How does software volume control work ? Options

[goodsound]

How exactly does software (windows mixer, players like foobar, etc..) volume control work ? Is it the equivalent of replay gain or normalizing ? or is it more "electronic" or "hardware" than that ?
Thanks.

[Fandango]

What bothers me all the time is that there is very rarely any values shown of how much the volume is changed. At most we get a slider, that's all. No percent scale is shown, you have to "guess" it with your eyes or count the marks, steps on the slider, which is either no guarentee that you will set the volume to a specific level or very cumbersome to hit the cursor keys 20-40 times every time you or worse an application has changed the driver volume settings. This is too old-way analog for me, using a slider. I want to be able to set the volume more precisely, or at best lock them, so that no program can change them on their own (Real Player/Plugin).

The only mixer control programs that I remember that let the user do this were made for Linux/BSD type systems. There were many of them because it was as easy as opening a file (/dev/mixer) to manipulate the drivers settings.