Update: Looks like hardware.opengl.extraPackages = with pkgs; [ vaapiIntel ]; fixed it, although that was just a shot in the dark. I can’t find any documentation about when one should use the variously named VA API/VDPAU packages.
Even though the libvdpau package is installed I get messages such as this when playing a video in VLC:
libva info: VA-API version 1.4.0
libva info: va_getDriverName() returns 0
libva info: Trying to open /run/opengl-driver/lib/dri/i965_drv_video.so
libva info: Trying to open /usr/lib/dri/i965_drv_video.so
libva info: Trying to open /usr/lib32/dri/i965_drv_video.so
libva info: va_openDriver() returns -1
[00007ff204001ff0] glconv_vaapi_drm gl error: vaInitialize: unknown libva error
Failed to open VDPAU backend libvdpau_i965.so: cannot open shared object file: No such file or directory
The relevant file is not on my system:
$ sudo updatedb
$ sudo locate libvdpau_i965.so
[no output]
Maybe it’s not in any package:
$ nix search --update-cache libvdpau_i965
error: no results for the given search term(s)!
but I’m unsure how nix search works.
Is this a user error, a missing patch to make VLC look at the right path, or something else?