Excerpts from b4283's message of Fri Jul 24 10:47:30 -0400 2009:
According to developer Cirrus, the relative volume adjusting method has been deprecated for 5 years. which is finally abandoned in the git version. (does anybody know why mpd in the repo hasn't been updated for sometime while stable 0.15.1 is around?)
So anyone who uses mpc to bind a hotkey to shortcut such as "mpc volume -5" or "mpc volume +10" is likely to get a error from mpd.
I've written a script to realize such functionality, please follow: http://dpaste.com/70907/ save it as script, chmod +x to it and put the relative values as parameter.
E.g. "vol.sh +5" or "vol.sh -10"
What?! That's so damn silly... why the heck would they deprecate that, it's so handy? Guess I'll have to update my mpd frontend/library... -- Andrei Thorp, Developer: Xandros Corp. (http://www.xandros.com)