Method and apparatus for reference sample memory reuse for intra picture block compensation

A method of video decoding for a decoder, the method comprising:

• receiving a coded video bitstream;
• determining whether a reference block for a current block is located in a different coding tree unit (CTU) than a CTU of the current block, the reference block and current block being located in a picture which is part of the coded video bitstream;
• in response to the determination that the reference block is located in the different CTU:
• (i) determining a first area in the CTU of the current block that is collocated with a second area in the different CTU, the first area and the second area having a same position in the CTU of the current block and the different CTU of the reference block;
• (ii) determining, based on a decoding status of the first area, whether a memory location of a reference sample memory for the reference block is available;
• and
• (iii) in response to the determination that the memory location for the reference block is available, retrieving, from the memory location corresponding to the reference block, one or more samples to decode the current block.

A video decoding apparatus for video decoding, comprising:

• processing circuitry configured to:
• receive a coded video bitstream,
• determine whether a reference block for a current block is located in a different coding tree unit (CTU) than a CTU of the current block, the reference block and current block being located in a picture which is part of the coded video bitstream,
• in response to the determination that the reference block is located in the different CTU:
• (i) determine a first area in the CTU of the current block that is collocated with a second area in the different CTU, the first area and the second area having a same position in the C U of the current block and the different CTU of the reference block,
• (ii) determine, based on a decoding status of the first area, whether a memory location of a reference sample memory for the reference block is available, and
• (iii) in response to the determination that the memory location for the reference block is available, retrieve, from the memory location corresponding to the reference block, one or more samples to decode the current block.

A non-transitory computer readable medium having instructions stored therein, which when executed by a processor in a video decoder causes the processor to execute a method comprising:

• receiving a coded video bitstream;
• determining whether a reference block for a current block is located in a different coding tree unit (CTU) than a CTU of the current block, the reference block and current block being located in a picture which is part of the coded video bitstream;
• in response to the determination that the reference block is located in the different CTU:
• (i) determining a first area in the CTU of the current block that is collocated with a second area in the different CTU, the first area and the second area having a same position in the CTU of the current block and the different CTU of the reference block;
• (ii) determining, based on a decoding status of the first area, whether a memory location of a reference sample memory for the reference block is available;
• and
• (iii) in response to the determination that the memory location for the reference block is available, retrieving, from the memory location corresponding to the reference block, one or more samples to decode the current block.