Research On Streaming Application And QoS Control

Streaming media is a continuous time-based media transmitted in a real-time and streaming mode over the network. Users can play back some parts of a streaming media which is being downloaded. Streaming applications are related to real-time technology, multimedia technology, high throughput storage technology, high-speed network technology, communication technology, etc. Streaming technology can be used in many fields, such as distance learning, telemedicine, VOD, living broadcast, video phone, video conference, interactive games, e-commercial, multimedia advertising, real-time monitoring, etc.An integrated streaming application system has been designed and implemented based on Windows Media Technologies in this thesis. The system consists mostly of streaming servers, storage subsystem, player, programs and users management. The application system can be used in such fields as VOD, living broadcast and multimedia advertising.The key of streaming applications in some network with enough bandwidth, like LAN, is the performance of streaming server. By measuring and analyzing the performance of three VOD systems, we have found that storage throughput, bandwidth and CPU of streaming servers are the hardware bottlenecks of streaming applications, and the scheduler of servers are the software bottleneck of streaming applications, which is main problems for performance optimization.Since Internet can not provide reliable Quality of Service(QoS), bandwidth shortage and congestion have become the bottlenecks of streaming applications over the Internet. Therefore QoS control mechanism is the key of streaming application over the Internet. An QoS control mechanism based on RTP protocol and MPEG-4 scalable coding has been designed and implemented in this thesis. The mechanism is a part of a smart streaming service system over the Internet and have three characteristics as following:1. TCP-friendly and TCP-fairly. To avoid using too much resource by multimedia flows and leading abnormal transmission of conventional TCP flows, the rates of multimedia flows have been limited and controlled in a similar way to TCP congestion control mechanisms in this thesis.2. Unequal QoS control. Since the significance for each part of multimedia data is different, varied QoS control strategies have been deployed for different multimedia flows in dealing with bandwidth pre-allocation, stream scheduling,...