midi delta time

i need help..

i need to know exactly midi delta time format?is it millisecond,tick or what??

and i need formula to convert timestamp in millisecond into midi delta开发者_如何学编程 time...

thanks before..

Delta time is always specified in ticks, which are determined by the PPQ (pulses per quarter note).

So given an offset in milliseconds, you must first convert that to samples (using the sample rate), and then to pulses based on the current tempo and the PPQ.