Elisabeth Francisca Maria Steffens

Multimedia QoS in consumer terminals

Over the past years, there has been a considerable amount of research in the field of QoS support for (distributed) multimedia systems, ie, multimedia processing in, for example, a (networked) workstation environment. QoS for multimedia systems is about media processing in software, using dynamically scalable functions, and trading resources for quality. Unlike QoS for mainstream multimedia systems, QoS support for high volume electronics (HVE) consumer terminals (CT), such as digital TV sets, digitally improved analog TV sets and STB (set-top boxes), has received little attention in the literature. This paper considers multimedia QoS for consumer terminals, with focus on the high-quality video domain.

Best-Case Response Times and Jitter Analysis of Real-Time Tasks

In this paper, we present a simple recursive equation and an iterative procedure to determine the best-case response times of periodic tasks under fixed-priority preemptive scheduling and arbitrary phasings. The approach is of a similar nature as the one used to determine worst-case response times (Joseph and Pandya, 1986) in the sense that where a critical instant is considered to determine the latter, we base our analysis on an optimal instant. Such an optimal instant occurs when all higher priority tasks have a simultaneous release that coincides with the completion of an execution of the task under consideration. The resulting recursive equation closely resembles the one for worst-case response times. The iterative procedure is illustrated by means of a small example. Next, we apply the best-case response times to analyze jitter in distributed multiprocessor systems. To this end, we discuss the effect of the best-case response times on completion jitter, as well as the effect of release jitter on the best-case response times. The newly derived best-case response times generally result in tighter bounds on jitter, in turn leading to tighter worst-case response time bounds.

Scalable 3D graphics processing in consumer terminals

In this paper, we present how scalable 3D graphics fits into a quality-of-service resource management approach for high volume electronics consumer terminals. Resource management is based on guaranteed and enforced resource budgets, which are allocated by a global quality manager. A specific 3D QoS manager makes sure that a 3D graphics service performs acceptably within the limitations of its budget. Based on models that estimate the quality and workload of functional tasks, such as rendering and decoding, for 3D objects, the scaling parameters of these tasks are adapted to guarantee real-time operation, possibly at a slightly degraded perceived quality. The validity of the approach is demonstrated with a 3D graphics application running in conjunction with video decoding on a Philips set-top box containing a TriMedia/spl trade/ processor.

User Focus in Consumer Terminals and Conditionally Guaranteed Budgets

Media processing in software enables consumer terminals to become open and flexible. Because consumer products are heavily resource constrained, this processing is required to be cost-effective. Our QoS approach aims at cost-effective media processing in software. QoS resource management is based on multilevel control, corresponding to different time-horizons, and resource allocation below worst-case using periodic budgets provided by a budget scheduler.Multilevel control combined with budgets below worst-case gives rise to a problem related to user focus. Upon a sudden increase in load of an application with user focus, its output will have a quality dip. To resolve this user focus problem, we present the novel concept of a conditionally guaranteed budget (CGB). A feasible extension of our budget scheduler with CGBs is briefly described.

Dynamic behavior of consumer multimedia terminals: system aspects

Increasingly, media processing in high volume electronics (HVE) consumer multimedia terminals, such as digital TV sets and set-top boxes, is performed by powerful programmable components. These programmable components enable media processing in software, allowing the terminals to become open and flexible. HVE consumer terminals are heavily resource constrained, and therefore demand for a minimal dimensioning of these terminals. This paper presents the dynamic behavior of HVE consumer multimedia terminals, and describes the implications for the system in general and resource management in particular.

On-the-fly darbage collection: an exercise in cooeration

A technique is presented which allows nearly all of the garbage detection and collection activity to be performed by an additional processor, operating concurrently with the processor carrying out the computation proper. Exclusion and synchronization contraints between the processors have been kept weak.