Method and apparatus for processing video signal
The present invention relates to a method and apparatus for processing a video signal, which can increase the accuracy of the motion vector prediction through motion vector scaling which takes a difference in the temporal distance between reference pictures into consideration. To this end, the present invention provides a video signal processing method and a video signal processing apparatus using the same, and the method comprises the steps of: scaling at least one neighboring partition motion vector for a motion vector prediction of the current partition; scaling the neighboring partition motion vector, which has been selected, when the reference picture of the neighboring partition motion vector is different from the reference picture of the current partition; acquiring a motion vector prediction value of the current partition using the scaled motion vector; and acquiring a motion vector of the current partition using the motion vector prediction value.
1. A method of processing a video signal, the method comprising:
obtaining index information from the video signal, the index information specifying a motion vector candidate to be used as a motion vector predictor of a current block;
deriving at least one spatial motion vector from at least one neighboring block satisfying one of selection conditions, the at least one neighboring block being adjacent to the current block;
constructing a motion vector candidate group of the current block, the motion vector candidate group comprising a plurality of motion vector candidates including the derived at least one spatial motion vector;
assigning a motion vector candidate specified by the index information from among the motion vector candidate group to the motion vector predictor of the current block; and
obtaining a prediction sample of the current block based on the motion vector predictor,
wherein the selection conditions include:
a first condition that the at least one neighboring block has a different reference picture list from the current block and a same reference picture as the current block, and
wherein whether the at least one neighboring block has the same reference picture as the current block is determined based on picture order count (POC) information.
2. The method of claim 1 , wherein the selection conditions further include:
a second condition that the at least one neighboring block has a same reference picture list and the same reference picture as the current block.
3. The method of claim 1 , wherein the selection conditions further include:
a third condition that the at least one neighboring block has a same reference picture list as the current block and a different reference picture from the current block, and
a fourth condition that the at least one neighboring block has a different reference picture list and a different reference picture from the current block.
4. The method of claim 3 , further comprising:
scaling the at least one spatial motion vector using a temporal distance between a reference picture of the at least one neighboring block and a reference picture of the current block.
5. The method of claim 1 , wherein the at least one neighboring block includes at least one of a bottom left neighboring block of the current block, a lowest neighboring block among left neighboring blocks of the current block, a top right neighboring block of the current block, a rightmost neighboring block among top neighboring blocks of the current block, and a top left neighboring block of the current block.
6. The method of claim 5 , wherein the selecting the at least one spatial motion vector includes:
checking whether the bottom left neighboring block satisfies one of the selection conditions, and
when the bottom left neighboring block satisfies none of the selection conditions, checking whether the lowest neighboring block satisfies one of the selection conditions.
7. The method of claim 5 , wherein the selecting the at least one spatial motion vector includes:
checking whether the top right neighboring block satisfies one of the selection conditions,
when the top right neighboring block satisfies none of the selection conditions, checking whether the rightmost neighboring block satisfies one of the selection conditions, and
when the rightmost neighboring block satisfies none of the selection conditions, checking whether the top left neighboring block satisfies one of the selection conditions.
8. The method of claim 2 , wherein the selecting the at least one spatial motion vector includes:
checking whether the at least one neighboring block satisfies the second condition, and
when the at least one neighboring block does not satisfy the second condition, checking whether the at least one neighboring block satisfies the first condition.
9. An apparatus for processing a video signal, the apparatus comprising:
a memory; and
a processor operatively connected to the memory and configured to:
obtain index information from the video signal, the index information specifying a motion vector candidate to be used as a motion vector predictor of a current block,
derive at least one spatial motion vector from at least one neighboring block satisfying one of selection conditions, the at least one neighboring block being adjacent to the current block,
construct a motion vector candidate group of the current block, the motion vector candidate group comprising a plurality of motion vector candidates including the derived at least one spatial motion vector,
assign a motion vector candidate specified by the index information from among the motion vector candidate group to the motion vector predictor of the current block, and
obtain a prediction sample of the current block based on the motion vector predictor,
wherein the selection conditions include;
a first condition that the at least one neighboring block has a different reference picture list from the current block and a same reference picture as the current block, and
wherein whether the at least one neighboring block has the same reference picture as the current block is determined based on picture order count (POC) information.
10. The apparatus of claim 9 , wherein the selection conditions further include:
a second condition that the at least one neighboring block has a same reference picture list and the same reference picture as the current block.
11. The apparatus of claim 9 , wherein the selection conditions further include:
a third condition that the at least one neighboring block has a same reference picture list as the current block and a different reference picture from the current block, and
a fourth condition that the at least one neighboring block has a different reference picture list and a different reference picture from the current block.
12. The apparatus of claim 11 , further comprising:
scaling the at least one spatial motion vector using a temporal distance between a reference picture of the at least one neighboring block and a reference picture of the current block.
13. The apparatus of claim 9 , wherein the at least one neighboring block includes at least one of a bottom left neighboring block of the current block, a lowest neighboring block among left neighboring blocks of the current block, a top right neighboring block of the current block, a rightmost neighboring block among top neighboring blocks of the current block, and a top left neighboring block of the current block.
14. The apparatus of claim 13 , wherein the selecting the at least one spatial motion vector includes:
checking whether the bottom left neighboring block satisfies one of the selection conditions, and
when the bottom left neighboring block satisfies none of the selection conditions, checking whether the lowest neighboring block satisfies one of the selection conditions.
15. The apparatus of claim 13 , wherein the selecting the at least one spatial motion vector includes:
checking whether the top right neighboring block satisfies one of the selection conditions,
when the top right neighboring block satisfies none of the selection conditions, checking whether the rightmost neighboring block satisfies one of the selection conditions, and
when the rightmost neighboring block satisfies none of the selection conditions, checking whether the top left neighboring block satisfies one of the selection conditions.
16. The apparatus of claim 10 , wherein the selecting the at least one spatial motion vector includes:
checking whether the at least one neighboring block satisfies the second condition, and
when the at least one neighboring block does not satisfy the second condition, checking whether the at least one neighboring block satisfies the first condition.