Feature: Bars

[tkell]

@bmcfee had some thoughts about this - I feel like we said that we would not use librosa for this?

[wxy656]

This feature can be obtained by matching algorithm：
1. create a variety of tempo template set, for example, 2/4 template is {strong, weak, strong, weak, strong, weak}, 4/4 template is {strong, weak , The second strong, weak}；
2. use total beats to match every templates and the one with highest match-rate maybe the music's time signature , so that each cycle is a bar.

[tkell]

As per an email from @bmcfee, we can use an incoming Python lib from McFee Labs(tm) for this. ETA is July 2017 or so.