Macroblock-level Reduced Resolution Video Coding Allowing Adaptive DCT Coefficients Selection

Reduced resolution update (RRU) video coding provides a better compression performance than H.264/AVC does. It is implemented by encoding the predicted residuals after down-sampling at the encoder and at the decoder, is up-sampled to the full-resolution size while motion compensation prediction signal are still yielded in the full-resolution spatial domain. In this paper, the authors first extend the frame-level RRU to the macroblock-level to obtain better coding performance than the frame-level RRU. Furthermore, a novel macroblock-level reduced resolution coding scheme was proposed which adaptively selects the part of DCT coefficients in the zigzag scan order to obtain better coding efficiency in terms of rate distortion performance. Experimental results exhibit that the proposed methods can achieve obvious improvements in both compression efficiency and decoding complexity compared with the frame-level RRU and H.264/AVC.