I need to downmix from stereo to mono (my system only has one speaker) on a raspberry pi running runeaudio. I tried to apply the solution here Force downmix to mono on Linux but it does not work in my situation.
speaker-test gives following error. Can you tell me what's wrong?
speaker-test -Dmakemono -c2 -t wav
Playback device is makemono Stream parameters are 48000Hz, S16_LE, 2 channels WAV file(s) Broken configuration for playback: no configurations available: Invalid argument Setting of hwparams failed: Invalid argument