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🎤 MICFix — Microphone Volume Lock Service

A lightweight Windows service (DLL) that permanently locks your default microphone volume to a specified level. No matter what — system changes, apps resetting volume, or manual adjustments — the volume snaps back instantly.

✨ Key Features

Feature	Description
🔒 Volume Lock	Enforces mic volume even if the system or user changes it
⚡ Zero CPU Usage	Fully event-driven architecture — no polling, no timers
📦 DLL Service	Runs through svchost.exe — no separate .exe process
🔄 Live Config	Edit volume.json → volume updates instantly
🎯 Auto-detect	Automatically follows default microphone changes
🚀 One-Click Install	Single MICFixInstall.exe — run once, done forever
🧹 Clean Uninstall	MICFixUninstall.exe removes everything

🏗️ Architecture

svchost.exe -k MICFixGroup
    └── MICFixService.dll
            ├── IAudioEndpointVolumeCallback  → volume changed? → set it back
            ├── IMMNotificationClient         → mic changed? → re-attach
            └── FindFirstChangeNotification   → config changed? → re-read

How it achieves 0% CPU: The service sleeps in WaitForMultipleObjects and wakes up only when one of these OS-level events fires. No loops, no Sleep() polling, no CPU burn.

📥 Installation

Pre-built (Recommended)

1. Download MICFixService.dll + MICFixInstall.exe from Releases
2. Place both files in the same folder
3. Run MICFixInstall.exe as Administrator
4. ✅ Done! Microphone volume is now locked

Build from Source

Requires MSVC Build Tools 2022 (or Visual Studio with C++ workload).

# Open "Developer Command Prompt for VS 2022"
git clone https://github.com/bangtony2/MicVolumeService.git
cd MicVolumeService
build.bat

Output:

• MICFixService.dll — Service DLL (loaded by svchost.exe)
• MICFixInstall.exe — One-time installer
• MICFixUninstall.exe — Uninstaller

CMake alternative:

cmake -B build -G "Visual Studio 17 2022"
cmake --build build --config Release

⚙️ Configuration

After installation, a config file is created at:

Documents\MICFix\volume.json

{
  "volume": 85
}

• Change the value (0–100) and save — the volume updates instantly
• No need to restart the service

🧹 Uninstall

1. Run MICFixUninstall.exe as Administrator
2. Service is stopped and removed
3. Your config (volume.json) is preserved

🔧 How It Works

Component	Purpose
MICFixService.dll	Core service DLL loaded by svchost.exe
IAudioEndpointVolumeCallback	COM callback — fires when anyone changes mic volume
IMMNotificationClient	COM callback — fires when default mic device changes
FindFirstChangeNotification	Win32 API — fires when volume.json is modified
WaitForMultipleObjects	Sleeps thread until any event fires (0% CPU)

What the Installer Does

1. Creates Documents\MICFix\volume.json (default 85%)
2. Copies MICFixService.dll to C:\ProgramData\MICFix\
3. Registers a svchost group (MICFixGroup)
4. Creates the Windows service with SERVICE_AUTO_START
5. Starts the service immediately

📁 Project Structure

MicVolumeService/
├── MICFixService.cpp    # Service DLL — Core logic (audio, config, events)
├── MICFixService.def    # DLL export definition (ServiceMain)
├── MICFixInstall.cpp    # Installer (run once)
├── MICFixUninstall.cpp  # Uninstaller
├── build.bat            # MSVC build script
├── CMakeLists.txt       # CMake build configuration
└── README.md

📋 Requirements

• OS: Windows 10 / 11
• Build: MSVC Build Tools 2022+ (or Visual Studio with C++ Desktop workload)
• Runtime: None — statically linked (/MT), zero external dependencies

📜 License

MIT