An electronic apparatus performs a method of decoding video data. The method comprises: receiving, from bitstream, video data corresponding to a transform-skip mode coded block; decoding, from the video data, a first codeword, a second codeword and a first group of codewords for a pixel within the transform-skip mode coded block; deriving an initial level value from the first group of codewords; converting the first codeword into a remainder of the pixel in accordance with a predefined mapping relationship that is generated using a constant Rice parameter; converting the second codeword into a sign value of the remainder; and deriving a quantified residual of the pixel from the remainder, the sign value and the initial level value.