Based on
https://ffmpeg.org/pipermail/ffmpeg-user/2024-March/057775.html
loudnorm is a low quality filter.
Some research gave some alternatives.
One of these is "pyloudnorm", a native python module implementing
EBU R 128 loudness normalization.
This is what I have implemented now instead of the old ffmpeg
filter.
In the future additional rewrites to use the official FLAC and OPUS
encoders might be desirable for better compression.
