Direction-based prediction for intra block copy in video coding

An apparatus for processing video data comprising a processor and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to:

• determine, for a conversion of a current video block of a video and a bitstream of the video, that a first coding mode is applied on the current video block;
• derive a first block vector (BVx, BVy) for the current video block;
• generate prediction samples for the current video block based on the first block vector and a sample buffer, wherein reconstructed samples of previous video blocks without being applied a filtering operation are stored in the sample buffer, and wherein in the first coding mode, the prediction samples are derived from a same picture including the current video block, and a bit-depth of the sample buffer is identical to a bit-depth of a reconstruction buffer used during the conversion;
• and
• perform the conversion based on the prediction samples;
• wherein for generating a prediction sample of a first sample (x0, y0) in the current video block, a location converting operation is applied on (x0+BVx, y0+BVy) to derive a position in the sample buffer for the first prediction sample;
• wherein the location converting operation is a modulus operation, and the position of the first prediction sample is represented by ((x0+BVx) mod M, (y0+BVy) mod N), and mod is a modulus function;
• and
• wherein M and N are related to the size of a coding tree block comprising the current video block.

A non-transitory computer-readable storage medium storing instructions that cause a processor to:

• determine, for a conversion of a current video block of a video and a bitstream of the video, that a first coding mode is applied on the current video block;
• derive a first block vector (BVx, BVy) for the current video block;
• generate prediction samples for the current video block based on the first block vector and a sample buffer, wherein reconstructed samples of previous video blocks without being applied a filtering operation are stored in the sample buffer, and wherein in the first coding mode, the prediction samples are derived from a same picture including the current video block, and a bit-depth of the sample buffer is identical to a bit-depth of a reconstruction buffer used during the conversion;
• and
• perform the conversion based on the prediction samples;
• wherein for generating a prediction sample of a first sample (x0, y0) in the current video block, a location converting operation is applied on (x0+BVx, y0+BVy) to derive a position in the sample buffer for the first prediction sample;
• wherein the location converting operation is a modulus operation, and the position of the first prediction sample is represented by ((x0+BVx) mod M, (y0+BVy) mod N), and mod is a modulus function;
• and
• wherein M and N are related to the size of a coding tree block comprising the current video block.

A non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises:

• determining, for a conversion of a current video block of a video and a bitstream of the video, that a first coding mode is applied on the current video block;
• deriving a first block vector (BVx, BVy) for the current video block;
• generating prediction samples for the current video block based on the first block vector and a sample buffer, wherein reconstructed samples of previous video blocks without being applied a filtering operation are stored in the sample buffer, and wherein in the first coding mode, the prediction samples are derived from a same picture including the current video block, and a bit-depth of the sample buffer is identical to a bit-depth of a reconstruction buffer used during the conversion;
• and
• generating the bitstream based on the prediction samples;
• wherein for generating a prediction sample of a first sample (x0, y0) in the current video block, a location converting operation is applied on (x0+BVx, y0+BVy) to derive a position in the sample buffer for the first prediction sample;
• wherein the location converting operation is a modulus operation, and the position of the first prediction sample is represented by ((x0+BVx) mod M, (y0+BVy) mod N), and mod is a modulus function;
• and
• wherein M and N are related to the size of a coding tree block comprising the current video block.