Good news for mobile TV

Abstract — Previous studies have found mobile TV usage durations to be shorter than 10 minutes [1]. News programmes fit this requirement and were identified by mobile phone users in focus groups and surveys as the most interesting content type [2]. This paper presents two studies that investigate human requirements on the delivery and presentation of TV news footage at different video and audio encoding bitrates. The effects of resolution, picture size, different mobile presentation devices, encoding schemes and audio on the news content are presented. To ensure validity both studies were carried out on mobile devices. Study 1 examined video and audio encoding bitrates on a 3G phone and an IPAQ PDA whereas study 2 looked at various resolutions and picture sizes ranging from 120x90 to 240x180 on an IPAQ. Index Terms — Mobile TV, image resolution, image size, text in videos I NTRODUCTION EWS was identified by users in focus groups and surveys as the most interesting content type for mobile consumption. [2].The typical length of a News bulletin also fits well with observed use of mobile TV in bursts of less than ten minutes. However, to ensure an optimal supply of news content to a mobile audience the following questions need to be addressed: 1. Is it possible to repurpose standard TV news without reediting? 2. How does the reduced resolution of the mobile screen affect the acceptability of the service? 3. How do different encoding bitrates of both audio and video affect the perceived quality? 4. What price are people willing to pay for this news service? The answers to these questions have ramifications for both the production and the delivery of news. Since is not clear whether the audience of mobile TV will support the cost involved in editing content especially for mobile TV the simplest and cheapest solution would be to deliver TV material without additional editing. However, little is known about the technical requirements to deliver content at an acceptable quality to a mobile audience. The visual resolution of the content affects the required bandwidth for transmission and the amount of visual detail that can be displayed, and consequently limits the content that can be presented. Sensible resolutions for the content depend on the resolution of the target device, the physical size of the picture and the viewing distance which – if too close – may contribute to eyestrain [3]. The portability of mobile devices is also a major concern of mobile users and violating this for the sake of bigger screens may inhibit uptake of mobile TV [2]. Lowering the video resolution might have two opposing effects. A reduction in the amount of pixels lowers the amount of detail that can be represented in the video. On the other hand a reduced resolution increases the encoding bitrate per pixel and might therefore