An example device includes a memory and one or more processors implemented in circuitry and communicatively coupled to the memory. The one or more processors are configured to determine a value of a first syntax element indicative of a number of subpictures in a picture of video data. The one or more processors are configured to determine, for each subpicture among the subpictures in the picture, a value of a respective second syntax element indicative of an identification of a respective subpicture. The one or more processors are also configured to code the respective subpicture identified by the respective second syntax element.