Method for encoding/decoding video signal, and apparatus therefor

1. A method of decoding a video, the method comprising:

parsing a first flag indicating whether inter prediction based on merge related data is applied to a current block; and

parsing a second flag indicating whether a regular merge mode or a merge offset encoding mode is applied to the current block, when the first flag is true,

wherein when the second flag is true, the method comprises parsing a third flag indicating whether the merge offset encoding mode is applied to the current block,

wherein when the third flag is true, the merge offset encoding mode is applied to the current block and when the third flag is false, the regular merge mode is applied to the current block,

wherein when the second flag is false, the method comprises parsing a fourth flag representing whether a combined prediction mode is applied to the current block, and

wherein a merge mode with prediction unit partitioning is applied when the fourth flag is false.

2. The method of claim 1 , wherein when it is determined to apply the merge offset encoding mode to the current block, a motion vector of the current block is derived by summing an offset vector and an initial motion vector.

3. The method of claim 2 , wherein only merge candidates, each of which has an index less than a threshold value, are available for deriving the initial motion vector.

4. The method of claim 1 , wherein when it is determined to apply the combined prediction mode to the current block, a prediction block of the current block is generated based on a weighted sum of a first prediction block and a second prediction block, and

wherein the first prediction block is obtained based on motion information derived from a merge candidate and the second prediction block is obtained by performing intra prediction.

5. The method of claim 1 , wherein when it is determined to apply the merge mode with prediction unit partitioning to the current block, a prediction block of the current block is generated based on a weighted sum of a first prediction block and a second prediction block, and

wherein the first prediction block is obtained based on first motion information derived from a first merge candidate and the second prediction block is obtained based on second motion information derived from a second merge candidate.

6. A method of encoding a video, the method comprising:

encoding a first flag indicating whether inter prediction based on merge related data is applied to a current block; and

encoding a second flag indicating whether a regular merge mode or a merge offset encoding mode is applied to the current block, when the inter prediction based on the merge mode is applied to the current block,

wherein when either of the regular merge mode or the merge offset encoding mode is applied to the current block, the method further comprises encoding a third flag indicating whether the merge offset encoding mode is applied to the current block,

wherein when the merge offset encoding mode is applied to the current block, the third flag is set to be true, and when the regular merge mode is applied to the current block, the third flag is set to be false,

wherein when none of the regular merge mode or the merge offset encoding mode is applied to the current block, the method further comprises encoding a fourth flag indicating whether a combined prediction mode is applied to the current block, and

wherein when the combined prediction mode is applied to the current block, the fourth flag is set to be true, and when a merge mode with prediction unit partitioning is applied to the current block, the fourth flag is set to be false.

7. The method of claim 6 , wherein when the merge offset encoding mode is applied to the current block, a motion vector of the current block is derived by summing an offset vector and an initial motion vector.

8. The method of claim 7 , wherein only merge candidates, each of which has an index less than a threshold value, are available for deriving the initial motion vector.

9. A non-transitory computer-readable medium for storing data associated with a video signal, comprising:

a data stream stored in the non-transitory computer-readable medium, the data stream being encoded by an encoding method which comprising:

encoding a first flag indicating whether inter prediction based on merge related data is applied to a current block; and

encoding a second flag indicating whether a regular merge mode or a merge offset encoding mode is applied to the current block, when the inter prediction based on the merge mode is applied to the current block,

wherein when either of the regular merge mode or the merge offset encoding mode is applied to the current block, the method further comprises encoding a third flag indicating whether the merge offset encoding mode is applied to the current block,

wherein when the merge offset encoding mode is applied to the current block, the third flag is set to be true, and when the regular merge mode is applied to the current block, the third flag is set to be false,

wherein when none of the regular merge mode or the merge offset encoding mode is applied to the current block, the method further comprises encoding a fourth flag indicating whether a combined prediction mode is applied to the current block, and

wherein when the combined prediction mode is applied to the current block, the fourth flag is set to be true, and when a merge mode with prediction unit partitioning is applied to the current block, the fourth flag is set to be false.