rill-patchbay

Automation and control system — LFOs, envelopes, sequencers, sensors, servos, and event mapping for the Rill audio graph.

Architecture

Two-thread design. Automata run inside Servos on the control thread (tokio actors) and communicate with the signal graph through lock-free actor mailboxes (ActorRef<CommandEnum>).

Control thread (soft-RT):                     Signal thread (hard-RT):
  ┌──────────┐   ┌──────────┐
  │ Automaton│   │  Sensor  │                 ┌──────────────────┐
  │ (LFO,ENV)│   │(MIDI,OSC)│                 │  I/O callback    │
  └────┬─────┘   └────┬─────┘                 │  actor.drain()   │
       │              │                       │  generate()      │
       ▼              ▼                       │  process()       │
  ┌──────────────────────────┐   ClockTick    │  propagate()     │
  │        Servo             │◄───────────────│                  │
  │  automaton.step()       │                └────────▲─────────┘
  │  mapping.apply()        │                         │
  │  strategy: control+     │    SetParameter          │
  │            conflict     │─────────────────────────┘
  └──────────────────────────┘

Conflicts between automaton output and HID input (MIDI knob, OSC fader) are resolved inside the Servo via ControlStrategy and ConflictStrategy. See strategy.rs.

Key components

• Automata — LfoAutomaton, EnvelopeAutomaton, RandomWalkAutomaton, SequencerAutomaton, FunctionAutomaton, CellularAutomaton
• Servos — bridge automatons to graph node parameters via ParameterMapping (Linear, Exponential, Logarithmic, Inverted, Custom). Also apply sensor event mappings (MIDI CC → param, OSC address → param). Built-in conflict resolution via ControlStrategy (Absolute / Modulation) and ConflictStrategy (TouchOverride / BasePlusModulation / LastWriteWins).
• Sensors — acoustic (pitch, envelope follower), physical (knobs, buttons), MIDI, OSC (UDP-based address/argument sensors).
• Event mapping — MIDI CC → parameter, OSC address → parameter, with transforms.
• Engine — centralised API for adding automata, servos, and mappings (fka PatchbayControl).

Usage

use rill_core_actor::ActorRef;
use rill_patchbay::prelude::*;

let (actor_ref, _mailbox) = ActorRef::new_pair();
let mut engine = Engine::new(actor_ref);

engine.add_lfo(
    "vibrato", 5.0, 0.5, 0.0, LfoWaveform::Sine,
    osc_node_id, "frequency", 400.0, 480.0,
);

engine.add_envelope(
    "amp", 0.01, 0.1, 0.7, 0.2,
    vca_node_id, "gain", 0.0, 1.0,
);

engine.update(1.0 / 60.0);

Feature flags

Dependencies

• rill-core — node traits, queues, types
• crossbeam-channel, parking_lot, tokio — green thread infrastructure

Links

• Repository: https://github.com/DigitalRats/rill
• Documentation: https://docs.rs/rill-patchbay