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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).
Master and slave
In this document, the following terms are used:
• The “timecode master” is the device generating position information or
timecode.