R128GAIN is a FFmpeg and SoX based EBU R128 compliant loudness scanner for audio and video files. It helps you normalizing the loudness of your audio and video files to the same level.
A big pity that the developer seems to have left the stage, and there is no active forum on this tool. It looks promising, but without an active community with it's input and dialogue this will probably not reach it's potential. That's a shame.