What does the range 0 to 100 mean here? (What units are being used here?)
What value in this range corresponds to the sound file being played at its original volume?
Also, how do you access this particular variable using syntax? (XAudio2.??)
It's a percentage value. 100% should match 0 dB and 0% should match -inf dB. Original volume always is 0 dB, so 100% = original volume.
Sadly there's only a setter for music volume, no getter. You have to create a pv or global and store/change the value there, then set the music volume to that pv/global.