I am converting files from one format to another using afconvert in OS X. The files are stereo and now I am trying to have them come out as mono by mixing the two channels into one. There seems to be an option to downmix channels using the option --mix, but I am not sure how it works. Whatever I try, I only get stereo output.
Update: I installed ffmpeg using homebrew, and added this step to my script: ffmpeg -i file.wav -ac 1 file_mono.wav
seems is ok, but I haven't confirmed yet that this is really mixing, and not just dropping of channels. works.