An example device includes one or more memories configured to store a current real-time transport protocol (RTP) packet and one or more processors. The one or more processors are configured to determine a protocol data unit (PDU) set, the PDU set comprising a plurality of PDUs, each PDU comprising a corresponding RTP packet. The one or more processors are configured to determine, for a current RTP packet of the PDU set, a remaining PDU set size, the remaining PDU set size being indicative of a size of the sum of a remainder of the PDUs of the PDU set. The one or more processors are configured to transmit the current RTP packet including an RTP header extension comprising a value indicative of the remaining PDU set size.