Specifications
Chapter 35: Working with Synchronization 573
Troubleshooting
Synchronization
Getting SMPTE synchronization to work prop-
erly can seem like a formidable task at times.
The following suggestions may help you trou-
bleshoot and solve common problems.
Use the Incoming/Current Time Field in the
Session Setup Window as a Reference
The Current Time field in the Session Setup win-
dow indicates whether or not Pro Tools is receiv-
ing time code. If this field appears to be inactive
when inputting time code into your time code
reading device, check your hardware device set-
tings, the device’s connection to your computer,
and your OMS Setup (Mac OS 9) or Multimedia
Setup (Windows).
Stripe SMPTE Before You Record
All tapes in your setup (both audio and video)
must be striped with SMPTE Time Code before
any audio is recorded onto them or to Pro Tools.
If tapes aren’t striped, your system may seem to
work, but synchronization will never properly
occur. The machines and Pro Tools will drift far-
ther and farther apart the longer they run.
The same problem occurs when audio is re-
corded into Pro Tools without a resolved SMPTE
source (for example, if it was recorded before the
current session). The audio cannot be accurately
synchronized with an analog tape recorder or
video tape deck, since the Pro Tools audio was
not recorded referenced to the SMPTE time code
from the analog tape deck or video tape deck.
Resolve All Components of Your System
When striping time code, make sure that the
time code generator and the video record deck
are resolved to the same crystal reference. For
example, when striping 29.97 Drop Frame time
code onto a VTR, both the SMPTE generator and
the VTR should be resolved to the same “black
burst” or house sync generator. During play-
back, the master deck should be resolved to
“black burst” or house sync.
This convention provides compatibility for your
tape between the record and playback passes,
and when it’s played back in other facilities on
different equipment. This also means that when
playing back a tape striped with time code, the
playback deck should be resolved to the same
synchronization rate as the record deck was re-
solved to at the time of the striping. When you
stripe time code using an audio transport, it
should be “free-running” and unresolved, but
should be resolved with a house sync-referenced
synchronizer during playback.
Know the True Frame Rate on Your Work Tape
If you get your video tapes from a production
company instead of recording them yourself, be
absolutely sure that they indicate the SMPTE
frame rate used on the tape correctly. Several
time code formats use the same frame count
(such as 23.976 fps and 24 fps) yet they run at
slightly different frame rates per second.
The Digidesign SYNC I/O (and some third-party
products) can be used to help determine frame
rate. See “Determining SMPTE Frame Rate” on
page 556.
When using MachineControl, the Current
Time field will display 9pin code, even
though the LTC device may not be con-
nected.