With an Intel or AMD GPU, hardware decoding with the gstreamer open-source VAAPI gstreamer plugin is preferable. The open-source “Nouveau” drivers for NVIDIA graphics are also in principle supported: see here, but this requires VAAPI to be supplemented with firmware extracted from the proprietary NVIDIA drivers.
NVIDIA with proprietary drivers
The nvh264dec plugin (included in gstreamer1.0-plugins-bad since GStreamer-1.18.0) can be used for accelerated video decoding on the NVIDIA GPU after NVIDIA’s CUDA driver libcuda.so is installed. This plugin should be used with options uxplay -vd nvh264dec -vs glimagesink. For GStreamer-1.16.3 or earlier, replace nvh264dec by the older pluginnvdec, which must be built by the user: See these instructions.
Support for the Raspberry Pi Broadcom GPU
+Video4Linux2 support for the Raspberry Pi Broadcom GPU
Raspberry Pi (RPi) computers can run UxPlay with software decoding of h264 video (by adding -avdec to the uxplay options) but this usually has unacceptable latency, and hardware-accelerated GPU decoding should be used. The unmaintained 32-bit-only omx (OpenMAX) driver used for this by RPiPlay is no longer officially supported by RPi OS (Bullseye): the replacement is v4l2 (Video4Linux2). Fixes to the GStreamer v4l2 plugin that allow it to work with UxPlay on RPi are now in the GStreamer development branch, and will be available in the upcoming GStreamer-1.22 release, A (partial) backport (as gstreamer1.0-plugins-good-1.18.4-2+~rpt1) has already appeared in RPi OS updates. Until the full update appears, or if you are using a different distribution, you can find patching instructions for GStreamer in the UxPlay Wiki. Patches are available for all GStreamer releases 1.18.4 and later.