Augmenting STM5 bit rate control scheme for improving coding quality of MPEG2 video encoders

We have proposed two techniques to augment the MPEG2 STM5 bit rate control scheme for improving the coding quality of video encoders. The first technique can help control the quantization level in such a way that its statistics such as average and variance can be changed as desired through the adjustment of control parameters. Since the quantization level has very high correlation with the coding quality, this implies that the coding quality can be improved if the control parameters are properly adjusted. This technique improves coding quality at the expense of an increase in encoder output buffer fullness, resulting in extra buffer delay. To alleviate this problem a sliding window based bit budget allocation technique is added. The sliding window technique is effective for absorbing the peaks as well as uniformly lowering the level of the buffer fullness. Combination of the two techniques has brought in average gains in Peak Signal to Noise Ratio (PSNR) roughly from 0.5 dB to 1 dB while maintaining low memory space requirement and reasonable buffer delay