PrismGB

A desktop streaming and capture application for the Mod Retro Chromatic

Installation • Features • Usage • Architecture • Troubleshooting • License

DISCLAIMER

This is an unofficial, community-developed application.

PrismGB is not affiliated with, endorsed by, or sponsored by Mod Retro. The Chromatic is a product of Mod Retro.

For official Chromatic support and information, please visit modretro.com.

PrismGB is a free, open-source desktop application that lets you stream and capture video from your Mod Retro Chromatic handheld gaming device. Connect your Chromatic via USB and enjoy your gameplay on a larger screen, take screenshots, or record your gaming sessions with GPU-accelerated rendering and professional-grade video output.

Features

Video Streaming & Display

Render Presets

PrismGB includes 6 carefully tuned render presets:

Capture & Recording

User Interface

Device Support

Requirements

• A Mod Retro Chromatic device
• USB connection to your computer
• Windows 10+, macOS 10.15+, or Linux (Ubuntu 18.04+, Fedora, Arch, etc.)

Supported Devices

Installation

Download Pre-built Releases

Download the latest release for your operating system from the Releases page:

Note: Replace x.x.x with the actual version number (e.g., 1.2.1).

Windows Installation

Using the Installer (recommended):

1. Download PrismGB-Setup-x.x.x.exe
2. Run the installer and follow the prompts
3. Launch PrismGB from the Start Menu or desktop shortcut

Using the Portable Version:

1. Download PrismGB-x.x.x-portable.exe
2. Run the executable directly - no installation required
3. Great for USB drives or systems where you can't install software

macOS Installation

1. Download the appropriate DMG for your Mac:
   • Apple Silicon (M1/M2/M3/M4): PrismGB-x.x.x-mac-arm64.dmg
   • Intel: PrismGB-x.x.x-mac-x64.dmg
2. Open the DMG file
3. Drag PrismGB to your Applications folder
4. Launch PrismGB from your Applications folder or Spotlight

Tip: Not sure which Mac you have? Click the Apple menu → "About This Mac". If it says "Apple M1/M2/M3/M4", use the ARM64 version. If it says "Intel", use the x64 version.

Linux Installation

Option 1: AppImage (recommended for most users)

# Make the AppImage executable
chmod +x PrismGB-x.x.x-linux-x64.AppImage    # Intel/AMD
chmod +x PrismGB-x.x.x-linux-arm64.AppImage  # ARM64

# Run the application
./PrismGB-x.x.x-linux-x64.AppImage    # Intel/AMD
./PrismGB-x.x.x-linux-arm64.AppImage  # ARM64

AppImages are self-contained and work on most Linux distributions without installation.

Option 2: Debian/Ubuntu (.deb)

# Install the package (automatically installs libusb dependency)
sudo dpkg -i PrismGB-x.x.x-linux-x64.deb    # Intel/AMD
sudo dpkg -i PrismGB-x.x.x-linux-arm64.deb  # ARM64

# If there are dependency errors, run:
sudo apt-get install -f

Option 3: Tar Archive

# Extract the archive
tar -xzf PrismGB-x.x.x-linux-x64.tar.gz
tar -xzf PrismGB-x.x.x-linux-arm64.tar.gz

# Run PrismGB from the extracted folder
./PrismGB-x.x.x-linux-x64/prismgb
./PrismGB-x.x.x-linux-arm64/prismgb

Required: USB Library

PrismGB requires libusb for USB device communication. Install it if not already present:

# Debian/Ubuntu
sudo apt install libusb-1.0-0

# Fedora
sudo dnf install libusb

# Arch Linux
sudo pacman -S libusb

Building from Source

If you're building from source (or if prebuilt binaries aren't available for your Node.js version), you'll need additional build tools:

# Debian/Ubuntu
sudo apt install build-essential python3 libusb-1.0-0-dev libudev-dev

# Fedora
sudo dnf install gcc gcc-c++ make python3 libusb-devel systemd-devel

# Arch Linux
sudo pacman -S base-devel python libusb

See DEVELOPMENT.md for full build instructions.

Usage

1. Connect your Chromatic to your computer via USB
2. Launch PrismGB
3. Click the video area to start streaming
4. Use the control buttons to:
   • Take a screenshot
   • Start/stop video recording
   • Choose a render preset
   • Adjust brightness and volume
   • Toggle the notes panel
   • Enter fullscreen mode
   • Toggle cinematic mode for a cleaner viewing experience
5. Open the settings menu to manage:
   • Status strip visibility
   • Performance mode
   • Fullscreen on startup
   • Recording format (WebM, MP4, MOV)
   • Update checks and installs

File Locations

Screenshots and recordings are automatically saved to your Downloads folder:

• Screenshots: prismgb-screenshot-YYYYMMDD-HHMMSS.png
• Recordings: prismgb-recording-YYYYMMDD-HHMMSS.<format> (WebM, MP4, or MOV based on settings)

Settings

Local Data

• Settings and notes are stored locally in browser localStorage
• Device IDs are cached locally to speed up reconnects
• Clear app data to reset all settings

Architecture

PrismGB uses a modern three-process Electron architecture with clean separation of concerns:

┌─────────────────────────────────────────────────────────────────────────┐
│                              Main Process                                │
│  ┌─────────────┐ ┌─────────────┐ ┌─────────────┐ ┌─────────────────────┐│
│  │   Window    │ │    Tray     │ │   Device    │ │     Transcode       ││
│  │  Service    │ │   Service   │ │   Service   │ │      Service        ││
│  └─────────────┘ └─────────────┘ └─────────────┘ └─────────────────────┘│
│  ┌─────────────┐ ┌─────────────┐ ┌───────────────────────────────────┐  │
│  │   Update    │ │ Performance │ │         IPC Handler Registry      │  │
│  │   Service   │ │   Metrics   │ │                                   │  │
│  └─────────────┘ └─────────────┘ └───────────────────────────────────┘  │
└────────────────────────────────┬────────────────────────────────────────┘
                                 │ IPC (contextBridge)
┌────────────────────────────────┴────────────────────────────────────────┐
│                            Preload Script                                │
│                     (Secure IPC bridge, no Node.js)                      │
└────────────────────────────────┬────────────────────────────────────────┘
                                 │
┌────────────────────────────────┴────────────────────────────────────────┐
│                           Renderer Process                               │
│  ┌─────────────────────────────────────────────────────────────────────┐│
│  │                      Streaming Orchestrator                          ││
│  │  ┌───────────────┐ ┌───────────────────┐ ┌───────────────────────┐  ││
│  │  │   Streaming   │ │  Render Pipeline  │ │    GPU Render Loop    │  ││
│  │  │    Service    │ │  (4-pass shader)  │ │   (WebGL2/WebGPU)     │  ││
│  │  └───────────────┘ └───────────────────┘ └───────────────────────┘  ││
│  └─────────────────────────────────────────────────────────────────────┘│
│  ┌─────────────────────────────────────────────────────────────────────┐│
│  │                       Capture Orchestrator                           ││
│  │  ┌───────────────┐ ┌───────────────────┐ ┌───────────────────────┐  ││
│  │  │   Capture     │ │   GPU Recording   │ │    Save Service       │  ││
│  │  │   Service     │ │     Service       │ │  (format routing)     │  ││
│  │  └───────────────┘ └───────────────────┘ └───────────────────────┘  ││
│  └─────────────────────────────────────────────────────────────────────┘│
│  ┌──────────────┐ ┌──────────────┐ ┌──────────────┐ ┌──────────────────┐│
│  │   Device     │ │   Settings   │ │    Notes     │ │      Update      ││
│  │   Service    │ │   Service    │ │   Service    │ │     Service      ││
│  └──────────────┘ └──────────────┘ └──────────────┘ └──────────────────┘│
│  ┌─────────────────────────────────────────────────────────────────────┐│
│  │                          UI Layer                                    ││
│  │   Shell • Toolbar • Settings Menu • Notes Panel • Status Strip      ││
│  └─────────────────────────────────────────────────────────────────────┘│
└─────────────────────────────────────────────────────────────────────────┘

Key Patterns

GPU Rendering Pipeline

The 4-pass shader pipeline processes each frame:

1. Pass 1: Upscale - Bilinear/nearest-neighbor scaling to output resolution
2. Pass 2: Unsharp Mask - Edge sharpening (configurable strength 0.0-0.8)
3. Pass 3: Color Elevation - Gamma, saturation, brightness, contrast, green bias
4. Pass 4: CRT/LCD - Scanlines, pixel mask, bloom, curvature, vignette

Technology Stack

Troubleshooting

Device Not Detected

1. Ensure your Chromatic is powered on and connected via USB
2. Try a different USB port or cable
3. On Linux, you may need to configure udev rules for USB access
4. Restart the application after connecting the device

Video Not Displaying

1. Click on the video area to initiate the stream
2. Check that no other application is using the Chromatic's video feed
3. Try disconnecting and reconnecting the device

GPU or Rendering Issues

1. Enable Performance Mode in Settings to reduce rendering load
2. Disable GPU acceleration by launching with PRISMGB_DISABLE_GPU=1

App Keeps Running After Closing the Window

PrismGB stays in the system tray so device monitoring can continue. Use the tray icon and choose Quit to exit.

Permission Issues (Linux)

If you encounter USB permission errors, you have two options:

Option 1: Add user to plugdev group

sudo usermod -a -G plugdev $USER

Log out and back in for changes to take effect.

Option 2: Create a udev rule (recommended)

Create a file /etc/udev/rules.d/99-chromatic.rules with this content:

# Mod Retro Chromatic
SUBSYSTEM=="usb", ATTR{idVendor}=="374e", ATTR{idProduct}=="0101", MODE="0666"

Then reload udev rules:

sudo udevadm control --reload-rules
sudo udevadm trigger

Reconnect your Chromatic after applying the rule.

Recording Format Issues

If transcoding fails, ensure FFmpeg binaries are included in the application package.

Documentation

Testing

PrismGB includes comprehensive test coverage:

Run tests:

npm test              # Watch mode
npm run test:run      # Single run
npm run test:coverage # Coverage report
npm run test:e2e      # E2E tests

Coverage thresholds: 80% line/function/statement, 75% branches.

Contributing

Contributions are welcome! See DEVELOPMENT.md for build instructions and CONTRIBUTING.md for guidelines.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Trademark: PrismGB™ and the gem logo are trademarks of josstei. See TRADEMARK for usage guidelines.

Acknowledgments

• Mod Retro for creating the Chromatic handheld

Support

If you find PrismGB useful, consider supporting its development: