A method of decoding a block of video samples from a video bitstream is provided in which the method includes decoding a DQPRP value, deriving a PQP value for a block having a non-zero residual, decoding a DDQP value for the block, deriving a SDQP value for the block from the DDQP value and the DQPRP value, deriving a block QP value for the block from the SDQP value and the PQP value, decoding at least one non-zero coefficient of the block, deriving values of a residual block for the block by first scaling the at least one non-zero coefficient using the QP value and thereafter applying an inverse transform, deriving values of a prediction block spatial or temporal prediction, and deriving decoded sample values for the block by adding the values of the residual block and the values of the prediction block.