211 sor
10 KiB
Markdown
211 sor
10 KiB
Markdown
# InstaShadow
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Free, open-source dual-stage mastering compressor plugin inspired by the Shadow Hills Mastering Compressor, built with JUCE. Available as VST3, AU and LV2.
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## What Is This?
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InstaShadow is a dual-stage mastering compressor that combines an **optical compressor** and a **discrete VCA compressor** in series, followed by a switchable **output transformer** saturation section. The design is inspired by the Shadow Hills Mastering Compressor — a legendary hardware unit used in professional mastering studios worldwide.
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The optical stage provides smooth, program-dependent compression with a natural two-stage release, while the VCA stage offers precise, fast compression with selectable ratio, attack, and release settings. The transformer section adds subtle harmonic coloration with three distinct characters.
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## Download
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**[Latest Release: v1.0](https://github.com/hariel1985/InstaShadow/releases/tag/v1.0)**
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### Windows
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| File | Description |
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|------|-------------|
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| [InstaShadow-VST3-Win64.zip](https://github.com/hariel1985/InstaShadow/releases/download/v1.0/InstaShadow-VST3-Win64.zip) | VST3 plugin — copy to `C:\Program Files\Common Files\VST3\` |
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### macOS (Universal Binary: Apple Silicon + Intel)
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| File | Description |
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|------|-------------|
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| [InstaShadow-VST3-macOS.zip](https://github.com/hariel1985/InstaShadow/releases/download/v1.0/InstaShadow-VST3-macOS.zip) | VST3 plugin — copy to `~/Library/Audio/Plug-Ins/VST3/` |
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| [InstaShadow-AU-macOS.zip](https://github.com/hariel1985/InstaShadow/releases/download/v1.0/InstaShadow-AU-macOS.zip) | Audio Unit — copy to `~/Library/Audio/Plug-Ins/Components/` |
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### Linux (x64, built on Ubuntu 22.04)
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| File | Description |
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|------|-------------|
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| [InstaShadow-VST3-Linux-x64.zip](https://github.com/hariel1985/InstaShadow/releases/download/v1.0/InstaShadow-VST3-Linux-x64.zip) | VST3 plugin — copy to `~/.vst3/` |
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| [InstaShadow-LV2-Linux-x64.zip](https://github.com/hariel1985/InstaShadow/releases/download/v1.0/InstaShadow-LV2-Linux-x64.zip) | LV2 plugin — copy to `~/.lv2/` |
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> **macOS note:** Builds are Universal Binary (Apple Silicon + Intel). Not code-signed — after copying the plugin, remove the quarantine flag in Terminal:
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> ```bash
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> xattr -cr ~/Library/Audio/Plug-Ins/VST3/InstaShadow.vst3
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> xattr -cr ~/Library/Audio/Plug-Ins/Components/InstaShadow.component
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> ```
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## Signal Flow
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```
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Input → Sidechain HPF → Optical Compressor (T4B) → VCA Compressor → Transformer → Output
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```
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Each stage can be independently bypassed. The sidechain HPF prevents low-frequency energy from triggering excessive compression (pumping on bass-heavy material).
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## Features
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### Optical Compressor — Port-Hamiltonian T4B Model
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The optical stage physically models the electro-optical attenuator (T4B) found in classic hardware compressors like the LA-2A. Rather than using simplified envelope followers, InstaShadow implements a **Port-Hamiltonian** energy-based model:
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- **EL panel** modeled as a capacitive energy store — the audio signal charges the panel, which emits light proportional to stored energy
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- **CdS photoresistor** modeled as a nonlinear dissipator — resistance follows the gamma curve `R = k · L^(-γ)` where γ ≈ 0.7
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- **Implicit trapezoidal integration** with Newton-Raphson iteration (3-5 iterations per sample) for numerical stability
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- **2x oversampling** for the implicit solver
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- **CdS memory effect** — the photoresistor "remembers" past illumination, creating a natural two-stage release:
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- Fast phase (~60 ms): first 50-80% of gain reduction releases quickly
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- Slow phase (0.5-5 s): remaining recovery depends on how long and how hard the signal was compressed
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- **Fixed 2:1 ratio** and **soft knee** emerge naturally from the physics — not explicitly coded
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- **Program-dependent attack** (~10 ms average) — reacts differently to transients vs. sustained signals
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| Control | Range | Default |
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|---------|-------|---------|
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| Threshold | -40 to 0 dB | -20 dB |
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| Gain (makeup) | 0 to 20 dB | 0 dB |
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| Sidechain HPF | 20 to 500 Hz | 90 Hz |
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| Bypass | On/Off | Off |
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### Discrete VCA Compressor
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A feed-forward VCA compressor with precise, repeatable compression characteristics:
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- **Soft-knee** gain computer (6 dB knee width) for transparent threshold behavior
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- **7 ratio settings:** 1.2:1, 2:1, 3:1, 4:1, 6:1, 10:1, Flood (20:1)
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- **6 attack presets:** 0.1 ms, 0.5 ms, 1 ms, 5 ms, 10 ms, 30 ms
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- **6 release presets:** 100 ms, 250 ms, 500 ms, 800 ms, 1.2 s, **Dual**
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- **Dual release mode** mimics the optical stage's two-stage behavior within the VCA:
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- Fast release envelope (~60 ms) handles the initial recovery
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- Slow release envelope (~2 s) handles the tail
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- The deeper (more compressed) of the two envelopes is used at any given moment
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| Control | Range | Default |
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|---------|-------|---------|
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| Threshold | -40 to 0 dB | -20 dB |
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| Gain (makeup) | 0 to 20 dB | 0 dB |
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| Ratio | 1.2:1 — Flood | 2:1 |
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| Attack | 0.1 ms — 30 ms | 1 ms |
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| Release | 100 ms — Dual | 500 ms |
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| Bypass | On/Off | Off |
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### Output Transformer Saturation
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Three switchable transformer types add subtle harmonic coloration, modeled with 4x oversampled waveshaping:
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| Type | Character | Harmonics | Drive | Wet Mix |
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|------|-----------|-----------|-------|---------|
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| **Nickel** | Transparent, clean | Minimal | 1.05 | 30% |
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| **Iron** | Warm, musical | Even-order (2nd) | 1.15 | 50% |
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| **Steel** | Aggressive, present | Even + odd (2nd + 3rd) | 1.3 | 60% |
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- Waveshaping: `tanh(drive · x) / drive` — preserves unity gain at low levels
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- Even harmonics via `x · |x|` (asymmetric warmth)
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- Odd harmonics via `x³` (edge and presence)
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- Dry/wet blending keeps the effect subtle and musical
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- Iron adds a +0.2 dB low shelf at 110 Hz
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- Steel adds a +0.4 dB low shelf at 40 Hz
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- 4x oversampling (JUCE polyphase IIR) prevents aliasing artifacts
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### Metering
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- **Analog-style needle VU meters** (L/R) with ballistic needle movement — cream-colored face, scale markings from -20 to +3 dB, red zone above 0 dB
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- **Optical GR meter** — horizontal bar showing optical stage gain reduction
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- **Discrete GR meter** — horizontal bar showing VCA stage gain reduction
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- **Output VU meter** — vertical stereo bar meter in the output section
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### Global Controls
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| Control | Description |
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|---------|-------------|
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| Stereo Link | Links L/R sidechain for matched stereo compression. Off = dual-mono |
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| Bypass | Global bypass — passes audio unprocessed |
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| Output Gain | -12 to +12 dB final output level |
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### GUI
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- Layout inspired by the original Shadow Hills Mastering Compressor hardware
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- Optical controls on the left, discrete controls on the right, meters in the center
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- Transformer and output controls at the bottom center
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- Dark modern UI with InstaDrums/InstaGrain visual style
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- 3D metal knobs with multi-layer glow effects (orange for main controls, blue for sidechain HPF)
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- Analog needle VU meters with inertial needle movement
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- Carbon fiber background texture
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- Rajdhani custom font (embedded)
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- Fully resizable window (800×500 — 1400×900) with proportional scaling
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- State save/restore — all settings recalled with DAW session
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## How It Works
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### The Port-Hamiltonian Approach
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Traditional plugin compressors use simplified envelope followers with fixed attack/release time constants. This misses the complex, program-dependent behavior of real optical compressors.
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InstaShadow uses a **Port-Hamiltonian** formulation — an energy-based modeling framework from mathematical physics. The system is described by two coupled energy ports:
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1. **Port 1 (EL panel):** A capacitive energy store with Hamiltonian `H = q²/(2C)`. The audio signal drives charge into the capacitor, which converts electrical energy to light.
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2. **Port 2 (CdS cell):** A nonlinear dissipative element whose resistance depends on illumination via a gamma curve. A separate "memory" state variable tracks accumulated illumination history, creating the characteristic two-stage release.
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The coupled system is solved using **implicit trapezoidal integration** — a symplectic integrator that preserves the energy structure of the Hamiltonian. Newton-Raphson iteration (3-5 steps per sample) resolves the implicit equation at each time step. 2x oversampling ensures numerical stability.
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This approach naturally produces:
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- Program-dependent attack and release (emerges from the physics)
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- Soft-knee compression (emerges from the nonlinear CdS gamma curve)
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- Approximately 2:1 ratio (emerges from the voltage divider topology)
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- Two-stage release with memory effect (emerges from the CdS illumination history)
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None of these behaviors are explicitly programmed — they are consequences of the physical model.
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## Building
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### Requirements
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- CMake 3.22+
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- JUCE framework (cloned to `../JUCE` relative to project)
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#### Windows
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- Visual Studio 2022 Build Tools (C++ workload)
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#### macOS
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- Xcode 14+
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#### Linux (Ubuntu 22.04+)
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```bash
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sudo apt-get install build-essential cmake git libasound2-dev \
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libfreetype6-dev libx11-dev libxrandr-dev libxcursor-dev \
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libxinerama-dev libwebkit2gtk-4.1-dev libcurl4-openssl-dev
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```
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### Build Steps
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```bash
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git clone https://github.com/juce-framework/JUCE.git ../JUCE
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cmake -B build -G "Visual Studio 17 2022" -A x64 # Windows
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cmake -B build -G Xcode # macOS
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cmake -B build -DCMAKE_BUILD_TYPE=Release # Linux
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cmake --build build --config Release
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```
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Output:
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- VST3: `build/InstaShadow_artefacts/Release/VST3/InstaShadow.vst3`
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- AU: `build/InstaShadow_artefacts/Release/AU/InstaShadow.component` (macOS)
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- LV2: `build/InstaShadow_artefacts/Release/LV2/InstaShadow.lv2`
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## Tech Stack
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- **Language:** C++17
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- **Framework:** JUCE 8
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- **Build:** CMake + MSVC / Xcode / GCC
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- **Optical DSP:** Custom Port-Hamiltonian solver (implicit trapezoidal + Newton-Raphson)
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- **VCA DSP:** Custom feed-forward compressor with soft-knee gain computer
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- **Transformer DSP:** Custom waveshaping with `juce::dsp::Oversampling` (4x polyphase IIR)
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- **Filters:** `juce::dsp::IIR` (sidechain HPF, tonestack EQ)
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- **Font:** Rajdhani (SIL Open Font License)
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## License
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GPL-3.0
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