Method of deriving motion information

1. A method of encoding video data in a merge mode, the method comprising:

determining motion information of a current block;

generating a prediction block of the current block using the motion information;

generating a residual block using the current block and the prediction block;

transforming the residual block to generate a transformed block;

quantizing the transformed block using a quantization parameter and a quantization matrix to generate a quantized block;

scanning coefficient components of the quantized block using a diagonal scan;

entropy-coding the scanned coefficient components of the quantized block; and

encoding the motion information,

wherein encoding the motion information comprises the sub-steps of:

constructing a merge list using available spatial and temporal merge candidates;

selecting a merge predictor among merge candidates of the merge list; and

encoding a merge index specifying the merge predictor,

wherein when the current block is a second prediction unit partitioned by asymmetric partitioning, the spatial merge candidate corresponding to a first prediction unit partitioned by the asymmetric partitioning is not to be listed on the merge list, and

wherein the quantization parameter is determined per a quantization unit and is encoded using a quantization parameter predictor,

a minimum size of the quantization unit is adjusted by a picture parameter set,

if two or more quantization parameters are available among a left quantization parameter, an above quantization parameter and a previous quantization parameter of a current coding unit, the quantization parameter predictor is generated using first two available quantization parameters among the left quantization parameter, the above quantization parameter and the previous quantization parameter, and

if only one is available among the left quantization parameter, the above quantization parameter and the previous quantization parameter, the available quantization parameter is set as the quantization parameter predictor.

2. The method of claim 1 , wherein an average of first two available quantization parameters among the left quantization parameter, the above quantization parameter and the previous quantization parameter is set as the quantization parameter predictor if at least two of a left quantization parameter, an above quantization parameter and a previous quantization parameter are available.

3. The method of claim 1 , wherein a reference picture index of the temporal merge candidate is set as 0.

4. The method of claim 1 , wherein the motion vector of the temporal merge candidate is a motion vector of a temporal merge candidate block within a temporal merge candidate picture, and a position of the temporal merge candidate block is determined depending on the position of the current block within the LCU.

5. The method of claim 4 , wherein the motion vector of the temporal merge candidate is a motion vector of a motion vector storing unit corresponding to the position of the temporal merge candidate block.

6. The method of claim 5 , wherein a size of the motion vector storing unit is 16×16.