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Synchronization
The only exception to this procedure is if you are using an
external clock – from a digital mixing desk or a special
word clock synchronizer, for example. In that case you
must leave all your ASIO cards in clock slave or AutoSync
mode and make sure that each of them is listening for the
signal coming from the synchronizer. This signal is usually
passed through your ADAT cables or word clock connec
-
tors in a daisy chain fashion.
VST System Link and latency
The general definition of latency is the amount of time it
takes any system to respond to whatever messages are
sent to it. For example, if your system’s latency is high and
you play VST instruments in realtime, you will get a notice
-
able delay between when you press a key and when you
hear the sound of the VST instrument. Nowadays, most
ASIO-compatible audio cards are capable of operating
with very low latencies. Also, all VST applications are de
-
signed to compensate for latency during playback, making
the playback timing tight.
However, the latency time of a VST System Link network
is the total latency of all the ASIO cards in the system
added together. Therefore it is extra important to minimize
the latency times for each computer in the network.
Ö The latency does not affect the synchronization – it is
always perfectly in time. But it can affect the time it takes
to send and receive MIDI and audio signals, or make the
system seem sluggish.
To adjust the latency of a system, you adjust the size of the
buffers in the ASIO control panel – the lower the buffer
size, the lower the latency. It is best to keep to fairly low la-
tencies (buffer sizes) if your system can handle it – about
12 ms or less is usually a good idea.
Setting up your software
Now it is time to set up your programs. The procedures
below describe how to set things up in Cubase. If you are
using another program on the other computer, please re
-
fer to its documentation.
Setting the sample rate
The projects in both programs must be set to use the
same sample rate. Select “Project Setup…” from the Proj-
ect menu and make sure that the sample rate is the same
in both systems.
Streaming digital audio between applications
1. Create input and output busses in both applications
and route these to the digital inputs and outputs.
The number and configuration of the busses depend on your audio hard-
ware and on your needs. If you have a system with eight digital i/o chan-
nels (such as an ADAT connection), you could create several stereo or
mono busses, a surround bus together with a stereo bus, or any combi
-
nation you need. The important thing is that you should have the same
configuration in both applications – if you have four stereo output busses
on computer 1, you want four stereo input busses on computer 2, etc.
2. Set things up so that computer 1 plays back some
audio.
For example, you could import an audio file and play it back in Cycle
mode.
3. In the Inspector or Mixer, make sure that the channel
containing the audio material is routed to one of the digital
output busses.
4. On computer 2, open the Mixer and locate the corre-
sponding digital input bus.
The audio being played back should now “appear” in the program run-
ning on computer 2. You should see the input bus level meters moving.
5. Reverse this procedure so that computer 2 plays back
and computer 1 “listens”.
Now you have verified that the digital connection works as
it should.
Ö From this point on in this chapter, we refer to the bus-
ses connected to the digital inputs and outputs as “VST
System Link busses”.
Settings for the audio hardware
When you exchange VST System Link data between com-
puters, it is important that the digital information is not
changed in any way between the programs. Therefore,
you should open the control panel (or additional applica
-
tion) for your audio hardware and make sure that the fol-
lowing conditions are met:
• If there are additional “format settings” for the digital
ports that you use for VST System Link data, make sure
that these are turned off.
For example, if you are using an S/PDIF connection for VST System Link,
make sure that “Professional format”, Emphasis, and Dithering are turned
off.