This is my preset for PulseEffects.
A Loudness Equalizer which performs automatic volume adjustment without the Auto Gain plugin. Useful if you're looking for a steady sound level in high dynamic contents like movies when you don't want to adjust volume too many times. It's similar to the Loudness Equalization option in Microsoft Windows.
Download Loudness Equalizer.json file and copy it inside ~/.config/PulseEffects/output folder. Close and restart PulseEffects, then apply the new preset.
If you have the FlatPak version of PulseEffects, place the preset file in ~/.var/app/com.github.wwmm.pulseeffects/config/PulseEffects/output folder.
It's recommended to use it with PulseEffects 4.8.0 or higher version.
An Upward Compressor is used to raise low level signals, then a downward Multiband Compressor is added to decrease the amplitude of the signal splitted in four different bands. At last, a Limiter makes sure no clipping occurs, taking the overall signal below 0 dB.
Since the upward compressor raises noise also, a Gate is used on top of everything to reduce this side effect. Multiband compressor will reduce sound quality, so the Perfect Equalizer (by Ziyad Nazem) is introduced to improve it before the limiter.
I used downward compressors many times and noticed that higher the rate, lower the quality. So if you want to preserve some quality, you need to set a low rate, but low rates do not reduce the dynamic range sufficiently as needed in certain situations.
Therefore an upward compressor is used to raise signals below a certain threshold, then a multiband compressor is set with a low rate.
Obviously, the quality is not the same as original, but it's better than a compressor with high rate. Take in consideration that this is intended to be used only to get a quite steady level in high dynamic contents.