I don't know of a way to fade in or out within BIAB. And, I usually create my own count in by turning off the count in in preferences.
For a drum into;...
Put cursor on bar 1
Edit
Insert Bars
2
You now have two bars in front of your song and your whole song including start/begin/repeat/tag/end/etc has moved over 2 bars. Repeats will now go back to bar 3 if that's what you had it set to. Or, set the start bar to bar 3.
On bar 1 enter a chord that rests everything except drums like this:
A#m.d
You will have drums playing for 2 bars, then the song starts.
If there is a part marker (colored square) at the 3rd bar you will get a drum roll just before the first 3rd bar.
Regenerate for different drum patterns. Or,...
Right click directly on top of the bar number 3. This will give you the option to have a drum fill just before bar 3 and also lets you force/choose from the style your beginning drum pattern. Which you can have different for the 2 bar into if you like.
For a shorter drum roll in try this;
Rest all instruments on first bar. Like this: A#m.
Put a A#m.d on the 3rd beat of the 2nd bar. Or wherever you think works best.

Last edited by Tobias; 02/05/17 06:48 PM.
Does the noise in your head bother me ?