基于DSP的网络流媒体播放系统的实现

【作者】 王玮；

【导师】 张卫宁；

【作者基本信息】 山东大学 ， 信号与信息处理， 2007， 硕士

【摘要】 随着多媒体技术的发展和互联网技术的普及，网络流媒体通信已经成为多媒体通信的必需。利用现有的音视频编解码算法可大大减少传输的数据量，进而降低网络传输的带宽要求，但由于网络流媒体应用的实时性要求往往很高，因此编解码算法的实时实现就成了一个关键的问题。使用纯软件实现的系统虽易于升级和移植，但实时性较差；采用专用的编解码算法芯片虽能保证实时性，但系统的灵活性太差，不利于算法升级；而TI公司专为多媒体应用而设计的芯片TMS320DM642(简称DM642)很好地解决了这些问题。DM642是目前业界公认的性能良好的媒体处理器，它基于C64xDSP内核，采用两级缓存，提供了包括视频口、以太网口等丰富的外设接口，使得它近乎是一个多媒体嵌入式系统的单芯片硬件平台，它的完全可编程性，又使其能兼容正在发展的各种多媒体信号处理标准，构成通用的软件平台。利用嵌入式处理芯片为核心处理器的软硬件相结合的方法已成为一种有效的视频编解码的实现途径。本系统使用两块SEED-VPM642实现了单通道视频流的网络传输及实时解码播放，该系统具有以下突出特点：(1)使用数字媒体处理器实现视频编解码算法，既保证了系统的实时性，又保证了算法的灵活性。(2)使用TI提供的H.263XDAIS算法避开了复杂的算法优化，大大提高了系统的开发效率，使用时只需研究算法接口的使用规则即可。(3)系统的整个框架结构清晰易懂，可以方便地将H.264、MPEG-4、G.729等音视频算法集成到系统中，该框架可作为基于TMS320C6000系列的DSP进行多媒体系统开发的一个基本框架，若将音视频算法相结合并应用在多媒体通讯系统标准协议H.323上，可为IP视频电话的实现奠定基础。(4)使用NDK进行网络功能的开发，可将当前常用的上层网络应用程序的开发方法应用到DSP开发中，避开了复杂的DSP底层硬件研究，极大地提高了开发效率。本论文深入研究了利用DM642和H.263 XDAIS算法进行网络流媒体播放系统开发的一般过程。在该开发过程的研究学习中，主要做了以下几项工作：(1)研究了DM642及其硬件开发平台SEED-VPM642的结构和工作原理。(2)研究了目前在TMS320C6000系列DSP开发中常用且有效的参考框架标准5(RF5)，并根据系统的需要搭建了所需的框架。(3)研究了H.263 XDAIS算法的原理及其使用方法，并将该算法加到系统框架中以实现数字视频的编解码。(4)对TMS320C6000系列DSP网络功能开发通用的网络开发工具包NDK进行了深入研究，并在DM642上实现了系统的网络通信。目前，系统已实现单通道视频的实时网络播放，该系统模型不仅可用于基于局域网的区域监控，也可通过Internet用于跨地区的远程监控，可以将该系统作为网络视频监控系统的一个通用平台。更多还原

【Abstract】 With the development of multimedia and internet technology, the stream media communication on the network has become a necessary of the multimedia communication. We can reduce the data quantity making use of the coding and decoding algorithm for the audio and video, so that we decrease the bandwidth request of the network transmission, in order to assure the real -time request, the real time realization of the algorithm becomes a key problem. It is easy to upgrade and transplant using the pure software method, but the real-time capability can’t be satisfied. Using the special codec can satisfy the real-time capability, but the flexible capability is not good and it goes against the algorithm upgrade. The TMS320DM642 (for short DM642) which is designed by TI Corporation solves the questions above successfully.The TMS320DM642 Digital Media Processor is considered to work well for people who use DSP at present. It is based on the C64x CPU, which is part of the C6000 DSP family. The DM642 integrates a number of peripherals to address the development of video and imaging applications, such as video port, EMAC and so on. Its entire programmable capability makes it compatible to all kinds of multimedia processing standard and form a universal software platform. It has become an effective approach that combines software and hardware method which make the embedded processing chip as the core processor.The system realizes single channels video stream transmit on the internet and realtime decode play using two pieces of SEED-VPM642. The system has following characters: (1) the use of Digital Media Processor not only ensures the real-time realization of the system, but also the flexible of the algorithm. (2) The use of H.263 XDAIS algorithm from TI avoids the algorithm optimize which improves the development efficiency. User only needs to know the interface of the algorithm. (3) The framework of the system is clear and understandable, so the H.264、MPEG4、G.729 algorithms can be transplanted to the system easily. The system framework can work as a standard framework for the system development of the DSP which belongs to the TMS320C6000 series. And if the audio and video algorithms combined based on the multimedia communication system standard protocol-H.323, the system can establish the foundation for the IP video phone. (4) The development of network function which uses NDK can apply the usual method for network development to the DSP development. It avoids the complicated hardware research, and improves the efficiency greatly.In this paper, the development of network stream media play system with DM642 and H.263 XDAIS algorithm has been introduced. In the research process, the following work has been done. (1) The structure and principle of the hardware platform of DM642 have been studied. (2) The framework RF5 which is regular used in the development of TMS320C6000 series DSP has been researched. Then constructs the framework the system needed. (3) The principle of H.263 XDAIS algorithm and the approach to use have been studied, then transplant the algorithm to the system framework to realize encode and decode of the digital video. (4) The NDK which is used to add the network function for the TMS320C6000 DSP has been studied in detail, and the network communication function using the EMAC of DM642 is realized.At present, the system has accomplished the real-time network play of single channels video; the system model can be used not only on the region monitor based on the LAN, but also on the long-distance monitor through internet. This system can be served as a network video monitor system universal platform.更多还原