1. A method of decoding a video, which performs deblocking filtering based on coding units, the method comprising: receiving a bitstream including data of a picture, information about a size of a maximum coding unit, and split information; splitting the picture into a plurality of maximum coding units using the information about the size of the maximum coding unit; hierarchically splitting the maximum coding unit into one or more coding units based on the split information; determining one or more prediction units in one of the coding units using partition type information, wherein the partition type information indicates one of a symmetric type and an asymmetric type; determining one or more transform units in the coding unit using size information of a transform unit, wherein the transform unit is rectangular with a horizontal size and a vertical size indicated by the size information; performing prediction on the prediction unit in the coding unit and inverse-transformation on the transform unit in the coding unit, in order to generate a reconstructed coding unit; when a boundary included in the reconstructed coding unit corresponds to at least one of a boundary of the prediction unit and a boundary of the transform unit, determining a boundary strength for the boundary based on at least one of non-zero transformation coefficients, prediction mode, a motion vector, and a reference index; determining a deblocking filtering method including at least one of a number of filter-taps and a location of pixels to be deblocking-filtered, based on at least one of the boundary strength and neighboring pixels adjacent to the boundary; performing deblocking filtering of neighboring pixels according to the deblocking filtering method, in order to generate a filtered coding unit including the deblocking-filtered pixels; and determining a reconstructed picture including the deblocking-filtered pixels, wherein: when the split information indicates a split for a current depth, a coding unit of a current depth is split into the coding units of a lower depth, independently from neighboring coding units, and when the split information indicates a non-split of a current depth, the one or more prediction units are obtained from the coding unit of the current depth and the one or more transform units are obtained from the coding unit of the current depth, wherein the determining of the boundary strength comprises determining the boundary strength based on whether the prediction mode of the coding unit to which the neighboring pixels belong is an intra mode or an inter mode, and wherein the deblocking filtering is performed according to the deblocking filtering method when the boundary is not a boundary of the picture.