基于ARM的嵌入式实时流媒体服务系统

发布时间：2018-04-17 03:39

本文选题：ARM + 嵌入式Linux　；参考：《杭州电子科技大学》2012年硕士论文

【摘要】：随着互联网技术的发展，网络的带宽越来越高，城市中ADSL等宽带网络变得普及。基于网络的各种应用需求应运而生，对网络多媒体信息的需要也越来越大了。多媒体编解码技术的发展，新的编解码方式使得音视频文件在保证清晰度的情况下，提高了压缩率，大大降低了文件的大小，使得其更适合网络传输了。流媒体技术是指视频、音频和文字等多媒体数据以连续流方式顺序从信息源端向目的地传输，目的地在接收到数据并进行短暂缓存后就立即播放的一种多媒体技术。流媒体技术采用流式传输的方式传输数据。它并不下载整个完整的文件，具有边下载边播放的特点。一开始只是传输部分的多媒体数据，流媒体客户端将接收的数据放入缓存中，同时播放器就开始播放。流媒体技术在安防监控、网络电视、视频会议等应用领域都起着重要的作用，为人们的工作生活带来了便利。嵌入式流媒体服务器不同于传统的基于PC架构的流媒体服务器，嵌入式的流媒体服务器建立于一体化的硬件结构之上，具有可移动性好，专业化高，稳定性好，，实时性高的优点，因而越来越多的厂商开始关注于嵌入式流媒体产品的开发。正是由于市场上对于嵌入式产品的需求，本文主要研究了流媒体的实时传输原理与协议，构建了一个能够进行音视频采集、编码压缩、网络传输以及解码播放的完整流媒体服务系统。流媒体服务器建立在基于ARM处理器HI3515的嵌入式平台之上，而客户端的解码播放则是在PC平台上实现的。本文对嵌入式HI3515平台进行了深入研究，基于HI3515平台进行嵌入式软件的开发设计。构建了HI3515的交叉编译的开发环境与嵌入式Linux操作系统。本文在设计流媒体服务传输系统时，选用实时流媒体协议（RTSP）来实现服务器与客户端之间的控制信息的交互传输，根据RTSP协议来进行多用户连接的管理与流控制。实现端对端的实时数据的网络传输要依据实时传输协议（RTP），特别对H.264编码的视频数据与G.711编码的音频数据的网络传输格式进行了研究。当传输的流媒体中既有视频数据又有音频数据时，需要考虑音频与视频之间的同步问题，通过实时流媒体控制协议（RTCP）在数据发送时进行控制，调整发送时RTP中的时间戳来消除音视频流不同步的情况。设计HTTP协议，嵌入式设备己接入网络的情况下，通过PC端的浏览器来访问嵌入式设备的IP地址，下载放置在嵌入式设备指定目录下的Web页面与播放器插件。用户在Web页面上进行参数设置，通过HTTP协议发送给设备，实现对设备的控制，同时播放插件对音视频解码播放，实现实时同步播放。最后对整个系统的功能的实现情况与各个性能指标进行测试，达到了实际应用中所要求的指标，完成了设计的目标。
[Abstract]:With the development of Internet technology, the bandwidth of network becomes higher and higher, and broadband networks such as ADSL become popular in cities.Various applications based on network emerge as the times require, and the need for network multimedia information is growing.With the development of multimedia coding and decoding technology, the new encoding and decoding method makes the audio and video files improve the compression ratio and greatly reduce the size of the files, which makes them more suitable for network transmission.Streaming media technology is a multimedia technology in which multimedia data, such as video, audio and text, are transmitted from the source to the destination in the order of continuous flow, and the destination plays the data immediately after receiving the data and caching briefly.Streaming media technology adopts streaming transmission mode to transmit data.It does not download the entire file, with download while playing features.In the beginning, the streaming media client puts the received data into the cache and the player begins to play.Streaming media technology plays an important role in security monitoring, network television, video conferencing and other applications, which brings convenience to people's work and life.The embedded streaming media server is different from the traditional streaming media server based on PC. The embedded streaming media server is based on the integrated hardware structure, which has good mobility, high specialization and good stability.Therefore, more and more manufacturers begin to pay attention to the development of embedded streaming media products.Because of the demand of embedded products in the market, this paper mainly studies the real-time transmission principle and protocol of streaming media, and constructs a audio and video collection, coding and compression.A complete streaming media service system for network transmission and decoding and playback.The streaming media server is built on the embedded platform based on the ARM processor HI3515, and the client decoding and playing is implemented on the PC platform.In this paper, the embedded HI3515 platform is deeply studied, and the embedded software is developed based on HI3515 platform.The development environment of cross compiling of HI3515 and embedded Linux operating system are constructed.In the design of streaming media service transmission system, the real-time streaming media protocol (RTSP) is used to realize the interactive transmission of control information between the server and the client. According to the RTSP protocol, the multi-user connection management and flow control are carried out.The network transmission of end-to-end real-time data should be based on the real-time transmission protocol, especially the network transmission format of H.264 encoded video data and G.711 encoded audio data.When there are both video data and audio data in the streaming media, the synchronization between audio and video should be considered, and the real-time streaming media control protocol (RTCPP) is used to control the transmission of data.Adjust the timestamp in the RTP at the time of sending to eliminate the synchronization of audio and video streams.The HTTP protocol is designed. When embedded devices are connected to the network, the IP address of embedded devices is accessed through the browser of PC, and the Web pages and player plug-ins placed in the specified directory of embedded devices are downloaded.The user sets the parameters on the Web page, sends them to the device through HTTP protocol, realizes the control of the device, and simultaneously plays the audio and video decoding and playing by the plug-in, and realizes the real-time synchronous play.Finally, the realization of the whole system function and the performance index are tested, which reach the requirements of practical application and achieve the goal of the design.
【学位授予单位】：杭州电子科技大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TP368.1;TN919.8

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