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v1.6.0 — The Host Contract

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@CristianMoresi CristianMoresi released this 12 Jun 22:57
· 299 commits to main since this release
v1.6.0
a4ea056

The Host Contract — the plugin layer now covers everything a host can offer an effect or an instrument. Each capability is one declarative member on your plugin struct, and each one is proven functionally in CI: measured, not just compiled.

Instruments & MIDI

  • handleMidiEvent(MidiEvent) adds a note input to every format: VST3 event bus plus IMidiMapping (pitch bend, mod wheel, sustain, channel pressure), CLAP note ports speaking both the CLAP and raw-MIDI dialects, AU MusicDevice selectors behind a lock-free queue.
  • Category::Instrument builds a true generator: no audio inputs in any format, an aumu Audio Unit, cleared output buffers that voices add into.
  • New reference instrument examples/plugin_synth/: 8 voices of Oscillator + ADSREnvelope, voice stealing, pitch bend, factory presets, sample-accurate note starts — auval-validated, and CI measures a 440 Hz note and its release decay from the audio output.

Host transport

  • setTransport(TransportInfo) delivers tempo, musical position, bar start, time signature, loop points and play/record state once per block — from the VST3 ProcessContext (requirements declared for you), the CLAP transport event and the AU host callbacks. samplesPerBeat() is the one-liner for tempo-synced delays, LFOs and gates.

Buses

  • Mono everywhere: every plugin negotiates 1-in/1-out and 2-in/2-out by default (ChannelSupport::StereoOnly restricts it for inherently stereo DSP). The sidechain always mirrors the main width.

Sample-accurate automation

  • On by default: parameter, bypass and note events ride one time-ordered stream and processing splits at 32-frame quantum boundaries, so fast curves land where the host drew them. Declarative opt-out (sampleAccurateAutomation = false) for plugins with a high fixed cost per call.

The professional details

  • Runtime latency changes notify the host natively (VST3 restartComponent, clap_host_latency, the AU property listeners) — switchable lookahead now re-compensates projects correctly.
  • setOfflineRendering(bool) exposes the render mode (VST3 kOffline, the CLAP render extension, AU OfflineRender) for higher-quality bounces.
  • factoryPresets publishes to every host's preset browser: a VST3 program list with a program-change parameter, CLAP preset-load + preset-discovery (the plugin binary is the preset container), AU factory presets with a full PresentPreset round-trip.
  • Host bypass and the active program persist in the shared state container (two real-world bugs caught by pluginval and clap-validator in CI — the bypass one latent since v1.3.0).
  • process()/render() run under DSPark's denormal guard in all three backends.

Proven by instrumentation

  • New tools/plugin_probe.cpp encodes what the wrapper delivers into its audio output, so the smoke hosts measure every capability end to end on all five CI targets: transport DC, the offline sign flip, an automation step landing on its exact sample, note pitch by zero crossings, pitch bend through both routes, the latency-changed notification, mono processing and the preset paths.
  • pluginval (strictness 8) and clap-validator now also gate the synth and the probe; macOS CI runs four auval validations including the new aumu.

Docs

  • docs/plugins.md: full contract table for the new capabilities, new "Instruments & MIDI" and "Host transport" sections, a from-a-blank-folder project guide, and the examples indexed in learning order (also in the new examples/README.md).
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