基于码率控制的DMB预警信息预处理系统

Pre-processing system of DMB early warning information based on bit-rate control

为解决预警信息音频广播的单一性,通过对数字多媒体广播(DMB)的标准研究,设计了基于码率控制的DMB预警信息预处理系统.该系统采用MPEG-4HE AAC和H.264/AVC编码算法对预警音视频信息分别进行信源编码,实现将编码后信息合成为TS码流;采用RS和卷积交织的信道编码方法实现TS码流的纠错控制,提高传输可靠性.针对传输码率不稳定、音视频传输容量和速率不匹配的技术难点,提出基于码率控制的音视频匹配控制传输方法,通过空包插入法实现对编码输出数据码率的智能控制,达到音视频预警信息的稳定实时输出.该预处理系统目前已通过验证,可显著提高预警信息传输的可靠性、稳定性和实时性.

To solve the singleness of audio broadcasting of the early warning information,a pre-processing system of DMB（ Digital Multimedia Broadcasting） early warning information based on rate control was designed according to the study of DMB standards. The audio and video of the warning information were encoded by the algorithm of MPEG-4 HE AAC and H.264/AVC and synthesized into transport streams in this system firstly.Then in order to im-prove communication reliability,the transport streams were error corrected by Reed Solomon encoding and convolu-tional interleaving.Meanwhile,to solve the problem of the transmission instability rate and ensure the value of the rate to be constant,a transportation control method of audio and video matching control based on rate control is pro-posed.Through this method,the intelligent controlling of the output rate is realized by adopting inserting null packa-ges.The whole system is validated by experiments and outperforms former DMB preprocessing system in both relia-bility and stability.