Volume 54, Number 2, 2013 ACTA TECHNICA NAPOCENSIS Electronics and Telecommunications ________________________________________________________________________________ Manuscript received April 21, 2013; revised May 28, 2013 48 ADVANCED METHODS AND TOOLS FOR ONLINE EVALUATION OF MULTIPLEXING SERVICES AND ENCODING PARAMETERS IN DIGITAL VIDEO BROADCASTING Alexandru Florin ANTONE, Radu ARSINTE Technical University of Cluj-Napoca, Faculty of Electronics, Telecommunications and Information Technology, Communications Department, Tel: +40-264-595699, Str. Baritiu 26-28, antonealexandru@yahoo.com, Radu.Arsinte@com.utcluj.ro Abstract: The paper contains a practical study regarding some aspects of multiplexing and encoding implementation in DVB systems. Starting from the ITU-R DTV model, the main blocks are investigated from theoretical point of view, emphasizing the points where is still possible to bring improvements in optimized practical implementation. The theoretical considerations are followed by an experimental study, performed online, using as a core element TSReader Pro, a software package developed to realize the analysis of different aspects (services, multiplexing, RF channel) in DTV (Digital TV). The results are useful in future service improvements, revealing, for example, the unused capacity in each distribution scenario. Keywords: ITU-R DTV model, DVB, Statistical multiplexing, Multiplex analysis I. INTRODUCTION DVB is already a mature technology, verified over more than 15 years in many countries. With its variants S/T/C of the first generation, and T2/C2/S2 of the second one, DVB is used by a large number of audio/video content distributors around the world. Broadcasters, network operators direct satellite broadcasting and other digital video services providers are seeking to increase the number of services transmitted in a fixed channel bandwidth, while maintaining high quality video. Today, for this purpose, it is used the statistical multiplexing system with a feedback between the multiplexer and encoders. Considering implementation of DVB as digital fixed and mobile television in the world, providers and end- users are looking for optimizations in the transmission chain. Optimization is desired both from technical point of view and from business point of view, distributing more attractive services, lower maintaining costs etc. Statistical multiplexing is a critical factor in static or mobile DVB, with the (still) reduced data capacity of the mobile network. Even the basic generations of DVB (T/S/C) are taking a benefit from statistical multiplexing, applying new methods bringing the increase of audio-video streaming capacity. One of key factors in obtaining this desiderate is the statistical multiplexing. It implies a better use of network capacity through medium bandwidth allocation of every link connection, instead of absolute/dedicated bandwidth allocation. Statistical multiplexing architectures in DVB allows media broadcasters the increase the efficiency in distributing digital services, thing that leads to an increase of profits along with customer satisfaction due to a broad variety of audio video services. It has been noticed that in case of video coders operating in constant bit rate mode, complex video scenes don’t have sufficient bandwidth and therefore are error prone (for e.g. art effect can be noticed) opposed to simple video scenes which don’t require as much bandwidth. Therefore in case of simple video scenes most of bandwidth is wasted. Conducted studies analyzing several parallel video streams showed that simultaneous existence of complex video scenes in parallel video streams are very rare. Therefore an advantage is to use a variable coding bit rate (of such streams) using a lower coding rate for simpler video scenes and allowing a higher coding rate for other streams with complex animations, taking advantage of a higher bandwidth. Another advantage is to use the gained bandwidth (by using lower coding rates for simpler video scenes) for inserting additional services (as text or other non time-critical application). In this paper, we are focused on conducting a study of classical or statistical multiplexing, used by different service providers of DVB content, transmitted by telecommunications satellites or terrestrial, having as a final goal a better usage of channel capacity, and the possibility to offer new services in DVB networks. A secondary objective is to evaluate the encoding methods. II. DTV DISTRIBUTION MODEL All digital TV broadcasting systems are following the general model proposed by ITU, two decades ago. ITU established a model of a digital television broadcasting system and this was used as the basis for all DVB implementations. The model was divided into four subsystems (or three in some approaches). The model, presented in figure 1, has mainly three blocks. Source coding and compression – contains the bit-rate reduction methods also known as data compression and error protection techniques that are appropriate for