Estimating the impact of single and multiple freezes on video quality

Abstract

This paper studies the impact of freezing of video on quality as experienced by users. Two types of freezes are investigated. First a freeze where the image pauses, so no frames were lost (frame halt). In the second type of freeze, the image freezes and skips that part of the video (frame drop). Measuring Mean Opinion Score (MOS) was done by subjective tests. Video sequences of 20 seconds were displayed for four types of content, to a total of 23 test subjects. We conclude there is no difference in the perceived quality between frame drops and frame halts. Therefore one model for single freezes was constructed. According to this model the acceptable freezing time (MOS>3.5) is 0.36 seconds.Pastrana -Vidal et al. (2004) suggested a relationship between the probability of detection and the duration of the dropped frames. They also found that it is important to consider not only the duration of the freeze but also the number of freeze occurrences. Using their relationship between the total duration of the freeze and the number of occurrences, we propose a model for multiple freezes, based upon our model for single freeze occurrences. A subjective test was designed to evaluate the performance of the model for multiple freezes. Good performance was found on this data i.e a correlation higher than 0.9.

On subjective quality assessment of adaptive video streaming via crowdsourcing and laboratory based experiments

“…The Football video (56,29) is from a TV broadcast of a football match and has moderate motion and wide angle camera sequences with panning. The ClosetoEdge video (43,24) is from a documentary and is mostly shot with a handheld camera and features varying characteristics. The Rollingstone video (45,42) is from a concert recording, where the lead singer moves around a lot and the video has some sudden scene changes.…”

Performance Analysis of a No-Reference Temporal Quality Assessment Metric for Videos Impaired by Frame Freezing Artefacts

“…Every sixth frame for each video was copied in the following frames of the video sequence in order to create a frame halt or frame freeze. There were in total six different frame freeze durations as described in Table I and for every video, all the frame freeze durations were used [13]. Thus, there were a total of 30 videos for the test subjects to perform the assessments.…”

“…For the multiple freeze experiment, same videos were used but this time for a different set of frame freezes and number of freeze even occurrences which have been described in Table II [13]. So, a total of 110 videos were generated for the multiple freeze experiment.…”

“…The duration of the video, frame freeze and the number of frame freezes have to be selected carefully as the test are of high importance in order to assess the VQA metric. There are different sets of test conditions available and we have used the ones in [13], which comprises of single freeze experiment and multiple freeze experiments. There is a broad range of test scenarios for different frame freeze durations available but we have selected two of them for our test and they have been described in Table I and Table II.…”

Recent developments in visual quality monitoring by key performance indicators

“…The visibility of a freezing artefact also depends on its duration. The shortest time for which viewers can perceive the presence of this artefact equals 100 milliseconds, which is estimated based on the work of van Kester et al [16].…”