An apparatus for encoding a video, wherein slices of the video are split into a quadtree of largest coding units (LCUs) which are further split into a plurality of coding units (CUs) until a minimum CU size, the apparatus comprising: a quantization differential value storage block unit determination module to determine for which CUs to store a quantization parameter differential value, wherein when a CU is split into four CUs in the quadtree, a first CU is determined to store a quantization parameter differential value and the remaining CUs use the same quantization parameter differential value as the first CU; a quantization module to perform quantization using a determined quantization parameter value for a current CU; a quantization parameter value prediction block determination module to determine a quantization parameter prediction value for the current CU based on a left neighboring CU and a top neighboring CU which are adjacent to the current CU, wherein, when there are only two neighboring CUs on the top of the current CU and when both of the two neighboring CUs have the same largest size which is half horizontal size and half vertical size comparing to the current CU, a left CU among the two neighboring CUs on the top of the current CU is used as the top neighboring CU, wherein, when there are only two neighboring CUs on the left of the current CU and when both of the two neighboring CUs have the same largest size which is half horizontal size and half vertical size comparing to the current CU, an upper CU among the two neighboring CUs on the left of the current CU is used as the left neighboring CU, wherein the quantization parameter prediction value for the current CU results from an average operation of a quantization parameter of the left neighboring CU and a quantization parameter of the top neighboring CU, a quantization parameter differential value generation module to generate a single quantization differential value which is a difference between the quantization parameter of the current CU and the determined quantization parameter prediction value, and a QP storage module to record the generated QP differential value and information on the determination of the quantization differential value storage block unit. a quantization differential value storage block unit determination module to determine for which CUs to store a quantization parameter differential value, wherein when a CU is split into four CUs in the quadtree, a first CU is determined to store a quantization parameter differential value and the remaining CUs use the same quantization parameter differential value as the first CU; a quantization module to perform quantization using a determined quantization parameter value for a current CU; a quantization parameter value prediction block determination module to determine a quantization parameter prediction value for the current CU based on a left neighboring CU and a top neighboring CU which are adjacent to the current CU, wherein, when there are only two neighboring CUs on the top of the current CU and when both of the two neighboring CUs have the same largest size which is half horizontal size and half vertical size comparing to the current CU, a left CU among the two neighboring CUs on the top of the current CU is used as the top neighboring CU, wherein, when there are only two neighboring CUs on the left of the current CU and when both of the two neighboring CUs have the same largest size which is half horizontal size and half vertical size comparing to the current CU, an upper CU among the two neighboring CUs on the left of the current CU is used as the left neighboring CU, wherein the quantization parameter prediction value for the current CU results from an average operation of a quantization parameter of the left neighboring CU and a quantization parameter of the top neighboring CU, a quantization parameter differential value generation module to generate a single quantization differential value which is a difference between the quantization parameter of the current CU and the determined quantization parameter prediction value, and a QP storage module to record the generated QP differential value and information on the determination of the quantization differential value storage block unit.