Interface types explained (VST, RTAS, AU, etc.)

The multiple interface types are a result of ongoing efforts in the industry to create standards that utilise the capabilities of either Digital Audio Workstations (or DAWs – the host platformst for plugins) or hardware.

By interface we mean a way for a plugin to communicate with its host. Metaphorically you can look at it as a plug and a socket – both have to fit together. Just like a 1/4" jack and the respective socket (used in mixers, instrument ins/outs, etc).

The most common interface types that you'll find on PluginBoutique are:

  • Native PC (or Native Windows) - This means all interface types supported by Windows-based music platforms. This includes VST (and VSTi, which is simply a VST instrument) RTAS and DX.
  • Native Mac - This covers all interface types supported by OSX-based music platforms - VST, AudioUnits and RTAS.

By "Native" we mean an interface technology whereby all DSP Processing is done by the host computer's CPU, as opposed to outboard gear.

The individual interface technologies used are:

  • VST (Virtual Studio Technology) – Introduced by Steinberg in 1996 in Cubase ver. 3.02. It is the most known interface type for effects and instruments. As of today VST has evolved into its 3rd version and is commonly referred to as VST3. You may also come across VSTi which simply stands for VST Instrument – it does not have any different the technical requirements, however. VST is the most widely implemented standard in the industry and is supported by (this list is not exhaustive): Ableton Live, Acid PRO, Cubase, Nuendo, FL Studio, Samplitude or Sonar. More on VST on Wikipedia.
  • AU (AudioUnits) – Apple’s proprietary audio technology, part of the Core Audio provided by Mac X OS. It is part of the operating system so it provides low latency and system-level support for the interface. Most DAWs developed for the Macs support the AudioUnits interface due to its stability and system-level solutions (which also means faster processing). Ableton Live, Logic Pro, Cubase, Garage Band, Presonus Studio One and many others. More on AudioUnits on Wikipedia
  • RTAS (Real-Time Audio Suite) – implemtned in ProTools series by Digidesign. Many plugin manufacturers develop RTAS versions of their plugins for the sake of compatibility with the ProTools series of DAWs. RTAS plugins can only be used in the ProTools system. More on RTAS on Wikipedia
  • TDM (Time-division Multiplexing) – a version of ProTools plugins which are installed on outboard hardware such as dedicated DSP Processors for ultra-high precision and quality. TDM Plugins are usually installed in high-quality studio setups equipped with dedicated chips that process the audio signal – as opposed to having all processing done natively by the computer’s CPU.

Additionally in our offer you will find interface types that may not sound like real interfaces. This is what they stand for:

  • Standalone – These are applications that can be used without a host OR are host applications themselves. This category covers all DAWS as well as software that can run on its own, without the host.
  • Any – These are products that are not assigned to any particular interface type. A typical example of this are Preset Banks that work with a particular application – whether it’s a synth, sampler, groovebox or effects unit. The “ANY” interface simply matches the interface of the application it is made for. If a Synth works under VST, RTAS and AU interfaces then the presets will also work in the same environment.

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