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Versions: 00 01                                                         
Internet Engineering Task Force                                 A. Clark
Internet-Draft                                     Telchemy Incorporated
Expires: 29th December 2007                                 A. Pendleton
                                                                  Nortel
                                                               July 2007






                RTCP XR - Audio Metrics Report Block
                 draft-ietf-avt-rtcpxr-audio-00.txt

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   By submitting this Internet-Draft, each author represents that any
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   This Internet-Draft will expire on 29th December 2007.

Copyright Notice


   Copyright (C) The IETF Trust (2007).

Abstract

   This document defines extensions to the RTCP XR extended report
   packet type blocks to support the performance monitoring of audio
   streams transmitted using RTP.
   This draft is one of a set of four that replace the -00 version
   of the ietf-avt-rtcpxr-video-00.txt draft.




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Table of Contents

   1.   Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
   2.   Definitions  . . . . . . . . . . . . . . . . . . . . . . . . 2
   3.   Audio Metrics Report Block . . . . . . . . . . . . . . . . . X
   4.   Summary  . . . . . . . . . . . . . . . . . . . . . . . . . . X
   5.   Security Considerations  . . . . . . . . . . . . . . . . . . 13
   6.   IANA Considerations  . . . . . . . . . . . . . . . . . . . . 13
   7.   Acknowledgements . . . . . . . . . . . . . . . . . . . . . . X
   8.   Informative References . . . . . . . . . . . . . . . . . . . 13
        Authors' Addresses . . . . . . . . . . . . . . . . . . . . .
        Intellectual Property and Copyright Statements . . . . . . .




1.  Introduction

   This draft defines a block type to augment those defined
   in RFC3611 for use in Quality of Service reporting for audio over IP.
   The new block type defined in this draft is the IP Audio Metrics
   Report Block. This is intended to support both the identification of
   problems affecting performance and the collection of data that may
   be useful in optimizing system configuration.

   Audio performance may be measured using zero (no) reference, partial
   (reduced) reference or full reference.  The primary application of
   this draft is to support the reporting of real-time, in-service
   performance obtained using a zero or partial reference model however
   this approach could also be used to support the remote reporting of
   metrics from a full reference test.


2.  Definitions



3  Audio Metrics Report Block

3.1 Block Description

    0               1               2               3
    0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     BT=N      |   Reserved    |         block length          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                             SSRC                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |0 0 0|       Program ID        |           Reserved            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Report Timestamp                        |

Clark                                                          [Page  2]

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   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Measurement Interval (ms)                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   MOS-A - Audio Quality (M/L) |    MOS-A Audio Quality (R)    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Mean Audio bit rate (bits/sec)               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Round Trip Delay        |    A-V Delay (Video I/F)      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Playout Interrupt Count    |  Mean Playout Interrupt Size  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Audio Playout buffer size    |        Mean buffer level      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

3.2 Definition of Metrics

  3.2.1 Header
  The header comprises:
    (i) Block Type for this report block
    (ii) Reserved (set to 0xFF)
    (iii) Block length in words (set to 0x0009)
    (iv) SSRC of the received RTP stream that this report refers to
    (v) Program ID (PID) for the audio stream (if MPEG Transport
        encapsulation is used)
    (vi) Reserved (set to 0xFFFF)

  3.2.2 Report Timestamp
  The time at which this report was generated (format?)

  3.2.3 Measurement Interval
  The interval of time over which these metrics were measured,
  expressed in milliseconds.

  3.2.4 MOS-A (M/L) and MOS-A (R)
  An estimate of the quality of the received audio stream expressed
  as a Mean Opinion Score.

     (i) MOS-A (M/L).  The quality score for a monophonic stream or
         the Left channel for a stereophonic stream

     (ii) MOS-A (R).   The quality score for the Right channel of a
         stereophonic stream

  3.2.5 Mean Audio Bit Rate
  The average bit rate of the audio stream expressed in bits per
  second.

  3.2.6 Round Trip Delay
  The Round Trip Delay between the originating and terminating ends
  of this RTP stream, expressed in millseconds.  In unicast or
  multicast applications this parameter may be set to "undefined"
  (0xFFFF).


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draft-ietf-avt-rtcpxr-audio-00.txt                             July 2007

  3.2.7 A-V Delay
  The relative delay between decoded audio and video streams expressed
  in milliseconds.

  3.2.8 Playout Interrupt Count
  The number of interruptions that occurred during playout, due to
  either packet loss or buffer underrun.

  3.2.9 Mean Playout Interrupt Size
  The mean duration of interruptions in playout expressed in
  milliseconds.

  3.2.10 Audio Playout Buffer Size
  The available playout buffer size, expressed in milliseconds.

  3.2.11 Mean Buffer Level
  The mean playout buffer size, expressed in milliseconds.



4. Summary

  This draft defines an RTCP XR block for audio quality reporting.
  This is intended for in-service monitoring of audio streaming, IPTV
  and IP videoconferencing services to provide real time performance
  feedback and support performance management.


5. IANA Considerations

  The block type "mmm" will need to be replaced with an IANA assigned
  number within those allocated for RTCP XR report blocks (RFC 3611).

6.  Security Considerations

   RTCP reports can contain sensitive information since they can provide
   information about the nature and duration of a session established
   between two endpoints.  As a result, any third party wishing to
   obtain this information should be properly authenticated and the
   information transferred securely.

7. Acknowledgments


8.  Informative References

   [1]  Bradner, S., "Key words for use in RFCs to Indicate Requirement
        Levels", BCP 14, RFC 2119, March 1997.

   [2]  Schulzrinne, H., Casner, S., Frederick, R. and V. Jacobson,
        "RTP: A Transport Protocol for Real-Time Applications", STD 64,
        RFC 3550, July 2003.


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   [3]  Friedman, T., Caceres, R. and A. Clark, "RTP Control Protocol
        Extended Reports (RTCP XR)", RFC 3611, November 2003.

Authors' Addresses

   Alan Clark
   Telchemy Incorporated
   2905 Premiere Parkway, Suite 280
   Duluth, GA 30097
   Email: alan@telchemy.com

   Amy Pendleton
   Nortel
   2380 Performance Drive
   Richardson, TX  75081
   Email: aspen@nortel.com

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Clark                                                          [Page  5]

draft-ietf-avt-rtcpxr-audio-00.txt                             July 2007



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Clark                                                        [Page  6]