DigiDesign SYNC HD, Manual

Page: 50 / 103

SYNC HD Guide 44
Make sure you select the appropriate clock refer-
ence, sample rate, frame rate, and freewheel du-
ration. Also make sure the LTC signal is routed
properly to the SYNC HD LTC In connector.
Freewheel Duration
Freewheel duration (time code freewheel) con-
figures the SYNC HD for a maximum number of
frames it should continue generating if time
code drops out or is otherwise interrupted. Free-
wheel settings are ignored when the SYNC HD is
in Internal/Generate mode.
Example of Time Code Freewheel
In a 30 fps Pro Tools session, if Freewheel Dura-
tion/Time Code Freewheel is 28 frames, the
SYNC HD will continue to generate until either
the incoming time code signal is restored, or un-
til 28 frames elapse, whichever occurs first.
To set the freewheel duration:
From Pro Tools:
„
In the Time Code Settings section of the Ses-
sion Setup window, enter a number of frames
for time code Freewheel.
From the front panel:
1
Press Set, and use the Up or Down switches to
display Freewheel Length (FrEE LEn).
2
Press Set to display freewheel duration
choices.
3
Use the Up or Down switches to scroll through
available choices (lowest is “4 Fr” or four frames,
highest is “40 Fr” or 40 frames).
4
Press Set.
From the SYNC Setup software utility
(Windows only):
„
Choose a value from the Freewheel Duration
menu.
VITC and Positional Reference
VITC is a commonly used positional reference in
professional audio post-production. Since VITC
is time code information that is embedded as
part of the video signal, VITC can be read when
the VTR is paused or crawling slowly. When
working with Pro Tools, this means that VITC
can be used for Auto-Spotting regions to partic-
ular video frames.
VITC is less prone to tape drop outs, and in this
sense, is inherently more reliable than LTC.
VITC can be embedded into any video signal,
including digital video signals (tape or nonlin-
ear), without requiring an extra audio track to
carry time code.
Tape Protection Mode and VITC
In order for VITC to be read when a videotape is
paused, the picture must remain visible. How-
ever, to reduce wear on the video heads, after a
few minutes of still/pause mode, many VTRs
will automatically drop into stop mode—which
means the tape will be disengaged from the
heads, and VITC can no longer be read off the
tape. To continue reading VITC, you may need
to reengage still/pause, or press play and re-shut-
tle the tape to the desired frame.
SYNC HD accepts Freewheel duration val-
ues from 4 to 40 frames, in increments of 4
frames, but Pro Tools allows duration val-
ues from 1 to 120 frames (for MTC readers).
If you enter a Freewheel durations value
lower than 4, the SYNC HD will automati-
cally set to 4; if you enter a Freewheel value
greater than 40, SYNC HD will automati-
cally set to 40.