Streaming video continues to experience unprecedented growth. This underscores the need to identify user-centric performance measures and models that will allow operators to satisfy requirements for cost-effective network dimensioning delivered with an acceptable level of user experience. This paper presents an analysis of two novel metrics in the context of fixed capacity links: (i) the average proportion of a video’s playing time during which the quality is reduced and (ii) the average proportion of videos which experience reduced quality at least once during their playing time, based on an M/M/$\infty$ system. Our analysis is shown to hold for the more general M/G/$\infty$ system for metric (i), but not for (ii) and simulation studies show an unexpected form of sensitivity of metric (ii) to the flow duration distribution, contrary to the norm of increasing variance causing worse performance. At typical operational loads these new metrics provide a more sensitive and information rich guide for understanding how user experience degrades, than the widely used average throughput metric does. We further show that only the combined use of this existing and our new metrics can provide a holistic perspective on overall user performance.

流媒体视频将继续经历前所未有的增长。这强调了需要确定以用户为中心的性能指标和模型，这些指标和模型将使运营商能够满足以可接受的用户体验水平交付的具有成本效益的网络尺寸的要求。本文介绍了在固定容量链接的情况下对两种新颖指标的分析：（i）视频播放时间的平均比例降低了质量；（ii）视频质量降低了至少一次的平均比例在他们的游戏时间中，根据M / M /$\infty$系统。我们的分析表明可以适用于更一般的M / G /$\infty$度量标准（i）的系统，但不适用于（ii）的系统，模拟研究表明，度量标准（ii）对流量持续时间分布的敏感性出乎意料，这与方差增大导致性能下降的规范相反。与广泛使用的平均吞吐量指标相比，这些新指标在典型的操作负载下提供了更敏感和信息更丰富的指南，用于了解用户体验如何下降。我们进一步证明，只有结合使用现有指标和我们的新指标，才能提供整体用户性能的整体视角。