Application And Research Of The H.264 In Multimedia Communication

In recent years, with the prevalence of broadband, and with the development of multimedia processing technology, digital video service has gained people's attention greatly. Realtime multimedia applications, such as videoconference systems video monitor systems HDTV etc., have been widely used. Although network environment has been progressing a lot, the bandwidth resource is still limited as far as the fast growth of multimedia applications is concerned. Therefore, video coding technologies that can produce high compression ratio and high picture quality have been a hot spot issue in multimedia field.The H.264 is the newest international video-coding standard established and released by the ITU-T and ISO/IEC together. A number of new features have been applied to the new standard, including multi-block inter prediction, 1/4 fractional pixel motion estimation, 4x4 block integer transform, CABAC etc., and therefore it has enhanced compression performance. Experimental result reveals that the bit rate reduces about 50% under the same visual quality, compared with the former video-coding standard H.263. However, the algorith complexity increases greatly at the same time, so it needs be optimized when applied in multimedia communication systems. This Paper studies the H.264 standard in detail, analyze the bottleneck of the coding speed, and implement an optimized codec. Experimental result reveals that, compared with the reference codec, the PSNR and compression ratio of the optimized codec fall off slightly, while the coding velocity advances greatly, and afford satisfaction to realtime multimedia applications' needs.Based on the implemented H.264 codec, this paper also implements an audio-video communication software AVChat in LAN. AVChat provides point to point audio and video communications in realtime. Experimental result shows that the H.264 codec implemented in this paper works smoothly in AVChat. It performs a good video quality while costs a low bit rate. AVChat can be expanded, and put to use of realtime multimedia applications such as videoconference systems, etc.