1. Source-adaptive multilayered multicast algorithms for real_time video distribution Brett J. Vickers, Celio Albuquerque, Tatsuya Suda IEEE/ACM TRANSACTIONS ON NETWORKING, VOL. 8, NO. 6, Dec. 2000

2. Outline Introduction Background SAMM Architecture and algorithms Encoder rate control algorithm Simulations

3. Introduction network source receivers...

4. Background Sender-driven Unicast Multicast with single layer Independently encoded video streams … Receiver-driven Transcoding Trade-off Network utilization and video quality Response time

5. SAMM Architecture Adaptive layered video source Feedback merger Layered video receiver Multicast capable router - basic functions - priority dropping - flow isolation - congestion control

6. SAMM Algorithm (network-based) Basic ideas Source periodically multicasts “forward feedback packet” to receivers Router marks packet to explicit indicate the network status  Monitor the bandwidth available for video  Track the number of video multicast flows  Calculate the fair share of the available bandwidth for each video flow Receiver copies the contents into a “backward feedback packet” and return to source

7. Modified ERICA algorithm (Explicit Rate Indication for Congestion Avoidance, from ATM) Basic functions Set target utilization Monitor the number of active SAMM flows Calculate SAMM capacity (remaining BW for SAMM flow) Calculate SAMM traffic overload (SAMM arvl. rate / capacity) Calculate flow share (current transmission rate / overload) Calculate fair share (capacity / no. of SAMM flows) Set the explicit rate R E into forward feedback packet

8. Contents of feedback packet L Maximum number of video layers allows RCRC current combined rate of the source’s video layers RERE the maximum explicit rate allowed on the path NlNl current number of video layers rlrl A vector (i=1, … N l ) listing the cumulative rates of each clcl A vector (i=1, … N l ) listing the number of receivers requesting each layer in the rate vector r l

9. Video encoder rate control F i (r i, e i, b i ) = r i – (  e i +  (b i – T d * r i ) /  ) r i : the rate requested for layer i e i : layer i ’ s encoder rate error b i : number of bits from layer i currently stored in the buffer

10. Performance (CBR 3Mbps) (VBR 4 and 7Mbps)

11. Scalability study

12. Buffer size study