User`s guide

Chapter 24: Time Code Synchronization 341
either 16-bit Optimized or 24-bit Opti-
mized. “CPU Mixer” is displayed in this
field on a Pro Tools LE system.
Ch 1-2 Input
(TDM Systems Only)
This allows you to choose an audio input
format (analog or digital) for channels 1
and 2 of your master Audio Interface.
Sync Mode
This allows you to choose the clock mode
for your master Audio Interface, Audiome-
dia III card, or Digi 001. Choices are Inter-
nal or Digital on an Audio Interface or Au-
diomedia III card, and Internal, Optical, or
S/PDIF (RCA) on the Digi 001.
Internal Sync Mode In internal sync mode,
your system will reference your Digidesign
card or peripheral’s quartz crystal oscillator
and play back at the sample rate selected in
the Sample Rate field.
Digital Sync Mode (including Optical and
S/PDIF on Digi 001)
In digital sync mode,
your system’s sample rate is adjusted to
match the sample rate received from the se-
lected digital peripheral. In digital sync
mode, your Pro Tools sync rate must match
the rate received by your digital peripheral.
Incorrectly set peripheral devices will result
in incorrect playback speeds when your
system is set back to internal sync mode.
With TDM systems, the Session Setup win-
dow provides a source link feature that tog-
gles the sync mode of your audio interface
when you switch your input source from
analog to digital. This helps to ensure that
the clock source for your system will match
the digital input source when you are
working.
You can override this toggled behavior by
changing the pop-ups to the opposite
choice. For example, if you are using a mas-
ter AES/EBU null clock or video black burst
signal source as the master sync source for
all digital audio devices in your studio
setup, your Sync Mode pop-up should be
set to digital at all times. In this case,
Pro Tools uses this master sync source as a
reference.
Session Start
This allows you to specify a SMPTE start
frame location for your session. The SMPTE
value that you enter here will be used to
trigger playback and record when Pro Tools
is online. See “Setting a SMPTE Start
Frame” on page 344.
Current Time
This displays incoming time code.
Frame Rate
This allows you to set the SMPTE frame rate
for the current session.
Generate Time Code
This allows Pro Tools to output time code
using a USD (communicating directly via a
serial port), or using a SSD (communicating
via a serial port or using MIDI sys-ex via a
designated OMS destination port). Gener-
ating time code is covered in the section
“Generating Time Code” on page 347.