Method for generating prediction block in amvp mode

Abstract

An apparatus for decoding video data, the apparatus comprising an entropy decoder configured to separate at least motion information, a quantization parameter and a quantized coefficient sequence from a coded bit stream by decoding the coded bit stream; an inverse quantizer/inverse transformer configured to convert the quantized coefficient sequence to a quantization block using a scan pattern, inversely quantize coefficients of the quantization block using the quantization parameter to generate a transform block, and inversely transform the transform block to generate a residual block; and a motion compensation predictor configured to generate a prediction block of a current prediction unit using a reference index and a motion vector derived from the motion information, wherein the inverse quantizer/inverse transformer inversely quantizes the coefficients of the quantization block by selecting two effective quantization parameters that are available and exist among left, upper, and previous quantization parameters according to an order of priority levels set for the left, upper, and previous quantization parameters and using an average of the two effective quantization parameters, and wherein the motion vector is decoded using a motion vector predictor which is set equal to one of an effective spatial motion vector candidate and an effective temporal motion vector candidate.