Video signal encoder employing an adaptive quantization technique

摘要

An Encoder encodes a video signal comprising a multiplicity of frames, wherein each frame includes object pixel block data having one or more object pixels therein and background pixel block data having no object pixel therein. The encoder comprises a transform coder 310 to transform pixel block data to provide a set of transform coefficients; a control signal generator 303 to generate a first control signal if object pixel block data is inputted and a second control signal if background pixel block data is inputted a quantization parameter controller 300 to generating a modified quantization parameter in response to either one of the first and the second control signal 5 based on the data inputted thereto; and a quantizer 320 to quantize the set of transform coefficients by using the modified quntization parameter to thereby provide a set of quantized transform coefficients.