According to Wikipedia 'Replay Gain is a proposed standard published in 2001 to normalize the perceived loudness of computer audio formats such as MP3 and Ogg Vorbis'.
Due to the fact that my favourite method of listening to music is loading the whole library into my WinAmp and starting shuffled playback, I was very interested of the function of 'Normalizing' to take all the pleasure from the listening process without my any manual control since the very start of the playback. Really I don't like to excurse from what I'm doing just to find the new suitable volume level—that's annoying! Well, this can be a weak arguement for someone else with different preferences.
Another example is you are with the friends in your room chatting. You have set the WinAmp to play that loud to let you enjoy both the music and the conversation comfortably. In some tracks comes your favourite theme from your favourite album. But unfortunately that album was mastered by some.. h-m-m, let's call him very-odd-person, so the peak level is that high it can outheight Empire State Building twice!!! I mean, it is really much louder than the previous track. Surely your friends won't like it much. And they make you pay for that. Most surely, pay hard! So, now you see how useful normalization can be.
First normalization I tried was not even good enough. The principle was to calculate average level on-the-fly and apply the corresponding volume correction. The flaw of this method you see exactly the first time you start to play the song with the quiet introduction and much louder main part. In this case you actually hear when the volume is changed! And that's definitely doesn't reflect what was intended to by the artist.
Replay Gain solution offers the pre-calculating of the perceived volume based on the psychoacoustic analysis of both the current track separately and the album at whole. After that the values are stored in the header of the file. Now replaygain-compliant players can take advantage of it!
WinAmp is surely among them. Also it is supported by the majority of the most popular players: foobar2000, XMMS, Xbox Media Center, etc.
Hardware mp3-players are not that much favorable to this standard. Although there is a Rockbox firmware, but the coverage of supported mp3-players is not that wide to include iRiver T-30 I have chosen to be the one belonging to me...
Whatever, Replay Gain Rocks! Absolutely.
