A C++ library for overlaying animated sign language subtitles on videos, enhancing accessibility for deaf and hard-of-hearing individuals.

This library processes videos by adding sign language subtitles based on provided subtitle tracks. It features dynamic animations that reflect subtitle intensity, supporting three levels:

• High Intensity: Subtitles grow progressively larger
• Medium Intensity: Subtitles oscillate with ±15 degrees rotation
• Low Intensity: Subtitles remain static

• Overlay sign language subtitles on video frames
• Support for intensity-based animations
• Multi-word subtitle handling with vertical stacking
• Dynamic subtitle track processing via JSON input
• Automatic video processing and subtitle embedding

• C++ Compiler (GCC 9+ or equivalent)
• CMake (Build system generator)
• OpenCV (Video processing and image manipulation)
• nlohmann/json (JSON subtitle track parsing)

sudo apt-get update
sudo apt-get install -y build-essential cmake libopencv-dev

git clone https://github.com/your-repo/sign-language-subtitle-processor.git
cd sign-language-subtitle-processor

mkdir build
cd build
cmake ..
make

The library is accessed through the video_overlay executable:

./video_overlay <input_video> <subtitles_json> <image_folder> <output_video>

Example:

./video_overlay ../src/input.mp4 ../src/subtitles.json ../images/ ../src/output.mp4

[
    {
        "term": "Header Goal",
        "start_time": 1.00,
        "end_time": 4.00,
        "intensity": "High"
    },
    {
        "term": "Welcome Goal",
        "start_time": 5.00,
        "end_time": 8.00,
        "intensity": "Medium"
    }
]

Place sign language gesture images in the images/ folder:

• Required format: PNG files named a.png through z.png
• Each image represents a single character's sign language gesture

.
├── src/
│   ├── VideoProcessor.cpp/h
│   ├── SubtitleTrack.cpp/h
│   ├── ImageLoader.cpp/h
│   ├── SignLanguageCombiner.cpp/h
│   ├── OverlayManager.cpp/h
│   └── main.cpp
├── include/
├── images/
├── subtitles.json
├── input.mp4
├── output.mp4
├── CMakeLists.txt
└── README.md

Words are stacked vertically for improved readability:

Header
Goal

• High Intensity: Progressive scaling effect
• Medium Intensity: Smooth ±15° rotation
• Low Intensity: Static display
• Dynamic scaling to fit video frame

1. Missing Dependencies

   • Verify OpenCV and nlohmann/json installation
   • Check CMakeLists.txt for correct library paths

2. Incorrect File Paths

   • Confirm paths to input.mp4, subtitles.json, and images/

3. Clipping/Missing Subtitles

   • Ensure images/ contains all required character images (a-z)

• Additional language and alphabet support
• Real-time video processing capabilities
• Customizable subtitle animations and styles

We welcome contributions! Please:

1. Fork the repository
2. Create a feature branch
3. Submit a pull request