A method to generate chroma offset parameters for chroma quantization, the method being performed in a video encoder, the method comprising: determining (105, 110) target chroma bit rates for a first chroma component and a second chroma component; for a chroma quantization model, given a set of model parameters comprising a luminance base quantization parameter (baseQP), a first subset of chroma offset parameters, and a second subset of chroma offset parameters, wherein the second subset of chroma offset parameters comprise the QPScale and QpOffset parameters: setting the second subset of chroma offset parameters to zero; for one or more video sequences, computing actual chroma bit rates for one or more values of the baseQP parameter and one or more target values of each parameter of the first subset of chroma offset parameters; for the one or more video sequences, computing based on the computed actual chroma bit rates and the target chroma bit rates a reference mapping between each of the one or more values of the baseQP parameter and a corresponding target value of each parameter of the first subset of chroma offset parameters that yields the target chroma bit rates; identifying actual values of the first subset of chroma offset parameters and of the second subset of chroma offset parameters calculated according to the chroma quantization model; generating a computed mapping between each of the one or more values of the baseQP parameter and a corresponding actual value of each parameter of the first subset of chroma offset parameters such that the target values of the first subset of chroma offset parameters and the actual values of the first subset of chroma offset parameters are as close as possible to each other; and generating an optimum set of model parameters by minimizing, over the one or more values of the baseQP parameter and the parameters of the first subset of chroma offset parameters, the error between the target value of the respective parameter of the first subset of chroma offset parameters assigned to the respective value of the baseQP parameter in the reference mapping and the corresponding actual value of the same parameter of the first subset of chroma offset parameters assigned to the same value of the baseQP parameter in the computed mapping. determining (105, 110) target chroma bit rates for a first chroma component and a second chroma component; for a chroma quantization model, given a set of model parameters comprising a luminance base quantization parameter (baseQP), a first subset of chroma offset parameters, and a second subset of chroma offset parameters, wherein the second subset of chroma offset parameters comprise the QPScale and QpOffset parameters: setting the second subset of chroma offset parameters to zero; for one or more video sequences, computing actual chroma bit rates for one or more values of the baseQP parameter and one or more target values of each parameter of the first subset of chroma offset parameters; for the one or more video sequences, computing based on the computed actual chroma bit rates and the target chroma bit rates a reference mapping between each of the one or more values of the baseQP parameter and a corresponding target value of each parameter of the first subset of chroma offset parameters that yields the target chroma bit rates; identifying actual values of the first subset of chroma offset parameters and of the second subset of chroma offset parameters calculated according to the chroma quantization model; generating a computed mapping between each of the one or more values of the baseQP parameter and a corresponding actual value of each parameter of the first subset of chroma offset parameters such that the target values of the first subset of chroma offset parameters and the actual values of the first subset of chroma offset parameters are as close as possible to each other; and generating an optimum set of model parameters by minimizing, over the one or more values of the baseQP parameter and the parameters of the first subset of chroma offset parameters, the error between the target value of the respective parameter of the first subset of chroma offset parameters assigned to the respective value of the baseQP parameter in the reference mapping and the corresponding actual value of the same parameter of the first subset of chroma offset parameters assigned to the same value of the baseQP parameter in the computed mapping.