A video data processing method includes receiving a bitstream; decoding an index associated with a coding unit based on the bitstream, the index indicating a selection mode among at least four selection modes; determining whether a plurality of top neighboring samples and a plurality of left neighboring samples are available; determining four samples based on the index; determining two parameters based on the four samples; determining predicted samples of the coding unit based on the two parameters; and decoding the coding unit based on the predicted samples; wherein determining the four samples based on the index further comprises: determining the four samples based on an availability of the plurality of the top neighboring samples and the plurality of the left neighboring samples.