2001/02/15Chin-Kai Wu, CS, NTHU1 Adaptive Playout Mechanisms for Packetized Audio Applications in Wide-Area Networks Ramachandran Ramjee, Jim Kurose, Don Towsley Henning Schulzrinne INFOCOM '94. Networking for Global Communications., 13th Proceedings IEEE, 1994

2001/02/15Chin-Kai Wu, CS, NTHU2 Outline Introduction Adaptive playout adjustment algorithms Notations Playout Mechanism Algorithms Experiment Environment Result

2001/02/15Chin-Kai Wu, CS, NTHU3 Introduction

2001/02/15Chin-Kai Wu, CS, NTHU4 Notations

2001/02/15Chin-Kai Wu, CS, NTHU5 Notations (Cont’d) t i : time packet i is generated at the sending host a i : time packet i is received at the receiving host p i : time packet i is played out at the receiving host D prop : propagation delay from sender to receiver v i : the queueing delay b i : time packet i spends in the buffer at the receiver d i : playout delay of packet i n i : network delay of packet i

2001/02/15Chin-Kai Wu, CS, NTHU6 Playout Mechanism Absolute timing method if (packet i is the first packet of a talkspurt) p i = t i + ˆd i + 4 * ˆv i else p j = p i + t j – t i /* offset */ ˆd i and ˆv i are estimates of the mean and variation in the end-to-end delay

2001/02/15Chin-Kai Wu, CS, NTHU7 Playout Mechanism (Cont’d)

2001/02/15Chin-Kai Wu, CS, NTHU8 Algorithms Algorithm 1. Algorithm 2. Algorithm 3.

2001/02/15Chin-Kai Wu, CS, NTHU9 Algorithms (Cont’d) Algorithm 4.

2001/02/15Chin-Kai Wu, CS, NTHU10 Experiment Environment NeVoT (Network Voice Terminal) Transmits 160 bytes every 20ms Traces

2001/02/15Chin-Kai Wu, CS, NTHU11 Experiment Result (Buffer Effect)

2001/02/15Chin-Kai Wu, CS, NTHU12 Experiment Result (Effect of Duration of trace)

2001/02/15Chin-Kai Wu, CS, NTHU13 Experiment Result (Effect of Jitter)