Method and apparatus for video coding

A method for video decoding in a decoder, comprising:

• decoding partition information from a coded video bitstream, the partition information indicating that a chroma coding tree structure in a dual tree is applied to a chroma block, the partition information further indicating a block size of the chroma block in luma samples, a chroma vertical subsampling factor, and a minimum allowed chroma quaternary tree (QT) leaf node size;
• determining a parameter that is equal to the minimum allowed chroma QT leaf node size in luma samples multiplied by the chroma vertical subsampling factor and divided by a chroma horizontal subsampling factor;
• and
• determining that a QT split is disallowed for the chroma block in response to the block size of the chroma block in luma samples being less than or equal to the parameter;
• and
• in response to the QT split being disallowed for the chroma block, determining whether at least one of a binary tree split and a ternary tree split is disallowed for the chroma block.

An apparatus for video decoding, comprising processing circuitry configured to:

• decode partition information from a coded video bitstream, the partition information indicating that a chroma coding tree structure in a dual tree is applied to a chroma block, the partition information further indicating a block size cbSize of the chroma block in luma samples and a minimum allowed chroma quaternary tree (QT) leaf node size MinQtSizeC in luma samples, the MinQtSizeC indicating a minimum allowed chroma block size for QT splitting;
• determine whether the block size cbSize of the chroma block in luma samples is less than or equal to the minimum allowed chroma QT leaf node size MinQtSizeC in luma samples such that cbSize<=MinQtSizeC;
• and
• in response to the block size cbSize of the chroma block in luma samples being less than or equal to the minimum allowed chroma QT leaf node size MinQtSizeC in luma samples, determine that a QT split is disallowed for the chroma block.