Abstract
The MPEG-DASH protocol has been rapidly adopted by most major network content providers and enables clients to make informed decisions in the context of HTTP streaming, based on network and device conditions using the available media representations. A review of the literature on adaptive streaming over mobile shows that most emphasis has been on adapting the video quality whereas this work examines the trade-off between video and audio quality. In particular, subjective tests were undertaken for live music streaming over emulated mobile networks with MPEG-DASH. A group of audio/video sequences was designed to emulate varying bandwidth arising from network congestion, with varying trade-off between audio and video bit rates. Absolute Category Rating was used to evaluate the relative impact of both audio and video quality in the overall Quality of Experience (QoE). One key finding from the statistical analysis of Mean Opinion Scores (MOS) results using Analysis of Variance indicates that providing reduced audio quality has a much lower impact on QoE than reducing video quality at similar total bandwidth situations. This paper also describes an objective model for audiovisual quality estimation that combines the outcomes from audio and video metrics into a joint parametric model. The correlation between predicted and subjective MOS was computed using several outcomes (Pearson and Spearman correlation coefficients, Root Mean Square Error (RMSE) and epsilon-insensitive RMSE). The obtained results indicate that the proposed approach is a viable solution for objective audiovisual quality assessment in the context of live music streaming over mobile network.
Highlights
A relatively recent development, the evolution and penetration of HTTP Adaptive Streaming (HAS) has been rapid over the last years
It is worth noting here that this study has considered neither impairments introduced by UDP-based video streaming nor impairments introduced by TCP-based video streaming such as MPEG-DASH in the subjective tests and these are not reflected in the model development
This study shows that audio has only a minor impact on overall quality perceived by the end user, assessed according to the methodology defined in ITU-T Rec
Summary
A relatively recent development, the evolution and penetration of HTTP Adaptive Streaming (HAS) has been rapid over the last years. The common objective across these solutions was to provide a media consumption platform that piggy-backed on existing web infrastructure, and that was client driven and adaptive This allowed the client to make informed decisions based on a range of factors, principally real time network characteristic estimates, user device type/capabilities, and client preferences. The client first pulls this file and makes decisions based on this and the other variables, listed above Such a model fits very well with best-effort Internet infrastructure and maps well to user demands to consume media on a wide variety of devices under differing scenarios. Most studies to date have focused on individual modalities, i.e. audio and video separately This has resulted in relatively mature and well researched subjective approaches and objective metrics. It is common to adapt Image Quality Metrics, such as PSNR (Peak Signal-to-Noise Ratio) and MS-SSIM [24] using the average of frame-wise measurements
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