`sound.enableMediaKeys` values in percent instead of hardware value

[dermetfan]

Issue description

sound.enableMediaKeys works, but changes the volume by +/- 1 (hardware value). In practice this makes no perceptible difference, at least on some systems. I'd like to propose to change by +/- 1 % instead.

I would send a PR but am not yet involved enough to try and test this myself. The necessary change is merely an additional %-sign in the amixer command line in nixos/modules/services/audio/alsa.nix:

# "Lower Volume" media key
{ keys = [ 114 ]; events = [ "key" "rep" ]; command = "${alsaUtils}/bin/amixer -q set Master 1%- unmute"; }

# "Raise Volume" media key
{ keys = [ 115 ]; events = [ "key" "rep" ]; command = "${alsaUtils}/bin/amixer -q set Master 1%+ unmute"; }

Technical details

• System: 16.09pre85931.125ffff (Flounder)
• Nix version: nix-env (Nix) 1.11.2
• Nixpkgs version: 16.09pre85931.125ffff

[laMudri]

Do make this an option, and default false for least surprise to upgrading users. I might do it myself if I get some spare time.

[dermetfan]

Closing as this has been handled in #21538.