Videophone Video Encoder Implementation And Optimization,

In recent years, along with the fast development of multi-media technique and the communication technique, simple speech correspondence method cant satisfy the need of people's correspondence, it's hoped to multi-media communication for people. So, we need a multi-media platform. Viewphone is a kind of video communication terminal that base on point to point, it makes use of current telephone network to transmit real-time bi-directional video and audio. Along with the development of the communication industry and people to demanding increment of multimedia technique, we can see the viewphone will become new consumption heat after mobile phone.Because Public Switched Telephone Network currently almost completes universal, our viewphone is according to common telephone line. Its platform is Trimedia of Philips;its main processor is TM1300.The key technological of Videophone is video encoding and decoding. ITU issued a lot of standard, such as H.261, H.263, MPEG-1, MPEG-2, MPEG-4.MJPE ,etc. It depends on that fine definition requirement and bandwidth of the channel which kind of standard is chosen on earth. As to PSTN low speed channel, we selected low bit rate video encode standard H.263, and optimized our terminal base on characteristic of TM1300. In test, we used PSTN of YanTai, the transmission speed of our terminal is up to 33.6kbps, video is smooth and delay of audio is very little, so video and audio are synchronization.This paper first presents the developing history and the situation of viewphone. The next introduces H.324 standard, RTOS (real-time OS) pSOS, the performance and construction of TM1300, the system implement and its performance. Next, introduce H.263 standard, mainly introduce Quantization, the motion estimation and DCT, etc. Last, introduces controlling of bits rates, optimization methods is depicted in detail on TM1300 and some optimization methods are introduced.