question: public void update ( int length , long rtpts ) throws IOException { mPacketCount += 1 ; mOctetCount += length ; setLong ( mPacketCount , 20 , 24 ) ; setLong ( mOctetCount , 24 , 28 ) ; now = SystemClock . elapsedRealtime ( ) ; delta += oldnow != 0 ? now - oldnow : 0 ; oldnow = now ; if ( interval > 0 ) { if ( delta >= interval ) { send ( System . nanoTime ( ) , rtpts ) ; delta = 0 ; } } }
target:  Updates the number of packets sent, and the total amount of data sent.