Transform unit design for video coding

A device for coding video data, the device comprising:

• a memory configured to store the video data;
• and
• one or more processors implemented in circuitry and communicatively coupled to the memory, the one or more processors being configured to:
• determine whether a first coding tree unit (CTU) is coded using single tree;
• determine, based on the first CTU being coded using single tree, a first transform unit (TU) based on a first set of transform block (TB) samples comprising a first TB of luma samples and a first two corresponding TBs of chroma samples;
• code a coding unit (CU) of the first CTU based on the first TU;
• determine whether a second CTU is coded using dual tree;
• determine, based on the second CTU being coded using dual tree, a second TU based on a second set of TB samples comprising either (i) a second TB of luma samples or (ii) a second two TBs of chroma samples;
• and
• code a CU of the second CTU based on the second TU,
• wherein the first TU comprises syntax structures used to transform the first set of TB samples and the second TU comprises syntax structures used to transform the second set of TB samples.

A non-transitory computer-readable storage medium having instructions stored thereon which, when executed by one or more processors, cause the one or more processors to:

• determine whether a first coding tree unit (CTU) is coded using single tree;
• determine, based on the first CTU being coded using single tree, a first transform unit (TU) based on a first set of transform block (TB) samples comprising a first TB of luma samples and a first two corresponding TBs of chroma samples;
• code a coding unit (CU) of the first CTU based on the first TU;
• determine whether a second CTU is coded using dual tree;
• determine, based on the second CTU being coded using dual tree, a second TU based on a second set of TB samples comprising either (i) a second TB of luma samples or (ii) a second two TBs of chroma samples;
• and
• code a CU of the second CTU based on the second TU,
• wherein the first TU comprises syntax structures used to transform the first set of TB samples and the second TU comprises syntax structures used to transform the second set of TB samples.

A device for coding video data, the device comprising:

• means for determining whether a first coding tree unit (CTU) is coded using single tree;
• means for determining, based on the first CTU being coded using single tree, a first transform unit (TU) based on a first set of transform block (TB) samples comprising a first TB of luma samples and a first two corresponding TBs of chroma samples;
• means for coding a coding unit (CU) of the first CTU based on the first TU;
• means for determining whether a second CTU is coded using dual tree;
• means for determining, based on the second CTU being coded using dual tree, a second TU based on a second set of TB samples comprising either (i) a second TB of luma samples or (ii) a second two TBs of chroma samples;
• and
• means for coding a CU of the second CTU based on the second TU,
• wherein the first TU comprises syntax structures used to transform the first set of TB samples and the second TU comprises syntax structures used to transform the second set of TB samples.