THIS FROM STEINBERG ABOUT VST3:
Managing large plug-in sets and multiple virtual instruments on typical studio computer systems can often be difficult because of CPU performance limits. VST3 helps to improve overall performance by applying processing to plug-ins only when audio signals are present on their respective inputs. Instead of always processing input signals, VST3 plug-ins can apply their processing economically and only when it is needed.
A typical issue with current virtual instruments is their audio output bussing system and how they’re connected to the mixer after loading. Especially virtual samplers with multiple outputs often occupy more mixer channels than need. The VST3 interface offers the possibility to deactivate unused busses after loading and even reactivate those when needed. This cleans up the mixer and further helps to reduce CPU load.
VST3 also features vastly improved parameter automation with sample accuracy and support for ‘ramped’ automation data, allowing completely accurate and rapid parameter automation changes.
Optional VST3/SKI combination
As a direct result of the modular interface design of VST3, the Steinberg Kernel Interface (SKI) can be combined with VST3 plug-ins. SKI is an additional SDK that allows extremely close integration of a plug-in with a Steinberg host application, and allows functions to be carried out almost from within the application. This extends to the ability to create tracks, copy, cut, paste or process events in the Steinberg host application. SKI is provided to selected industry partners upon request.
UTF16 for localized parameter naming
In VST3, all strings that can be displayed to the user are in Unicode (UTF16) format. Usage of this universal character base allows the host application to display characters in localized languages.
Multiple dynamic I/Os
VST3 plug-ins are no longer limited to a fixed number of inputs and outputs. Their I/O configuration can dynamically adapt to the channel configuration they’re inserted in, meaning that any VST3 plug-in can be surround-capable with true multi-channel processing. For example, all the new VST3 plug-ins in Nuendo 4 can work in stereo-mode when inserted into a stereo channel, but switch to 6 channels when inserted into a 5.1 channel. Each audio channel is processed independently. Interaction between channels depends on the type and design of the plug-in. In addition to their flexible audio bussing capabilities, VST3 plug-ins may also offer a dedicated event bus. Typically, this is a MIDI input for control/modulation but these busses are no longer restricted to MIDI standard only. Future plug-ins may replace the common MIDI interface with alternative methods of control.
Resizable edit windows
VST3 introduces a new approach to plug-in GUIs though window resizing, allowing for extremely flexible use of valuable screen space
Logical parameter organization
The plug-in parameters are displayed in a tree structure. Parameters are grouped into sections which represent the structure of the plug-in. Parameters like “Cutoff” and “Resonance” could be grouped into a section called “Filter”. This makes searching for a certain parameters easier, such as on an automation track. This also allows assigning a group of parameters to a specific MIDI Channel input and audio output bus.
VSTXML for remote controllers
Remote controllers for audio and MIDI software applications have become increasingly popular. With VSTXML, VST3 offers far more flexible control of VST plug-ins by remote controllers. Using the knobs and faders on the control surface, parameters can be recorded, renamed and edited in many ways. Parameters that cannot be edited can be routed for display purposes to the control surface, for example to show Gain Reduction on compressor.
No MIDI restriction for parameter value transfers
VST3 has a dedicated interface for event handling that carries a much wider range of functionality than standard MIDI events would be able to provide. This opens up a big range of opportunities for musical use cases with very high potential for innovative product design. For example with VST3 some controller events (for example, pitch) can be referred to a note event (using a note unique ID). This offers the possibility to e.g. modulate only a single note which itself is part of a chord.
Multiple MIDI inputs/outputs
Unlike with VST 2.x, a VST3 plug-in can have more than only one MIDI input or one MIDI output at the same time.
I would assess there are many advantages if all this holds true. — Corky