Geiss HDR

Welcome to Geiss HDR, a music visualizer.

This program is a modern rewrite of the 1998 Geiss screensaver & Winamp plug-in.

New Features

• High Dynamic Range (HDR) rendering: brighter, more vivid colors, higher contrast
• Cross-platform (PC, Mac, etc; it runs in a browser)
• More dynamic motion: up to 4 motions can be smoothly mixed and faded at a time, instead of just 1 fixed motion
• Ultra-high resolutions (up to 8K x 8K) at 120 Hz
• 16-bit precision in the warped image (up from 8)
• Supersampling (anti-aliasing)

For best results

• Use a laptop or desktop -- not a phone.
• Google Chrome is strongly recommended.
• An HDR display with 1000+ nits is recommended, but not required.
• Note that all MacBook Pros from 2021 onward have suitable HDR displays.

Compatibility

• As of March 2026, only Chrome supports all of the required features.
• Firefox mostly works, but the browser doesn't support HDR yet, so you'll get SDR.
• Safari is not recommended. It doesn't support HDR properly yet and has a number of other issues.
• Developers: The HDR path is currently disabled for non-Chrome browsers, but you can force the code to try the HDR path by appending "?force_hdr=1" to the URL.

Audio Source Options

• Play the included demo tracks -- very easy; start with this.
• Use microphone (or line input) -- requires permission.
• Drag-and-drop your mp3 files or folders onto it -- or press CTRL + L.
• Listen to audio from another browser tab, or window, or your whole screen -- but this mode requires (sometimes complex) permissions grants, and it prevents true fullscreen mode, due to the privacy warning banner.

Tips

• For the best experience, view on a laptop or desktop. Although phones technically work, the experience isn't great, so it's not recommended. But if you must run it on a phone, you can tap on the screen to randomize the visuals.
• The microphone source works best for voices, live music, or music played from speakers on other devices. Don't use it if your music is playing from the same device's speakers; it won't pick up the music well. (Laptops and phones are designed this way -- to minimize feedback in voice calls.)
• To capture the audio from a browser tab or window, or your whole screen, on Mac OS, you might need to (just once) go to System Settings -> Privacy & Security -> Screen & System Audio Recording, then under 'System Audio Recording Only', enable it for 'Google Chrome'. If 'Google Chrome' does not show in the list, click the + symbol and add 'Google Chrome.app', then enable it.
• To see the difference between SDR and HDR, run it on a system with a suitable HDR display, and then press CTRL + H to toggle between HDR and SDR rendering.

Legal

• Visual imagery generated by running Geiss HDR (including still images and still image sequences) may be used, published, modified, sold, and sublicensed for any purpose without restriction. See OUTPUTS.txt
• License: Apache-2.0 - see LICENSE.txt
• Attribution Notice: see NOTICE.txt
• Naming / Branding Notice: see NOTICE.txt