HDMI Monitor

Use your laptop as a monitor for another computer (a mini PC, Raspberry Pi, Jetson, console...) through a cheap USB HDMI capture card.

Plug the other computer's HDMI output into the capture card, plug the card into your laptop, and run hdmi-monitor. You get a low-latency, full-screen picture with sound.

Install

Linux (Ubuntu, Debian, Mint, Fedora, Arch...)

sudo apt install pipx libxcb-cursor0     # Fedora: sudo dnf install pipx xcb-util-cursor
pipx ensurepath                          # then open a new terminal
pipx install hdmi-monitor
hdmi-monitor --create-shortcut           # optional: add it to your applications menu

Windows 10/11

Install Python 3.10 or newer first if you don't have it. Then, in PowerShell:

py -m pip install --user pipx
py -m pipx ensurepath                    # then open a new terminal
pipx install hdmi-monitor
hdmi-monitor --create-shortcut           # optional: add it to the Start menu

If you already use uv, uv tool install hdmi-monitor works on both systems.

Update: pipx upgrade hdmi-monitor · Uninstall: hdmi-monitor --remove-shortcut, then pipx uninstall hdmi-monitor

Why not just use the Camera app?

• It finds the capture card automatically (skipping the built-in webcam) and uses its best mode, e.g. 1920x1080 @ 60 fps.
• It plays the HDMI audio through the laptop speakers.
• True borderless full screen. The mouse pointer hides when idle, and the screen won't sleep or blank.
• It remembers your source, resolution, audio, volume, and window options.
• It reconnects automatically when the capture card is unplugged and plugged back in.
• Only one copy runs at a time, because a capture card can only be read by one program. Opening it again brings the existing window to the front.

Controls

Troubleshooting

• Black picture or "Could not open the capture device": close any other app using the card (Camera, OBS, Teams, Zoom, a browser tab).
• Linux: Could not load the Qt platform plugin "xcb": install libxcb-cursor0 (Debian/Ubuntu) or xcb-util-cursor (Fedora).
• Linux: ImportError: lib....so: cannot open shared object file (only on very minimal installs): on Debian/Ubuntu run sudo apt install libgl1 libegl1 libglib2.0-0 libgssapi-krb5-2 libxkbcommon-x11-0 libpulse0.
• Windows: install fails with a "Long Path" hint: use Python from python.org rather than the Microsoft Store, or enable long paths.
• Linux: no picture, or permission denied: make sure your user can access /dev/video* (usually the video group).
• What did it detect? Run hdmi-monitor --diagnose. After 6 s it writes the devices, mode, and frame rate to hdmi_monitor_diagnose.txt in your temp folder (/tmp on Linux, %TEMP% on Windows).

Alternatives

• OBS Studio: add a Video Capture Device, then right-click → Fullscreen Projector. Heavier, and audio needs extra setup.
• VLC: Open Capture Device. Set caching to about 0 ms, or the picture lags.
• Over the network (no capture card): NoMachine, VNC, RustDesk, or Sunshine/Moonlight. These also give you keyboard and mouse control, but the other computer must be booted and on the network.

A capture card sees everything, including BIOS and boot screens, and needs no software on the other computer. Expect about 50–100 ms of delay with typical MS2109-based cards.

For developers

pip install -e .              # run from source: python -m hdmi_monitor
python -m build               # build the PyPI wheel + sdist into dist/

Stand-alone installers that don't need Python, built from Windows:

• powershell -ExecutionPolicy Bypass -File build.ps1 builds the Windows setup .exe. It needs Inno Setup 6.
• wsl -d Ubuntu -u root -- sh linux/wsl_build.sh builds the Linux .deb and AppImage inside an Ubuntu 22.04 chroot in WSL.

Built with PySide6 / Qt Multimedia (FFmpeg backend). MIT licensed.