David Lindegren

IP-Based Mobile and Fixed Network Audiovisual Media Services

This article provides a tutorial overview of current approaches for monitoring the quality perceived by users of IP-based audiovisual media services. The article addresses both mobile and fixed network services such as mobile TV or Internet Protocol TV (IPTV). It reviews the different quality models that exploit packet- header-, bit stream-, or signal-information for providing audio, video, and audiovisual quality estimates, respectively. It describes how these models can be applied for real-life monitoring, and how they can be adapted to reflect the information available at the given measurement point. An outlook gives insight into emerging trends for near- and mid-term future requirements and solutions.

Parametric model for audiovisual quality assessment in IPTV: ITU-T Rec. P.1201.2

A parametric packet-based model has been created to estimate user perceived audiovisual quality of Internet Protocol Television (IPTV) services. It is divided into three modules, for audio, video and audiovisual quality. The model is applicable to the quality monitoring of encrypted and non-encrypted audiovisual streams. Typical audio and video degradations for IPTV are covered for Standard Definition (SD) and High Definition (HD) video formats. The model supports the H.264 video codec and the audio codecs MPEG-I Layer II, MPEG-2 AAC-LC, MPEG-4 HE-AACv2 and AC3. It handles various types of IP-network layer transmission errors. The model was developed and validated using a large database of subjective tests. The underlying concept is based on an impairment factor approach, which enables detection of how users build their individual judgment of quality of a given audiovisual signal. Each impairment factor captures the perceived quality impact of a possible degradation and therefore enables diagnostic analysis of quality problems. The model shows high performance results, both in terms of Pearsons Correlation coefficient (r) and Root-Mean-Square-Error (RMSE). The model is standardized as ITU-T Recommendation P.1201.2, the higher resolution (IPTV and Video on Demand (VoD)) algorithm of Recommendation P.1201.

HTTP adaptive streaming QoE estimation with ITU-T rec. P. 1203: open databases and software

This paper describes an open dataset and software for ITU-T Ree. P.1203. As the first standardized Quality of Experience model for audiovisual HTTP Adaptive Streaming (HAS), it has been extensively trained and validated on over a thousand audiovisual sequences containing HAS-typical effects (such as stalling, coding artifacts, quality switches). Our dataset comprises four of the 30 official subjective databases at a bitstream feature level. The paper also includes subjective results and the model performance. Our software for the standard was made available to the public, too, and it is used for all the analyses presented. Among other previously unpublished details, we show the significant performance improvements of using bitstream-based models over metadata-based ones for video quality analysis, and the robustness of combining classical models with machine-learning-based approaches for estimating user QoE.