Maolan Plugins

A collection of audio plugins written in Rust for the Maolan ecosystem. All plugins implement the CLAP plugin API and include an Iced-based GUI using the TokyoNight theme.

Plugins

Plugin	ID	I/O	Description
Drust	rs.maolan.drust	8× Stereo	DrumGizmo-inspired drum sampler
Maolan Kick	rs.maolan.kick	16× Mono	Percussive synthesizer with layered oscillators and noise
Maolan Compressor	rs.maolan.compressor	Mono / Stereo	4-band multiband compressor with lookahead and sidechain boost
Maolan DeEsser	rs.maolan.deesser	Stereo	Sibilance reduction processor
Maolan Delay	rs.maolan.delay	Mono / Stereo	Delay with ms / note-sync modes and smooth chasing
Maolan EQ	rs.maolan.equalizer	Mono / Stereo	Parametric EQ with peaking biquad filters
Maolan Limiter	rs.maolan.limiter	Stereo	Adaptive clipper/limiter with Vintage and Modern variants
Maolan Monitoring	rs.maolan.monitoring	Stereo	Monitoring toolbox with 17 reference modes
Maolan Reverb	rs.maolan.reverb	Mono / Stereo	Stereo reverb
Maolan Sampler	rs.maolan.sampler	Stereo	Polyphonic sample player
Maolan Saturator	rs.maolan.saturator	Stereo	Waveshape saturation with sine-based distortion
Maolan Synth	rs.maolan.synth	Stereo	Polyphonic synthesizer inspired by Surge XT
Maolan Stereo	rs.maolan.stereo	Stereo	Stereo width processor
Maolan Widener	rs.maolan.widener	Stereo	Multiband stereo width processor
Rural Modeler	rs.maolan.ruralmodeler	Mono	Neural Amp Modeler with IR convolution

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Drust

A drum sampler plugin based on DrumGizmo. Supports loading drum kits asynchronously, MIDI note triggering with velocity mapping, round-robin sample selection, humanization, and per-output channel balancing. Includes a built-in limiter and 16 mono outputs.

Parameters

Parameter	Range	Default	Description
Master Gain	−60.0 ... 12.0 dB	0.0	Output gain
Enable Resampling	0 / 1	1	Enable sample-rate conversion
Min Velocity	0 ... 127	0	Minimum input velocity
Max Velocity	0 ... 127	127	Maximum input velocity
Resample Quality	0 ... 3	1	Resampler quality level
Humanize Amount	0.0 ... 100.0	8.0	Timing humanization
Round Robin Mix	0.0 ... 1.0	0.7	Round-robin blend
Bleed Amount	0.0 ... 100.0	100.0	Mic bleed level
Limiter Threshold	−48.0 ... 0.0 dB	−3.0	Limiter threshold
Normalize Samples	0 / 1	1	Auto-normalize loaded samples
Random Seed	0 ... 1000	0	Humanization seed
Voice Limit Max	1 ... 128	128	Max simultaneous voices
Voice Limit Rampdown	0.01 ... 2.0	0.5	Voice release rampdown
Balance 1–2 ... 15–16	−1.0 ... 1.0	0.0	Per-output stereo balance

Output channels: Kick L/R, Snare L/R, HiHat L/R, Toms L/R, Ride L/R, Crash L/R, China/Splash L/R, Ambience L/R

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Maolan Compressor

A 4-band multiband compressor with LR4 crossover splits. Supports Peak/RMS sidechain detection, downward/upward/boosting modes, lookahead delay, and sidechain boost options. Based on the LSP compressor design.

Parameters

Parameter	Range	Default	Description
Input Gain	−24.0 ... 24.0 dB	0.0	Input gain staging
Output Gain	−24.0 ... 4.0 dB	−8.0	Output gain staging
Dry Gain	0.0 ... 1.0	0.0	Dry mix amount
Wet Gain	0.0 ... 1.0	1.0	Wet mix amount
Sidechain Mode	0=Peak, 1=RMS	1	Sidechain detection type
Bypass	0 / 1	0	Global bypass
Split 1 / 2 / 3	20 ... 18000 Hz	120, 1000, 6000	Crossover frequencies
Band 1–4 Threshold	−60.0 ... 0.0 dB	−12.0	Band compression threshold
Band 1–4 Ratio	1.0 ... 100.0	4.0	Band compression ratio
Band 1–4 Attack	0.0 ... 2000.0 ms	20.0	Band attack time
Band 1–4 Release	0.0 ... 5000.0 ms	100.0	Band release time
Band 1–4 Knee	0.0 ... 24.0 dB	6.0	Band knee width
Band 1–4 Makeup	−24.0 ... 24.0 dB	0.0	Band makeup gain
Mode	0=Downward, 1=Upward, 2=Boosting	0	Compression mode
Lookahead	0.0 ... 20.0 ms	0.0	Lookahead delay
SC Boost	0=Off, 1=BT+3dB, 2=MT+3dB, 3=BT+6dB, 4=MT+6dB	0	Sidechain boost option
Topology	0=Classic, 1=Modern	1	Compressor topology

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Maolan DeEsser

A sibilance reduction processor that detects ess sounds by analyzing slew-rate patterns across a configurable sample window. Uses IIR smoothing and dynamic ratio reduction to attenuate sibilance while preserving the rest of the signal. Includes a monitor mode for hearing exactly what is being removed.

Parameters

Parameter	Range	Default	Description
Intensity	0.0 ... 1.0	0.5	Sensitivity / threshold
Sharpness	0.0 ... 1.0	0.5	Detection window size (2–40 samples)
Depth	0.0 ... 1.0	0.5	Maximum reduction amount
Filter	0.0 ... 1.0	0.5	IIR smoothing amount
Monitor	0 / 1	0	Output delta (removed signal) when enabled

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Maolan Delay

A stereo delay with two time modes: fixed milliseconds or tempo-synced note divisions. Uses circular buffers with linear interpolation and smooth delay-time chasing to avoid clicks when the time changes.

Parameters

Parameter	Range	Default	Description
Time Mode	0=ms, 1=Note	0	Toggle between fixed ms and tempo-synced note
Time (ms)	1.0 ... 5000.0 ms	375.0	Fixed delay time
Time (note)	0.0 ... 1.0	0.75	Maps to 16 note divisions (1/1 ... 1/8d)
Feedback	0.0 ... 1.0	0.3	Feedback amount
Dry/Wet	0.0 ... 1.0	0.5	Mix balance

Note divisions: 1/1, 1/2, 1/3, 1/4, 1/6, 1/8, 1/12, 1/16, 1/24, 1/32, 1/48, 1/64, 1/1d, 1/2d, 1/4d, 1/8d

In Note mode the plugin reads the host BPM from the CLAP transport each process call.

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Maolan EQ

A Parametric equalizer using peaking biquad filters. Each band has independent frequency, gain, and Q controls.

Parameters

Parameter	Range	Default	Description
Input Gain	−24.0 ... 24.0 dB	0.0	Input gain staging
Output Gain	−24.0 ... 24.0 dB	0.0	Output gain staging
Bypass	0 / 1	0	Global bypass
Freq	20.0 ... 20000.0 Hz	1000.0	Band center frequency
Gain	−24.0 ... 24.0 dB	0.0	Band gain
Q	0.1 ... 24.0	1.0	Band Q factor

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Maolan Limiter

Adaptive clipper/limiter with two distinct variants.

Parameters

Parameter	Range	Default	Description
Variant	0=Vintage, 1=Modern	0	Algorithm selector
Boost	0.0 ... 1.0	0.0	Input gain boost (up to +18 dB)
Soften	0.0 ... 1.0	0.5	Vintage softness amount
Enhance	0.0 ... 1.0	0.5	Vintage highs/subs lift
Ceiling	0.0 ... 1.0	0.5	Modern output ceiling
Mode	0–7	0	Processing mode (Normal, Atten, Clips, Afterbr, Explode, Nuke, Apocaly, Apothes)

Algorithms

• Vintage - Boost-based clipping with overshoot detection, highs/lifts enhancement, and adaptive reference clipping
• Modern - Multi-stage clip-only processor with configurable ceiling and stage-based gain staging

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Maolan Monitoring

Monitoring toolbox with 17 reference modes for checking mixes on different playback systems.

Parameters

Parameter	Range	Default	Description
Mode	0–16	0	Monitoring mode selector

Modes: Out24, Out16, Peaks, Slew, Subs, Mono, Side, Vinyl, Aurat, MonoRat, MonoLat, Phone, Cans A, Cans B, Cans C, Cans D, VTrick

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Maolan Reverb

Stereo reverb built from three allpass-like delay blocks with cross-feedback between channels, vibrato predelay, and input/output lowpass filters.

Parameters

Parameter	Range	Default	Description
Replace	0.0 ... 1.0	0.5	Reverb density / replacement
Brightness	0.0 ... 1.0	0.5	High-frequency content
Detune	0.0 ... 1.0	0.5	Pitch modulation depth
Bigness	0.0 ... 1.0	1.0	Room size
Dry/Wet	0.0 ... 1.0	1.0	Mix balance

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Maolan Sampler

A production-grade polyphonic sample player supporting SFZ (v1/v2) and SoundFont 2 (SF2.01/SF2.04) formats alongside standalone WAV/audio files. Features 32 polyphonic voices, multi-EG envelopes, auxiliary LFOs, multimode filter, modulation matrix, and non-blocking background sample parsing and resampling.

Format & Feature Highlights

• SFZ v1/v2 Support:
  • Header scope precedence (control → global → master → group → region).
  • Preprocessing with #include directives, #define macros, and #if/#else/#endif conditional blocks.
  • Core opcodes for key/velocity mapping, key fades (xf*), tuning, volume, pan, looping (continuous, sustain, one-shot, alternate), playback offset/direction, trigger modes (attack, release, first, legato), group choking, keyswitches (sw_last, sw_down, sw_up, sw_default), and round-robin / random variants (seq_length, lorand/hirand).
  • Amp/Filter envelope generators and LFO opcodes mapped directly to group DSP modules.
• SoundFont 2 (SF2) Support:
  • RIFF sfbk structure parser supporting 16-bit PCM and 24-bit PCM (sm24 / smpl-24) audio chunks.
  • INFO chunk metadata extraction (INAM, ICRD, IENG, etc.).
  • Generator merging across preset-zone, preset-global, instrument-zone, and instrument-global scopes.
  • Supported generators: keyRange, velRange, sample start/end/loop address offsets, coarseTune, fineTune, scaleTuning, overridingRootKey, initialAttenuation (centibels), pan, exclusiveClass, sampleID, and sampleModes.
  • Default and custom imod modulator mapping to internal modulation matrix (Mod Wheel CC1, Channel Volume CC7, Pan CC10, Expression CC11, Velocity, and Key tracking).
  • Multi-preset selection: Exposes all (bank, preset) pairs in loaded SF2 files via the GUI preset dropdown selector.
• Background Loading & Engine Isolation:
  • File parsing, sample decoding, and sample-rate conversion occur on a background worker thread.
  • Audio thread stays click-free by atomically swapping loaded patches via AtomicArc<Patch>.
  • Active voices maintain Arc references to previous samples to gracefully finish playback when reloads occur.
  • Integrated LRU caching based on path and file modification timestamp (mtime).
• GUI Features:
  • Drag-and-drop file loading for .sfz and .sf2 files.
  • Preset picker dropdown for multi-preset SoundFont files.
  • Real-time progress bar for sample loading and resampling.
  • Reload button for quick iteration when editing .sfz files on disk.
  • Scrollable load status and error log view.

Parameters

Parameter	Range	Default	Description
Gain	0.0 ... 2.0	1.0	Master output gain
Pan	−1.0 ... 1.0	0.0	Master pan
Amp EG Attack	0.0 ... 10.0 s	0.01	Amplitude envelope attack
Amp EG Decay	0.0 ... 10.0 s	0.2	Amplitude envelope decay
Amp EG Sustain	0.0 ... 1.0	1.0	Amplitude envelope sustain
Amp EG Release	0.0 ... 1.0	0.3	Amplitude envelope release
Bend Up	0 ... 24 semitones	2	Pitch-bend up range
Bend Down	0 ... 24 semitones	2	Pitch-bend down range
Filter Type	0 ... 48	1	Multimode filter type
Filter Cutoff	20.0 ... 20000.0 Hz	20000.0	Filter cutoff
Filter Resonance	0.01 ... 10.0	0.7	Filter resonance
Filter EG Amount	−1.0 ... 1.0	0.0	Filter envelope modulation
Filter Enabled	0 / 1	0	Enable filter
Filter EG Attack	0.0 ... 10.0 s	0.01	Filter envelope attack
Filter EG Decay	0.0 ... 10.0 s	0.2	Filter envelope decay
Filter EG Sustain	0.0 ... 1.0	0.0	Filter envelope sustain
Filter EG Release	0.0 ... 10.0 s	0.3	Filter envelope release
EG2–EG5 Attack	0.0 ... 10.0 s	0.01	Auxiliary envelope attack
EG2–EG5 Decay	0.0 ... 10.0 s	0.2	Auxiliary envelope decay
EG2–EG5 Sustain	0.0 ... 1.0	1.0	Auxiliary envelope sustain
EG2–EG5 Release	0.0 ... 10.0 s	0.3	Auxiliary envelope release
LFO1/2 Rate	0.01 ... 20.0 Hz	1.0	LFO rate
LFO1/2 Amount	0.0 ... 1.0	0.0	LFO depth
LFO1/2 Shape	0 ... 9	0	LFO waveform
LFO1/2 Enabled	0 / 1	0	Enable LFO

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Maolan Saturator

Simple but effective stereo saturator using sine-wave distortion with an intensity-dependent blend.

Parameters

Parameter	Range	Default	Description
Drive	0.0 ... 1.0	0.0	Saturation amount

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Maolan Synth

A polyphonic synthesizer inspired by Surge XT. Features three oscillators with multiple synthesis modes (including wavetable, FM, and physical-modeling flavors), two multimode filters with configurable routing, three envelopes, six LFOs, a 12-slot modulation matrix, an MSEG, a step sequencer, noise and waveshaper sections, and microtonal tuning support.

Parameter groups

Group	Description
Osc1–Osc3	Type, octave, semitone, fine, shape, skew, formant, level, unison, sync, sub, routing, solo/mute
Filter1–Filter2	Type, subtype, cutoff, resonance, EG amount, key tracking, drive, feedback, enable
Filter	Filter routing and balance
AmpEG / FilterEG / PitchEG	Attack, decay, sustain, release, mode, shapes, retrigger, tempo sync, uber release
LFO1–LFO6	Rate, shape, amount, deform, trigger, sync mode/division, envelope, phase, unipolar
Mod	Fixed mod depths (velocity/key/LFO to filter, mod wheel/aftertouch to filter)
ModRoute1–12	Source, target, depth, curve
Noise	Type, level, color, filter, stereo, enabled
Waveshaper	Shape, drive, mix, enable
Flavor	Additional filter-like flavor stage
Step Seq	16 step values, loop start/end, shuffle, trigger targets
MSEG	128 nodes, 127 segment curves, loop, retrigger targets
Macros	Macro1–8 modulation sources
Master	Volume, pan, width, polyphony, portamento, pitch-bend range, play mode, voice priority
Tuning	Scale, root, SCL index
FM / Twist / String / Alias	Oscillator-specific parameters for FM, twist, string, and alias engines

Note: The synth exposes a large parameter set (712 parameters). The exact ranges and defaults are defined in the plugin parameter list; the table above summarizes the available groups.

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Maolan Stereo

Stereo width processor.

Parameters

Parameter	Range	Default	Description
Width	0.0 ... 1.0	0.5	Stereo width
Focus	0.0 ... 1.0	0.5	Focus / center control
Amount	0.0 ... 1.0	1.0	Effect amount

Mid/side processing with density controls and delay-based focus.

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Maolan Widener

A multiband stereo width processor with independent Low, Mid, and High band controls. Uses LR4 crossover filters and mid/side processing per band.

Parameters

Parameter	Range	Default	Description
Output Gain	−24.0 ... 24.0 dB	0.0	Output gain staging
Boost	0.0 ... 4.0x	1.0	Global side boost
Low	0.0 ... 200.0 %	100.0	Low-band width
Mid	0.0 ... 200.0 %	100.0	Mid-band width
High	0.0 ... 200.0 %	100.0	High-band width
Solo Low	0 / 1	0	Solo low band
Solo Mid	0 / 1	0	Solo mid band
Solo High	0 / 1	0	Solo high band
X1	40.0 ... 1000.0 Hz	400.0	Low/mid crossover
X2	1000.0 ... 18000.0 Hz	4000.0	Mid/high crossover
Strength	1.0 ... 20.0 ms	5.0	Width strength
Monitor Mode	0=Stereo, 1=Mono, 2=Side	0	Output monitor mode

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Rural Modeler

A Neural Amp Modeler (NAM) plugin that loads neural network amp models and impulse responses (IRs). Features a noise gate, tone stack (Bass/Mid/Treble), input/output calibration, and DC blocking.

Parameters

Parameter	Range	Default	Description
Input	−20.0 ... 20.0 dB	0.0	Input gain
Threshold	−100.0 ... 0.0 dB	−80.0	Noise-gate threshold
Bass	0.0 ... 10.0	5.0	Tone-stack bass
Middle	0.0 ... 10.0	5.0	Tone-stack mid
Treble	0.0 ... 10.0	5.0	Tone-stack treble
Output	−40.0 ... 40.0 dB	0.0	Output gain
Noise Gate Active	0 / 1	1	Enable noise gate
Tone Stack	0 / 1	1	Enable tone stack
IR Toggle	0 / 1	1	Enable impulse response
Calibrate Input	0 / 1	0	Enable input calibration
Input Calibration Level	−60.0 ... 60.0 dB	12.0	Calibration reference
Output Mode	0=Raw, 1=Normalized, 2=Calibrated	1	Output loudness mode

Model/IR loading: Via GUI file picker, or set the environment variables RURAL_MODELER_MODEL and RURAL_MODELER_IR before starting the host.

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Build

Unix

cargo build --release

Windows

In the Windows environment execute the following: powershell -ExecutionPolicy Bypass -File "\\172.16.0.254\repos\maolan\plugins\build.ps1"

Platform Support

Linux, FreeBSD, and Windows are supported.

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Only CLAP support

As only CLAP supports changing number of channels while plugin instance is loaded, the decision is to support only that plugin format. With other formats one has to implement mono and stereo plugin and those can not be swapped easily. On top of that, once there's an option for mono, stereo, 2.1, 5.1 and 7.1 the number of plugins becomes huge. Just imagine having 10 plugins with all channel variations: that makes 50 plugins to choose from in a plugin browser. That being said, if LV2 gets support for changing channel number, it will be implemented, but only then.