Congestion Control for Scalable VBR Video with Packet Pair Assistance

The SVC (scalable video coding) extension to the recent video compression standard H.264/MPEG-4 AVC paves the way for video congestion control, by allowing flexible on-the-fly adjustments of the sending rate. We study the interaction between TFRC (TCP-friendly rate control) and application level rate control, and observe that TFRC requires relatively large router buffers to keep packet loss on acceptable levels. In turn, this leads to increased jitter which excludes delay sensitive applications. As a response, the packet pair assisted congestion control is presented and compared with TFRC. The two transport protocols are simulated in a DiffServ environment, and we find that proper congestion control may replace complex admission control mechanisms without sacrificing utilization or QoS guarantees. In fact, the results indicate that semi-elastic video can be sent in an AF (assured forwarding) class with small buffers, leaving the EF (expedited forwarding) class to traffic with more extreme delay requirements.