Multimedia applications have intrinsic quality of service (QoS)
requirements that may not be captured by the simple traditional
completion ratio model. We have proposed a new quantitative
QoS metric based on task completion ratio while differentiating
firm and soft deadlines and taking data dependency into
consideration. Using the decoding of MPEG movies as an
example, we have shown that the proposed QoS metric is much
better than completion ratio in measuring the quality of
presentation (QoP) of the movies. Based on the new QoS metric,
we present a set of new online algorithms that outperform popular
scheduling algorithms (such as EDF, FCFS, and LETF) and
enhance QoP significantly, particularly when the system is
overloaded. All the proposed online algorithms have low
computation overhead and can be easily integrated into real-time
operating systems to improve multimedia embedded system’s
performance and/or to save system resources.
