A Low Complexity Rate-Distortion Source Modeling Framework

An accurate rate-distortion model, which characterizes the relationship among bitrate, distortion, and quantization parameter (QP), is very desirable for real time video transmission. It has been reported that the actual coding bitrates can be estimated by a linear combination of two characteristic rate curves in rho-domain where rho is defined as the percentage of zeros among the quantized transform coefficients. The process is referred as the "pseudocoding" process. Unfortunately, since rho values are real numbers, an interpolation process must be required for the domain transformation from rho-domain to q-domain. Thus, the prediction inaccuracy can not be avoided and even be "propagated" due to the interpolation uncertainty error. Hence, three parameters are addressed in this paper to support a more accurate and direct estimate of encoding bit rates based on q-domain. They include the number of nonzero coefficients, the count of zeros before the last nonzero coefficient in the zigzag-scan order, and the sum of absolute quantized nonzero coefficients, respectively. We surprisingly find that the estimation accuracy in q-domain is better than currently well-known rho-domain based R-Q model. In addition, a quantization-free extraction method, which only involves some additions and a few multiplications, is developed. That is, the implementation complexity of the proposed mechanism is very low. Consequently, the proposed R-Q model is very suitable for real time applications