mpv volume controls via keyboard or mouse under macos?

Solution 1:

Have you taken a look at the manual?

You can decrease/increase the volume in several ways:

9    decrease
0    increase

/    decrease
*    increase

If your mouse supports it, you can use the mouse wheel…

Wheel left/right
    Decrease/increase volume

Within the OSC, you can use the mouse wheel to increase or decrease volume while hovering over the volume indicator.

mouse wheel     volume up/down

Finally, you can create an input.conf file and add commands to it. The documentation explains how. I have the following in my own file to change the volume by 10% with each button press.

- add volume -10
= add volume 10