1. A video decoding method, comprising: extracting a merge flag and a merge index from a bitstream; when the merge flag indicates a merge mode, checking for whether predetermined candidate adding conditions are satisfied, and adding into a merge candidate set including the merge candidates corresponding to neighboring blocks of a current block, a combined bi-predictive motion parameter, the combined bi-predictive motion parameter generated by combining a list 0 motion parameter of a first available candidate block and a list 1 motion parameter of a second available candidate block, when the predetermined candidate adding conditions are satisfied; and generating a predicted block of the current block by using a motion parameter corresponding to a merge candidate selected from the merge candidate set, the merge candidate selected by the extracted merge index, wherein the merge candidate set is generated based on a maximum number of the merge candidates, the maximum number of the merge candidates decided using information on the number of the merge candidates included in the bitstream.
1. A video decoding method, comprising: extracting a merge flag and a merge index from a bitstream; when the merge flag indicates a merge mode, checking for whether predetermined candidate adding conditions are satisfied, and adding into a merge candidate set including the merge candidates corresponding to neighboring blocks of a current block, a combined bi-predictive motion parameter, the combined bi-predictive motion parameter generated by combining a list 0 motion parameter of a first available candidate block and a list 1 motion parameter of a second available candidate block, when the predetermined candidate adding conditions are satisfied; and generating a predicted block of the current block by using a motion parameter corresponding to a merge candidate selected from the merge candidate set, the merge candidate selected by the extracted merge index, wherein the merge candidate set is generated based on a maximum number of the merge candidates, the maximum number of the merge candidates decided using information on the number of the merge candidates included in the bitstream. 2. The video decoding method of claim 1 , wherein the first available candidate block correspond to a combination of two merge candidates of the neighboring blocks and selected based on a predetermined combination priority of the neighboring blocks.