If you are using the headphone jack of your Raspberry Pi as a sound output and sound is not available with the N64 emulator mupen64plus, please follow the steps below.
mupen64plus configuration file with the following command:nano /recalbox/share/system/configs/mupen64/mupen64plus.cfg
OUTPUT_PORT = 1
Change this line to this:
OUTPUT_PORT = 0
CTRL + X then Y to confirm, and validate with Enter.reboot command.Once rebooted, the sound should be available.
This modification can also be done from WinSCP, Cyberduck or MobaXTerm if you are allergic to the terminal