Usage parameter control schemes for improving MPEG video quality over ATM networks

An MPEG encoder compresses moving pictures into I-, P-, and B-frames, where the most important I-frames generate traffic with the highest bit rate. For MPEG videos transmitted over ATM networks, invalid cells are discarded by a usage parameter control scheme at the user network interface and thus cause error propagation in both spatial and temporal domains. For spatial error propagation, the effect of a lost cell depends on the position located in a slice: the farther the position is, the lesser affected are the data. Besides, lost data near the edge of a screen is more tolerable than those at the central part. In order to improve the quality of the received video, we propose two methods to impute the violation of non-conforming cells to others located at a less important position of the same slice. Simulation results reveal that the quality is improved based on both PSNR and subjective visual feeling.