Method and apparatus for predicting frequency transform coefficients in video codec, video encoder and decoder having the apparatus, and encoding and decoding method using the method

Abstract

Provided are a method and apparatus for predicting frequency transform coefficients in a video codec, a video encoder and decoder having the apparatus, and an encoding and decoding method using the method. The method of predicting the frequency transform coefficients in a frequency transform domain includes: calculating a cost between a DC coefficient of a current frequency transformed block that is to be predicted and DC coefficients of frequency transformed blocks adjacent in horizontal, vertical, and diagonal directions with respect to the current frequency transformed block; and selecting an adjacent block with the smallest calculated cost, and predicting DC and AC coefficients of the current frequency transformed block using coefficients of the selected adjacent block. Accordingly, compression efficiency can be improved, and video data can be effectively encoded reflecting the characteristics of various patterns by calculating prediction values of numerous patterns.

Description

[0001] Cross reference of related applications [0002] This application claims the priority and rights of 10-2005-0005005 in the Korean patent filed at the Korean Intellectual Property Office on January 19, 2005, and the entire content is incorporated herein by reference. Technical field [0003] The present invention relates to video data encoding and decoding, and more specifically, to a method and device for predicting frequency transform coefficients in a video codec, a video encoder and decoder using the device, and a method using the method and device Encoding and decoding methods. Background technique [0004] If the video data of a single frame is transformed into the frequency domain, the energy is concentrated to the signal with low frequency components. Therefore, the frame is divided into macroblocks of a predetermined size, and when 4×4 or 8×8 DCT is performed on each macroblock, since data is concentrated to low-frequency components, compression efficiency can be si...

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Problems solved by technology

[0011] However, because for the current block, only the top or left block is used to predict the DC coefficient horizontally and vertically, and then predict the AC coefficient accordingly, encoding cannot be efficiently performed by reflecting various styles of the video

Also, since a block determined by DC coefficient prediction is also used to predict AC coefficients, efficient encoding cannot be performed when there is a difference in high frequency components and low frequency components of video

Furthermore, because only the AC coefficients at the same position of the adjacent block and the current block are compared and then predicted, a prediction reflecting the style characteristics of the video cannot be obtained

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