nih-plug/BREAKING_CHANGES.md

Breaking changes

Since there is no stable release yet, there is also no proper changelog yet. But since not everyone might want to dive through commit messages to find out what's new and what's changed, this document lists all breaking changes in reverse chronological order. If a new feature did not require any changes to existing code then it will not be listed here.

[2022-07-06]

• The block smoothing API has been reworked. Instead of Smoothers having their own built in block buffer, you now need to provide your own mutable slice for the smoother to fill. This makes the API easier to understand, more flexible, and it allows cloning smoothers without worrying about allocations for use with polyphonic modulation. In addition, the new implementation is much more efficient when the smoothing period has ended before or during the block.
• There are new NoteEvent::PolyModulation and NoteEvent::MonoAutomation as part of polyphonic modulation support for CLAP plugins.

[2022-07-05]

• The ClapPlugin::CLAP_HARD_REALTIME constant was moved to the general Plugin trait as Plugin::HARD_REALTIME_ONLY and best-effort support for VST3 was added.

[2022-07-04]

• There is a new NoteEvent::Choke event the host can send to a plugin to let it know that it should immediately terminate all sound associated with a voice or a key.
• There is a new NoteEvent::VoiceTerminated event to let the host know a voice has been terminated. This needs to be output by CLAP plugins that support polyphonic modulation.
• Most NoteEvent variants now have an additional voice_id field.
• The CLAP_DESCRIPTION, CLAP_MANUAL_URL, and CLAP_SUPPORT_URL associated constants from the ClapPlugin are now optional and have the type Option<&'static str> instead of &'static str.

[2022-07-02]

• The Params::serialize_fields() and Params::deserialize_fields() methods and the State struct now use BTreeMaps instead of HashMaps so the order is consistent the plugin's state to JSON multiple times. These things are part of NIH-plug's internals, so unless you're implementing the Params trait by hand you will not notice any changes.

[2022-06-01]

• The ClapPlugin::CLAP_FEATURES field now uses an array of ClapFeature values instead of &'static strs. CLAP 0.26 contains many new predefined features, and the existing ones now use dashes instead of underscores. Custom features are still possible using ClapFeature::Custom.

[2022-05-27]

• The Plugin::initialize() method now takes a &mut impl InitContext instead of a &mut impl ProcessContext.
• Plugin::process() now takes a new aux: &mut AuxiliaryBuffers parameter. This was needed to allow auxiliary (sidechain) inputs and outputs.

[2022-05-22]

• Previously calling param.non_automatable() when constructing a parameter also made the parameter hidden. Hiding a parameter is now done through param.hide(), while param.non_automatable() simply makes it so that the parameter can only be changed manually and not through automation or modulation.
• The current processing mode is now stored in BufferConfig. Previously this could be fetched through a function on the ProcessContext, but this makes more sense as it remains constant until a plugin is deactivated. The BufferConfig now contains a field for the minimum buffer size that may or may not be set depending on the plugin API.

...

Who knows what happened at this point!