Non-linear Editing System, Mpeg-4 Compression - Decompression Technology Research,

Non-linear Editing System(NLEs) appeared when television technology's digitization and computer technology in storge space, speed of data processing and the rest fields developed to a certain stage. It adopts both modern multimedia and computer, the latest technology in most advanced field of 21st centery. It has so much editing function. This changes people's concept of editing in turn of time and overcomes the fault of bad quality in video multi-tapes compounding and image copying. This also greatly improves the editing efficiency and develops a vast space for editors' art creation.At present, the compression format populary adopted by NLEs includes Motion-JPEG and MPEG-2 4:2:2P@ML. MPEG-4, as a newly compressing format gradually gets the attention of Non-Editing System's manufacturers. Motion-JPEG adopts intra-frame compress, the expense is quite low, but it lacks highly efficient compression possessed by inter-frame prediction and motion compensation. MPEG-2 adopts inter-frame compression format, inter-frame prediction and motion compensation technology. In this way compression effeciency is highly improved. After successfully solved frame accuracy editing, MPEG-2's high compressing effeciency and its advantage in transportation and storge make Motion-JPEG gradually disappear from market. MPEG-2 gradually becomes dominant in NLEs area. At present in order to solve the problem of net band, many manufacturers adopt compression format of MPEG-4 to pre-edit and browse, in this way, they can make the software coding in lOOkb/s GIF to frame accuracy editing.Motion-JPEG adopts intra-frame compression to supply the frame accuracy editing. MPEG-2 adopts hardware to solve this problem. But at present there is no NLEs cards which can support MPEG-4 compression format. MPEG-4 can only adopt software compress/decompress when used in NLEs. When frame accuracy editing begins, the file's random seeking will be delayed. This article analyses why this happens, peculiar filter reulation based on DirectShow/DES platform, which supplied by Microsoft Corpation, and highly efficient compressing are the main reasons. This article gives the solvement for random frame seeking : reading file, paraphrasing file and decompressing frame 3 in 1. Through the careful provement and programming realization, the biggest barricade of adopting MPEG-4 compression format in NLEs has been removed.