Embodiments of the disclosure provide methods, apparatus and computer programs for adaptive loop filtering in an encoder and in a decoder. One method, performed in an encoder, comprises: determining filter parameters for a plurality of filters to be used in encoding a frame or slice; determining respective activity values for each of a plurality of blocks in the frame or slice, wherein each block comprises a plurality of pixels; determining respective quantization parameters for each of the plurality of blocks; selecting, for each of the plurality of blocks, a filter from the plurality of determined filters based on the respective activity value and the respective quantization parameter; and applying the filter parameters for the respective selected filters to the plurality of blocks.