Method and device for video encoding/decoding using intra-block copy

1 . A method for encoding video data comprising:

determining that a coding tree block is in a dual tree type in which a luma coding tree block and a chroma coding tree block are separately partitioned according to different partitioning structures;

determining that a chroma block which is partitioned from the chroma coding tree block according to the dual tree type is encoded using intra-block copy;

identifying a previously encoded luma block which is predicted using a block vector in a luma area corresponding to the chroma block;

deriving a block vector for the chroma block based on a block vector of the previously encoded luma block;

deriving a prediction block for the chroma block using the block vector for the chroma block; and

encoding coding information for the chroma block in a bitstream.

2 . The method of claim 1 , further comprising determining a block vector resolution for the chroma block,

wherein the block vector resolution is an integer pixel resolution or a fractional pixel resolution.

3 . The method of claim 1 , wherein the block vector resolution for the chroma block is selected from a plurality of available resolutions.

4 . The method of claim 3 , wherein the deriving of the block vector for the chroma block further comprises rounding a block vector of the previously encoded luma block to the block vector resolution of the chroma block.

5 . The method of claim 3 , wherein coding information on the chroma block includes a syntax element indicating the block vector resolution for the chroma block among the plurality of available resolutions.

6 . The method of claim 1 , wherein the block vector resolution for the chroma block is determined separately for a horizontal direction component and a vertical direction component.

7 . The method of claim 1 , wherein the identifying of the previously encoded luma block includes searching predefined sample positions in a predefined order in a luma area corresponding to the chroma block until a luma block previously encoded in intra-block copy mode containing at least one of the predefined sample positions is found.

8 . The method of claim 1 , wherein the coding information on the chroma block includes a syntax element indicating intra prediction mode for the chroma block, wherein the syntax element indicates one of intra-block copy mode, Planar mode, DC mode, vertical mode, horizontal mode, Direct Mode (DM), and Linear Mode (LM).

9 . A method for decoding video data comprising:

determining that a coding tree block is in a dual tree type in which a luma coding tree block and a chroma coding tree block are separately partitioned according to different partitioning structures;

decoding coding information for a chroma block which is partitioned from the chroma coding tree block according to the dual tree type from a bitstream;

determining that the chroma block is decoded using intra-block copy based on the coding information;

identifying a previously decoded luma block which is predicted using a block vector in a luma area corresponding to the chroma block;

deriving a block vector for the chroma block based on a block vector of the previously decoded luma block; and

deriving a prediction block for the chroma block based on the block vector of the chroma block.

10 . The method of claim 9 , further comprising determining a block vector resolution for the chroma block,

wherein the block vector resolution is an integer pixel resolution or a fractional pixel resolution.

11 . The method of claim 9 , wherein the block vector resolution for the chroma block is selected from a plurality of available resolutions.

12 . The method of claim 9 , wherein the block vector resolution for the chroma block is determined separately for a horizontal direction component and a vertical direction component.

13 . The method of claim 11 , wherein the deriving of the block vector for the chroma block further comprises rounding a block vector of the previously decoded luma block to the block vector resolution of the chroma block.

14 . The method of claim 11 , wherein coding information on the chroma block includes a syntax element indicating the block vector resolution for the chroma block among the plurality of available resolutions.

15 . The method of claim 9 , wherein the identifying of the previously decoded luma block includes searching predefined sample positions in a predefined order in a luma area corresponding to the chroma block until a luma block previously decoded in intra-block copy mode including at least one of the predefined sample positions is found.

16 . The method of claim 9 , wherein the coding information on the chroma block includes a syntax element indicating intra prediction mode for the chroma block, wherein the syntax element indicates one of intra-block copy mode, Planar mode, DC mode, vertical mode, horizontal mode, Direct Mode (DM), and Linear Mode (LM).

17 . A method for providing encoded video data, the method comprising:

generating a bitstream by encoding video data; and

transmitting the bitstream to a video decoding apparatus,

wherein generating the bitstream comprises:

determining that a coding tree block is in a dual tree type in which a luma coding tree block and a chroma coding tree block are separately partitioned according to different partitioning structures;

determining that a chroma block which is partitioned from the chroma coding tree block according to the dual tree type is encoded using intra-block copy;

identifying a previously encoded luma block which is predicted using a block vector in a luma area corresponding to the chroma block;

deriving a block vector for the chroma block based on a block vector of the previously encoded luma block;

deriving a prediction block for the chroma block using the block vector for the chroma block; and

encoding coding information for the chroma block.