In some examples, a video encoder includes multiple sequence parameter set (SPS) IDs in an SEI message, such that multiple active SPSs can be indicated to a video decoder. In some examples, a video decoder activates a video parameter set (VPS) and/or one or more SPSs through referencing an SEI message, e.g., based on the inclusion of the VPS ID and one or more SPS IDs in the SEI message. The SEI message may be, as examples, an active parameter sets SEI message or a buffering period SEI message.