Quality delivery of mobile video

Proceedings of the 23rd …, 2011

The increase of powerful mobile devices has accelerated the demand for mobile videos. Previous studies in mobile video have focused on understanding of mobile video usage, improvement of video quality, and user interface design in video browsing. However, research focusing on a deep understanding of users' needs for a pleasing quality delivery of mobile video is lacking. In particular, what quality-delivery mode users prefer and what information relevant to video quality they need requires attention. This paper presents a qualitative interview study with 38 participants to gain an insight into three aspects: influencing factors of user-desired video quality, user-preferred qualitydelivery modes, and user-required interaction information of mobile video. The results show that user requirements for video quality are related to personal preference, technology background and video viewing experience, and the preferred quality-delivery mode and interactive mode are diverse. These complex user requirements call for flexible and personalised quality delivery and interaction of mobile video.

2012 4th International Workshop on Quality of Multimedia Experience, QoMEX 2012, 2012

International Journal of Software Engineering and Knowledge Engineering, 2010

Compared with viewing videos on PCs or TVs, mobile users have different experiences in viewing videos on a mobile phone due to different device features such as screen size and distinct usage contexts. To understand how mobile user's viewing experience is impacted, we conducted a field user study with 42 participants in two typical usage contexts using a custom-designed iPhone application. With user's acceptance of mobile video quality as the index, the study addresses four influence aspects of user experiences, including context, content type, encoding parameters and user profiles. Accompanying the quantitative method (acceptance assessment), we used a qualitative interview method to obtain deeper understanding of a user's assessment criteria and to support the quantitative results from a user's perspective. Based on the results from data analysis, we advocate two user-driven strategies to adaptively provide an acceptable quality and to predict a good user experience respectively. There are two main contributions from this paper. Firstly, the field user study allows a consideration of more influencing factors into the research on user experience of mobile video. And these influences are further demonstrated by user's opinions. Secondly, the proposed strategies -user-driven acceptance threshold adaptation and user experience predictionwill be valuable in mobile video delivery for optimizing user experience.

Proceedings of the 13th annual ACM international conference on Multimedia - MULTIMEDIA '05, 2005

Subjectively perceived video quality is a critical factor when adopting new mobile video applications. When video is used in mobile networks the most important requirements are related to low bitrates, framerates and the screen size of mobile device. In two tests we investigated the effects of codecs and combinations of audio and video streams with low bitrates and different contents on the perceived video quality of mobile devices. The first test showed that the codec H.264 produced the most satisfying video quality, but the quality was not high enough for the presentation of textual information. In the second test, the audio-video ratio 32/128kbps was found to be the most pleasant, but there were content dependent variations.

2010

People like to consume multimedia content on mobile devices. Mobile networks can deliver mobile TV services but they require large infrastructural investments and their operators need to make trade-offs to design worthwhile experiences. The approximation of how users experience networked services has shifted from the inadequate packet level Quality of Service (QoS) to the user perceived Quality of Experience (QoE) that includes content, user context and their expectations. However, QoE is lacking concrete operationalizations for the visual experience of content on small, sub-TV resolution screens displaying transcoded TV content at low bitrates. The contribution of my thesis includes both substantive and methodological results on which factors contribute to the QoE in mobile multimedia services and how. I utilised a mix of methods in both lab and field settings to assess the visual experience of multimedia content on mobile devices. This included qualitative elicitation techniques such as 14 focus groups and 75 hours of debrief interviews in six experimental studies. 343 participants watched 140 hours of realistic TV content and provided feedback through quantitative measures such as acceptability, preferences and eye-tracking.

Springer eBooks, 2015

Pervasiveness of mobile devices and ubiquitous broadband Internet access have laid foundations for video content to be consumed increasingly on smart phones or tablets. As over 85% of the global consumer traffic by 2016 is estimated to be generated by streaming video content, video quality as perceived by end-users of such devices is becoming an important issue. Most of the studies concerned with Video Quality Assessment (VQA) for mobile devices have been carried out in a carefully controlled environment, thus potentially failing to take into account variables or effects present in real-world conditions. In this paper, we compare the results of traditional approach to VQA for mobile devices to those obtained in real-world conditions by using a physical mobile device, for the same video test-set. Results indicate that a difference in perceived video quality between the two settings exists, thus laying foundations for further research to explain the reasons behind it.

Proc. of SPIE Conference on Visual Communications and Image Processing, Lugano, Switzerland, 2003

This paper presents the results of a quality evaluation of video sequences encoded for and transmitted over a wireless channel. We selected content, codecs, bitrates and bit error patterns representative of mobile applications, focusing on the MPEG-4 and Motion JPEG2000 coding standards. We carried out subjective experiments using the Single Stimulus Continuous Quality Evaluation (SSCQE) method on this test material. We analyze the subjective data and use them to compare codec performance as well as the effects of ...

Proc. NordiCHI '12, 2012

In developing countries, many would-be mobile internet users perceive downloadable video content as too expensive. Aggressively degrading this video could reduce its file size and therefore its cost. The studies presented here explore extreme cases of this quality/cost trade-off for mobile phone users in urban India. A series of online studies tested the effects of manipulating a video’s content, bit rate, frame rate, and audio quality on quality ratings and enjoyment. Results show that video quality and thus file size can be greatly reduced with relatively little decrease in these outcomes. A field experiment with low-income users in urban India explored consumers’ choices when presented with a trade-off between video quantity and quality and found that nearly one-third selected a lower quality video for the benefit of more video content. Results suggest that offering lower-quality videos to bandwidth-constrained users could provide monetary savings with only minimal reduction in consumer satisfaction.

Visual Communications and Image Processing 2003, 2003

This paper presents the results of a quality evaluation of video sequences encoded for and transmitted over a wireless channel. We selected content, codecs, bitrates and bit error patterns representative of mobile applications, focusing on the MPEG-4 and Motion JPEG2000 coding standards. We carried out subjective experiments using the Single Stimulus Continuous Quality Evaluation (SSCQE) method on this test material. We analyze the subjective data and use them to compare codec performance as well as the effects of transmission errors on visual quality. Finally, we use the subjective ratings to validate the prediction performance of a real-time non-reference quality metric.

The inclusion of multimedia content in different web-based services has increased significantly. Through an extensive subjective testing campaign, we analyse the quality of experience concerning video transmissions associated to these types of services when accessed from mobile devices and mobile Internet connections. Contrary to traditional normalised quality assessment studies, we point out the service context as a key aspect in quality assessments. Specifically, we analyse the impact of the duration of the test material on quality assessments. We find out that tolerance to visual degradations is higher in the specific context of use compared to when using standardised methodologies for quality assessment, which has a significant impact in terms of commercial service acceptability.