double dribble / ball control?

[MrPlywood]

I get the impression that it's OK to bat the ball to the floor at least once in order to control a pass and then gather the ball, and then start a dribble at any time. Last night a stationary player received a pass and batted it once, then twice (which did look under control) before holding the ball. Then he started a dribble and was called for double dribble. Is there a guideline (and/or unwritten rule) for how many "bats" there can be before it's considered that "dribbling" has started? It looked like a legit call to me, since the second bat/dribble looked under control...

Hope that makes sense.