No abstract

No abstract

The conventional video subjective test design, in which subjects view and rate multiple versions of each source video sequence, was used for decades. New technology, like adaptive streaming, makes it almost impossible to use this design since much longer sequences are needed. In this paper we examine three experiment designs: the conventional design and two alternatives that use each source sequence only once. Based on data collected by three laboratories, we compare the accuracy and scoring behavior of these three designs. We check whether there is a significant difference in scoring behavior between the experiment designs. One of the proposed experiment designs is proposed for immediate use.

No abstract

This article presents the current development of degradation decomposition tools for the assessment of voice communications. Overall quality scores, represented as Mean Opinion Scores (MOS) produced by subjective test methodologies such as ITU-T P.800 Absolute Category Rating (ACR), remains the most popular quality metric in the industry. While MOS is a great indicator to evaluate quality issues, it does not provide information on the cause of issues. To address this gap, work items are currently active within ITU-T to provide the industry with means to understand the cause of lower scores by perceptual or technical degradation decompositions. The goal is to produce objective models that enable automated degradation decomposition. The first step in such a development is the construction of databases for model training and validation. For this, in sum four experiments using a potential diagnostic test method discussed within ITU-T are conducted. In addition, two optional improvements for the test method are presented and discussed. The results of the experiments show that for standardization the analyzed test method still leaves room for validation and further improvements.