CStrip2 Visual

Version: v0.1.0
License: GNU General Public License v3.0 or later (GPL-3.0-or-later)
Formats: Windows (x86_64) VST3 & CLAP · macOS (Universal 2: arm64 & x86_64) VST3, CLAP & AUv2
Original DSP: Chris Johnson / Airwindows (MIT License) · Visual Interface & Rust Port: AMR

Download Latest Release (v0.1.0) · Documentation (docs/) · Changelog · Español

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Overview

CStrip2 Visual brings the musical character of Chris Johnson's (Airwindows) CStrip2 channel strip into a clear, modern visual workflow. Designed for everyday mixing and production, it combines four essential tone-shaping stages in a single window:

• Clean up the extremes with smooth high-pass and low-pass filters (Capacitor).
• Control dynamics and peaks with a responsive, program-dependent compressor (ButterComp).
• Sculpt lows, mids, and highs using a 3-band equalizer with adjustable crossover frequencies (3-Band EQ).
• Set your final level or add warmth with an output stage (Output) that transitions smoothly from clean unity gain into progressive Spiral and Density harmonic saturation.

You can adjust the processing stages to suit each track, monitor the results using the real-time stereo spectrum analyzer and interactive Tone Curve, and use the built-in A/B slots to compare different parameter settings.

CStrip2 Visual in use: real-time stereo spectrum analyzer (IN/OUT/BOTH), interactive Tone Curve, metering, and four processing modules.

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DSP Signal Chain & Technical Reference

Built in Rust with NIH-plug and egui, the audio engine ports the Airwindows CStrip2 algorithms across four processing stages accompanied by a lock-free visual analysis engine:

1. Capacitor (Input High-Pass / Low-Pass Filters)

• Port of the Airwindows Capacitor input filter stage (Hi-Pass and Lo-Pass).
• Implementation: Non-linear 6-stage interleaved IIR filter array (count: 0..5) evaluated sample-by-sample.
• Technical note: Uses the dedicated Airwindows Capacitor algorithm rather than conventional Butterworth filter topologies.

2. ButterComp (Class AB Dynamic Compressor)

• Port of the original Airwindows ButterComp non-linear dynamic compressor (Compres and Speed).
• Implementation: Sample-by-sample bipolar flip/flop alternation (flip = !flip), independent asymmetric tracking of positive and negative signal halves, golden-ratio weighted moving average (0.6180339887...), and dual-speed smoothing.
• Technical note: Does not include an expander or noise gate stage, and follows the distinctive Airwindows ButterComp character rather than a conventional VCA/mastering bus compressor topology.

3. 3-Band Complementary Split EQ

• Three bands: Bass (with adjustable crossover Bass Frq), Mid, and Treble (with adjustable crossover Treb Frq).
• Implementation: Logarithmic density-to-dB mapping, consecutive sample-difference filtering, and non-linear cubic harmonic correction (triplet factor).
• Interactive crossover markers (LOW, MID, HIGH) and draggable band handles on the graphical display.

4. Output Stage (Saturation & Floating Point Dither)

• Output Gain & Saturation: Output control (0.0 to 1.0 normalized, corresponding to 0x–3x gain). Unity gain is at approximately 0.333 (one third of the control range, with 0.33 as the control's default value). Driving Output above unity progressively engages Airwindows Spiral and Density harmonic saturation stages.
• Dither: Final Airwindows Floating Point Dither output stage.

5. Real-Time Spectrum Analyzer, Tone Curve & Workflow Controls

• Zero-Allocation Audio Thread: Lock-free ring buffer transfer from the real-time audio thread to the GUI FFT worker.
• Tone Curve Overlay: Real-time theoretical frequency-response curve showing the combined Capacitor + 3-Band EQ transfer function across 20 Hz – 20 kHz.
• Analyzer Controls:
  • Source: OUT, IN, or BOTH (simultaneous orange Input and cyan Output overlay).
  • Resolution: 31 bands, 63 bands, 128 points, or CONT (continuous).
  • Line Mode: CRV (curve), FILL (filled area), or BAR (bars).
  • Speed & Hold: SLOW, MED, FAST decay presets and peak HOLD toggle.
• Metering & State Management: Stereo IN and OUT peak/RMS meters, dedicated GR (ButterComp gain reduction) meter (0 to -20 dB), built-in preset browser with SAVE, and A/B comparison slots (COPY A->B, COPY B->A).

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Available Formats & Verified Testing Scope

Platform	Binary Architecture	Included Formats	Release Package
Windows	x86_64 (64-bit)	VST3 (cstrip2.vst3), CLAP (cstrip2.clap)	CStrip2_Visual_Windows_v0.1.0.zip
macOS	Universal 2 (arm64 Apple Silicon + x86_64 Intel)	VST3 (CStrip2.vst3), CLAP (CStrip2.clap), AUv2 (CStrip2.component)	CStrip2_Visual_macOS_Universal_v0.1.0.zip

Verified Testing Record

• Windows (x86_64): Verified locally with the full 85-test DSP/GUI unit and integration test suite (cargo test -p cstrip2 --locked) and release bundle packaging (cargo xtask bundle cstrip2 --release).
• macOS Real DAW Production Environment: Verified on an Apple MacBook Pro M3 (Apple Silicon) running Ableton Live 12 (installation, authorization, plugin loading, FFT analyzer, Tone Curve, parameter controls, and audio processing validated in collaboration with Javier Alarco).
• macOS Automated CI Runner (arm64):
  • 85/85 Rust unit and integration tests passed.
  • Official Apple Audio Unit validation passed autonomously (auval -v aufx Cs2A AMR2) with CStrip2.component operating as a self-contained bundle.
  • Strict ad-hoc code signature verification passed (codesign --verify --deep --strict --verbose=2).
• Verification Boundaries: Compatibility is not claimed or guaranteed on unverified macOS versions, physical Intel Mac hardware, Linux, or untested DAWs/hosts beyond the environments documented above.
• macOS Bundle Metadata Note: The public release version is 0.1.0 (reflected in Cargo.toml and CStrip2.component/Contents/Info.plist). The macOS CStrip2.vst3 and CStrip2.clap bundles retain CFBundleShortVersionString = 1.0.0 in their internal Info.plist files due to the static template in nih_plug_xtask.

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Installation

Download the appropriate package for your operating system from the Releases page.

Windows (x86_64)

Extract CStrip2_Visual_Windows_v0.1.0.zip and copy the plugins to your standard system folders:

• VST3: Copy cstrip2.vst3 (the complete .vst3 bundle folder) to:

  C:\Program Files\Common Files\VST3\
  

• CLAP: Copy cstrip2.clap to:

  C:\Program Files\Common Files\CLAP\
  

macOS (Universal 2: Apple Silicon & Intel)

Extract CStrip2_Visual_macOS_Universal_v0.1.0.zip and copy the desired plugin bundles (CStrip2.vst3, CStrip2.clap, CStrip2.component) to either your per-user directory (recommended, does not require administrator privileges) or the global system directory:

• Per-User Installation (Recommended):
  • VST3: ~/Library/Audio/Plug-Ins/VST3/
  • CLAP: ~/Library/Audio/Plug-Ins/CLAP/
  • AUv2: ~/Library/Audio/Plug-Ins/Components/
• Global System Installation (All users):
  • VST3: /Library/Audio/Plug-Ins/VST3/
  • CLAP: /Library/Audio/Plug-Ins/CLAP/
  • AUv2: /Library/Audio/Plug-Ins/Components/

Safe macOS Gatekeeper Authorization Procedure

Because this free open-source build uses an ad-hoc code signature rather than commercial Apple Developer ID notarization, macOS may prompt for authorization on first launch:

1. Step 1 — Authorize via System Settings (Recommended Primary Method):
   • Copy the plugin to your chosen Plug-Ins folder and open your DAW.
   • If macOS displays a warning that the developer cannot be verified or blocks the plugin:
     1. Open System Settings (or System Preferences) > Privacy & Security.
     2. Scroll down to the Security section where the blocked plugin message appears.
     3. Click "Allow Anyway" (or "Open Anyway"), authenticate with your macOS password if prompted, and confirm "Open" when rescanning or loading the plugin in your DAW.
2. Step 2 — Targeted Quarantine Removal via Terminal (Only if necessary):
   • Only if your DAW scans plugins silently in the background without triggering the System Settings prompt, remove specifically the com.apple.quarantine attribute from the affected bundle in Terminal:
   • Per-user installation:

     xattr -dr com.apple.quarantine ~/Library/Audio/Plug-Ins/VST3/CStrip2.vst3
     xattr -dr com.apple.quarantine ~/Library/Audio/Plug-Ins/CLAP/CStrip2.clap
     xattr -dr com.apple.quarantine ~/Library/Audio/Plug-Ins/Components/CStrip2.component

   • Global installation:

     sudo xattr -dr com.apple.quarantine /Library/Audio/Plug-Ins/VST3/CStrip2.vst3
     sudo xattr -dr com.apple.quarantine /Library/Audio/Plug-Ins/CLAP/CStrip2.clap
     sudo xattr -dr com.apple.quarantine /Library/Audio/Plug-Ins/Components/CStrip2.component

   • Security note: Target only com.apple.quarantine on the specific plugin bundle and never disable Gatekeeper globally.

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Documentation (docs/)

All official user manuals, quick-start guides, and the macOS installation guide are included in the docs/ directory as well as inside the release packages:

Document	Language	Link
User Manual	English	docs/CStrip2_Visual_User_Manual_EN.pdf
Quick Start Guide	English	docs/CStrip2_Visual_Quick_Start_EN.pdf
Manual de Usuario	Español	docs/CStrip2_Visual_Manual_ES.pdf
Guía Rápida	Español	docs/CStrip2_Visual_Guia_Rapida_ES.pdf
Guía de Instalación en macOS	Español	docs/CStrip2_Visual_Guia_Instalacion_macOS_ES.pdf

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Building from Source & Corresponding Source (GPLv3)

Building from this Git Repository (Online Dependencies)

With a standard Rust stable toolchain installed:

# Run the 85-test DSP and GUI verification suite
cargo test -p cstrip2 --locked

# Build VST3 and CLAP bundles for the host platform
cargo xtask bundle cstrip2 --release

On macOS, Universal 2 (arm64 + x86_64) VST3, CLAP, and self-contained AUv2 bundles are built using cargo xtask bundle-universal cstrip2 --release and cmake/auv2/CMakeLists.txt as automated in .github/workflows/build-macos.yml.

Complete Offline Corresponding Source Archive

In compliance with Sections 1 and 6 of the GNU General Public License v3.0, the official GitHub Release (v0.1.0) provides the dedicated archive:

• CStrip2_Visual_Source_v0.1.0.zip (SHA-256: 89a8d873f05b13fb06d770ce4de68b06f8e03f5ce56feda0a6af9db99d2f3173)

Unlike GitHub's automatically generated "Source code (zip / tar.gz)" snapshots (which only archive the Git tree), CStrip2_Visual_Source_v0.1.0.zip includes the complete offline vendor/ directory (276 external Rust dependencies from crates.io and Git, out of the 278 total packages in Cargo.lock alongside the 2 workspace crates cstrip2 and xtask) plus the exact pinned sources of clap-wrapper (v0.16.0), clap (1.2.3), and AudioUnitSDK (1.1.0) for air-gapped builds (--locked --offline).

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License & Third-Party Notices

CStrip2 Visual is distributed under the terms of the GNU General Public License v3.0 or later (GPL-3.0-or-later).

• LICENSE — Full GNU GPLv3 license text.
• THIRD_PARTY_NOTICES.md — Complete third-party license texts and verified copyright notices.
• CORRESPONDING_SOURCE_MANIFEST.md — Technical manifest of the Corresponding Source and dependency graph.
• AIRWINDOWS_NOTICE.txt — Original MIT license and copyright notice by Chris Johnson (Airwindows).
• CLAP_NOTICE.txt — MIT notices for CLAP SDK 1.2.3, clap-sys, and clap-wrapper.
• STEINBERG_VST3_NOTICE.txt — VST3 SDK licensing context, vst3-sys GPLv3 notice, and Steinberg trademark notice.
• APPLE_AUDIOMAC_NOTICE.txt — Apache License 2.0 notice for Apple AudioUnitSDK.

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Credits & Acknowledgments

• Chris Johnson (Airwindows): Creator and author of the original CStrip2 DSP algorithms (Capacitor, ButterComp, 3-Band EQ, Spiral/Density Output saturation, and Airwindows Floating Point Dither), released under the MIT License.
• Javier Alarco: Special thanks for his collaboration on the macOS installation guide and validation testing on an Apple MacBook Pro M3 running Ableton Live 12.
• Open-Source Ecosystem: Built with NIH-plug by Robbert van der Helm, egui by Emil Ernerfeldt, clap-wrapper, CLAP, and Apple AudioUnitSDK.

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Español

CStrip2 Visual (v0.1.0) traslada el carácter sonoro del channel strip CStrip2 de Chris Johnson (Airwindows) a una interfaz visual moderna, clara e intuitiva para mezcla y producción musical. Reúne cuatro etapas de procesamiento en una sola ventana —filtros de limpieza de extremos, compresión dinámica expresiva, ecualizador de 3 bandas y etapa de salida con saturación armónica progresiva— junto con un analizador espectral en tiempo real, curva de respuesta interactiva (Tone Curve) y comparación instantánea A/B.

Etapas de procesamiento y funciones principales

1. Capacitor (Filtros de entrada): Filtros de paso alto (Hi-Pass) y paso bajo (Lo-Pass) basados en el array IIR no lineal intercalado de 6 etapas de Airwindows (no utiliza filtros Butterworth convencionales).
2. ButterComp (Compresor dinámico): Compresor no lineal de Airwindows con seguimiento independiente de semiciclos positivos y negativos, alternancia bipolar por muestra y suavizado de doble velocidad (Compres y Speed; no incluye expansor ni puerta de ruido).
3. EQ de 3 Bandas: Graves (Bass, Bass Frq), medios (Mid) y agudos (Treble, Treb Frq) con división complementaria y corrección armónica cúbica.
4. Output (Salida y Saturación): Control de salida con ganancia unitaria en aproximadamente 0.333 (un tercio del recorrido, siendo 0.33 el valor predeterminado del control), saturación progresiva Spiral y Density al incrementar el nivel, y etapa final Airwindows Floating Point Dither.
5. Analizador Espectral y Curva de Tono (Tone Curve): Analizador FFT estéreo en tiempo real libre de bloqueos (IN, OUT, BOTH), curva de respuesta combinada de Capacitor + EQ, medidores de nivel y reducción de ganancia (GR), gestor de presets y comparador A/B.

Formatos e Instalación

• Windows (x86_64): cstrip2.vst3 (copiar en C:\Program Files\Common Files\VST3\) y cstrip2.clap (copiar en C:\Program Files\Common Files\CLAP\).
• macOS (Universal 2: Apple Silicon arm64 + Intel x86_64): CStrip2.vst3, CStrip2.clap y CStrip2.component (AUv2 autónomo).
  • Instalación por usuario (recomendada): ~/Library/Audio/Plug-Ins/{VST3,CLAP,Components}/
  • Instalación global: /Library/Audio/Plug-Ins/{VST3,CLAP,Components}/
  • Autorización segura en macOS (Gatekeeper):
    1. Primero intente autorizar el plugin desde Ajustes del Sistema > Privacidad y seguridad > Seguridad pulsando "Permitir de todos modos" ("Abrir de todas formas").
    2. Solo si fuera necesario porque el DAW bloquee el escaneo en segundo plano, elimine específicamente el atributo com.apple.quarantine del plugin afectado mediante Terminal (xattr -dr com.apple.quarantine <ruta_del_plugin>). Consulte INSTALACION_MACOS.txt y docs/CStrip2_Visual_Guia_Instalacion_macOS_ES.pdf.

Documentación, Código Fuente y Créditos

• Manuales y guías en español e inglés disponibles en la carpeta docs/.
• Código Fuente Correspondiente (GPLv3): En la página de Releases se incluye el paquete CStrip2_Visual_Source_v0.1.0.zip con las 276 dependencias externas de Rust archivadas en vendor/ (de los 278 paquetes totales de Cargo.lock, junto a los 2 crates propios cstrip2 y xtask) y los SDKs nativos fijados para compilación offline.
• Créditos: Algoritmo DSP original por Chris Johnson / Airwindows (bajo licencia MIT). Agradecimiento especial a Javier Alarco por su colaboración en la guía de instalación de macOS y por las pruebas de validación en un MacBook Pro M3 con Ableton Live 12.