VVC normative and encoder-side adaptations for ABT

An apparatus, comprising:

• a processor, configured to perform:
• determine an asymmetric binary tree split mode for encoding a parent coding unit;
• determine an index of a sub-block of the parent coding unit;
• determine whether a split mode is allowed based on factors comprising the asymmetric binary tree split mode for the parent coding unit and the index of the sub-block of the parent coding unit;
• and
• encode the parent coding unit using the split mode that is allowed.

A method, comprising:

• determining an asymmetric binary tree split mode for decoding a parent coding unit;
• determining an index of a sub-block of the parent coding unit;
• determining whether a split mode is allowed based on factors comprising the asymmetric binary tree split mode for the parent coding unit and the index of the sub-block of the parent coding unit;
• and
• decoding the parent coding unit using the split mode that is allowed.

An apparatus, comprising:

• a processor, configured to:
• determine an asymmetric binary tree split mode for decoding a parent coding unit;
• determine an index of a sub-block of the parent coding unit;
• determine whether a split mode is allowed based on factors comprising the asymmetric binary tree split mode for the parent coding unit and the index of the sub-block of the parent coding unit;
• and
• decode the parent coding unit using the split mode that is allowed.