A method operates a two-dimensional (2D) separable interpolation filter for coding a video. The 2D separable interpolation filter includes a first second one-dimensional (1D) interpolation filter and a temporal buffer. The method includes: obtaining filter coefficients for the first 1D 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, the filter coefficients being amended such that a sum of positive 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.