What Is It?
Audio Random Access (commonly abbreviated to ARA) is an extension for audio plug-in interfaces, such as AU, VST and RTAS, allowing them to exchange a greater amount of information with digital audio workstation (DAW) software. It was developed in a collaboration between Celemony Software and PreSonus.
The overwhelming majority of audio plug-ins have no need for ARA. It's used by applications such as Melodyne that are both stand alone audio programs / editors and also plug-ins to improve the plug-in workflow.
What Does It Do?
ARA increases the amount of communication possible between DAW software and a plug-in, allowing them to exchange important information, such as audio data, tempo, pitch, and rhythm, for an entire song, rather than just at the moment of playback.
This increased amount of information exchange, and availability of data from other points in time, removes the need for audio material to be transferred to & from the plug-in, allowing that plug-in to be used as a more closely integrated part of the DAW's overall interface.
ARA gives the plug-in access to:
entire audio files and regions
tempo map
bar/beat positions
edit boundaries
playback state
non-realtime analysis
How Is It Used?
A plug-in that supports ARA is inserted directly onto an audio event, which is known as Event FX in Studio One and Studio Pro. This is because the ARA data model operates on regions of audio on the timeline, not on continuous audio streams like traditional insert plug-ins.
Any audio plug-in inserted directly on an audio event (whether ARA-enabled or not), is processed before the track’s channel inserts. The only exception is other plug-ins placed earlier in the same Event FX chain, which will process the audio before it.
Please remember that ARA does not process audio. It only provides a mechanism for a plug-in to access and analyze audio data directly from the DAW. Signal processing is performed by the plug-in (for example Melodyne) while ARA manages the communication and data access.
The distinction is essentially implementation vs. protocol.
- ARA = the communication protocol / API specification.
- Melodyne ARA = A plug-in using that protocol to perform audio analysis and editing.
We hope that article helps to avoid any confusion for new users.