A method of decoding video data, the method comprising: decoding one or more syntax elements at a region-tree level of a region-tree of a tree data structure for a coding tree block, CTB, of video data, the region-tree having one or more region-tree nodes including zero or more region-tree non-leaf nodes and one or more region-tree leaf nodes, each of the region-tree non-leaf nodes having four child region-tree nodes; determining, using the syntax elements at the region-tree level, how the region-tree nodes are split into the child region-tree nodes; decoding one or more syntax elements at a prediction-tree level for each of the region-tree leaf nodes of one or more prediction trees of the tree data structure for the CTB, the prediction trees each having root nodes corresponding to one or more of the region-tree leaf nodes and one or more prediction-tree nodes including zero or more prediction-tree non-leaf nodes and one or more prediction-tree leaf nodes, each of the prediction-tree non-leaf nodes having either two child prediction tree nodes or three child prediction tree nodes obtained using a center-side triple partitioning, with at least one prediction-tree non-leaf node having three child prediction tree nodes obtained using a center-side triple partitioning, each of the prediction-tree leaf nodes defining respective coding units, CUs; determining, using the syntax elements at the prediction-tree level, how the prediction-tree nodes are split into the child prediction-tree nodes; and decoding video data, including prediction data and transform data, for each of the CUs based at least in part on the syntax elements at the region-tree level and the syntax elements at the prediction-tree level, wherein the prediction data indicates a prediction mode for forming a predicted block for a corresponding one of the CUs, and wherein the transform data includes transform coefficients representing transformed residual data for the corresponding one of the CUs. decoding one or more syntax elements at a region-tree level of a region-tree of a tree data structure for a coding tree block, CTB, of video data, the region-tree having one or more region-tree nodes including zero or more region-tree non-leaf nodes and one or more region-tree leaf nodes, each of the region-tree non-leaf nodes having four child region-tree nodes; determining, using the syntax elements at the region-tree level, how the region-tree nodes are split into the child region-tree nodes; decoding one or more syntax elements at a prediction-tree level for each of the region-tree leaf nodes of one or more prediction trees of the tree data structure for the CTB, the prediction trees each having root nodes corresponding to one or more of the region-tree leaf nodes and one or more prediction-tree nodes including zero or more prediction-tree non-leaf nodes and one or more prediction-tree leaf nodes, each of the prediction-tree non-leaf nodes having either two child prediction tree nodes or three child prediction tree nodes obtained using a center-side triple partitioning, with at least one prediction-tree non-leaf node having three child prediction tree nodes obtained using a center-side triple partitioning, each of the prediction-tree leaf nodes defining respective coding units, CUs; determining, using the syntax elements at the prediction-tree level, how the prediction-tree nodes are split into the child prediction-tree nodes; and decoding video data, including prediction data and transform data, for each of the CUs based at least in part on the syntax elements at the region-tree level and the syntax elements at the prediction-tree level, wherein the prediction data indicates a prediction mode for forming a predicted block for a corresponding one of the CUs, and wherein the transform data includes transform coefficients representing transformed residual data for the corresponding one of the CUs.