Rate control for MPEG-2 SNR scalability and stream morphing using codeword estimation and overhead modelling

摘要

Many encoder architectures, notably for scalable systems such as MPEG-2 SNR scalability and stream morphing, require DCT-domain techniques for the estimation of the rate-distortion characteristics of a video frame for use in the rate control process. This paper develops a CBR rate control framework that can be used for single-layer MPEG-4 Simple Profile as well as two MPEG-4-based scalable systems, one following the structure described in MPEG-2 and also stream morphing. The framework supports perceptual quantization and also low bit rate operation by modelling macroblock overhead as well as the bits required to code non-zero DCT coefficients. Experimental results demonstrate the performance of stream morphing, in both objective and subjective measures, is in almost all cases superior to the MPEG-2 SNR scalability and MPEG-4 Fine Granularity Scalability.