Silentium v0.1.0

Silentium is a tight, lookahead noise gate built on JUCE 8, aimed at killing amp hiss/hum in the silence between palm-muted chugs. In a heavy-music signal chain it sits early on the rhythm guitar bus: it detects transients on a sidechain-filtered copy of the input (so hum/rumble can't falsely hold it open), opens fast with a lookahead head start so it never clips the leading edge of a pick attack, and uses two separate open/close thresholds so a signal hovering near the threshold can't chatter the gate open and closed.

This is the first tagged release, closing milestone M1 (DSP completion & test coverage).

What's in 0.1.0

Added

• Project bootstrap: README, license, contributing guide, architecture and build docs, ADRs, and CI workflow.
• DSP core: initial working Silentium signal path (sidechain-filtered detection, stereo-linked peak envelope, hysteresis comparator + hold timer, dB-domain attack/release gain ramp, exact-integer lookahead delay with latency reporting) with unit tests.
• Knee parameter (0-24 dB, default 0 dB): soft-knee blend of the gain computer's target across a band centred on Threshold, in place of the original instant on/off snap; Knee = 0 dB reproduces v0.1 behaviour exactly, and the Hold timer still guarantees a fully open target for its whole duration regardless of Knee.
• Duck parameter (off by default): inverts the gain computer into a ducker - attenuate above Threshold instead of opening above it - reusing the same detection/hysteresis/hold/knee machinery.
• Listen parameter (off by default): routes the sidechain-filtered detection signal (post SC HPF, pre envelope-follower) directly to the output, bypassing the gain computer, for auditioning what the gate's detector hears.
• Optional external sidechain input bus ("Sidechain", stereo, disabled by default): lets the detection path be keyed from another track (e.g. a kick drum or a reference DI) instead of the main input; isBusesLayoutSupported accepts the bus disabled, mono, or stereo independent of the main bus's own channel count, and a disabled/unconnected sidechain falls back to self-detection automatically.
• docs/manual.md: a full user manual (what the plugin is, where it sits in a heavy production chain, signal-flow description, complete parameter reference, mixing tips).
• Broadened Catch2 suite: dedicated coverage for Knee/Duck/Listen/external sidechain (engine and processor level), bus-layout negotiation (mono/stereo main bus, sidechain enabled/disabled/mono/stereo/rejected), a 44.1-192 kHz sample-rate sweep, and a long-run (~21 s of audio) NaN/Inf stability test with continuously varying parameters/content; existing null/reference, hysteresis, latency, and state round-trip tests extended to cover the three new parameters and still pass unmodified at their defaults.

Changed

• Parameter count grew from 7 to 10 (Knee, Duck, Listen added); all existing v0.1 parameter IDs, ranges, and defaults are unchanged.
• GateEngine::process() gained an optional second sidechainBlock parameter (default nullptr, fully backward compatible with the v0.1 single-block call).
• docs/architecture.md and README.md updated to describe the full v0.1.0 signal path (knee/duck/listen/sidechain), and the v0.1.0 GUI now also exposes Knee, Duck, and Listen.

Formats & platforms

• AU (Audio Unit), VST3, and Standalone
• macOS (Universal Binary: arm64 + x86_64) and Windows

Installation

macOS

Format	Path
AU (Component)	~/Library/Audio/Plug-Ins/Components/
VST3	~/Library/Audio/Plug-Ins/VST3/

If your host doesn't pick up the plugin after installing, force a rescan by resetting the AU cache:

killall -9 AudioComponentRegistrar
auval -a

Windows

Format	Path
VST3	C:\Program Files\Common Files\VST3\

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.)