@oloff3 You could try something like:

input_volume_up = +<button value> input_volume_down = -<button value>

or another approach is described here https://retropie.org.uk/forum/topic/2377/control-volume-through-retroarch-with-keyboard/4, outside of RetroArch. The example in the topic is more for the keyboard use, but if you can make the events appear as keypresses, the principle is the same.

I also tried with the Adafruit DAC bonnet, same issue, can't launch any MAME games

I just get

lvl0: volumecontrol::init() - failed to find mixer elements

... and then it goes straight back to ES menu

I would really like a solution!

/Thanx

@BuZz said in usb audio and mame4all incompatibility ?:

@rig if you have a rpi3, you will find lr-mame2003 a better emulator.

Yea, I have lr-mame2003 but I don't use it as much. when I first started using mame I played a few roms on both emulators and came to the conclusion that mame4all worked better. By "worked better" I mean that the sound was cleaner/clearer on a few games and the video resoulution looked sharper on a few games. However I have run into exceptions-- I use lr-mame-2003 for St Dragon because it sounds much better compared to mame4all; I also play x-men on lr-mame 2003 becsuse the sprite shadows look better.
I didn't run a thorough test and I could be mistaken. Maybe I should give lr-mame2003 another go. What do you mean specifically by lr-mame2003 being a better emulator?
I can say that I do prefer lr-mame4all over mame4all because of the retroarch support.

p.s. I am using a rpi3