Patent ID: 6385241
Filing Date: 2002-05-07
Classification: H04N

Abstract:
A method for controlling a video rate for Constant Bit Rate (CBR) video coders, the video rate controlling method comprising:(a) calculating three values for scene change features for input video which are intra-frame variance, inter-frame variance, and picture type value; (b) estimating a video rate by taking the three values of the scene change features using a Radial Basis Function (RBF); and (c) estimating a buffer occupancy by an estimated video rate cbfe(k), a current buffer occupancy O(kâˆ’1), and Mean Bits per Frame (MBF), wherein the video rate controlling method comprises, (d) determining a quantization step size by a mapping curve of an exponential function type or a logarithmic function type using the current and the estimated buffer occupancy, and (e) quantizing a Discrete Cosine Transform (DCT) video input using the quantization step size which is determined in the fourth step and encoding a quantized DCT video input, thereby outputting a video rate as a result of compression, wherein in said step (d), the mapping curve of a logarithmic function type is selected in case the estimated buffer occupancy is larger than a prescribed value, and wherein in said step (d), the mapping curve of an exponential function type is selected in case the estimated buffer occupancy is smaller than a second prescribed value.