DBNBarTrackingProcessor doesn't accept a single beats_per_bar

[radkoff]

Expected behaviour

According to the docs, DBNBarTrackingProcessor "can be either a single number or a list with bar lengths".

Actual behaviour

If I pass a single integer, I get TypeError: 'int' object is not iterable on line 1097 of downbeats.py If I pass [4] I get ZeroDivisionError: float division by zero on line 467 of beats_hmm.py I can get it working by passing a second funky number like [4, 17], but this is very hacky

Reproducing code

act = madmom.features.downbeats.RNNBarProcessor()((path, beats))
proc = madmom.features.downbeats.DBNBarTrackingProcessor(fps=100, beats_per_bar=4)
downbeats = proc(act)

or

act = madmom.features.downbeats.RNNBarProcessor()((path, beats))
proc = madmom.features.downbeats.DBNBarTrackingProcessor(fps=100, beats_per_bar=[4])
downbeats = proc(act)

Information about installed software

I'm using version 0.17.dev0

[superbock]

Thanks for reporting #394 should fix it.