Replay Gain

[ZeroDot1]

Add a function for Replay Gain in the settings.

[Bleuzen]

I haven't done something with replaygain yet, so I'm not sure what you need.
Do you have an example ffmpeg command that would fit your needs?

As I found out so far, changing volume by replaygain can be done by an audio filter.
See:
http://ffmpeg.org/ffmpeg-all.html#volume

Audio filters can already be used in FFaudioConverter.
An example in settings may be:

[ZeroDot1]

Sorry for the late answer.

I already tried the filters, but this is not working for many users.

I recommend to add an extra tab to the settings which is only for Replaygain.

Users should be able to set up the preferences to automatically detect the volume of the music and to select album or track volume.
And the db value should be customizable.