Transform unit partitioning for chroma components in video coding

A video decoding device comprising:

• a memory configured to store video data;
• and
• one or more processors in communication with the memory, the one or more processors being configured to:
• obtain a plurality of sub-arrays of transform coefficients for a luma component of a block of the stored video data;
• obtain, in accordance with a 4:2:2 sample format, a plurality of smaller sub-arrays of transform coefficients for a chroma component of the block of the stored video data that corresponds to the luma component, such that each of the plurality of smaller sub-arrays for the chroma component has a same aspect ratio as each of the sub-arrays for the luma component, and such that each of the plurality of smaller sub-arrays has a smaller dimensionality than a dimensionality of each of the plurality of sub-arrays for the luma component;
• perform an inverse transform on each of the plurality of sub-arrays of transform coefficients for the luma component to generate a plurality of residual sample values for the luma component;
• combine the plurality of residual sample values for the luma component to obtain an N by N array of residual sample values for the luma component of the block of the stored video data;
• combine the plurality of residual sample values for the chroma component of the block of the video data to form an N/2 by N array of residual sample values for the chroma component, the N/2 by N array of residual sample values for the chroma component of the block having a different aspect ratio from the N by N array of residual sample values for the luma component of the block of the video data;
• and
• reconstruct the block of the video data based on the N by N array of residual samples for the luma component and the N/2 by N array of residual samples for the chroma component that has the different aspect ratio from the N by N array of residual samples for the luma component.

A method for encoding video data comprising:

• obtaining an N by N array of residual values for a luma component of a block of the video data;
• obtaining an N/2 by N array of residual values for a chroma component of the block of the video data that corresponds to the luma block of the video data, the N/2 by N array of residual sample values for the chroma component having a different aspect ratio from the N by N array of residual sample values for the luma component of the block of the video data;
• partitioning, in accordance with a 4:2:2 sample format, the N/2 by N array of residual values for the chroma component into two N/2 by N/2 sub-arrays of chroma residual values;
• partitioning, in accordance with the 4:2:2 sample format, the N by N array of residual values for the luma component into a plurality of sub-arrays of luma residual values;
• further partitioning each of the two N/2 by N/2 sub-arrays of the chroma residual values into a plurality of smaller sub-arrays such that the smaller sub-arrays of chroma residual values have the same aspect ratios as the corresponding sub-arrays of luma residual values;
• and
• performing a transform on each of the plurality of smaller sub-arrays of the chroma residual values to generate transform coefficients for the chroma component of the block of the video data.

A video encoding device comprising:

• a memory configured to store video data;
• and
• one or more processors in communication with the memory, the one or more processors being configured to:
• obtain an N by N array of residual values for a luma component of a block of the stored video data;
• obtain an N/2 by N array of residual values for a chroma component of the stored video data that corresponds to the luma block of the stored video data, the N/2 by N array of residual sample values for the chroma component having a different aspect ratio from the N by N array of residual sample values for the luma component of the block of the video data;
• partition, in accordance with a 4:2:2 sample format, the N/2 by N array of residual values for the chroma component into two N/2 by N/2 sub-arrays of chroma residual values;
• partition, in accordance with the 4:2:2 sample format, the N by N array of residual values for the luma component of the block of the stored video data into a plurality of sub-arrays of luma residual values;
• further partition each of the two N/2 by N/2 sub-arrays of the chroma residual values into a plurality of smaller sub-arrays such that the smaller sub-arrays of chroma residual values have the same aspect ratios as the corresponding sub-arrays of luma residual values;
• and
• perform a transform on each of the plurality of smaller sub-arrays of the chroma residual values to generate transform coefficients for the chroma component of the block of the stored video data.

A non-transitory computer-readable storage medium comprising instructions stored thereon that, when executed, cause one or more processors to:

• obtain an N by N array of residual values for a luma component of a block of video data;
• obtain an N/2 by N array of residual values for a chroma component of the block of the video data that corresponds to the luma block of the video data, the N/2 by N array of residual sample values for the chroma component having a different aspect ratio from the N by N array of residual sample values for the luma component of the block of the video data;
• partition, in accordance with a 4:2:2 sample format, the N/2 by N array of residual values for the chroma component into two N/2 by N/2 sub-arrays of chroma residual values;
• partition, in accordance with the 4:2:2 sample format, the N by N array of residual values for the luma component into a plurality of sub-arrays of luma residual values;
• further partition each of the two N/2 by N/2 sub-arrays of the chroma residual values into a plurality of smaller sub-arrays such that the smaller sub-arrays of chroma residual values have the same aspect ratios as the corresponding sub-arrays of luma residual values;
• and
• perform a transform on each of the sub-arrays of chroma residual values to generate transform coefficients for the chroma component.

A method of encoding video data, the method comprising:

• determining whether a first transform unit associated with a chroma component includes at least one nonzero transform coefficient;
• determining whether a second transform unit associated with the chroma component includes at least one nonzero transform coefficient;
• and
• generating a joint coded block flag for the first transform unit and the second transform unit, the joint coded block flag indicating whether either of the first transform unit or the second transform unit includes at least one nonzero transform coefficient.