SrtExtractor

Overview

SrtExtractor is a powerful Windows application that extracts and converts subtitles from video files (MKV and MP4) into SRT format. Built with .NET 9 and WPF, it provides an intuitive interface for both single-file and batch processing operations.

🆕 What’s New in v2.6.0

Subtitle Timing and Overlapping:

• Fix for subtitles with overlapping timestamps. When subtitle timestamps overlap (our test show was “The 100”) timestamps would show from the bottom up instead of the top down. Implemented fix to grouping of subtitles to correct for this error.

🆕 What’s New in v2.5.1

Architecture Refactoring & Code Quality:

• 🏗️ Major Code Restructuring - Eliminated God Object anti-pattern from MainViewModel
• 📉 46% Code Reduction - MainViewModel reduced from 2,190 to 1,172 lines
• 🎯 Coordinator Pattern - Introduced 5 focused coordinators for better separation of concerns
• ✨ Better Maintainability - Each coordinator has a single, clear responsibility
• 🧪 Improved Testability - Coordinators can be unit tested independently
• 📚 Enhanced Readability - No file exceeds 600 lines, easier to understand
• 🔧 Zero Breaking Changes - Fully backward compatible, all features preserved

What This Means for You:

• Same powerful features, better code architecture
• Foundation for faster future development
• More reliable and maintainable codebase
• Easier to extend with new features

Key Features

• 🎬 Multi-Format Support: Extract subtitles from both MKV and MP4 files
• 🔄 OCR Conversion: Convert image-based subtitles (HDMV PGS, VobSub) to text
• 🧠 Smart Correction: Intelligent multi-pass OCR correction system
• 📦 Batch Processing: Process multiple files or entire folders at once
• ⚡ Fast & Efficient: Built on .NET 9 for optimal performance
• 🎯 Smart Track Selection: Automatically recommends the best subtitle track
• 🔧 Auto-Detection: Finds and configures external tools automatically

Quick Start

Installation

1. Download the latest installer from the Releases page
2. Run SrtExtractorSetup.exe
3. External tools (MKVToolNix, FFmpeg) are auto-detected or installed

Basic Workflow

1. Load Video: Click “Select File” to choose your MKV or MP4 file
2. Choose Track: Select the subtitle track (or use the recommended one)
3. Configure: Set your preferred language and output options
4. Extract: Click “Extract” to create your SRT file

Smart Features

Intelligent Track Recommendation

SrtExtractor automatically analyzes available subtitle tracks and recommends the best option based on:

• Format Priority: Prefers SubRip/SRT over image-based formats
• Language Match: Considers your preferred language setting
• Forced/CC Status: Respects your subtitle preference settings
• Visual Indicators: Shows 🌟 for recommended tracks in the UI

Multi-Pass OCR Correction

The advanced correction system ensures professional-quality subtitles, powered by ZentrixLabs.OcrCorrection - our comprehensive OCR error correction library with ~841 professionally-tested patterns.

Correction Modes

• Quick Mode (1 pass): Fast processing for obvious errors
• Standard Mode (3 passes): Recommended balance of speed and quality
• Thorough Mode (5 passes): Maximum quality, no stone unturned

Smart Convergence

Automatically stops when no more corrections are found, saving time while ensuring quality.

What It Fixes

• Extra Spaces: T he → The, sh it → shit
• Missing Spaces: Yougotanybiscuits → You got any biscuits
• Character Substitutions: RipIey → Ripley, HeIIo → Hello (capital I ↔ lowercase l)
• Pipe Character Issues: | think → I think, | am → I am (~668 patterns)
• Apostrophe Issues: you)re → you're, dont → don't (~42 patterns)
• Number Confusion: I 00 → 100, $I O → $10 (~20 patterns)
• Spacing Errors: th e → the, confus i on → confusion (~287 patterns)

Real-World Results

• Average: 1,000+ corrections per SRT file
• Large Collections: 80,000+ total corrections across batch operations
• Multi-Pass Benefits: Each pass finds 5–15% additional corrections
• Observed Success Rate: ~99% on our internal test set of 10,000+ subtitles
• Low False Positives: Patterns designed to minimize changes to valid words

Batch Processing

Batch Extraction

Process multiple video files at once:

1. Enable Batch Mode: Toggle the batch processing switch
2. Add Files: Drag & drop or use “Add Files” button
3. Queue Management: Reorder, remove, or clear the queue
4. Process All: Click “Process Batch” to extract from all files
5. Monitor Progress: Real-time progress tracking with file status

Batch SRT Correction

Clean up existing SRT files in bulk:

1. Select Folder: Choose a directory containing SRT files
2. Scan Files: Discover all SRT files (optionally include subfolders)
3. Configure: Choose correction mode and backup options
4. Process: Apply OCR corrections to all files at once
5. Review: See correction counts and detailed statistics

Example Results: 79 files processed with 81,000+ corrections in minutes!

Bundled Tools

All tools are included in the SrtExtractor release - no installation, downloads, or internet connection required!

Tesseract OCR

• Purpose: High-quality OCR for image-based (PGS) subtitles
• Included: tesseract.exe + 51 DLLs (~160 MB)
• Language Data: English training data (eng.traineddata) included
• License: Apache 2.0
• Quality: High accuracy on clear subtitle images in our tests

MKVToolNix

• Purpose: MKV file analysis and subtitle extraction
• Included: mkvmerge.exe, mkvextract.exe + DLLs (~37 MB)
• License: GPL-2.0
• Version: Latest stable release bundled

FFmpeg

• Purpose: MP4 file processing and subtitle extraction
• Included: ffmpeg.exe, ffprobe.exe (~334 MB)
• License: GPL
• Version: Latest stable release bundled

Total Size: ~530 MB (fully portable, zero dependencies)

User Interface

Modern Design

• Clean, intuitive WPF interface
• Real-time progress indicators
• Visual tool status indicators
• Network file detection with time estimates
• Drag & drop support

Dedicated Windows

• Main Window: Single-file extraction interface
• Batch Queue Panel: Multi-file processing management
• Batch SRT Correction: Bulk SRT file cleanup
• About Window: Credits and version information

File Naming Pattern

Customize output filenames with flexible patterns:

Default Pattern: {basename}.{lang}{forced}{cc}.srt

Variables:

• {basename} - Original video filename (without extension)
• {lang} - Subtitle language code
• {forced} - “.forced” if it’s a forced subtitle
• {cc} - “.cc” if it’s a closed caption

Examples:

• Movie.eng.forced.srt
• Show.eng.cc.srt

Settings & Configuration

Subtitle Preferences

• Choose between forced subtitles or closed captions
• Set OCR language (default: English)
• Customize filename patterns

Correction Settings

• Enable/disable multi-pass correction
• Select correction mode (Quick/Standard/Thorough)
• Configure smart convergence
• Set maximum correction passes

Technical Details

Architecture

Built with modern .NET 9 and WPF, SrtExtractor follows the MVVM pattern with clean separation of concerns:

• Models: Data structures for tracks, settings, and tool status
• ViewModels: UI coordination, track selection, and settings management
• Views: XAML-based user interface with modern design
• Coordinators (NEW in v2.5.0): Focused business logic handlers
  • ExtractionCoordinator: Extraction strategies and OCR correction
  • BatchCoordinator: Batch queue management and processing
  • FileCoordinator: File picking, recent files, network detection
  • ToolCoordinator: Tool detection and path management
  • CleanupCoordinator: Temporary file cleanup operations
• Services: External tool integration and file operations
• State: Observable state management for data binding
• Recommendation Engine: Intelligent track selection prioritizing SubRip/SRT over HDMV PGS

Logging

Comprehensive logging system:

• UI Log: Real-time display in application
• File Log: Rolling daily logs in C:\ProgramData\ZentrixLabs\SrtExtractor\Logs\
• Format: srt_YYYYMMDD.txt
• Transparency: Track recommendation decisions are logged

Troubleshooting

Common Issues

1. Tools Not Found: Use “Re-detect Tools” button or check tool installation
2. Extraction Fails: Verify the selected track is a supported format
3. OCR Issues: Ensure Tesseract is properly bundled and available
4. Batch Mode Not Working: Switch to the Batch tab and add files to the queue via drag & drop
5. Network Files Slow: Files on network drives will take longer - this is normal
6. Temporary Files Left Behind: Use the ”🧹 Cleanup Temp Files” button if needed
7. Cancellation Issues: If processes don’t stop, restart the application
8. Batch SRT Correction Shows “None Found”: Ensure you’ve selected a folder and clicked “Scan for SRT Files”
9. SRT Files Not Updating: Check that files aren’t read-only or locked by another application
10. Wrong Track Recommended: Check the log for recommendation decisions; you can manually select a different track

Log Files

Check the log files in C:\ProgramData\ZentrixLabs\SrtExtractor\Logs\ for detailed error information.

Contributing

Contributions are welcome! Please submit issues and pull requests on GitHub.

License

Licensed under the MIT License.

Acknowledgments

• ZentrixLabs.OcrCorrection - Advanced OCR error correction engine
• MKVToolNix - Matroska tools for video container operations
• Subtitle Edit - BluRay SUP parsing library for image-based subtitle conversion
• Tesseract OCR - High-quality optical character recognition engine
• FFmpeg - Complete multimedia framework for MP4 processing

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Developed by ZentrixLabs - Making video processing simple and efficient.

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