Quantization noise reduction in hybrid video coding by a system of three adaptive filters

Hybrid video coding algorithms, e.g. H.264/MPEG-4 AVC [1], apply prediction and subsequent prediction error coding introducing quantization noise. The quantized prediction error signal and the prediction signal are added for reconstruction. Deblocking filters reduce quantization noise of the reconstructed signal at block boundaries. To further reduce quantization noise, adaptive Wiener filters are applied to the deblocked signal [2, 3, 4]. In this paper, the adaptive Wiener filter is extended to a system of three adaptive filters in order to improve the quantization noise reduction. A first filter is applied to the deblocked signal, a second filter to the quantized prediction error signal, and a third filter to the prediction signal. The three filtered signals are added for reconstruction. For a set of thirteen test sequences, the system of three adaptive filters achieves an average bit rate reduction at the same quality of 1.9% compared to the adaptive Wiener filter and of 4.9% compared to no Wiener filter. For particular sequences, a bit rate reduction of 6.1% is achieved compared to the adaptive Wiener filter and of 17.1% compared to no Wiener filter.