Encoding/decoding method and apparatus with vector derivation mode

1. A method of encoding for a video image, comprising:

determining an optimal merged candidate block for a current block based on a motion vector merging technology, wherein a motion vector of the optimal merged candidate block is closest to and used as a substitute of a motion vector for the current block in the motion vector merging technology;

based on one or a combination of a prediction direction of the optimal merged candidate block and an instruction flag which is carried in an encoded bit stream and is for instructing a decoder to use a motion vector derivation mode or not, determining whether to use the motion vector derivation mode;

determining, based on the prediction direction of the optimal merged candidate block, the motion vector derivation mode that needs to be used by a decoder;

correcting the motion vector of the current block based on the motion vector derivation mode;

determining a residual between a predicted value of the current block and an original value of the current block based on the corrected motion vector, wherein the predicted value of the current block is based on the corrected motion vector; and

encoding the residual and an index value of the optimal merged candidate block into an encoded bit stream transmitted to the decoder.

2. The method according to claim 1 , wherein the correcting a motion vector of the current block comprises:

correcting the motion vector of the current block according to the motion vector and reference frame information of the optimal merged candidate block.

3. The method according to claim 2 , wherein the correcting a motion vector of the current block comprises:

determining an initial reference block in a forward reference frame and an initial reference block in a backward reference frame for the current block based on the motion vector and the reference frame information;

searching sub-pixel neighborhoods of the initial reference blocks for reference blocks having a minimum matching error; and

correcting the motion vector of the current block based on the found reference blocks.

4. The method according to claim 1 , wherein the encoding the residual and an index value of the optimal merged candidate block into an encoded bit stream transmitted to the decoder comprises:

upon determining the residual is smaller than an initial residual that is determined based on the motion vector merging technology, carrying the residual and a first instruction flag for instructing the decoder to use the motion vector derivation mode into the encoded bit stream.

5. The method according to claim 4 , wherein the encoding the residual and an index value of the optimal merged candidate block into an encoded bit stream transmitted to the decoder further comprises:

upon determining the residual is greater than or equal to the initial residual, carrying the initial residual and a second instruction flag for instructing the decoder not to use the motion vector derivation mode into the encoded bit stream.

6. A method of decoding for a video image, comprising:

determining an optimal merged candidate block for a current block based on an index value of the optimal merged candidate block in an encoded bit stream which is received from an encoder and obtained by the encoder using a motion vector merging technology, wherein a motion vector of the optimal merged candidate block is closest to and used as a substitute of a motion vector for the current block in the motion vector merging technology;

based on one or a combination of a prediction direction of the optimal merged candidate block and an instruction flag which is carried in the encoded bit stream and is for instructing a decoder to use a motion vector derivation mode or not, determining whether to use the motion vector derivation mode;

determining, based on the prediction direction of the optimal merged candidate block, the motion vector derivation mode that needs to be used;

correcting the motion vector of the current block based on the determined motion vector derivation mode; and

decoding the current block based on the corrected motion vector and a residual carried in the encoded bit stream.

7. The method according to claim 6 , wherein the correcting a motion vector of the current block comprises:

correcting the motion vector of the current block according to the motion vector and reference frame information of the optimal merged candidate block.

8. The method according to claim 7 , wherein the correcting a motion vector of the current block comprises:

determining an initial reference block in a forward reference frame and an initial reference block in a backward reference frame for the current block based on the motion vector and the reference frame information;

searching sub-pixel neighborhoods of the initial reference blocks for reference blocks having a minimum matching error; and

correcting the motion vector of the current block based on the found reference blocks.

9. An encoding apparatus for a video image, comprising:

at least one hardware processor;

a memory including instructions to control the at least one hardware processor to:

determine an optimal merged candidate block for a current block based on a motion vector merging technology, wherein a motion vector of the optimal merged candidate block is closest to and used as a substitute of a motion vector for the current block in the motion vector merging technology;

based on one or a combination of a prediction direction of the optimal merged candidate block and an instruction flag which is carried in an encoded bit stream and is for instructing a decoder to use a motion vector derivation mode or not, determining whether to use the motion vector derivation mode;

determine, based on the prediction direction of the optimal merged candidate block, the motion vector derivation mode that needs to be used by a decoder;

correct the motion vector of the current block based on the motion vector derivation mode; determine a residual between a predicted value of the current block and an original value of the current block based on the corrected motion vector, wherein the predicted value of the current block is based on the corrected motion vector; and

encode the residual and an index value of the optimal merged candidate block into an encoded bit stream transmitted to the decoder.

10. The encoding apparatus according to claim 9 , wherein the instruction further control the at least one hardware processor to correct the motion vector of the current block according to the motion vector and reference frame information of the optimal merged candidate block.

11. The encoding apparatus according to claim 10 , wherein the instruction further control the at least one hardware processor to:

determine an initial reference block in a forward reference frame and an initial reference block in a backward reference frame for the current block based on the motion vector and the reference frame information;

search sub-pixel neighborhoods of the initial reference blocks for reference blocks having a minimum matching error; and

correct the motion vector of the current block based on the found reference blocks.

12. The encoding apparatus according to claim 9 , wherein the instruction further control the at least one hardware processor to:

upon determining the residual is smaller than an initial residual that is determined based on the motion vector merging technology, carry the residual and a first instruction flag for instructing the decoder to use the motion vector derivation mode into the encoded bit stream.

13. The encoding apparatus according to claim 12 , wherein the instruction further control the at least one hardware processor to:

upon determining the residual is greater than or equal to the initial residual, carry the initial residual and a second instruction flag for instructing the decoder not to use the motion vector derivation mode into the encoded bit stream.

14. A decoding apparatus for a video image, comprising:

at least one hardware processor;

a memory including instructions to control the at least one hardware processor to:

determine an optimal merged candidate block for a current block based on an index value of the optimal merged candidate block in an encoded bit stream which is received from an encoder and obtained by the encoder using a motion vector merging technology, wherein a motion vector of the optimal merged candidate block is closest to and used as a substitute of a motion vector for the current block in the motion vector merging technology;

based on one or a combination of a prediction direction of the optimal merged candidate block and an instruction flag which is carried in the encoded bit stream and is for instructing a decoder to use a motion vector derivation mode or not, determine whether to use the motion vector derivation mode;

determine, based on the prediction direction of the optimal merged candidate block, the motion vector derivation mode that needs to be used;

correct the motion vector of the current block based on the determined motion vector derivation mode; and

decode the current block based on the corrected motion vector and a residual carried in the encoded bit stream.

15. The decoding apparatus according to claim 14 , wherein the instructions further control the at least one hardware processor to correct the motion vector of the current block according to the motion vector and reference frame information of the optimal merged candidate block.

16. The decoding apparatus according to claim 15 , wherein the instructions further control the at least one hardware processor to:

determine an initial reference block in a forward reference frame and an initial reference block in a backward reference frame for the current block based on the motion vector and the reference frame information;

search sub-pixel neighborhoods of the initial reference blocks for reference blocks having a minimum matching error; and

correct the motion vector of the current block based on the found reference blocks.