A Real-time Transport Protocol (RTP) Header Extension for Client-to-Mixer Audio Level Indication
RFC 6464
Document | Type | RFC - Proposed Standard (December 2011; No errata) | |
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Authors | Jonathan Lennox , Enrico Marocco , Emil Ivov | ||
Last updated | 2015-10-14 | ||
Replaces | draft-lennox-avt-rtp-audio-level-exthdr | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Reviews | |||
Stream | WG state | Submitted to IESG for Publication | |
Document shepherd | Keith Drage | ||
IESG | IESG state | RFC 6464 (Proposed Standard) | |
Action Holders |
(None)
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Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Gonzalo Camarillo | ||
IESG note | Keith Drage (keith.drage@alcatel-lucent.com) is the document shepherd. | ||
Send notices to | (None) |
Internet Engineering Task Force (IETF) J. Lennox, Ed. Request for Comments: 6464 Vidyo Category: Standards Track E. Ivov ISSN: 2070-1721 Jitsi E. Marocco Telecom Italia December 2011 A Real-time Transport Protocol (RTP) Header Extension for Client-to-Mixer Audio Level Indication Abstract 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. Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc6464. Lennox, et al. Standards Track [Page 1] RFC 6464 Client-to-Mixer Audio Level Indication December 2011 Copyright Notice Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction ....................................................2 2. Terminology .....................................................3 3. Audio Levels ....................................................3 4. Signaling (Setup) Information ...................................5 5. Considerations on Use ...........................................6 6. Security Considerations .........................................6 7. IANA Considerations .............................................7 8. References ......................................................7 8.1. Normative References .......................................7 8.2. Informative References .....................................8 1. Introduction In a centralized Real-time Transport Protocol (RTP) [RFC3550] audio conference, an audio mixer or forwarder receives audio streams from many or all of the conference participants. It then selectively forwards some of them to other participants in the conference. In large conferences, it is possible that such a server might be receiving a large number of streams, of which only a few are intended to be forwarded to the other conference participants. In such a scenario, in order to pick the audio streams to forward, a centralized server needs to decode, measure audio levels, and possibly perform voice activity detection on audio data from a large number of streams. The need for such processing limits the size or number of conferences such a server can support. As an alternative, this document defines an RTP header extension [RFC5285] through which senders of audio packets can indicate the audio level of the packets' payload, reducing the processing load for a server. Lennox, et al. Standards Track [Page 2] RFC 6464 Client-to-Mixer Audio Level Indication December 2011 The header extension in this document is different than, but complementary with, the one defined in [RFC6465], which defines a mechanism by which audio mixers can indicate to clients the levels of the contributing sources that made up the mixed audio. 2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119] and indicate requirement levels for compliant implementations.Show full document text