User manual

496
Synchronization
Clock sources (speed references)
Once the position is established, the next essential factor
for synchronization is the playback speed. Once two de-
vices start playing from the same position, they must run at
exactly the same speed in order to remain in sync. There
-
fore, a single speed reference must be used and all devices
in the system must follow that reference. With digital audio,
the speed is determined by the audio clock rate. With
video, the speed is determined by the video sync signal.
Audio clock
Audio clock signals run at the speed of the sample rate
used by a digital audio device and are transmitted in sev
-
eral ways:
Word clock
Word clock is a dedicated signal running at the current
sample rate that is fed over BNC coaxial cables between
devices. It is the most reliable form of audio clock and is
relatively easy to connect and use.
AES/SPDIF Digital Audio
An audio clock source is embedded within AES and SPDIF
digital audio signals. This clock source can be used as a
speed reference. Preferably, the signal itself does not con-
tain any actual audio (digital black), but any digital audio
source can be used if necessary.
ADAT Lightpipe
ADAT Lightpipe, the 8-channel digital audio protocol de-
veloped by Alesis, also contains audio clock and can be
used as a speed reference. It is transmitted via optical ca-
bles between devices.
Ö Do not confuse the audio clock embedded in the
Lightpipe protocol with ADAT Sync, which has timecode
and machine control running over a proprietary DIN plug
connection.
MIDI clock
MIDI clock is a signal that uses position and timing data
based on musical bars and beats to determine location
and speed (tempo). It can perform the same function as a
positional reference and a speed reference for other MIDI
devices. Cubase supports sending MIDI clock to external
devices but cannot slave to incoming MIDI clock.
The Project Synchronization Setup
dialog
Cubase’s Project Synchronization Setup dialog provides a
central place to configure a complex synchronized system.
In addition to settings for timecode sources and machine
control settings, project setup parameters are available
along with basic transport controls for testing the system.
To open the Project Synchronization Setup dialog, pro-
ceed as follows:
• On the Transport menu, select the “Project Synchroni-
zation Setup…” option.
• On the Transport panel, [Ctrl]/[Command]-click the
Sync button.
The dialog is organized into sections separating related
groups of settings. The arrows shown between the vari
-
ous sections of the dialog indicate how settings in one
section influence settings in another section. In the follow
-
ing, the available sections are described in detail.
The Cubase section
At the center of the Project Synchronization Setup dialog
is the Cubase section. It is provided to help you visualize
the role that Cubase takes in your setup. It shows which
external signals enter or leave the application.
!
MIDI clock cannot be used to synchronize digital au-
dio. It is only used for MIDI devices to play in musical
sync with one another. Cubase does not support be-
ing a MIDI clock slave.