Systems and methods for varying quantization parameters

Abstract

A method of encoding video data by a device is provided. Transform coefficient values associated with a chroma coding block are received. The chroma coding block is one of chroma coding blocks resulting from partitioning a chroma coding tree block and misaligned with a luma coding tree block corresponding to the chroma coding tree block and partitioned into luma coding blocks which are organized into quantization groups such that luma quantization parameters are determined for the luma coding tree block. One of the luma quantization parameters that is mapped to the chroma coding block is identified. A predictive quantization parameter is derived by using a value derived from the identified luma quantization parameter. A chroma quantization parameter is determined by adding a delta quantization parameter associated with each of the chroma coding blocks to the predictive quantization parameter. Level values are generated based on the determined chroma quantization parameter.