PreSonus Blog

The new ARA audio plug-in standard

Audio Random Access, or ARA, is an extension to existing plug-in models like VST 3, VST 2, and Audio Units.

When we planned the PreSonus Studio One 2 release cycle, one of the features that we discussed was pitch editing, a function that many users need to fix errors in a performance. Some competing applications have pitch editing built in, but in a limited way, lacking access to details like vibrato. We considered building a solution using technology supplied by zPlane, who make the timestretch engine built into Studio One, but it would have been a very labor-intensive project.

Celemony’s Melodyne
seemed to be the best solution for graphical pitch editing, so we looked at the reasons a user would want an integrated solution instead of using the Melodyne VST plug-in. It turned out that a number of workflow issues made the VST plug-in inconvenient to use, but these issues could be solved by a collaboration between Celemony and PreSonus. We proposed to Celemony an extension of existing audio plug-in APIs that would give them the required additional access to the host audio data.

The major workflow issues we identified were these:

  1. The Melodyne VST plug-in uses a recording process to transfer the audio that is to be edited in Melodyne. But with ARA technology, Melodyne now has direct access to the audio data via the ARA interface, so that the user does not have to record manually.
  2. Once the audio was transferred to the Melodyne VST plug-in, there was no way to arrange the material, as Melodyne did not have any notion of what an audio event in the application was. Now, with, ARA Melodyne “knows” that an audio event is being edited, and because the Melodyne editing data travels with the audio event, the user can still freely edit the data.
  3. To free the processing power that a plug-in like Melodyne needs to do its tricks, the user had to “freeze” the material. At that point, the editing data was lost, and the user could not go back to make changes. Now, in Studio One, you can just freeze an event-based effect such as Melodyne to free the processing power. This freeze is reversible, so you can simply go back to the real-time processing and continue editing.

Our solution fixes all of these issues and gives us options to use additional capabilities of Melodyne and similar plug-ins in the future. For instance, Melodyne has the ability to extract a tempo curve from the audio material, which could be used.

If you want to see ARA in action, click here.

ARA will be licensed to other interested plug-in vendors in the future, free of charge. Companies interested in using the API should contact Celemony.

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