It is kind of weird … I have a couple of mp3 files which the player does not like to play in the background… I can play long songs usually without any problems and lighten up a couple of LEDs from the main loop - no problem. But for particular mp3s it seems something is blocking the mainloop until the mp3 finished playing.
It seems to happen always with the same files and I can’t figure out what it is …the length does not seem to be important as longer mp3s do also work while others (but always the same others) do not …
This one won’t play in the background (or the main loop is kind of blocked):
https://drive.google.com/file/d/0B94OULS6inTJUmxJUF9QWUduR3c/view?usp=sharing
This one will play just fine in the background (LEDs are blinking - all other things are going normal):
https://drive.google.com/file/d/0B94OULS6inTJLUhIUXhQdm8xdkE/view?usp=sharing
I’ve even removed all additional calls from the main loop but it even seems subscribed events, external function calls (i.e. over the cloud) won’t be processed at all… it’s completely blocking but playing music …
this happens on two different core at the same time (don’t ask 
) so it is no coincidence …