Hadamard transform domain filter for video coding

This paper proposes a filter for video coding in Hadamard transform domain. The filter is applied to decoded samples at the block level directly after reconstruction. The filter parameters are derived from the coded information depending on quantization parameter (QP) avoiding additional signaling overhead. The filter is designed in hardware friendly manner targeting to exclude multiplication and division operations by using look-up table (LUT). Total LUT size is 70 bytes where only 16 of them are required for one block filtering with certain QP. That allows to keep required loop-up table in one 128-bit register which is beneficial for SIMD software implementation. The method was tested on top of VTM2.0 according to the JVET common test conditions. The experimental results demonstrated 0.7% of bitrate reduction with 3% of encoding time and 1% of decoding time increase.