ARA Audio Random Access is an extension for established plug-in standard APIs such as
VST3,
Audio Units,
AAX or CLAP 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) 2012-2024, 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
Similar to VST3, you can set ARA_CLAP_SDK_DIR to use an existing local copy of the CLAP SDK, which can be downloaded directly from the CLAP github page:
cmake -P install_CLAP.cmake
The ARA AAX integration is an optional part of the AAX SDK and not included here. The AAX SDK can be downloaded from Avid after registering with them, see Avid's developer site.
In order to provide an example with extensive UI, Celemony has created an experimental fork of the JUCE framework which contains an extended ARA demo plug-in that allows for studying ARA GUI integration both for host and plug-in developers.
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 this optional module run:
cmake -P install_JUCE_ARA.cmake
Now build and launch the Projucer found in extras/Projucer/Builds, choose Open Example > Plugins > ARAPluginDemo and export the project for your IDE of choice.