Specifications

Chapter 34: Synchronization Concepts 547
Rate Conversion option on the 192 I/O, to
record the audio into Pro Tools at the proper
sample rate. Or you may choose only to pull
Pro Tools up or down on delivery of the audio.
Because mistakes in pull factors can be expen-
sive, good communication with other partici-
pants in the project is critical. Find out as soon
as possible how your task relates to the rest of
the project.
Final Audio Destination: Film
If your final destination is film, your source au-
dio is at film speed, and your goal is to edit and
mix audio in Pro Tools and then lay back to a
device that runs at film speed (such as mag or
time code DAT), you can temporarily pull down
the audio in Pro Tools for NTSC video work,
then return the audio back to film speed when
you're finished (by disengaging pull down).
For example, film speed audio from a field audio
recorder that is referenced to 30 fps time code is
recorded into your Pro Tools system at a sample
rate of 44.1 or 48 kHz. Keeping in mind that
film speed is faster than video speed, select
30 fps in your Session Setup window in
Pro Tools, and record in your audio online and
referenced to the time code on the field audio
recorder.
Once all the audio has been recorded, and you
are locked to a video work print (at video speed),
enable Pull Down. If you are using a Digidesign
SYNC I/O, select Pull Down in the Session Setup
window. If your synchronizer is not a Digide-
sign product, select Pull Down on the front of
your synchronizer, then enable Pull Down in
the Pro Tools Session Setup window. At this
point, it is highly recommended that you verify
whether the video you’re working with is
striped with 29.97 Drop Frame or Non-Drop
Frame time code. While in Pull Down mode,
you can work with your reference video and ev-
erything will remain synchronized and run at
the proper speed (assuming your system is com-
pletely resolved).
Once you are ready to lay back your completed
project to an audio device running at film speed,
deselect Pull Down in the Session Setup win-
dow, and from your synchronizer if it is not a
SYNC I/O. Then change your time code frame
rate in the Pro Tools session back to 30 fps.
Once Pull Down has been deselected, the audio
played back from Pro Tools will synchronize
perfectly with the edited film.
Alternatively, you can pull down the source au-
dio deck while recording audio into Pro Tools,
work at 29.97 fps with no Pull-Down selected in
Pro Tools, and then switch to 30 Non-Drop
frame format, and select Pull Up during the de-
livery stage. You will have to perform a sample
rate conversion on the audio either digitally or
by using an analog stage (D-A-D).
Only the inputs on the Digital I/O card (on the
192 I/O) feature real-time sample rate conver-
sion.
Most “simul-dats” or “simo-dats” already
have their audio pulled down, and should
not be pulled down further.
You will also need to select the Audio Rate
Pull Up/Down option in the Session Setup
window.