System Volume Control (rfe)

In order to control my system volume, I used to bind my laptop media keys like this:
spawn "command='amixer -q set Master 5%+'; pgrep -f \"^$command$\" || exec $command")
for:
XF86XK_AudioLowerVolume 0x1008FF11
XF86XK_AudioRaiseVolume 0x1008FF13

which, would unfortunately spawn lots of subshells if I held down the keys:
/bin/sh -c "command='amixer -q set Master 5%+'; pgrep -f \"^$command$\" || exec $command")"
... x100
pgrep -f amixer -q set Master 5%+'
... x100
amixer -q set Master 5%+'
... x100

All these asynchronous backgrounded amixer process would try accessing the volume at once, the result being that even though the volume channels remain locked, the channels go out of sync. So for example, channel 0 of Master would be at "50%" while channel 1 of Master would be at "76%". Annoying.

Now I do:
#!/bin/bash

trap 'adjust_volume 5 -' SIGRTMIN+5
trap 'adjust_volume 5 +' SIGRTMAX-5

function adjust_volume {
    if [[ "$run_times" -eq 0 ]]; then
        amixer -q set Master "$1%$2"
        run_times=$((run_times + 1))
    fi
}

while : ; do
    run_times=0
    sleep 0.05
done

Which is great, but requires starting a separate service in ~/.xinitrc or whatever rocks your boat.
And then I found panflute, so I thought the two could be combined... as so:

on "org.mpris.panflute" add a new "/System" object with the following methods:
RaiseVolume or RaiseSystemVolume
LowerVolume or LowerSystemVolume
that behave in the same manner as the bash script, that is
"dbus-send --session --print-reply --type=method_call --dest=org.mpris.panflute /System org.freedesktop.MediaPlayer.RaiseVolume string:5%-" will only lower the volume by 5% every X seconds per dbus request.

Even better, instead of using amixer, this can be accomplished through pyalsaaudio.