Some days ago I have upgraded to Opensuse Leap 15.4 on an old laptop which had Leap 15.3 installed. I once again ran into a problem regarding Pulseaudio and its Ladspa based equalizer. The equalizer did not work, although you could start its GUI.
The problem: The Ladspa equalizer’s interface shows up – but the equalizer is not working and not usable as a Pulseaudio sink
You can start the pulseaudio-equalizer, its graphical interface shows up on your desktop (in my case a KDE desktop) – but it is not doing its work on any sound streams. One could also say: You can switch the Pulseaudio LADSPA equalizer on, but it has no effect on any sound. You do not see it as a sink in the Pulseaudio tools either. pavucontrol will not show it as a device we could attach a sound source to. Regarding KDE we can not define it as the standard device which sound sources should use for handling their output. A Pipewire installation alone does not solve this problem.
The Cause: A missing link to a library
A lot of programs try to find shared system library objects in the directory “/usr/lib64/”. Normally, an installation procedure would set up a soft link to required so-libs it brings with it in a sub-directory of “/usr/lib64”. The problem is that such a link is missing after the installation of the RPM “pulseaudio-equalizer” on Leap 15.4. The missing link is one to /usr/lib64/ladspa/mbeq_1197.so.
mytux:~ # cd /usr/lib64 mytux:/usr/lib64 # ln -s /usr/lib64/ladspa/mbeq_1197.so mbeq_1197.so
And your Pulseaudio – Ladspa – Equalizer will work again.