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If you now set the MIDI Sync Reference setting in the Audio System dialog to

Time Code, and Cubase VST receives time code, it will vary its overall playback

speed (the “song position speed”) to compensate for such ﬂuctuations in the speed

of the time code, that’s the whole purpose of synchronization.

What happens with the Digital Audio?

The fact that Cubase VST’s playback is synchronized to the time code does not af-

fect the playback of the digital audio. It still relies on the perfectly stable, built-in

clock in the audio hardware.

As you may understand by now, problems will appear when the perfectly stable

digital audio gets related to the slightly varying speed of a system synchronized to

time code.

The playback timing of each segment will not be in total accordance with the tape

or the MIDI playback, since the playback speed of the audio is determined by the

digital audio hardware’s built-in clock.

So, what can I do about it?

There are generally two methods that solve the problem, and a few others that min-

imize the problem to an acceptable level without actually solving it.

Resolving

The ﬁrst – and best – solution is to use one external clock for all components in the

system. One master clock is used to derive whatever type of clock signal each com-

ponent in the system needs. For example, something called a house clock can be

used to generate sample rate clocks for the digital audio hardware and time code for

Cubase VST. This ensures all components in the system use the same reference

source for their timing.

Synchronizing digital audio to external clocks running at sample rate is often called

“resolving” or “synchronizing to word clock”.

However this option is not available on standard PC audio cards. It might be possi-

ble to do on more advanced audio hardware, but even then it requires additional,

fairly expensive synchronizing hardware.

Continuous Resynchronization

Some systems use digital signal processing techniques to simulate variations in

playback speed. In a typical such situation you feed the digital audio hardware time

code (or MIDI Time Code) and it uses this to calculate in what way it should adjust

the playback speed to stay in sync with the time code (and hence with Cubase

VST). This method is often called “continuous resync”.

Cubase VST Solutions

The third solution is offered by Cubase VST, and comprises a set of tools and strat-

egies to minimise the problems without the need of additional hardware, and with-

out compromising audio quality. These solutions are described in the following

paragraphs:

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VST OneTrack Spezifikationen Seite 456