Study Of Multimedia File I/O Technologies Of Networked Embedded Systems

The RISC (Reduced Instruction Set Computer) is developing quickly in recent years, and the Linux operating system is also getting increasingly sophisticated. Besides, nowadays network facilities are widespread and the Internet media is on the increase, enriching sources of networked programs. The progress in the technologies and the maturity of the business environment are propitious to the product development of the new high-definition media. The newly networked high-definition (HD) multimedia player is one such embedded consumer electronics. Normally, it is running Linux on a kind of RISC platform. In home-use, the core functionality lies mainly on two fields. First it serves as a home Internet terminal for reviewing and downloading Internet media files. Second, it is supposed to be a multimedia processor in the home LAN, reading files from PC and providing programs to home terminals. Our main tasks are to increase the LAN reading speed of HD files and to provide multimedia copy function via LAN to users. This thesis systematically introduces the research and development of a typical embedded HD multimedia player. The technical difficulties of networked HD player in LAN will be studied intensively, and software solutions will be probed.Using SMB in LAN as the file sharing protocol between the Linux-based HD player and the Windows-based PC, the first critical technology is to achieve a higher reading speed of HD files. By large amount of network experiments on I/O performances, some valuable expert experience knowledge is concluded. In the user space layer, a module is devised using the expert knowledge. To some degree, the structure of the module takes that of the expert system for reference. After the processing by this module, network I/O performances can fit for some LAN HD applications. Tests in the home LAN model show that the HD player gains about 20% reading speed increase. The thesis also analyses different methods to improve file I/O from different angles. As a LAN multimedia server, the second problem of the HD player is providing the file copy function on some media. We consider in the kernel layer and try to export everything as a file, so as to unify the operations on all sorts of multimedia that are supported. Specifically, the audio files are implemented as a file system in form of a kernel module, accommodated into the root system. It provides several operations defined by the POSIX.1 standard, including those necessary for the file copy. The success of file copy makes the HD player more perfect as a multimedia server. Improving the performances of embedded systems by software solutions has the advantages of lower cost and easier upgrade.