Apple Logic Pro 8 - Manual (Page 837)

Chapter 36 Synchronizing Logic Pro 837
Audio Sync Mode
This is where you define how each individual piece of audio hardware should be
synchronized to an external time code master.
Not all audio hardware can work in every sync mode described below. This is
particularly dependent on whether or not the hardware’s sample rate can be
controlled.
There are two pop-up menus available, for Core Audio and DAE/TDM hardware. Use
one or both, as applicable to the hardware installed on your system. You can choose
the following options:
 MTC Continuous (default): Audio regions are started in sync, and the sample rate is
continuously regulated to match variations in the time code master signal. Even very
long audio regions stay in sync in this mode.
 MTC Trigger + Auto Speed Detection: Similar to MTC Trigger (see below), but the
tempo of the time code master is constantly monitored while Logic Pro is running.
The next time you start Logic Pro, it will use an adapted sample rate. This mode
keeps long regions in better sync with the time code master, although not as closely
as MTC Continuous. It does, however, use a constant sample rate, which is not
affected by variations in the time code master signal.
 MTC Trigger: Audio regions are started in sync, but are then played at a constant
sample rate, regardless of any variations in the time code master signal. Logic Pro
always uses the set nominal sample rate (44.1, 48, 88.2, 96, 192 kHz). This mode is
suitable when it is vital to retain the absolute pitch of a recording. If the speed of the
time code master deviates from the nominal value, you may need to split long audio
regions into shorter sections.
 External or Free: Logic Pro has no influence on the sample rate. The audio hardware is
responsible for ensuring that the position and sample rate of audio regions match.
This mode is only advisable if you are sure that the Word Clock and time code master
are running in sync—by using an external SMPTE or Word Clock synchronizer, for
example.
 Digital: Similar to External or Free, but the DAE/TDM hardware is also set up to
synchronize to the sample rate of the incoming digital signal.
 SSD/VSD Type: Exactly the same as Digital, but a SMPTE Slave Driver (SSD) or Video
Slave Driver (VSD) is used in addition—to synchronize with the sample and frame
rates used in Logic Pro. The SMPTE slave driver is a device which synchronizes Pro
Tools hardware to incoming time code or word clock signals.