Volume normalization

[GoogleCodeExporter]

Describe the feature you want implemented.
Make the volume similar for all tracks. Right now some tracks may have a high 
volume while another may have very low.

Describe why you think that this feature is needed.
It is annoying to have tracks with different volume for the same reason why the 
higher volume in commercials on TV compared to the movie/show is annoying. :)

Do you have any suggestions on how we could implement, design or present
this feature in an easy and intuitive way?
Stoffi could run a background thread which samples each song and calculates an 
absolute value of the mean volume level. This value could then be used along 
with the value from the volume slider to set the volume of the sound stream.

Original issue reported on code.google.com by ephracis on 18 Sep 2012 at 12:40