Technical Issues In Low Rate Transform Coding

The transmission of video information through a narrow band channel requires a significant degree of image compression. In addition to the actual coding procedure, the frame rate is reduced, the spatial sample rate is lowered and the color components are further filtered. Via the review of a practical and flexible image compression configuration, the important technical aspects of videocoding is presented. The complexity of the currently developed system is discussed for the operation over a 64 kbit/sec communication channel. The specific and primary considerations include the following: After a reduction of temporal and spatial resolution, the luminance and color difference signals are divided in pixel blocks of 16 x 16 and 8 x 8, respectively. Then, they are passed on to a motion compensated DPCM coding system with a subsequent discrete cosine transform of the prediction error. The appropriate quantization is performed via several Huffman tables.