Method and apparatus for decoding video that alternately store lines of picture in pixel units and method of storing reference picture

A method of decoding a picture in a video decoding system including a memory the method comprising:

• storing M lines of the picture in N interleave lines in the memory, wherein M is a natural number and N is a natural number smaller than M;
• and
• decoding the picture by receiving the interleave lines,
• wherein pixel data of a part of the lines from among the M lines is alternately stored in each interleave line.

A method of storing a reference picture, the method comprising:

• classifying M lines of the reference picture into N groups, wherein M is a natural number and N is a natural number smaller than N;
• and
• storing the lines belonging to the N groups as N interleave lines,
• wherein pixel data of a part of the lines from among the M lines is alternately stored in each interleave line.