Reducing seam artifacts in 360-degree video

A device comprising a video coder for processing video data, comprising:

• a memory;
• and
• a processor configured to perform a method comprising:
• obtaining a 360-degree rectangular formatted projected picture, wherein the 360-degree rectangular formatted projected picture comprises at least a first region, wherein the at least first region comprises at least one region boundary, and wherein the at least first region comprises a first region area;
• identifying a plurality of coding tree units (CTUs) within the first region area;
• selectively identifying a first coding unit (CU) and a second CU from within the plurality of CTUs;
• determining an initial QP value for the first CU;
• determining an initial QP value for the second CU;
• identifying the first CU as a region boundary CU;
• identifying the second CU as a non-region boundary CU, wherein the non-region boundary CU is a CU that is not on a region boundary;
• reducing the initial QP value for the first CU to a final first QP value in response to identifying the first CU as a region boundary CU;
• identifying a third CU as a region boundary CU;
• selectively not reducing a QP value for the third CU when a QP value of the 360-degree rectangular formatted projected picture is below a threshold value;
• and
• generating an encoded video bitstream comprising:
• the final QP value for the first CU,
• the initial QP value for the second CU, and
• the QP value for the third CU.

A non-transitory computer-readable medium for processing video data at a video coder, the non-transitory computer-readable medium storing a program containing instructions that, when executed by a processor of a device, cause the device to perform a method comprising:

• obtaining a 360-degree rectangular formatted projected picture, wherein the 360-degree rectangular formatted projected picture comprises at least a first region, wherein the at least first region comprises at least one region boundary, and wherein the at least first region comprises a first region area;
• identifying a plurality of coding tree units (CTUs) within the first region area;
• selectively identifying a first coding unit (CU) and a second CU from within the plurality of CTUs;
• determining an initial QP value for the first CU;
• determining an initial QP value for the second CU;
• identifying the first CU as a region boundary CU;
• identifying the second CU as a non-region boundary CU, wherein the non-region boundary CU is a CU that is not on a region boundary;
• reducing the initial QP value for the first CU to a final first QP value in response to identifying the first CU as a region boundary CU;
• identifying a third CU as a region boundary CU;
• selectively not reducing a QP value for the third CU when a QP value of the 360-degree rectangular formatted projected picture is below a threshold value;
• and
• generating an encoded video bitstream comprising:
• the final QP value for the first CU,
• the initial QP value for the second CU, and
• the QP value for the third CU.