Efficient rate control algorithm for fast transcoding

In this paper, a new rate control algorithm is introduced for a fast rate control requirement in transcoding. The specific transcoding issue mentioned in this paper is referred to as bit-rate conversion. For video services in heterogeneous network environments, it is necessary to convert the bit-rate of compressed video to match it to given transmission channels of lower capacity. The transcoding of coded video streams by requantization in the DCT (Discrete Cosine Transform) domain is considered as a promising technique for its low complexity and acceptable picture quality. We carried out experiments for various video sequences to validate the existence of a novel R-Q (Rate-Quantization) model in the requantization process and found a piecewise linearly decreasing model. Based on this model, we present an efficient rate control algorithm for transcoding, that requires much lower complexity than conventional one. Simulation results show that the proposed algorithm provides a significant advantage over conventional method in both. picture quality and bit-rate deviation.