Ok here's a beautiful run down of Basically everything I just asked about... This was all taken from :
http://www.tweakheadz.com/software_plugins.htm
There are 3 basic software devices that work in the software realm of the digital audio sequencer. They are: Soft Synths, Soft Samplers and Software Processors. This article chats about all three in general to get you grounded. Then we'll devote a class on each of them specifically. We'll also talk about Rewire applications here as they often contain softsynths, samplers and processors.
All 3 of these categories are sometimes referred to as "plugins". They are called that because these are little computer applications that run inside a "host" application, i.e., a sequencer, typically. These plugin devices are very important, as they have led the software revolution towards our virtual studios which is changing all recording studios, both home and pro. Today there are few hardware devices left that cannot be emulated by plugins and software. As you see from this page, software based synthesizers, effects processors, samplers and multi-track recorders can all work together on one single computer.
But how well can these devices work together? Aha! You are thinking! Good! That is a matter of utmost critical importance. There's a lot of toys in the toybox, but a lot of them will not play well together, if at all. Ok, now remember this: Bad Plugins Crash Sequencers. This is one reason to avoid free plugins. I have used nearly every sequencer out there and can affirm that over half the reasons for instable, flaky operations is due to a poorly written plugins. You really have to be careful. If you are having stability problems with any sequencer always check the soundcard driver and the plugins installed. Even expensive plugins are often released full of bugs and fixed "eventually" as users complain. Never trust stuff that was released last week or stuff that has not had an update in a few years. Plugins typically break when upgraded operating systems are released. So keep an eye on these things and talk to actual users that use your platform and sequencer and get their take on stability.
But I digress; let's get back to the topic. Each sequencer has its favored protocol, and may refuse to work with the rest. Cubase Sonar, Logic, Pro Tools LE and Digital Performer all want plugins to follow defined rules, which we will call plugin formats.
Formats: VSTi, DXi, RTAS, MAS, AU and Rewire
Here it is plain and simple.
VSTi (virtual studio technology instrument) was developed by Steinberg as a Universal platform for soft synths and samplers. Not all the companies bought into it. Cubase and Nuendo use it extensively. You may also hear about VST2 and VSTi2 plugins. VST2 is simply an extension of the VST format. These pass on more parameters to the host for automation.
Are PC VSTs and VSTi compatible on Macs? Always assume the answer is no unless the developer makes it clear. If they made a Mac version, they will be sure to list that. Usually, developers will have a PC VSTi version and a Mac VSTi version, so be careful to get (and install) the right one. Usually, these days they are both on the same cd rom.
DXi: Cakewalk, initially, did not go with VSTi, it went with DXi, which is based on Microsoft direct X code. Today, however, they have relented an allow use of VSTis with Sonar in a shell. DXi's cannot be run on Macs.
Ok by now you may be wondering what this "i" business is. You see VST, then VSTi, then DX and DXi. The "i" stands for "instrument", like a softsynth or sampler to distinguish it from a plugin processor, like a compressor, reverb or delay.
AU, short for Audio Units, refers to a format developed by Apple for Mac OS 10.x Because there is support in Apple's operating system, AU is used by many Mac sequencers and audio applications, and is the major supported format in LogicPro.
Important note: Just because Logic favors AU does not mean it will run all Audio Unit Plugins. As of Logic 7, Apple got stricter. Logic only supports AUs that follow Apple's guidelines and not all of them do. This is Apple's way of forcing plugin developers to follow the rules it developed. Its a good thing, as the Audio Units that do pass are less likely to crash Logic.
MAS refers to plugins that work with the MOTU Audio System in Digital Performer (Mac only), which can also use VSTi, AU and ReWire. You'll note that fewer plugins support MAS, and that's because MOTU DP users can use AU as well as MAS.
RTAS is the format used by Digidesign, the maker of Pro Tools LE, which comes bundled with the popular Digi 002 interface. RTAS will also work in Pro Tools M-Powered, which works with M-audio interfaces. RTAS plugins, however, will not work in Logic, Cubase or Sonar.
Audiosuite is another Digidesign format which works with the above software packages and hardware interfaces.
Rewire, finally, is a scheme that pipes digital audio from Reason and Rebirth, Project 5 and Ableton's Live to other sequencers. It basically allows you to run a sequencer inside of a another sequencer. Its not a plugin per se, but because many soft synths use Rewire I include it here.
Q) What is a Plugin Wrapper
A) A plugin wrapper usually refers to a software device that fools a host (i.e., the sequencer) into using formats that would be incompatible without it. For example, in a VSTi to DXi shell you can run VSTis and the sequencer will treat them as DXis. Through the use of wrappers, Sonar users can use VSTis and Logic Users can use VSTis. Without a wrapper, Logic can only use AUs and Sonar (up to version 4) can only use DXis and Pro Tools LE not use VSTs.
There are some disadvantages to using wrappers. If the wrapper does not convert and pass on the data perfectly, there could be problems. Remember: Bad plugins crash sequencers. Right? Right!
