1. A method of coding video data, the method comprising: coding, by a processor, hypothetical reference decoder (HRD) parameters for each sub-layer of each bitstream partition of a video bitstream including the video data, wherein coding the HRD parameters comprises: coding a first BIRD parameters syntax structure for a first sub-layer of a bitstream partition; and coding a second HRD parameters syntax structure for a second sub-layer of the bitstream partition, wherein the first BIRD parameters syntax structure is different than the second BIRD parameters syntax structure, and wherein the first sub-layer is different than the second sub-layer; and processing, by the processor, the video bitstream using the HRD parameters, wherein processing the video bitstream comprises coding one or more pictures of the first sub-layer of the bitstream partition using the HRD parameters and coding one or more pictures of the second sub-layer of the bitstream partition using the HRD parameters.