This RFC specifies a Real-time Transport Protocol (RTP) payload format to be used for Adaptive Multi-Rate (AMR) and Adaptive Multi-Rate Wideband (AMR-WB) encoded speech signals. The payload format is designed to be able to interoperate with existing AMR and AMR-WB transport formats on non-IP networks.

This RFC specifies a few extensions to the messages defined in the Audio-Visual Profile with Feedback (AVPF). They are helpful primarily in conversational multimedia scenarios where centralized multipoint functionalities are in use. However, some are also usable in smaller multicast environments and point-to-point calls.

This RFC specifies Real-time Transport Protocol (RTP) payload formats to be used for the Enhanced Variable Rate Wideband Codec (EVRC-WB) and updates the media type registrations for EVRC-B codec. Several media type registrations are included for EVRC-WB RTP payload formats. In addition, a file format is specified for transport of EVRC-WB speech data in storage mode applications such as email.

Speex is an open-source voice codec suitable for use in VoIP (Voice over IP) type applications. This RFC describes the payload format for Speex-generated bit streams within an RTP packet. Also included here are the necessary details for the use of Speex with the Session Description Protocol (SDP).

This RFC describes the RTP payload format of a mU-law EMbedded Coder for Low-delay IP communication (UEMCLIP), an enhanced speech codec of ITU-T G.711. The bitstream has a scalable structure with an embedded u-law bitstream, also known as PCMU, thus providing a handy transcoding operation between narrowband and wideband speech.

• RFC 4788 - Enhancements to RTP Payload Formats for EVRC Family Codecs
• RFC 4749 - RTP Payload Format for the G.729.1 Audio Codec
• RFC 4425 - RTP Payload Format for Video Codec 1 (VC-1)