I installed mp3gain and looking at the manual it seems it is not possible to write replaygain tags while using album tags. BUT perhaps I missed something.
according to the manual:
mp3gain optionally writes gain adjustments directly into the encoded data. In this case, the adjustment works with all mp3 players, i.e. no support for a special tag is required. This mode is activated by any of the options -r, -a, -g, or -l.
If none of the above options are given, the recommended gain change is instead written to a special tag in the mp3 file. In this case, the adjustment only works with mp3 players that support this tag. Some mp3 players refer to this as ReplayGain. The tag is written either in APEv2 format (default) or in ID3v2 format (with -s i). If you only want to print the recommended gain change (and not modify the file at all) you may use the -s s (skip tag) option.
Can you please help? Thanks
Must you use mp3gain? If not, try foobar2000 (if you're on Windows) as it'll do it for you
mp3gain doesn't write replaygain tags as such. It modifies the internal gain settings for the audio. It also, or just, writes tags indicating what changes it made so that they can be undone at a later date. The tags are not the same as the replaygain tags that have come to be a standard now, and are not likely to be recognised by any decoder you are using. The (reversibly) modified audio will be played back at the adjusted gain by any decoder. It is worth noting that the gains from mp3gain are not very accurate compared to modern replaygain tags.
It is worth noting that the gains from mp3gain are not very accurate compared to modern replaygain tags.
"not very accurate" could mean at least one of two things here. The first is not up to discussion: due to the MP3 internals, volume can only be shifted in fixed increments (1.5 dB IIRC), while an RG tag allows for finetuning.
But a different question is whether the loudness measurement - how much
should one apply - is up-to-date. Opinions differ on whether the original RG specification or the EBU R128 specification (https://tech.ebu.ch/docs/r/r128-2014.pdf) is better at differentiating loudness.