Improving bits allocation and quantization level control for MPEG2 encoders

In this paper two techniques have been proposed for improving coding performance of MPEG2 Simulation Test Model 5 (STM5) bit rate control scheme for constant bit rate (CBR) transmission applications. The first technique is to modify the quantization level produced by the STMS rate control scheme in such a way that the statistics of the quantization level applied to macro blocks (MBs) can be changed as desired. By adjusting control parameters, a range of variable bit rate (VBR) bit streams can be produced. The second technique uses a sliding window instead of a fixed length of group of pictures (GOP) in bit budget allocations, which leads to a more reasonable and fair bit allocation scheme. Combination of the two techniques has brought in average gains in peak signal to noise ratio (PSNR) from about 0.5 dB to about 1 dB. The techniques are simple yet effective and are therefore suitable for improving MPEG2 bit rate control performance