基于频域的MPEG-2码率转换技术及其码率控制策略

摘要

本文针对MPEG-2三种不同的预测方式，讨论了由参考帧中各块的DCT系数直接求得匹配块的DCT系数的方法，提出了频域内运动补偿的概念和基于频域的无偏视频码率转换技术。其码率控制策略使用了率失真优化求得各编码帧最佳的量化参数，并在G-BFOS算法的基础上对率失真优化的快速算法进行了进一步简化，在保证解的精度的前提下大大降低了计算复杂度。%The methods of calculating the DCT coefficients of the matching blocks from the derived DCT coefficients of the blocks in the reference frames under three different prediction modes of MPEG-2 is discussed, based on which a drift-free MPEG-2 transcoder that achieves motion compensation in the frequency domain is proposed. The rate-distortion optimization is applied to the rate control strategy to get the optimal quantization parameter of each frame, with its fast algorithm further simplified on the basis of GBFOS method. Our approach can lead to the solutions of satisfactory accuracy but only with a fraction of the complexity of the existing algorithms.