Show HN: DIY virtual HDMI monitor using "AR" glasses

Attention this is still in early development and not fully functional yet. It will work but performance needs to be improved a lot.

v4l2_gl captures video from a HDMI-in on an OrangePI 5 Plus using the hdmirx V4L2 device, converts frames to RGB, and displays them in real-time on a textured quad in an OpenGL window. It supports Viture headset IMU integration, test patterns, and plane geometry.

To run this as intended you need an OrangePi 5 Plus with armbian ( we are using BredOS ) that has Device Tree Overlays enabled and has the hdmi-rx device tree overlay active.

If you are using a Raspberry Pi or other device without HDMI-in you need a USB capture card that is supported on your Linux version

For testing purposes you can run it on a laptop with a webcam but that does not provide you with a virtual display.

This requires a linux based OS and installed gcc and build tools.

To compile and run this application, ensure the following libraries are installed:

• OpenGL and GLUT libraries: These are essential for creating the window and rendering graphics. On Debian/Ubuntu-based systems, you can install them using:

  sudo apt update sudo apt install freeglut3-dev

• libv4l2 library:

  sudo apt install libv4l-dev

• libhidapi-dev (optional): If your are using the revers engineered protocol instead of the official Viture SDK

  sudo apt install libhidapi-dev

Depending on the architecture you are running it on use the reverse engineered protocol version ( ARM ) or the official Viture SDK version ( X86 )

This will generate the executable v4l2_gl

This will generate the executable v4l2_gl_viture_sdk

Execute the compiled application from your terminal:

or

Quickly shake your head left/right 3 times to reset the rotation to the center position after the IMU has drifted too far.

The application supports the following command-line options:

• --device <path>: Specifies the V4L2 device path (e.g., /dev/video0). Default: /dev/video0. Example: ./v4l2_gl --device /dev/video1

• --fullscreen: Runs the application in fullscreen mode. Default: false (disabled). Example: ./v4l2_gl --fullscreen

• --viture: Enables integration with Viture headset IMU for controlling the rotation of the displayed plane. The Viture SDK and device must be correctly set up. Default: false (disabled). Example: ./v4l2_gl --viture

• --test-pattern: Displays a generated test pattern on the plane instead of the live camera feed. Useful for testing rendering and transformations. Default: false (disabled). Example: ./v4l2_gl --test-pattern

• --plane-distance <distance>: Sets the distance at which the plane orbits the world origin. <distance> is a floating-point value. Default: 1.0. Example: ./v4l2_gl --plane-distance 0.5

• --plane-scale <scale>: Sets a scale multiplier for the size of the plane. <scale> is a floating-point value (must be > 0). Default: 1.0 (original size). Values greater than 1.0 enlarge the plane, less than 1.0 shrink it. Values <= 0.0 are reset to 1.0. Example: ./v4l2_gl --plane-scale 1.5

You can combine these options:

This command would:

• Use V4L2 device /dev/video1.
• Enable Viture IMU.
• Run in fullscreen.
• Set the plane orbit distance to 0.8 units.
• Scale the plane to 120% of its original size.
• Display the test pattern.

• Add support for USB HDMI capture cards to support SBCs that don't have HDMI-in like Raspberry PIs
• Fix errors in reverse engineered viture SDK
• Improve performance of the hdmi texture conversion
• Support MJPEG format to increase framerate of USB capture cards
• Add quick gesture to recenter the rotation
• Add curved screen option