FAQ#
Questions people actually asked. New ones get added here rather than invented.
Is it open source?#
No. This repository holds the documentation, the issue tracker and the releases; the product itself is closed source.
Does it work over the internet, or from a café?#
Not over the internet. The PC and the device have to be on the same local network — over Wi-Fi, over Ethernet, or over USB tethering. PrismDesk is a second monitor, not remote desktop, and it is not a way to reach your desktop from somewhere else.
With both in front of you in a café or a hotel, whose Wi-Fi often keeps devices apart, turn on Mobile hotspot on the PC and connect the device to it — see Troubleshooting.
Does it work on Windows 10?#
No. Windows 11 64-bit, build 22000 or later. The installer stops on anything older rather than installing something that half works. Windows 10 has not been tested, so it is not claimed.
Does it work with an iPad, or on macOS or Linux?#
No. Windows 11 on the PC side, Android 8.0 or later on the device side.
What frame rate do I get?#
We do not advertise one, and we would rather explain why than pick a number.
The rate follows what Windows composes for the virtual display. With a 75 Hz primary display, the achievable rates are 75, 37.5 and 25 — 60 is simply not on that list. On a 60 Hz machine the list is different again. Anyone promising you a frame rate is promising you the number from their monitor, not yours.
How fast is it? What is the latency?#
We do not publish a latency figure, because we have not measured one we would stand behind. Measuring end to end honestly is harder than it sounds, and a number taken from the app's own reporting would be marking our own homework.
If you know how you would measure it, we would like to hear it — Discussions.
Do I need a licence for every PC?#
No. One key covers three of your own Windows PCs. PrismDesk is US$22 — One-time purchase. No subscription, no account. The free edition covers the basics — one device, SDR, pen and touch input, and audio. Pro adds HDR, up to four devices at once, your device camera as a Windows webcam, and input device mode — the device as a pen tablet with shortcut keys for a screen your PC already has. Pro is sold by Polar Software, Inc. as merchant of record. If it does not work on a PC that meets the requirements and we cannot fix it with you, there is a refund within 14 days: https://prismdesk.app/refund.
Does it send anything to you?#
No usage data, ever. No account, no telemetry, and no automatic update check. The pixels go straight from your PC to your device.
PrismDesk reaches the internet only while you are pressing one of two kinds of button, and never in the background or at start-up:
- Check for updates (Settings tab) fetches one small file from our website that says which version is the latest. No version number, nothing about your PC, and no identifier of any kind is sent — we cannot tell one press from another. Nothing is downloaded or installed; if there is a newer version, PrismDesk says so and offers to open the download page.
- The three licence buttons below.
Press neither, and the app never leaves your own network.
PrismDesk Pro contacts our payment provider, Polar, only when you press Activate, Check license or Deactivate this PC — never in the background and never at start-up. What is sent is the licence key you typed in and a name for this PC that the app shows you first. After that, Pro needs no connection, and it keeps working even when Polar is unreachable. See https://prismdesk.app/privacy.
Is my screen encrypted on the wire?#
Yes. TLS 1.3 on the control and input channels; AES-256-GCM on video, audio and camera. The device pins the PC's certificate fingerprint, which is why connecting by QR code or connection URI is better than typing an address — those two carry the fingerprint, and a typed address does not.
Why does it want administrator rights?#
Creating the virtual display requires them: the display node belongs to the process that made it, and Windows only lets an elevated process make one. The start-up entry the installer creates runs it elevated at sign-in, so you are not asked every time.
My drawing app ignores the pen#
It is almost certainly set to WinTab. Switch it to Windows Ink — see Pen.
Do I have to turn HDR on?#
No. Both ends check what they can do and pick HDR when it would actually look different. The Color space setting says which answer your device will get before you connect, and you can still choose SDR or HDR10 by hand. See HDR.
I chose HDR10 and nothing changed#
Most often the panel reports HDR support but cannot actually go brighter than SDR; the app says so where you choose it. That is also why the automatic answer on such a panel is SDR. See HDR.
Can I use more than one device at once?#
Yes, with PrismDesk Pro: up to four, sharing one capture and one encoder. Four is the number that was verified — see Devices. The free edition connects one device at a time.
Does sound come across?#
Yes, the PC's audio can play on the device. It is chosen before connecting and cannot be switched mid-session.
What happens when I uninstall?#
The driver, the firewall rules, the start-up entry and the virtual camera registration all go, and settings and diagnostic logs are deleted by default — the uninstaller offers to keep them if you would rather.
One thing stays: the driver's signing certificate that the installer added to
the machine's Trusted Publishers. To remove it, open certlm.msc →
Trusted Publishers → Certificates and delete the Masato Okumura
certificate.
See also: Troubleshooting · Known issues · Devices · Discussions