PipeWire playback breaks when using channelmix configuration

Issue type

General playback bug

Description with steps to reproduce

On a fresh Ubuntu 26.04 LTS install, using MuseScore AppImage including but not limited to versions 4.6.5, 4.7.2 and 4.7.3, audio playback breaks when using a PipeWire channelmix configuration file. Playback does not start visually nor audibly.

This can in theory also be a PipeWire bug, but considering all other apps work nicely, I find it more prudent to start here.

Potentially relevant errors in terminal

[E][13:53:23.399659] pw.core      | [          core.c:  389 core_new()] 0x5f7d996172f0: can't find protocol 'PipeWire:Protocol:Native': Operation not supported
13:53:23.399 | ERROR | main_thread     | AudioDriverController::createDriver | PipeWire driver failed connected to server
13:53:23.401 | ERROR | main_thread     | AlsaAudioDriver::open | Unable to open device: default, err code: -95

Musescore config

Config can be anything, run after factory reset, or explicitly set to ALSA or PipeWire, all give the same result.

Pipewire config

The config in question is simple bass management and rear channel decoding. I have not tested with other/empty configs etc.

The file concerned is ~/.config/pipewire/client.conf which is linked to from each of client-rt.conf.d client.conf.d and pipewire-pulse.conf.d.

stream.properties = {
    channelmix.upmix = true # On
    channelmix.upmix-method = psd # Dolby surround logic
    channelmix.lfe-cutoff = 250 # Small satellites
    channelmix.fc-cutoff  = 12000 # Turns on center ever so slightly
    channelmix.rear-delay = 0.0 # No delay
    channelmix.stereo-widen = 0.0 # Other values sound mechanical
    channelmix.hilbert-taps = 255 # Makes rear channels very natural
}

Workaround

mv ~/.config/pipewire ~/.
./MuseScore
mv ~/pipewire ~/.config

Naturally, MuseScore will not sound like it is supposed to, but at least it works.

Supporting files, videos and screenshots

ms.zip

In which versions of MuseScore Studio is this issue present?

4.7.3

Regression

I was unable to check

Operating system

Ubuntu 26.04 LTS

Additional context

No response

Checklist

• This report follows the guidelines for reporting bugs and issues
• I have verified that this issue has not been logged before, by searching the issue tracker for similar issues
• I have attached all requested files and information to this report
• I have attempted to identify the root problem as concisely as possible, and have used minimal reproducible examples where possible