Design And Implementation Of Multimedia Information Services For Mobile Handheld Devices

With the development of multimedia networking technologies and the popularity of mobile handheld devices, the requirements of receiving and watching multimedia information through the handheld devices become stronger. However, due to the limited capability of the handheld devices and the bandwidth of wireless networks, currently most multimedia streaming services cannot be applied to handheld devices directly in wireless network. On the other hand, multimedia information services for handheld device with multiple ways to access to the information are scattered into different applications. Even if using one application, users would take a lot of time to search for information they need. Moreover, both costs too much resource of devices. Consequently, multimedia streaming adaptation and information sevice integration are valuable research subject.Referring to multimedia stream adaptation, this thesis summarizes some key technologies and suggests a novel gateway architecture for adapting multimedia streamings for handheld devices. The architecture mainly focuses on streaming transcoding and information feedback. After analyzing the capabilities of handheld devices and the features of multimedia streamings, and referring to the related work in previous literatures, the thesis generalizes several primary transcoding approaches which are based on resolution, frame rate, and the volume of the bits encoding, encoding format and so on. Comparing with current designs which provide only single transcoding approach, the thesis proposes multidimensional transcoding module design. On the other hand, according to the user's requirements and the capabilities of the devices, three solutions are designed for information feedback. Also, the mechanism of neural network is introduced to provide automatic control conducting a feedback loop.With regard to integrating multimedia information services for handheld devices, this thesis suggests a new architecture design which aims to integrating the modes of transmitting information and the classes of information. Especially, this architecture integrates real-time streaming services, interactive services and push services into one application. Furthermore, the information which users need are generally classified and provided to users by corresponsive modes referred above.Based on the architecture design described above, an application has been developed on top of Nokia N800, a handheld device with WLAN interface. A friendly user interface is implemented by using GTK+ and the integration as well as concurrency of multiple services is implemented by using multi-thread mechanism. Additionally, the media application MPLAYER is used in our application, which provides stronger capability to process multimedia streaming. The application has been test practically in the Multimedia and Information Gateway system developed in our lab. The test results show that the multimedia information application for handheld devices can satisfy the user's requirements well. The work in the thesis provides a solid foundation for the future work.