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ALSA software mixing (the dmix plugin) requires the user to be part of the audio group to work. The Arch Wiki systemd article warns against this however, as sound permissions should normally be allocated by logind. This appears to be broken on my system; with alsa-lib complaining of being unable to create an IPC semaphore and throwing an audio playback error.
I'm not sure how to configure polkit to allow non-root users to run dmix, if that is even possible. The systemd Arch Wiki page seems to imply that audio permissions should be granted automatically, and does not give any configuration information. I'm having this problem on my desktop and my laptop, so it doesn't seem to be hardware-specific. Any help finding a solution would be highly appreciated.
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