Method and apparatus for encoding video by using transformation index, and method and apparatus for decoding video by using transformation index

A video decoding apparatus comprising:

• a receiver which receives a bitstream of an encoded video;
• an extractor which extracts from the bitstream split information indicating whether a coding unit is split and transformation index information indicating whether a transformation unit of a current level included in a coding unit among at least one coding unit is split;
• and
• a decoder which determines the at least one coding unit by using the split information, splits the transformation unit of the current level into transformation units of a lower level when the transformation index information indicates a split of the transformation unit of the current level, and performs an inverse transformation on the transformation unit of the current level to generate residual data corresponding to the transformation unit of the current level when the transformation index information indicates a non-split of the transformation unit of the current level.