"New" can be determined by looking at the 12 bits from this sample and comparing them to a saved copy from the previous sample. (The current sample gets copied to this previous sample buffer at the end of the current processing state). Any bit now a 1 and previously a 0 has transitioned ON to a high in the last sample period. Likewise any bit now a zero that was previously a 1 has transitioned OFF to a low level.

Good Luck
Michael Karas