Hello,
I'm sorry for the trouble i caused, it was my fault as i was using custom remote.conf which i was using on my Ubuntu O.S
Here is the needed keys for the USB volume controls
KBD.Volume+ 000000000000002B
KBD.Volume- 000000000000002D
KBD.Mute 0000001B5B32307E
XKeySym.Volume+ KP_Add
XKeySym.Volume+ plus
XKeySym.Volume+ XF86AudioRaiseVolume
XKeySym.Volume- KP_Subtract
XKeySym.Volume- minus
XKeySym.Volume- XF86AudioLowerVolume
XKeySym.Mute XF86AudioMute
I figured it out while testing MLD v5.4.
lirc is not required and i don't have it installed.
Sorry again.
Edit: I unpacked vdr_2.2.0.213.8-214_amd64 today and it doesn't contain the XKeySym!
Which means that MLD 5.3 lacks the USB volume controls, If so then it wasn't my fault