| With the development of communication and multimedia technology, the transmission of speech and video based on networks has been possible .Recently, the research of video-phone has become a new hotpot and the standard (H.323) has been constructed. TMS320VC5471 is a new architecture chip that is released by Texas Instruments. It is different from other DSPs for its dual cores in a chip: one ARM7 core and one TMS320VC54X core. TMS320VC54X core is very fit to the application of signal processing because of its good performance in high-speed operations, such as encoding and decoding, etc. Though the working frequency of ARM core is lower than DSP core, it has amount of peripheral interfaces to be suitable to implement embedded system. At present, low rate and high compression ratio encoding/decoding technology has been nature. They make it possible to transmit multimedia data in 10M/100M Ethernet .G.723.1 and H.263 are regarded as the standards of speech and video encoding /decoding respectively. As a kind of low rate speech coding scheme,G.723.1 provides dual rates ,6.3kbit/s and 5.3kbit/swhich can be switched in the boundary of two frames. So, it is applied in multimedia communications of speech encoding and can receive good quality of reconstructed speech. Based on H.261, H.263 can provide better picture quality at low bit rates with little additional complexity .It also includes four optimal modes aimed to improve compressing performance. The thesis introduces how to use TMS320VC5471 to implement multimedia data transmission on Ethernet, by expanding speech module, video module and net module, and describes some problems encountered in the working. |
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