PERFORMANCE EVALUATION OF VIDEO QUALITY ASSESSMENT METHODS BASED ON FRAME FREEZING

Abstract: A Digital Video Communication System consists of a video encoder, a channel through which the video is transmitted and finally a video decoder. These three phases can cause different kinds of impairments or degradations in the quality of a video. One of the degradations that takes place due to an error prone channel is frame freezing and it affects the quality of a video. Frame freezing is a phenomenon in which a particular frame is repeated (displayed) for a certain period of time until the next correct frame is received hence producing a pause or a freeze in a video sequence. Frame freezing can be single or multiple depending on the channel characteristics. Research is being conducted in order to devise a metric which can help in quantifying a video sequence on the basis of its quality. Researchers design metrics and then using their mathematical models, they compare their results with subjective measurements. Subjective measurements help in telling the preciseness and correctness of the metric that whether the quality assessment metric is close enough to subjective test measurements. In this report, three metrics used for video quality assessment have been studied and compared mathematically as well as by careful experiments. The three metrics, chosen for this study, work on No Reference (NR) method for judging the quality of a video. Subjective tests have been performed keeping in view of the recommendations of ITU (International Telecommunication Union). After the study of these three metrics, their advantages and disadvantages over each other have been discussed and the metric that performs the best under certain conditions has been proposed. Finally, a conclusion has been made for the metric that performs the best and also for the metric that performs the worse or even does not perform at all under certain conditions.