Video QoS enhancement using perceptual quality metrics

Abstract

As the market for broadband video services matures, the ability to deliver high-value video content will become increasingly important. For the telecommunications industry to compete effectively with other video providers, it is vital that the quality of video services matches the expectations of customers. A major challenge lies in ensuring that the trade-off between price and quality is acceptable to consumers of broadband video. This paper introduces a new method for measuring in real-time the perceptual quality of video. The potential operational benefits of this method are discussed. The paper describes how a no reference video quality measurement method may be deployed as a mechanism for quality control at the point of video encoding and transmission. Further, it is proposed that a real-time video quality metric can be used to measure the quality received on end users' devices. By applying perceptual quality measurements for quality control and feedback, this mechanism can be used to ensure adequate quality is delivered to customers, make more efficient use of bandwidth and thereby reduce backhaul costs, and act as a quality assurance check on the customer's end device. IntroductionHigh-value video services are becoming more prominent as part of broadband packages. In mainland Europe, a number of service providers (e.g. Fastweb, Free) offer high-quality video delivered over fixed-line broadband networks and telecommunications operators (e.g. France Telecom) are trialling video delivered over DSL. The success of broadband video will be primarily dependent on content and cost. However, the reproduction quality of the video will affect take-up and, critically, churn between operators and service providers. Currently, broadband is capable of providing a variety of video services, including video-on-demand (VoD) sourced from a central server, peer-to-peer downloaded video, streamed real-time video, and videoconferencing. For the highest value services, such as VoD, it is essential that consumers have a range of desirable content to purchase. Once purchased, consumers will demand that the sound and vision they experience is of good quality. For operators and providers alike, there is a need to consider the trade-off between quality and capacity, particularly at the bottlenecks, such as network routers and residential gateways.Willis, in his paper [1], describes the range of factors affecting network quality of service (QoS). The proposition described here is concerned with QoS from an end user's perspective -in particular, the perceptual quality of broadband video. The perceptual quality of video is affected by a number of factors, including:• video content (as the amount of detail and/or motion in a scene increases, then the video becomes more difficult to encode),• encoding rate (typically, increasing the bit rate improves picture quality),• coding scheme (recent advances in video-coding algorithms have resulted in improved picture quality, especially at bit rates of 2 Mbit/s or less),• source video (a good qua...