TABLE OF CONTENTS Mobile video has been lauded as one of the key service innovations that justified the heavy investment in 3G licences across Europe some three years ago. While 3G undoubtedly has the capacity to provide compelling video-based applications, existing 2G-based technologies such as general packet radio service (GPRS) can be used to deliver mobile video services today.
This chapter considers the state of the art for mobile video streaming, discusses the international standards that are applicable for mobile streaming, and describes a mobile video-streaming system developed by BT, which enables high-quality video-streaming using both 3G and GPRS networks.
Real-time video applications require media packets to arrive in a timely manner excessively delayed packets are useless and are treated as lost. This causes the synchronisation between encoder and decoder to be broken, and errors to propagate in the rendered video. The technical implication for IP networks is that the data representing the compressed audio and video cannot be considered as ordinary data files transfer methods such as ftp are not appropriate. The actual transfer methods for streamed media are discussed later.
By way of example, consider an audio/video clip of duration one minute, that has been compressed at an average data rate of 20 kbit/s. To stream this clip to a user, not only must the network provide an average throughput of 20 kbit/s, but the instantaneous throughput of the link...
