| In recent years, the progress of computer technology and communicationtechnology promotes the fast transmission of digital information products. Theinformation obtained great changes from individual form to multimedia forms, andproduced a new communication type—multimedia communication. Communicationtechnology appears everywhere, and more and more multimedia services become apart of our lives, such as video conference, video broadcast, network television,long-distance teaching, multimedia net game, Computer Supported CollaborativeWork (CSCW) and so on. The key point of all these applications is how to control thesynchronization between audio signal and video signal in multimedia communication.Therefore, the research on synchronization between audio signal and video signal ismeaningful. Multimedia synchronization technology mainly focuses on thesynchronous controlling between audio signal and video signal in the procedure ofdata collection, transmission, receiving. And the final goal is to obtain thesynchronous play between the audio signal and video signal at the receiver.This paper proposes a multiplexing synchronization method to solve the completeaudio-video synchronization at the transmitter and receiver. By this method, audiostream is multiplexed into video stream, and the time relation between audio unit andvideo unit is maintained. The complexity of controlling the synchronization at thereceiver is reduced. This method always considers the multimedia stream’scharacteristics and syntax in order to have no destroying to the data. And the kind ofmethods is based on a particular video coding standard. We make use of thehighest-frequency sign bit of the Trailing Ones, which is in the4×4luminance blocks,to embed audio information. In the decoder, the embedded audio information can beextracted directly from the encoded mixed streams. And the second method ofCAVLC compression coding approach for H.264/AVC to realize audio-videosynchronization during the entropy coding process is proposed. In the encoder, theaudio information is embedded in the last non-zero quantized coefficient except forthe trailing coefficients and I frames. In the decoder, the embedded audio informationcan be extracted directly from the encoded mixed streams.In order to prove the feasibility of the algorithm, the paper chooses H.264codec-JM for realization. JM is an official standard codec, and it is the most widely used open source codec. The algorithm tests nine different video sequences based onJM software, and uses the subjective quality, PSNR, embedding overhead as thestandards of anglicizing. The experimental results show that by using thissynchronization algorithm, embedded systems have little overhead, and have no effecton synchronization transmission and saving. The impact on video is small, changes inthe subjective test are also very difficult to detect and the PSNR drop can be ignore.And it is an algorithm with no impact of audio. |
