Dynamics

Source of truth: the doc comments on each module struct in patches-modules/src/ define the canonical port names, parameter ranges, and behaviour. This page is kept in sync with those comments.

Limiter — Lookahead peak limiter

Transparent peak limiter with true lookahead. The attack_ms parameter determines how far ahead the detector looks, giving the gain envelope time to ramp down before a transient arrives at the output — eliminating the overshoot that zero-latency limiters suffer.

Inter-sample peaks (peaks that fall between base-rate samples) are caught by internally upsampling the detector path to 2× rate. The extra precision prevents hard-clipped peaks from sneaking through at high signal levels.

The output is hard-clipped to ±1.0 as a final safety stage.

Signal chain (per base-rate sample)

input ──► dry delay (lookahead + group delay)
      │
      └─► 2× interpolator
              │
              ▼
           peak window [t-L .. t]
              │
              ▼
           gain computation (attack / release smoothing)
              │
              ▼
           output = clamp(delayed_input × gain, −1.0, 1.0)

Parameters

Inputs

Outputs

Notes

• The module introduces a latency of attack_ms plus a small FIR group delay (~8 samples at base rate for the interpolator). Account for this when mixing a limited signal against an unlimitated reference.
• All buffers are pre-allocated at prepare time for the maximum attack_ms value (50 ms), so changing attack_ms at runtime never allocates.

StereoLimiter — Stereo lookahead limiter

Stereo variant of Limiter with linked gain reduction across channels. See patches-modules/src/stereo_limiter.rs for the current parameter set.

Compressor — Feed-forward compressor

Feed-forward compressor with soft knee, peak / RMS detection, and a sidechain input. When sidechain is unconnected the detector self-keys from in (the standard hardware default — see ADR 0076).

The static gain curve is C¹-continuous across the knee region: at the boundaries threshold ± knee_width/2 both value and slope match the linear / no-reduction branches, so the knee introduces no kink. A high ratio value asymptotically approaches a limiter shape; no special casing of ratio = ∞ is required.

Parameters

Inputs

Outputs

StereoCompressor — True-stereo feed-forward compressor

Stereo variant of Compressor with linked detection: a single magnitude derived from both channels drives one detector, and one gain reduction value is applied identically to L and R. This preserves the stereo image under asymmetric transients (a per-channel detector would shift the image on panned hits).

Detector magnitude:

• Peak: max(|L|, |R|)
• RMS: sqrt((L² + R²) / 2)

Parameters are identical to Compressor. The sidechain port is stereo; a mono source patched in is broadcast to both channels per ADR 0059.

Inputs

Outputs

Gate — Threshold gate with hysteresis

Threshold gate with hysteresis, attack / hold / release ballistics, and a sidechain input. The detector self-keys from in when sidechain is unconnected (ADR 0076). Gating is binary in intent — there is no mix parameter; a patch author wanting ducking-with-blend uses Compressor with high ratio and mix < 1.

The gate opens when the rectified detector key crosses threshold (the fire condition is armed && |x| > threshold — the threshold itself, not threshold - hysteresis). Hysteresis controls eligibility: after a fire the state machine disarms and only re-arms once the signal has dropped below threshold - hysteresis. Once open the gate cannot close for at least hold ms; after that it closes when the signal drops below threshold - hysteresis. Attack and release set the ramp times of the open/closed envelope.

Parameters

Inputs

Outputs

StereoGate — True-stereo threshold gate

Stereo variant of Gate with linked detection: one detector is fed by max(|L|, |R|) and one gate state drives both channels. This preserves the stereo image — per-channel detection would cause audible image shift on asymmetric transients.

Parameters are identical to Gate. The sidechain port is stereo; a mono source patched in is broadcast to both channels per ADR 0059.

Inputs

Outputs

Bitcrusher — Bit-depth and sample-rate reduction

Quantises samples to a configurable bit depth and decimates the sample rate. See patches-modules/src/bitcrusher.rs.

Drive — Nonlinear waveshaper

Soft-clip saturation / overdrive. See patches-modules/src/drive.rs.

TransientShaper — Attack/sustain emphasis

Envelope-follower-based transient emphasis and suppression. See patches-modules/src/transient_shaper.rs.