Layered DCT video coder for packet switched ATM networks

摘要

A digital video encoder encodes a video frame into a differential video frame for transmission over a packet switched network. The video encoder includes an inter-frame encoder, an intra-frame encoder, and an encoding selector for selecting between the inter-frame and intra- frame encoder depending on the relative motion between the video frame being encoded and the previous video frame.PPA composite frame combiner provides a composite intra/inter-frame encoded difference frame having one set of pixels encoded by the inter-frame encoder, and another set of pixels encoded by the intra-frame encoder. The set of intra-frame encoded pixels includes at least one square or rectangular pixel block, a vertical strip of pixel blocks, and a horizontal strip of pixel blocks. PPDifference frames are encoded into separable data sets representing video information within a particular range of image resolution. A discrete cosine transform (DCT) is used to transform the difference pixels into corresponding DCT coefficients which are separable, by resolution, into the data sets providing coefficient layers.P PA packetizer formats the data sets into asynchronous transfer mode (ATM) packets for transmission over network.