New Audio Plugin Standard, CLAP, offers Open Source alternative to VST and AU


Bitwig and u-he have announced new CLAP (CLever Audio Plug-in API), the new open standard for audio plug-ins and hosts.


Over the years, VST and AU have been the big two plugin standards that developers have adhered to. Now, is the writing on the wall for VST and AU


The ‘CLever Audio Plug-in API’ is described as a new open standard for audio plugins and hosts, and promises modern features, innate stability and rapid support for developers. And, because it’s open-source, there are no barriers to entry for developers.


Here’s are the benefits that the developers highlight:


Better Performance From Modern CPUs- CLAP offers several advantages in comparison to existing plugin standards, starting with better performance from modern CPUs. It promises to “take multi-thread management to a new level, with clear and efficient allocation of roles between plugin and host”. Preliminary tests are reported to show significant performance gains.


Better and Faster Organization – CLAP hosts can read plugin metadata and retrieve information from them without waiting for them to initialise, so scans should be faster.


Bitwig and u-he are also working on an extension which will enable plugins to tell the host which files they need (samples, wavetables, etc), so that these can be consolidated into the project file. This should make transferring projects between systems simpler and more reliable.


Better Modulation- There are also benefits for automation, modulation and expression. In accordance with the MIDI 2.0 spec, there’s per-note automation and modulation, while the non-destructive parameter modulation concept means that, as soon as modulation has finished, the target parameter will return to its original state.


In addition, polyphonic plugins can have their per-voice parameters modulated for individual notes – something that Bitwig and u-he describe as “MPE on steroids”.


Initial implementations by Bitwig, u-he and the Surge project demonstrate CLAP’s possibilities.


Information for Plug-In and Host Developers


The CLAP creators tout many benefits for plug-in and host developers:


“From the C-only ABI, which allows binding to any programming language, to the transparent client-server model between host and plug-in, the robustness and clarity of the threading model, and the single event queue for all kinds of parameter changes, timing and MIDI. Despite being so comprehensive, everything in CLAP is easy to find and easy to implement.


A single cpp/hpp glue layer for C++ offers a quick start into the ABI, and its built-in “proxy layer” finds common threading bugs in an instant. Apropos C-only ABI: There are no platform specific dependencies: In theory CLAP should also run well on embedded platforms, game consoles or specialized supercomputers.”


Open Source & Liberal License- CLAP is open source, released under the MIT license: No fees, memberships or proprietary license agreements are required before developing or distributing a CLAP capable host or plug-in, and the license never expires.


In a nutshell, there are no entry hurdles for developers, and plenty of open source projects already benefit from CLAP.


CLAP is available now via Github.


MIDI Just Works – CLAP is designed to be future-proof; although it’s inspired by MPE and MIDI 2.0, it can adapt to any future MIDI standard.


Extensibility & Governance- Companies can also develop their own proprietary extensions for specific features if they need to.


In short, this looks like a serious bid to disrupt the plugin landscape. CLAP 1.0 has been in development for several years, and it’s already being evaluated by the likes of Arturia, Avid, BespokeSynth, CableGuys, Expressive E, FabFilter, Image-Line, Oddsound, PreSonus, Valhalla DSP and Xfer Records.


This isn’t just a theoretical standard, either: CLAP is supported in the beta version of Bitwig Studio and the CLAP beta versions of u-he’s ACE, Diva, Hive 2 and MFM2.5.


Open Source Projects Using CLAP:

Avendish project

CLAP JUCE Extensions project


MIP2 framework

nih-plug framework

TheWaveWarden (Odin2)

For latest updates, example code and information are available at the CLAP Github page.


More details are also available on the Bitwig website.






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