A method of decoding a block of video data, the method comprising: decoding syntax information that indicates a selected intra prediction mode for the block of video data from among a plurality of intra prediction modes; applying an N -tap Gaussian intra interpolation filter to neighboring reconstructed samples of the block of video data according to the selected intra prediction mode, wherein N is greater than 2, and wherein the Gaussian interpolation filter comprises a parameter controlling a smoothing strength of the Gaussian interpolation filter, the parameter varying depending on the size of the block of video data; and reconstructing the block of video data based on the filtered neighboring reconstructed samples according to the selected intra prediction mode, wherein: the block of video data is a current coding unit in a current picture of the video data, the selected intra prediction mode for the block of video data is a selected intra prediction mode for a current prediction unit of the current CU, the method comprises, for each respective sample of a predictive block of the current PU, determining a fractional position between two neighboring reconstructed samples of a set of neighboring reconstructed samples by projecting, along a prediction direction associated with the selected intra prediction mode, a coordinate of the respective sample to a row or column of neighboring reconstructed samples containing the two neighboring reconstructed samples, wherein the set of neighboring reconstructed samples including reconstructed samples above and left of the current PU in the current picture; and calculating a prediction value of the respective sample by applying the N-tap Gaussian intra interpolation filter to neighboring reconstructed samples to interpolate a value at the determined fractional position, and reconstructing the block of video data comprises: reconstructing a coding block of the current CU using residual values by adding samples of the predictive blocks of PUs of the CU to corresponding samples of transform blocks of transform units (TUs) of the current CU. decoding syntax information that indicates a selected intra prediction mode for the block of video data from among a plurality of intra prediction modes; applying an N -tap Gaussian intra interpolation filter to neighboring reconstructed samples of the block of video data according to the selected intra prediction mode, wherein N is greater than 2, and wherein the Gaussian interpolation filter comprises a parameter controlling a smoothing strength of the Gaussian interpolation filter, the parameter varying depending on the size of the block of video data; and reconstructing the block of video data based on the filtered neighboring reconstructed samples according to the selected intra prediction mode, wherein: the block of video data is a current coding unit in a current picture of the video data, the selected intra prediction mode for the block of video data is a selected intra prediction mode for a current prediction unit of the current CU, the method comprises, for each respective sample of a predictive block of the current PU, determining a fractional position between two neighboring reconstructed samples of a set of neighboring reconstructed samples by projecting, along a prediction direction associated with the selected intra prediction mode, a coordinate of the respective sample to a row or column of neighboring reconstructed samples containing the two neighboring reconstructed samples, wherein the set of neighboring reconstructed samples including reconstructed samples above and left of the current PU in the current picture; and calculating a prediction value of the respective sample by applying the N-tap Gaussian intra interpolation filter to neighboring reconstructed samples to interpolate a value at the determined fractional position, and determining a fractional position between two neighboring reconstructed samples of a set of neighboring reconstructed samples by projecting, along a prediction direction associated with the selected intra prediction mode, a coordinate of the respective sample to a row or column of neighboring reconstructed samples containing the two neighboring reconstructed samples, wherein the set of neighboring reconstructed samples including reconstructed samples above and left of the current PU in the current picture; and calculating a prediction value of the respective sample by applying the N-tap Gaussian intra interpolation filter to neighboring reconstructed samples to interpolate a value at the determined fractional position, and reconstructing the block of video data comprises: reconstructing a coding block of the current CU using residual values by adding samples of the predictive blocks of PUs of the CU to corresponding samples of transform blocks of transform units (TUs) of the current CU.