SmartCompress

Real-time automatic multi-format file compression for Windows

Watches a folder for supported files, compresses them with high visual quality, and saves them to an output folder — automatically, silently, forever.

💡 Why I Built This

I wanted a lightweight local automation tool that could continuously compress files without relying on cloud services or manual processing.

Most existing tools were either:

• online only
• bloated
• subscription-based
• not automated

So I decided to build my own.

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✨ What It Does

INPUT/                               OUTPUT/
  ├── report.pdf        ──────►      ├── comp_report.pdf       ✔ compressed
  ├── image.jpg         ──────►      ├── comp_image.jpg        ✔ compressed
  ├── photo.png         ──────►      ├── comp_photo.png        ✔ compressed
  ├── comp_old.pdf      (skip)       └── ...
  └── notes.txt         (ignore)

• Monitors INPUT continuously using OS-level file events (no polling loop)
• Processes existing supported files in INPUT on startup
• Waits for file transfers to finish before compressing
• Supports multiple formats:
  • PDF
  • JPG / JPEG
  • PNG
  • WEBP
• Compresses PDFs with high visual quality optimisation
• Compresses images while preserving original format
• Renames output as comp_<originalname>
• Saves compressed files to OUTPUT, leaving originals untouched
• Ignores unsupported files and already-compressed files silently
• Logs all activity to logs/watcher.log
• Uses ~0% CPU while idle (fully event-driven)

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🚧 Planned Features

• Video compression
• Drag-and-drop UI
• Compression presets
• EXE installer
• Batch processing

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⚡ Automation Features

This project was designed to run fully autonomously in the background with minimal user interaction.

Current automation capabilities include:

• Silent background execution using pythonw
• Windows startup automation via shell:startup
• Optional Task Scheduler integration
• Standalone executable support using PyInstaller
• Continuous real-time folder monitoring
• Automatic file detection and processing
• Logging system for debugging and monitoring
• Lightweight idle performance (~0% CPU usage)

The system has been repeatedly tested across:

• system restarts
• startup execution
• silent background runs
• EXE-based deployment workflows

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📁 Project Structure

SmartCompress/
│
├── watcher.py          ← Main program (monitoring + compression logic)
├── config.py           ← YOUR settings (edit folder paths here)
├── requirements.txt    ← Python package dependencies
│
├── run.bat             ← Launch with a visible terminal window (easy debugging)
├── run_silent.pyw      ← Launch silently in background (no window)
├── stop.bat            ← Stop the background process
├── startup.vbs         ← Drop in Windows Startup folder for autostart on boot
│
├── build_exe.spec      ← Optional: build a standalone .exe with PyInstaller
│
└── logs/
    └── watcher.log     ← All activity and errors are logged here

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🚀 Setup (Step-by-Step)

Step 1 — Install Python

1. Go to https://www.python.org/downloads/
2. Click the big yellow "Download Python 3.x.x" button
3. Run the installer
4. ⚠️ Important: Check ✅ "Add Python to PATH" at the bottom of the first screen
5. Click "Install Now"

To verify it worked, open Command Prompt (Win+R → type cmd → Enter) and run:

python --version

You should see something like Python 3.12.3.

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Step 2 — Download / Place the Project

Save the entire SmartCompress folder somewhere permanent, for example:

C:\Users\YourName\Documents\SmartCompress\

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Step 3 — Edit config.py

Open config.py in Notepad (right-click → Open With → Notepad).

Change these two lines to your actual folder paths:

FOLDER_A = r"C:\Users\YourName\Documents\INPUT"   # watch this folder
FOLDER_B = r"C:\Users\YourName\Documents\OUTPUT"   # save compressed files here

Tips:

• Use r"..." (note the r before the quote) to avoid issues with backslashes
• Both folders must exist before running (Folder B is auto-created if missing)
• You can use any folder paths, including network drives like r"\\server\share\pdfs"

Optionally adjust compression quality (default 85 is excellent):

JPEG_QUALITY = 85    # 75 = smaller files, 92 = near-lossless

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Step 4 — Install Dependencies

Double-click run.bat — it will automatically install all required packages the first time you run it.

Or install manually via Command Prompt:

cd C:\Users\YourName\Documents\SmartCompress
pip install -r requirements.txt

This installs:

Package	Purpose
watchdog	Efficient OS-level folder monitoring
pypdf	Pure-Python PDF manipulation
Pillow	Image recompression within PDFs

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Step 5 — Run It!

Option A — With a terminal window (recommended for first use): Double-click run.bat

You'll see live output like:

2024-01-15 10:30:00  [INFO]  SmartCompress starting up
2024-01-15 10:30:00  [INFO]  Watching : C:\Users\You\Documents\INPUT
2024-01-15 10:30:00  [INFO]  Output   : C:\Users\You\Documents\OUTPUT
2024-01-15 10:30:00  [INFO]  → Detected: quarterly_report.pdf
2024-01-15 10:30:01  [INFO]    ✔ Compressed: 4.2 MB → 1.8 MB (57.1% smaller)
2024-01-15 10:30:01  [INFO]  Watching for supported files... (press Ctrl+C to stop)

Option B — Silent background (no window): Double-click run_silent.pyw

Nothing visible happens — the program runs quietly in the background. Check logs/watcher.log to confirm it's working.

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🔄 Run Automatically on Windows Startup

Recommended method: Windows Task Scheduler for silent startup automation.

startup.vbs is included as optional legacy support.

To start the compressor automatically every time you log into Windows:

1. Press Win+R, type shell:startup, press Enter → A folder opens (this is your Startup folder)

2. Open startup.vbs in Notepad and change this line:

   SCRIPT_PATH = "C:\Users\YourName\Documents\SmartCompress\run_silent.pyw"

   to match where you saved the project.

3. Copy startup.vbs into the Startup folder that opened in step 1.

4. Test it: Double-click startup.vbs — the watcher should start silently. Check logs/watcher.log to confirm.

5. On next login, it starts automatically. ✅

To remove autostart: Delete startup.vbs from the Startup folder.

To stop the background process: Double-click stop.bat

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📦 Optional: Build a Standalone .exe

If you want to share this tool with someone who doesn't have Python installed, you can build a single self-contained executable.

Install PyInstaller:

pip install pyinstaller

Build:

cd C:\Users\YourName\Documents\SmartCompress
pyinstaller build_exe.spec

Result:

dist\watcher\watcher.exe

Share the entire dist\watcher\ folder. The recipient just needs to:

1. Edit config.py inside the folder with their paths
2. Double-click watcher.exe

No Python installation required on their machine. ✅

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📋 Logs

All activity is saved to logs/watcher.log.

Example log output:

2024-01-15 09:00:00  [INFO]  ============================
2024-01-15 09:00:00  [INFO]  PDF Auto-Compressor starting
2024-01-15 09:00:00  [INFO]  Watching : C:\...\INPUT
2024-01-15 09:00:00  [INFO]  → Detected: contract.pdf
2024-01-15 09:00:01  [INFO]    ✔ Compressed: contract.pdf  8.3 MB → 2.1 MB (74.7% smaller)
2024-01-15 09:05:12  [INFO]  → Detected: scan.pdf
2024-01-15 09:05:13  [INFO]    ✔ Compressed: scan.pdf  12.0 MB → 3.4 MB (71.7% smaller)

The log file never grows unbounded — rotate it manually or let it grow (it's text, very compact).

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🛠 Troubleshooting

Problem	Solution
python not found	Re-install Python and check "Add to PATH"
pip install fails	Run Command Prompt as Administrator
File not being detected	Check Folder A path in config.py is correct
Output looks wrong	Raise JPEG_QUALITY in config.py to 92
No size reduction	PDF may contain vector art only (no images to compress) — this is fine, the file is still losslessly optimised
Process won't stop	Open Task Manager → Details tab → find pythonw.exe → End Task

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⚙️ How the Compression Works

The tool uses a two-stage approach for maximum quality-to-size ratio:

Stage 1 — Image recompression Each page's embedded images are extracted, decoded, re-encoded as JPEG at the configured quality level (default 85/100), and put back. Images are only replaced if the result is actually smaller. Vector graphics, text, and page structure are untouched.

Stage 2 — Lossless structural optimisation Duplicate PDF objects are merged, orphan objects are removed, and streams are compressed. This is always lossless and costs nothing in visual quality.

What's NOT changed:

• Text content
• Vector graphics / diagrams
• Page structure and layout
• Fonts
• Metadata (author, title, etc.)
• Original file (always kept)

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📦 Dependencies

Package	Version	License	Why
watchdog	4.0.1	Apache 2.0	OS-level folder monitoring
pypdf	4.3.1	BSD	PDF read/write, object deduplication
Pillow	10.3.0	HPND	JPEG image recompression

All are permissively licensed and safe for personal and commercial use.

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Built with Python 3.10+ • Tested on Windows 10/11