Firmament v0.1.0

Firmament is a Mid/Side stereo widener and imager plugin in the Basilica Audio suite — sacred-architecture DSP for heavy music. It scales the Side channel of a Mid/Side encode to control apparent stereo width, with an optional multiband crossover that keeps sub-bass content centered (or independently wide) regardless of how wide the rest of the spectrum is pushed. In a heavy-music mix chain it sits on lush layers — strings, choirs, synth pads — giving them a wider, more open stereo image without smearing the low end or breaking mono compatibility.

This is the first tagged release (v0.1.0), covering the M1 milestone: core DSP completion and broadened test coverage.

What's new in 0.1.0

Added

• Project bootstrap: README, license, contributing guide, architecture and build docs, ADRs, and CI workflow.
• DSP core: initial working Firmament signal path (Width, Bass Mono crossover, Output trim) with unit tests.
• Multiband width: independent Low Width (0-200%, default 0%) and Width controls for the Side signal's low/high bands, split at Bass Mono Freq. Low Width's default exactly reproduces the original "bass mono forces the low band to silence" behaviour.
• Auto Mono Safety: an optional, correlation-driven Side attenuation that reins in the stereo image whenever the input goes strongly out-of-phase, without ever touching Mid (so the mono-sum invariant holds regardless of whether it is engaged).
• Correlation/phase meter (DSP): a running, leaky-integrated input-correlation estimate exposed via FirmamentEngine::getCorrelationValue() and FirmamentAudioProcessor::getCorrelationMeterValue(), driving Auto Mono Safety internally and ready for a future GUI meter widget (M3).
• Haas Mode: an optional alternative widening technique (0-40 ms Right-channel delay after M/S decode, via juce::dsp::DelayLine) that can widen genuinely mono-compatible material, clearly documented as the one exception to Firmament's otherwise-provable mono-sum guarantee.
• docs/manual.md: a full user manual (what Firmament is, where it sits in a heavy production chain, signal flow, complete parameter reference, mixing tips).
• Broadened Catch2 test suite (24 -> 49 test cases): sample-rate sweeps (44.1-192 kHz), extreme/randomised parameter automation, mono/stereo bus-configuration coverage (including direct isBusesLayoutSupported() acceptance/rejection tests), and long-run NaN/Inf stability sweeps, alongside dedicated coverage for every M1 DSP addition above.

Changed

• PluginEditor: extended the v0.1-style functional editor with controls for every new M1 parameter (Low Width knob, Auto Mono Safety/Haas Mode toggles, Haas Time knob). A custom vector-drawn LookAndFeel and a visible correlation/phase meter widget remain M3 scope.
• docs/architecture.md: updated signal-flow diagram and per-stage documentation for the M1 signal path.

Fixed

• Corrected a documentation inaccuracy inherited from the v0.1 bootstrap: juce::dsp::LinkwitzRileyFilter's dual-output low/high bands sum to a flat-magnitude allpass, not an exact reconstruction of the input (per JUCE's own class documentation, confirmed empirically) - the original "Bass Mono" feature was unaffected by this (it only ever discards the low band rather than re-summing), but the documentation claim was corrected before it could mislead the new multiband-width design.

Supported formats

• Plugin formats: AU, VST3, Standalone
• Platforms: macOS (Universal Binary: arm64 + x86_64), Windows (x64)

Installation

Download the zip for your OS below, unzip, and copy the plugin into your system's plugin folder:

• macOS: AU -> ~/Library/Audio/Plug-Ins/Components/, VST3 -> ~/Library/Audio/Plug-Ins/VST3/. Standalone app can be run directly from wherever you unzip it (or moved to /Applications).
• Windows: VST3 -> C:\Program Files\Common Files\VST3\. Standalone app can be run directly from wherever you unzip it.

Rescan plugins in your DAW after installing.

Signed & notarized

The macOS binaries in this release are Developer-ID-signed, notarized by Apple and stapled — they install and open without Gatekeeper warnings. (Windows binaries remain unsigned for now; Authenticode signing is tracked as roadmap milestone M4.)