Method and apparatus for hierarchical data unit-based video encoding and decoding comprising quantization parameter prediction

A video decoding method comprising:

• obtaining a quantization parameter of a slice;
• generating a predicted quantization parameter of a current quantization group using the quantization parameter of the slice;
• generating a predicted quantization parameter of a next quantization group using the quantization parameter of the slice;
• and
• performing an inverse quantization on the current quantization group and the next quantization group,
• wherein the current quantization group is a first quantization group in a current row included in the slice,
• the next quantization group is a first quantization group in a next row included in the slice,
• each of the current row and the next row comprises a plurality of largest coding units,
• wherein a predicted quantization parameter of a quantization group in the current row which is not the current quantization group, is generated using a quantization parameter of a neighboring coding unit of the quantization group in the current row, and
• wherein a predicted quantization parameter of a quantization group in the next row which is not the next quantization group, is generated using a quantization parameter of a neighboring coding unit of the quantization group in the next row.