Hi, Mathias. Are your F0 files (data/lf0/*.lf0) normally generated? You should check those files. If your F0 files is generated normally, there must be 4 files as follows: gv-lf0.pdf gv-lf0.pdf.big gv-mgc.pdf gv-mgc.pdf.big in data/gv directory. Regards, Keiichiro Oura.