1. 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 Chin-Kai Wu, CS, NTHU

2. Outline • Introduction • Adaptive playout adjustment algorithms • Notations • Playout Mechanism • Algorithms • Experiment • Environment • Result Chin-Kai Wu, CS, NTHU

3. Introduction Chin-Kai Wu, CS, NTHU

4. Notations Chin-Kai Wu, CS, NTHU

5. Notations (Cont’d) • ti: time packet i is generated at the sending host • ai: time packet i is received at the receiving host • pi: time packet i is played out at the receiving host • Dprop: propagation delay from sender to receiver • vi: the queueing delay • bi: time packet i spends in the buffer at the receiver • di: playout delay of packet i • ni: network delay of packet i Chin-Kai Wu, CS, NTHU

6. Playout Mechanism • Absolute timing method if (packet i is the first packet of a talkspurt) pi = ti + ˆdi + 4 * ˆvi else pj = pi + tj – ti/* offset */ • ˆdi and ˆvi are estimates of the mean and variation in the end-to-end delay Chin-Kai Wu, CS, NTHU

7. Playout Mechanism (Cont’d) Chin-Kai Wu, CS, NTHU

8. Algorithms • Algorithm 1. • Algorithm 2. • Algorithm 3. Chin-Kai Wu, CS, NTHU

9. Algorithms (Cont’d) • Algorithm 4. Chin-Kai Wu, CS, NTHU

10. Experiment Environment • NeVoT (Network Voice Terminal) • Transmits 160 bytes every 20ms • Traces Chin-Kai Wu, CS, NTHU

11. Experiment Result (Buffer Effect) Chin-Kai Wu, CS, NTHU

12. Experiment Result(Effect of Duration of trace) Chin-Kai Wu, CS, NTHU

13. Experiment Result(Effect of Jitter) Chin-Kai Wu, CS, NTHU