Ever since I had my new laptop (a Thinkpad T14s Gen4 AMD, bought in November 2023, currently running Ubuntu 24.04.1), I had tried to use it to play some movies with 5.1 surround sound via its HDMI port (connected to my 5.1 receiver), but I had never managed to make that work. Whereas on other systems the pavucontrol utility shows an HDMI 5.1 option (among others), no such thing was shown on this machine. It only showed “Play HiFi quality Music” and a “Pro Audio” option, neither of which mentioned anything about 5.1 surround sound. Moreover, the Ubuntu sound settings panel only showed the stereo option for speaker testing.
All those times before I had taken a quick look around the web to see if someone had written about a way to fix this. That didn’t seem to be the case and, given that my goal at those times was to watch a film, I usually switched to an alternative way to do that.
Until tonight. With some time to spare and no immediate intention to watch a film, I thought I’d try to see if I could dig a bit deeper. Surprisingly, this time it took me less than 10 minutes to find a forum post that helped me out.
In this topic on the Linux Mint forum user silmaril describes the same problem as I had, as well as the solution. Apparently, the ALSA Use Case Manager, or alsa-ucm tries to be smart and offer the right kind of configuration, but fails. In the solution they point to this page on the Arch wiki, which describes how to fix this. However, user silmaril took a more drastic route and simply used APT to remove the alsa-ucm-conf package. I did the same and after a
systemctl --user restart pipewire
The regular HDMI stereo and surround devices popped up in pavucontrol, and a test with a 5.1 film via VLC worked just fine.
No idea why I hadn’t found that topic on the Linux Mint forum before…
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