User manual

Table Of Contents
650
Synchronization
Background
What is synchronization?
Synchronization is the process of getting two or more devices to play back together at
the same exact speed and position. These devices can range from audio and video
tape machines to digital audio workstations, MIDI sequencers, synchronization
controllers, and digital video devices.
Synchronization basics
There are three basic components of audio/visual synchronization: position, speed,
and phase. If these parameters are known for a particular device (the master), then a
second device (the slave) can have its speed and position “resolved” to the first in
order to have the two devices play in perfect sync with one another.
Position
The position of a device is represented by either samples (audio word clock), video
frames (timecode), or musical bars and beats (MIDI clock).
Speed
The speed of a device is measured either by the frame rate of the timecode, the
sample rate (audio word clock) or by the tempo of the MIDI clock (bars and beats).
Phase
Phase is the alignment of the position and speed components to each other. In other
words, each pulse of the speed component should be aligned with each
measurement of the position for the most accuracy. Each frame of timecode should
be perfectly lined up with the correct sample of audio. Put simply, phase is the very
precise position of a synchronized device relative to the master (sample accuracy).
Machine control
When two or more devices are synchronized, the question remains: how do we
control the entire system? We need to be able to locate to any position, play, record,
and even jog and scrub the entire system using one set of controls.
Machine control is an integral part of any synchronization setup. In many cases, the
device simply called “the master” will control the whole system. However, the term
“master” can also refer to the device that is generating the position and speed
references. Care must be taken to differentiate between the two.