Rate Adaptation and Content Delivery in Video Streaming.

摘要

Dynamic Adaptive Streaming over Http (DASH) is widely deployed on the Internet for live and on-demand video streaming services. Video adaption algorithms in existing DASH systems are either too sluggish to respond to congestion level shifts or too sen- sitive to short-term network bandwidth variations. Both degrade user video experience. Meanwhile, mobile devices are quickly becoming the main platform for streaming ser- vices. Adaptive streaming to mobile devices faces additional challenges of high TCP throughput variability and limited battery supply.;In dynamic streaming, a user can dynamically choose from different versions of the same video. In P2P dynamic streaming, there is one P2P swarm for each version, and within a swarm, peers can share video chunks with each other, thereby reducing the server's bandwidth cost. Due to economy of scale, cooperation among peers can also reduce the per-peer content price.;We formally study the responsiveness and smoothness tradeoff in DASH through analysis and experiments. We then propose novel video rate control algorithms that balance the needs for video rate smoothness and high bandwidth utilization. We show that a small video rate margin can lead to much improved smoothness in video rate and buffer size. The proposed DASH designs are also extended to work with multiple CDN servers. Also, we extend our design to mobile platform and P2P network. For mobile, we take into consideration of battery consumption modes and battery level. For P2P network, we use cooperative game theory to dynamically assign each peer to a version. To maximally incentivize peer cooperation, we use mechanism design to develop pricing schemes that reflect content and bandwidth cost savings derived from peer cooperation.;Another very important part of the work is extending content delivery from single path to multipath. Most end devices are now equipped with multiple network interfaces. We implement multipath transmission at the network layer and develop a Multipath IP (MPIP) design consisting of signalling, session and path management, multipath rout- ing, and NAT traversal. MPIP supports flexible multipath routing strategies to satisfy diverse application needs.