The Realization Of H.263 Video Compression Encoding Based On TMS320DM642

With the development of every aspect in society, communication has been an important part in people's life.Not only is voice and data transmission need but also the transmission of graphics information is in great need. The rapidly developments of DSP has made the range of application expand constantly. The application for real-time video coding has been used widely. The recent power increase of DSP make it tempting to use software implementation only which will result in a system design more maintainable and easier to upgrade than hardware. In this paper, we study the realization of H.263∕MPEG-4 video compression encode based on TMS320DM642. Responding to multimedia technology rapidly developing and application field promptly enlarging, many multimedia compression and coding standards develop continuously, H.263 and MPEG-4 are representatives among them. Obviously, it is realistic to realize these two kinds of video compression based on TMS320DM642. H.263 was developed on the basis of H.261 standard. In H.263 standard, the traditional hybrid video coding algorithms based on pixel block are used, including inter-picture prediction with motion compensation, DCT and variable length coding. With few increase of the algorithm complexity, H. 263 can offer better picture quality, lower bit rate. So it is very suitable for IP video conference system, videophone. At present, H. 263 standard is a most important kind of coding method adopted in video communication of IP, video communication system. MPEG-4 combines the search based on object with encoding to consider, firstly introduced the concept of video object, contained object-based coding and model-based coding and support object-based interactive and object-based scalable encoding. The establishment of MPEG-4 indicates that the compression of video is developed from the first generation of pixel-based coding to the second generation of content-based coding. The standard pays most attention to interaction and flexibility in multimedia communication .Compared with former The video part of MPEG-4 supports the following function: high compression ratio, interaction based on object, the hierarchical expansion based on object. Because these feature, compression ratio is improved by a lage way, and MPEG-4 offers new multimedia service. Multimedia communication will become more vivid, more convenient and more interact. MPEG-4 will produce enormous effect for the development of multimedia communication in the future. There were already applications and products based on H.263∕MPEG-4 video coding system by software, but the realization based on hardware is become the study and research focus, and was very practical nowadays. Digital signal processor (namely DSP chip) is a kind of microprocessor which is very suitable for dealing with digital signal operation. The primary use of DSP is to realize digital signal procession quickly. With peculiar feature of digital device: stability, repeatability, can be integrated on a large scale, especially high programmable and easy to realizing self-adaptation, DSP bring enormous opportunity to the development of digital signal processing. TMS320DM642, the chip we adopted, is a new programmable high-performance multimedia processing DSP that was produced by TI. The clock can be up to 600MHz, have eight parallel processing units and the process ability is 4800MIPS. In this paper, the real-time video encoder following H.263 recommendation on DSP is described. Detail of H.263 recommendation are introduced and software implementation scheme is provide. At last, system hardware optimization flow is supplied. On application of this encoder, the output data includes two kinds of information. One is texture information, namely the video compressed date. Other is motion information, which we can use to resume the P-VOP. By applying these algorithms on the encoder, we can obtain better compressed result. After real time performance evaluation, the video compression system proves to have remarkable compression ratio and quality. The main feature of MPEG-4 is the coding technique of based on object. But the algorithm based on objects is not mature indeed. People are discussing and studying extensively in this field. Correspond to digital monitor, we adopt the MPEG-4-SP module。MPEG-4-SP is a special simple MPEG-4 model. SP means simple profile. Because it's algorithm is simple correspondingly. It is suitable for realizing based on hardware real-time. Different from above mentioned MPEG-4standard, MPEG-4-SP is not a kind of encoding standard based on object, and it is not multi-object encoding tool at the same time . It encodes the video signal based on rectangle frames. It has no information of scenes and objects. In this paper we use the product of TI—TMS320DM642 to realize MPEG-4 encoder. We introduce the core architecture and main peripherals. The algorithm of the encoder is MPEG-4-SP, it has mature technology and simple operation. We also optimize the algorithm module according to the character of DSP and special video operation instruction in order to improve the performance of the whole system, striving to compress the video in real-time. We gave the experiment result of the encoder under different environment, we test the performance of the encoder. Because of time and my ability, this study only finished the transplant from code to hardware and some optimizations. But by this study, I have a deep understanding of the knowledge of digital signal compression, especially H.263 and MPEG-4 standard. There is a new understanding of DSP at the same time .These knowledge is very helpful to my work in future.