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RTP Control Protocol (RTCP) Extended Report (XR) Blocks for Synchronization Delay and Offset Metrics Reporting
RFC 7244

Internet Engineering Task Force (IETF)                         H. Asaeda
Request for Comments: 7244                                          NICT
Category: Standards Track                                          Q. Wu
ISSN: 2070-1721                                                 R. Huang
                                                                  Huawei
                                                                May 2014

        RTP Control Protocol (RTCP) Extended Report (XR) Blocks
         for Synchronization Delay and Offset Metrics Reporting

Abstract

   This document defines two RTP Control Protocol (RTCP) Extended Report
   (XR) blocks that allow the reporting of initial synchronization delay
   and synchronization offset metrics for use in a range of RTP
   applications.

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/rfc7244.

Copyright Notice

   Copyright (c) 2014 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.

Asaeda, et al.               Standards Track                    [Page 1]
RFC 7244                    SDO Report Blocks                   May 2014

Table of Contents

   1. Introduction ....................................................2
      1.1. Synchronization Delay and Offset Metrics Reporting Blocks ..2
      1.2. RTCP and RTCP XR Reports ...................................3
      1.3. Performance Metrics Framework ..............................3
      1.4. Applicability ..............................................3
   2. Terminology .....................................................4
      2.1. Standards Language .........................................4
   3. RTP Flow Initial Synchronization Delay Report Block .............4
      3.1. Metric Block Structure .....................................5
      3.2. Definition of Fields in RTP Flow Initial
           Synchronization Delay Metrics Block ........................5
   4. RTP Flow Synchronization Offset Metrics Block ...................6
      4.1. Metric Block Structure .....................................7
      4.2. Definition of Fields in RTP Flow General
           Synchronization Offset Metrics Block .......................7
   5. SDP Signaling ...................................................9
      5.1. SDP rtcp-xr-attrib Attribute Extension .....................9
      5.2. Offer/Answer Usage .........................................9
   6. IANA Considerations .............................................9
   7. Security Considerations ........................................10
   8. Acknowledgements ...............................................10
   9. References .....................................................10
      9.1. Normative References ......................................10
      9.2. Informative References ....................................11
   Appendix A. Metrics Represented Using the Template from RFC 6390 ..12

1.  Introduction

1.1.  Synchronization Delay and Offset Metrics Reporting Blocks

   This document defines two new block types to augment those defined in
   [RFC3611], for use in a range of RTP applications.

   The first new block type supports reporting of the Initial
   Synchronization Delay to establish a multimedia session.  Information
   is recorded about the time difference between the start of RTP
   sessions and the time the RTP receiver acquires all components of RTP
   sessions in the multimedia session [RFC6051].

   The second new block type supports reporting of the relative
   synchronization offset time of two arbitrary streams (e.g., between
   audio and video streams), with the same RTCP CNAME included in RTCP
   Source description items (SDES) packets [RFC3550].

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