When trying to convert multiple files, if the source directory has spaces in it, I get these errors when trying to convert multiple mp3 files to ogg (I will preserve the actual file paths in case they are useful):
As you can see, it tries to replace the space characters with the URL encoded equivalent %20[00007f91bc000d48] file access out error: cannot create /home/aidan/Documents/School/Jazz/What%20Is%20Jazz/WhatisJazz-3.ogg: No such file or directory
[00007f91bc001ee8] standard stream out error: no suitable sout access module for `file{no-overwrite}/ogg:///home/aidan/Documents/School/Jazz/What%20Is%20Jazz/WhatisJazz-3.ogg'
[00007f91bc002fe8] core stream output error: stream chain failed for `transcode{vcodec=none,acodec=vorb,ab=128,channels=2,samplerate=44100}:std{access=file{no-overwrite},mux=ogg,dst='/home/aidan/Documents/School/Jazz/What%20Is%20Jazz/WhatisJazz-3.ogg'}'
[00007f91c400c348] core input error: cannot start stream output instance, aborting
After renaming the directory without any spaces, it works perfectly.
Also, interestingly enough, it can convert single files inside a directory with spaces just fine.
Hopefully this is helpful, provided this is a bug and this isn't already known.