Patent ID: 9118918
Filing Date: 2015-08-25
Classification: H04N

Abstract:
1. A rate-distortion optimized (RDO) transform and quantization method, comprising a processor that performs the following steps: a frame classification step that classifies an input frame as either a key frame or a non-key frame; a rate model update step that generates at least one model parameter of a rate model according to a transform coefficient and a bitrate resulted from an encoded key frame; an RDO transform and quantization step that processes the input frame, thereby generating a quantized transform coefficient according to the model parameter; and storing a previous frame in a frame buffer, and estimating the bitrate according to the previous frame; wherein the bitrate B is estimated by a linear model around a given quantization parameter (QP): where α and β are the model parameters, ∥X∥ 1 is one norm of the quantized transform coefficient X, which is defined as a sum of absolute values of all elements in X; and wherein the RDO transform and quantization step is performed through a closed-form operation as where x i is an element of X, t i is an element of a quantized transform matrix T defined by T=Q −1 A −1 R, wherein Q −1 is a quantization matrix, A −1 is a transform matrix, R is a residual signal obtained by subtracting a predicted signal from an input signal of the input frame, is an adjustment term, and λ is a Lagrange multiplier defined by a cost function J=D+λB, wherein D is distortion.