Define downbeat

Is there anyway there could be more times to define a downbeat? If using sync not all songs end on the same timing as when started and since there is a clock per say that keeps it every 4 beats sometimes the beats don't cycle the correct way causing a improper launch from the program. This is using modern music. I'm not talking about songs that drift but songs that end up with extra fills that throws off the downbeat cycle. Thanks! Hope this makes sense.

 

I think even just having option to have is sync to beats instead of bars would help on that situation.