ARA Audio Random Access is an extension for established plug-in standard APIs such as
VST3 and
Audio Units to allow for a
much-improved DAW integration of plug-ins like Celemony's Melodyne which are conceptually
closer to a sample editor than to a conventional realtime audio processor.
It enables plug-ins to read audio samples from the DAW host at will, allowing them to implement more
sophisticated processing algorithms not possible when being tied to individual realtime buffers.
ARA further defines bi-directional exchange of audio content information such as tempo, keys and scales
between plug-in and host, upon which both host and plug-ins can build numerous advanced editing features.
This Software Development Kit allows digital audio workstation (DAW) plug-in and host developers to implement and utilize ARA enabled plug-ins. It is copyright (c) 2012-2022, Celemony Software GmbH, and published under the Apache License, Version 2.0.
Any public release of ARA-enabled software should be based on a tagged public release of the ARA API. If temporarily using HEAD to study current work-in-progress, keep in mind that in order to achieve a concise long-term change history, any changes since the last tagged release may eventually be rebased.
The ARA SDK consists of three components which are distributed as individual Git submodules so that dependent projects can pick only those parts of the SDK that are needed in their context. After cloning this top level module, you need to fetch these submodules, e.g. by running:
git submodule update --init --recursive
The ARA_API module contains the core headers that define the actual ARA C API.
ARAInterface.h is the main header, accompanied by a set of auxiliary headers for integrating ARA with
each of the supported Companion APIs like VST3 or Audio Units. Additionally, ARA Audio File Chunks
are defined in ARAAudioFileChunks.h.
It includes extensive printer-friendly documentation.
The ARA_Library module wraps the low-level ARA C API with extensive C++11 classes and provides
additional utility code that aides developers when implementing ARA-enabled products.
It includes extensive browser-friendly documentation.
The ARA_Examples module contains various sample code demonstrating how to both implement and host
ARA enabled plug-ins. For details on building and running the examples, see their accompanying
README.
Note that some of the examples rely on external dependencies, see separate
3rd party README.
Building ARA-enabled products relies on using at least one of the various established plug-in standard APIs as "Companion API" to ARA. Note that each of the Companion APIs comes with its own specific licensing conditions, as detailed in each SDK - some of these terms differ substantially from ARA's licensing conditions. The Companion APIs are therefore not installed automatically. However where applicable, optional install scripts for these SDKs are provided as convenience. Per default, these scripts will place the SDKs inside the ARA SDK folder, but this can be overridden by specifying alternate locations for each SDK, e.g. for VST3 by adding the argument:
-D ARA_VST3_SDK_DIR:PATH="your/path/to/vst3sdk"
You can set the variable ARA_VST3_SDK_DIR to an already existing local copy of the Steinberg VST3 SDK when generating the ARA example projects. Alternatively, a subset of the VST3 SDK sufficient for building the ARA examples can be fetched from GitHub via:
cmake -P install_vst3sdk.cmake
Similar to VST3, you can set ARA_AUDIO_UNIT_SDK_DIR to use an existing local copy of Apple's Audio Unit SDK (former Core Audio Utility Classes). They can also be downloaded directly from the Apple github page:
cmake -P install_AudioUnitSDK.cmake
To use AAX, set the variable ARA_AAX_SDK_DIR to your local copy of the AAX SDK when generating the ARA example projects. The AAX SDK is not publicly available so there is no install script for it. Instead, it must be manually downloaded from Avid after registering with them.
In order to provide an example with extensive UI, Celemony has created an experimental fork of the JUCE framework which contains an ARA demo plug-in that allows for studying ARA GUI integration both for host and plug-in developers. Plug-in developers already using JUCE will find this fork particularly interesting because it drafts a potential ARA integration into JUCE that may be used for other plug-ins.
Note that like some of the Companion APIs, JUCE imposes very different licensing conditions than the ARA SDK itself, see its included documentation.
To download and build this optional module run:
cmake -P install_JUCE_ARA.cmake
cmake "JUCE_ARA/examples/Plugins/ARAPluginDemo" -D JUCE_GLOBAL_ARA_SDK_PATH:PATH="." -B "JUCE_ARA/cmake-build" -G <desired generator for your development environment>