This document describes Real-time Transport Protocol (RTP) payload formats for carrying each of MPEG-4 Audio and MPEG-4 Visual bitstreams without using MPEG-4 Systems. This document obsoletes RFC 3016. It contains a summary of changes from RFC 3016 and discusses backward compatibility to RFC 3016. It is a necessary revision of RFC 3016 in order to correct misalignments with the 3GPP Packetswitched Streaming Service (PSS) specification regarding the RTP payload format for MPEG-4 Audio. For the purpose of directly mapping MPEG-4 Audio/Visual bitstreams onto RTP packets@ this document provides specifications for the use of RTP header fields and also specifies fragmentation rules. It also provides specifications for Media Type registration and the use of the Session Description Protocol (SDP). The audio payload format described in this document has some limitations related to the signaling of audio codec parameters for the required multiplexing format. Therefore@ new system designs should utilize RFC 3640@ which does not have these restrictions. Nevertheless@ this revision of RFC 3016 is provided to update and complete the specification and to enable interoperable implementations.