebase by
This setting lets you create an offset, positive or negative, between
the time code generated by the MIDI Timepiece AV and the time
code to which it is resolved. Click the +/- button to create a
positive (later) or negative (earlier) offset. For example, if you
create an offset of +1 hour, and you feed the MIDI Timepiece AV
time code starting at two hours (2:00:00:00), it will generate time
code starting at 3 hours (3:00:00:00). This is a global offset for the
entire MIDI Timepiece AV. (For information about programming
offsets for individual ADATs connected to the MIDI
Timepiece AV, see “Time code offset” on page 9.)
Sample Rate
The sample rate menu sets the digital audio word clock rate for the
MIDI Timepiece AV. There are six possible word clock rates:
normal, pull-up (+0.1%), and pull-down (-0.1%) for both
44.1kHz and 48kHz. These settings correspond to the settings in
the front-panel of the MIDI Timepiece AV. These settings are
grayed out if the MIDI Timepiece AV is in a time base mode where
it should determine the word clock rate on its own, such as when
it is slaving to an external word clock as a time base.
Figure 18: ClockWorks’ sample rate settings.
Offset entire ADAT chain
ADATs use absolute time (also referred to as ABS time) to cue to a
position on tape. Absolute time is based on the elapsed time from
the beginning of the tape, where the beginning equals time zero.
This can be an issue if you are working with time code that falls
beyond the approximate 45-minute length of an ADAT tape. For
example, if you are transferring audio tracks from video, and the
video is referenced to time code that starts at 3 hours, the MIDI
Timepiece AV itself will have no problem locking to the time code,
but the ADATs will try to cue to three hours, which is over two
hours beyond the end of the tape.
The Offset entire ADAT chain option solves this problem. Use this
option to bring the ADAT chain back into a time range between
zero and 45 minutes. Using the above example, you would offset
the ADAT chain by -3 hours (negative 3 hours). If the video cues
to 3:07:23:00, then the ADAT chain will then cue to 7 minutes, 23
seconds.