Void Linux: Video playback works in Firefox and mplayer, fails in other programs

Note: this question already posted to the Void forum. Repeating it here to
ask a different community. I'll duplicate any good answers from either side
to the other (or link) for maximum value.

Playing local files (OGG and MP4/H.264) works fine if I load them into a
Firefox tab, and also works if I run mplayer, but smplayer (which should
just be mplayer in a wrapper), vlc, mpv, and ffplay all show just a black
screen (while successfully playing audio from the files).

System: current Void
CPU: 12th Gen Intel(R) Core(TM) i9-12900K
GPU: AlderLake-S GT1

The problem may be that the GPU is not being used. I installed nvtop, and it always shows GPU usage as zero.

I have installed these packages: intel-video-accel, mesa-vulkan-intel,
xf86-video-intel.  Apparently that's not enough.

I found the instruction in the Void manual to turn off IOMMU
(https://docs.voidlinux.org/config/graph ...  intel.html).  Doing that ...
did very little.  Now mpv displays the first frame of the video, the just
flickers while the audio keeps playing.  (Interestingly, nvtop reveals that
smplayer calls mpv, not mplayer!) However, GPU utilization does now go up
above zero, so that change did activate the GPU.  Seemingly, something else
(missing library?) is preventing video playback for most software.

Firefox is playing video OK, but only because an i9 is really fast, is my
impression.  Hardware acceleration is not used.  Same with mplayer--GPU
usage remains zero, but the video does appear.

OK, the manual (https://docs.voidlinux.org/config/graph ... intel.html at the bottom) says:

    For newer Intel chipsets, the DDX drivers may interfere with correct
operation.  This is characterized by graphical acceleration not working and
general graphical instability.  If this is the case, try removing all
xf86-video-* packages.

So, I ran

xbps-remove xf86-video-amdgpu xf86-video-ati xf86-video-dummy
xf86-video-fbdev xf86-video-intel xf86-video-nouveau xf86-video-vesa
xf86-video-vmware

The system responds with:

Code: Select all

xf86-video-amdgpu-23.0.0_1 in transaction breaks installed pkg `xorg-video-drivers-7.6_23'
xf86-video-ati-22.0.0_1 in transaction breaks installed pkg `xorg-video-drivers-7.6_23'
xf86-video-dummy-0.4.1_1 in transaction breaks installed pkg `xorg-video-drivers-7.6_23'
xf86-video-fbdev-0.5.0_2 in transaction breaks installed pkg `xorg-video-drivers-7.6_23'
xf86-video-nouveau-1.0.17_2 in transaction breaks installed pkg `xorg-video-drivers-7.6_23'
xf86-video-vesa-2.6.0_1 in transaction breaks installed pkg `xorg-video-drivers-7.6_23'
xf86-video-vmware-13.4.0_1 in transaction breaks installed pkg `xorg-video-drivers-7.6_23'

Suggestions on getting proper video playback and acceleration?  I've never
had an Intel GPU on Linux before.

Thanks.
--
Carl Fink                                                  carl@finknetwork.com
https://reasonablyliterate.com                           https://nitpicking.com
If you want to make a point, somebody will take the point and stab you with it.
-Kenne Estes