ValueError: invalid literal for int() with base 10: '990 align:start position:0%'

[sylwesterdigital]

➜ srt2txt git:(master) ✗ python2 vtt2txt.py dupa.vtt dupa.txt
Traceback (most recent call last):
File "vtt2txt.py", line 111, in
convert(args.vttfile, args.txtfile, args.format, args.gap)
File "vtt2txt.py", line 90, in convert
last_end = to_frames(times[1])
File "vtt2txt.py", line 63, in to_frames
return ((int(elts[0])*3600 + int(elts[1])*60 + int(elts[2]))*1000 + int(ms)) * fps / 1000
ValueError: invalid literal for int() with base 10: '990 align:start position:0%'