This document defines a mechanism by which packets of Real-time Transport Protocol (RTP) audio streams can indicate@ in an RTP header extension@ the audio level of the audio sample carried in the RTP packet. In large conferences@ this can reduce the load on an audio mixer or other middlebox that wants to forward only a few of the loudest audio streams@ without requiring it to decode and measure every stream that is received.
RFC 6464-2011 history
2011RFC 6464-2011 A Real-time Transport Protocol (RTP) Header Extension for Client-to-Mixer Audio Level Indication