Encoder, decoder and corresponding methods using interpolation filtering

Abstract

A method for operating a two-dimensional (2D) separable interpolation filter for coding a video, wherein the two-dimensional separable interpolation filter comprises a first and a second one-dimensional (1D) interpolation filter and a temporal buffer of a predetermined buffer size, wherein the method comprises: obtaining filter coefficients for the first one-dimensional interpolation filter of the two-dimensional interpolation filter; comparing a sum of positive filter coefficients of the obtained filter coefficients with a threshold; and upon determining that the sum of positive filter coefficients is larger than the threshold, amending one or more of the filter coefficients to obtain amended filter coefficients, wherein the one or more filter coefficients are amended such that a sum of positive filter coefficients of the amended filter coefficients is not larger than the threshold; applying the amended filter coefficients to samples of the video to obtain a value of a fractional sample position of the video; re-scaling the value of the fractional sample position and storing the re-scaled value of the fractional sample position in the temporal buffer.