Mp3gain is a powerful utility to modify the real loudness of MP3 files automatically to one common level. It utilizes the psychoacoustic modell of replaygain to do the loudness analysis. The modifications to the MP3 files are lossless (i.e. without any additional losses) and reversible. See the original homepages for further details.

The modification of the MP3 files is done in place and lossless.

The utility can operate on MPEG 1, MPEG 2 and MPEG 2.5 file Layer 3 only.