MP3Gain analyzes and adjusts mp3 files so that they have the same volume.
It does not just do peak normalization, as many normalizers do. Instead,
it does some statistical analysis to determine how loud the file actually
sounds to the human ear. Also, the changes MP3Gain makes are completely
lossless. There is no quality lost in the change because the program
adjusts the mp3 file directly, without decoding and re-encoding.
There is no official package available for openSUSE Leap 15.4