Second , this dissertation implements separately a mpeg - 2 video decoder and a dolby ac - 3 digital audio decoder based on software mode , and gives a audio & video synchronization algorithm based on audio - clock - benchmark in mpeg - 2 system decoder , whose feasibility and practicability have been proved by experimenting . it is an all - purpose algorithm , which can perform different decoder according to mpeg - 1 or mpeg - 2 system models , and can also be used for reference to the implementation of other multiplex stream decoders 然后，论文实现了基于软件方式的mpeg - 2标准视频及ac - 3格式压缩音频的实时解码与回放，并依据mpeg - 2系统解码模型实现了一种基于音频基准时钟的mpeg解码器的视音频同步算法，实验证明该算法可行、实用、通用性好，对符合mpeg - 1或mpeg - 2系统标准的视音频解码器均具适用性。
The third generation ( 3g ) communication system is a brand new system which can meet the standard of imt - 2000 / fplmts put forwarded by itu . it is required that 3g system have a good net compatible ability and can realize the worldwide roam . it can offer the users not only the low - rate services but also the extensive multimedia services 第三代移动通信系统是能够满足国际电联提出的imt - 2000 fplmts系统标准的新一代移动通信系统，要求具有很好的网络兼容性，能够实现全球范围内多个不同系统间的漫游，不仅要为移动用户提供话音及低速率数据业务，而且要提供广泛的多媒体业务。
The design basis was the analysis of tetra protocols , especially the air interface related protocols , because the standards of digital trunking system in our country had adopted the air interface protocol of tetra protocol stack , but not decided other parts , which could be decided by the practical conditions Tetra协议分析是本论文研究的基础。特别是与空中接口相关的协议。这是因为我国的数字集群系统标准采用了tetra协议栈中的空中接口协议,而与管理方面相关的协议没有确定,可以根据具体情况自行决定。
The implementation of deltafile 3 . 0 can be divided into two modules ? real - time file system module and manage module for both facilities and drives . the real - time file system contains four parts ? system call api layer , file node manage layer , virtual file system layer , concrete file system layer , which perform the abstraction of the facility 实时文件系统模块包含系统调用api层、文件节点管理层、虚拟文件系统层、具体逻辑文件系统层四部分,主要完成与设备无关的数据存取接口抽象和各种文件系统标准的实现;设备与驱动管理模块包含逻辑设备管理层、物理设备管理层、设备缓冲区高速缓存层、设备驱动管理层四部分,主要完成外部存储设备管理及其驱动接口抽象功能。
First it supports the system call interfaces complied with the posix standard , which make convenience to the porting process to delta os for applications . second , delta file 3 . 0 offers the entire supports to the fat logic file system format , and make it suitable in multitasks environment through technique process . once more , delta file 3 . 0 support the flexible virtual file system interface and drive manage interface to make update easier 首先,其系统调用接口遵循posix规范,以便于应用向deltaos进行移植;其次, deltafile3 . 0提供了对fat全系列逻辑文件系统格式(含fat12 、 fat16 、 fat32 )的完全支持,并通过改造将fat这种源于单任务操作系统dos的文件系统标准应用于多任务环境;此外, deltafile3 . 0提供了灵活的虚拟文件系统接口和设备驱动管理接口,便于未来的升级和扩展。
The technologies in the dissertation mostly include : * the systemic architecture of both video encoding and video decoding principles ; * the tv principles and the video part of mpeg - 2 standard ; * the analysis and the comparison of the algorithm of bit - rate control ; * the realization of the algorithm and the evaluation of its results 主要技术包括： *视频编码与解码系统原理的体系结构； *电视原理、制式以及mpeg - 2视频编码解码系统标准； *对本次研究的mpeg - 2视频码流的码率变换的算法分析及性能比较； *实现算法且对码率变换后的码流质量进行评估；
The power control algorithm used in present cdma conunwhcation standar ( for examle , is - 95a and cdma2000 ) is to allocate ophmal power vector for the user in the system sboply by the distance betwen the base station and the user under a predefined norm ( for example , the transmitted power of user or the signalto - interfrence ratio ( sir received by the base station suffice to some a nddrization norm ) , 在现行cdma通信系统标准中(如is - 95a或cdma2000标准) ，采用的功率控制方法是在一定的标准下(如移动用户发射功率或信干比在到达基站时满足某一最低要求标准) ，根据移动台到基站的远近来为系统内用户分配功率的。
