Video coding using 3 dimensional DCT and dynamic code selection

Abstract

Summary only given. We address the quality issue, and present a method for improved coding of the 3D DCT coefficients. Performance gain is achieved through the use of dynamically selected multiple coding algorithms. The resulting performance is excellent giving a compression ratio of greater than to 100:1 for image reproduction. The process consists of stacking 8 frames and breaking the data into 8/spl times/8/spl times/8 pixel cubes. The three dimensional DCT is applied to each cube. Each cube is then scanned in each dimension to determine if significant energy exists beyond the first two coefficients. Significance is determined with separate thresholds for each dimension. A single bit of side information is transmitted for each dimension of each cube to indicate whether more than two coefficients will be transmitted. The remaining coefficients of all cubes are reordered into a linear array such that the elements with the highest expected energies appear first and lower expected energies appear last. This tends to group coefficients with similar statistical properties for the most efficient coding. Eight different encoding methods are used to convert the coefficients into bits for transmission. The Viterbi algorithm is used to select the best coding method. The cost function is the number of bits that need to be sent. Each of the eight coding methods is optimized for a different range of values.