New DCT computation algorithm for video quality scaling

The application of video coding systems, such as MPEG, in portable systems like organizers and mobile phones can be scaled down to a reduced complexity that matches with the desired video quality and/or display. A new DCT computation algorithm is presented, based on an analysis for optimizing the number of computations involved at each computing stage, using existing fast DCT calculation algorithms. The analysis is used to scale down the video quality, thereby lowering the computing power and resource usage. Compared to a diagonally oriented computation of coefficients that matches with the conventional MPEG scanning, a 2 to 4 dB SNR improvement is obtained when scaling down the video quality to half the computing resources