QoS Scalability for Streamed Media Delivery

Applications with real-rate progress requirements, such as mediastreaming systems, are difficult to deploy in shared heterogenous environments such as the Internet. On the Internet, mediastreaming systems must be capable of trading off resource requirements against the quality of the media streams they deliver, in order to match wide-ranging dynamic variations in bandwidth between servers and clients. Since quality requirements tend to be user- and task-specific, mechanisms for capturing quality of service requirements and mapping them to appropriate resource-level adaptation policies are required. In this paper, we describe a general approach for automatically mapping user-level quality of service specifications onto resource consumption scaling policies. Quality of service specifications are given through utility functions, and priority packet dropping for layered media streams is the resource scaling technique. The approach emphasizes simple mechanisms, yet facilitates fine-grained policy-driven adaptation over a wide-range of bandwidth levels. We demonstrate the approach in a streamingvideo player that supports user-tailorable quality adaptation policies both for matching its resource consumption requirements to the capabilities of heterogeneous clients, and for responding to dynamic variations in system and network load

Adaptive Live Video Streaming by Priority Drop

In this paper we explore the use of Priority-progress streaming (PPS) for video surveillance applications. PPS is an adaptive streaming technique for the delivery of continuous media over variable bit-rate channels. It is based on the simple idea of reordering media components within a time window into priority order before transmission. The main concern when using PPS for live video streaming is the time delay introduced by reordering. In this paper we describe how PPS can be extended to support live streaming and show that the delay inherent in the approach can be tuned to satisfy a wide range of latency constraints while supporting fine-grain adaptation

Supporting Low-Latency TCP-Based Media Streams

The dominance of the TCP protocol on the Internet and its success in maintaining Internet stability has led to several TCP-based stored media-streaming approaches. The success of these approaches raises the question whether TCP can be used for low-latency streaming. Low latency streaming allows responsive control operations for media streaming and can make interactive applications feasible. We examined adapting the TCP send buffer size based on TCP\u27s congestion window to reduce application perceived network latency. Our results show that this simple idea significantly improves the number of packets that can be delivered within 200 ms and 500 ms thresholds

Quality-Adaptive Media Streaming by Priority Drop

This paper presents a general design strategy for streaming media applications in best effort computing and networking environments. Our target application is video on demand using personal computers and the Internet. In this scenario, where resource reservations and admission control mechanisms are not generally available, effective streaming must be able to adapt in a responsive and graceful manner. The design strategy we propose is based on a single simple idea, priority data dropping, or priority drop for short. We evaluate the efficacy of priority drop as an adaptation tool in the video and networking domains. We show how common video compression formats can be extended to support priority drop, thereby becoming streaming friendly. In particular, we demonstrate that priority-drop video allows adaptation over a wide range of rates and with fine granularity, and the adaptation is tailorable through declarative adaptationpolicy specifications. Our technical contribution with respect to video is to show how to express adaptation policies and how to do priority-mapping, an automatic translation from adaptation policies to priority assignments on the basic units of video. For the networking domain, we present priority-progress streaming, a real-time best-effort streaming protocol. We have implemented and released a prototype video streaming system that incorporates prioritydrop video, priority mapping, and priority-progress streaming. The system has the following advantages: it maintains timeliness of the stream in the face of rate fluctuations in the network, it attempts to utilize available bandwidth fully so as to maximize the average video quality, it starts video display quickly after the user initiates the stream, and it limits the number of quality changes that occur. In summary, we will show that priority-drop is very effective: a single video source can be streamed across a wide range of network bandwidths, on networks saturated with competin

Priority-Progress Streaming for Quality-Adaptive Multimedia

The Internet's ubiquity amply motivates us to harness it for video distribution, however, its best-e#ort service model is in direct conflict with video's inherent timeliness requirements. Today, the Internet is unrivaled in its rich composition, consisting of an unparalleled assortment of networks and hosts. This richness is the result of an architecture that emphasizes interoperability over predictable performance. From the lowest levels, the Internet architecture prefers the best e#ort service model. We feel current solutions for mediastreaming have yet to adequately address this conflict between timeliness and best-e#ort service. We propose that streaming-media solutions targetted at the Internet must fully embrace the notion of graceful degradation, they must be architected with the expectation that they operate within a continuum of service levels, adjusting quality-resource trade-o#s as necessary to achieve timeliness requirements. In the context of the Internet, the continuum o..