(The) effectiveness of spatial loop filter in MC/DCT hybrid video coding

Abstract

The principal limitation on low rate coding system is the quantization noise in the reconstructed signal and in the prediction loop. This thesis has dealt with the effect of selective loop filtering in MC/DCT hybrid coding system at very low transmission rate. To overcome the difficulties inherent in such a low rate system, we have investigated the effect of a simple spatial averaging filter within the coding loop in making improvements in both the quality of reconstructed image and the information amount required to be transmitted. And also we have presented an effective method for filter selection that does not require the transmission of side information, using the characteristics of motion vectors for neighboring blocks. According to simulation results, SNR gain achieved was more than 1 dB and entropy of quantized coefficients considerably reduced with loop filterings. Moreover, motion vector control method performed very closely to the side information control method, especially for low level of threshold in CR. Subjective effect was even more advantageous; various artifacts, e.g., a "dirty window" and discontinuities of image detail between adjacent blocks, were less visible.