🛡️ Sentinel: High-Performance Multithreaded Security System

A latency-optimized security application built with C++ and OpenCV, featuring a Producer-Consumer architecture for asynchronous video processing.

📖 Overview

Sentinel is a smart surveillance system designed to solve the "dropped frame" problem common in single-threaded security apps. By decoupling frame capture from image processing, Sentinel ensures zero-latency monitoring even during high-load I/O operations (like writing video evidence to disk).

It features a Smart Hysteresis Recording System that prevents file fragmentation by maintaining a recording buffer for 5 seconds after motion stops, mimicking professional DVR behavior.

🚀 Key Technical Features

• Multithreaded Architecture: Uses a Producer-Consumer pattern. Thread 1 captures hardware frames; Thread 2 handles Computer Vision (Gaussian Blur, Thresholding) and Disk I/O.
• Memory Safety (RAII): Implements std::lock_guard for deadlock prevention and a Leaky Bucket ring buffer to cap memory usage.
• Smart Recording: Uses std::chrono timers to manage state transitions (Active vs. Buffering) and generates timestamped evidence_HH-MM-SS.avi files.

🛠️ Tech Stack

• Language: C++20 (Modern C++)
• Library: OpenCV 4.12.0
• Concurrency: std::thread, std::mutex, std::atomic
• IDE: Visual Studio 2026

📂 Project Structure

Sentinel/
├── SentinelSystem.h    # Header: Interface and Member declarations
├── SentinelSystem.cpp  # Source: Implementation of Threading & Vision Logic
└── main.cpp            # Entry Point: Instantiates the System

🔧 Build & Run

1. Prerequisites

• Visual Studio 2026 (Desktop C++ Workload).
• OpenCV 4.12.0 (Add opencv\build\x64\vc16\bin to System Path).

2. Setup

1. Clone:

   git clone https://github.com/Utkarsh-Dikshit/Sentinel.git

2. Link OpenCV: Open Sentinel.sln. Right-click Project → Properties:
   • Include Dir: Point to opencv\build\include
   • Library Dir: Point to opencv\build\x64\vc16\lib
   • Input: Add opencv_world4120.lib

3. Execution

1. Build: Set to x64 (Debug or Release) and press Ctrl+Shift+B.
2. Run: Press F5.
   • 🔴 REC: Motion Detected.
   • 🟡 BUFFER: 5s Cooldown (Hysteresis).
   • Quit: Press q.