A method to perform a derivation of a temporal candidate prediction motion vector selectively for video decoding comprising: performing the derivation of the temporal candidate prediction motion vector selectively based on information of a plurality of spatial candidate prediction motion vectors, wherein the plurality of spatial candidate prediction motion vectors are a first spatial candidate prediction motion vector and a second spatial candidate prediction motion vector, and wherein a candidate prediction motion vector list is generated based on the first spatial candidate prediction motion vector, the second spatial candidate prediction motion vector and the temporal candidate prediction motion vector, and at most one of the first spatial candidate prediction motion vector and the second spatial candidate prediction motion vector is added to the candidate prediction motion vector list in a case that the derivation of the temporal candidate prediction motion vector is performed, characterized in that: performing the derivation of the temporal candidate prediction motion vector selectively comprises that the temporal candidate prediction motion vector is derived and added to the candidate prediction motion vector list only in a case that the temporal candidate prediction motion vector is available and at least one of the plurality of spatial candidate prediction motion vectors is unavailable or the first spatial candidate prediction motion vector is equal to the second spatial candidate prediction motion vector, availability information for the temporal candidate prediction motion vector indicates whether the temporal candidate prediction motion vector is available or not, the availability information is set to indicate that the temporal candidate prediction motion vector is unavailable in a case that the plurality of spatial candidate prediction motion vectors are available and not equal, the first spatial candidate prediction motion vector is a motion vector for a first block, and the second spatial candidate prediction motion vector is a motion vector for a second block. performing the derivation of the temporal candidate prediction motion vector selectively based on information of a plurality of spatial candidate prediction motion vectors, wherein the plurality of spatial candidate prediction motion vectors are a first spatial candidate prediction motion vector and a second spatial candidate prediction motion vector, and wherein a candidate prediction motion vector list is generated based on the first spatial candidate prediction motion vector, the second spatial candidate prediction motion vector and the temporal candidate prediction motion vector, and at most one of the first spatial candidate prediction motion vector and the second spatial candidate prediction motion vector is added to the candidate prediction motion vector list in a case that the derivation of the temporal candidate prediction motion vector is performed, characterized in that: performing the derivation of the temporal candidate prediction motion vector selectively comprises that the temporal candidate prediction motion vector is derived and added to the candidate prediction motion vector list only in a case that the temporal candidate prediction motion vector is available and at least one of the plurality of spatial candidate prediction motion vectors is unavailable or the first spatial candidate prediction motion vector is equal to the second spatial candidate prediction motion vector, availability information for the temporal candidate prediction motion vector indicates whether the temporal candidate prediction motion vector is available or not, the availability information is set to indicate that the temporal candidate prediction motion vector is unavailable in a case that the plurality of spatial candidate prediction motion vectors are available and not equal, the first spatial candidate prediction motion vector is a motion vector for a first block, and the second spatial candidate prediction motion vector is a motion vector for a second block. performing the derivation of the temporal candidate prediction motion vector selectively comprises that the temporal candidate prediction motion vector is derived and added to the candidate prediction motion vector list only in a case that the temporal candidate prediction motion vector is available and at least one of the plurality of spatial candidate prediction motion vectors is unavailable or the first spatial candidate prediction motion vector is equal to the second spatial candidate prediction motion vector, availability information for the temporal candidate prediction motion vector indicates whether the temporal candidate prediction motion vector is available or not, the availability information is set to indicate that the temporal candidate prediction motion vector is unavailable in a case that the plurality of spatial candidate prediction motion vectors are available and not equal, the first spatial candidate prediction motion vector is a motion vector for a first block, and the second spatial candidate prediction motion vector is a motion vector for a second block.