A method includes receiving video data including one or more subpicture. The video data includes a flag, signaled in a sequence parameter set, indicating whether to use a network abstraction unit (NAL) layer identifier as a subpicture identifier, where the subpicture identifier is signaled in a NAL unit header based on the flag indicating to use the NAL layer identifier, and the subpicture identifier is signaled in a slice header based on the flag indicating not to use the NAL layer identifier. The video data is decoded based on the subpicture identifier.