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Versions: (draft-ietf-xrblock-rtcp-xr-concsec) 00 01 02 03 04 05 06 07 08 09 10 11 12 RFC 7294

Network Working Group                                              C. Bi
Internet-Draft                                                     STTRI
Intended status: Standards Track                                A. Clark
Expires: January 3, 2013                                        Telchemy
                                                                 G. Hunt
                                                            Unaffiliated
                                                                   Q. Wu
                                                                  Huawei
                                                            G. Zorn, Ed.
                                                             Network Zen
                                                            July 2, 2012


       RTCP XR Report Block for Loss Concealment Metric Reporting
             draft-ietf-xrblock-rtcp-xr-loss-conceal-02.txt

Abstract

   This document defines an RTCP XR Report Block that allows the
   reporting of loss concealment metrics primarily for audio
   applications of RTP.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 3, 2013.

Copyright Notice

   Copyright (c) 2012 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



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   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  . . . . . . . . . . . . . . . . . . . . . . . . . 3
     1.1.  Standards Language  . . . . . . . . . . . . . . . . . . . . 3
     1.2.  Loss Concealment Report Block . . . . . . . . . . . . . . . 3
     1.3.  RTCP and RTCP XR Reports  . . . . . . . . . . . . . . . . . 3
     1.4.  Performance Metrics Framework . . . . . . . . . . . . . . . 4
     1.5.  Applicability . . . . . . . . . . . . . . . . . . . . . . . 4
   2.  Loss Concealment Block  . . . . . . . . . . . . . . . . . . . . 4
     2.1.  Report Block Structure  . . . . . . . . . . . . . . . . . . 4
     2.2.  Definition of Fields in Loss Concealment Report Block . . . 4
   3.  SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . . 7
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8
     4.1.  New RTCP XR Block Type value  . . . . . . . . . . . . . . . 8
     4.2.  New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . . 8
     4.3.  Contact Information for Registrations . . . . . . . . . . . 8
   5.  Security Considerations . . . . . . . . . . . . . . . . . . . . 8
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 9
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 9
     7.1.  Normative References  . . . . . . . . . . . . . . . . . . . 9
     7.2.  Informative References  . . . . . . . . . . . . . . . . . . 9
























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1.  Introduction

1.1.  Standards Language

   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].

1.2.  Loss Concealment Report Block

   This draft defines a new block type to augment those defined in
   Friedman, et al. [RFC3611] for use in a range of RTP applications.

   At any instant, the audio output at a receiver may be classified as
   either 'normal' or 'concealed'.  'Normal' refers to playout of audio
   payload received from the remote end, and also includes locally
   generated signals such as announcements, tones and comfort noise.
   Concealment refers to playout of locally-generated signals used to
   mask the impact of network impairments or to reduce the audibility of
   jitter buffer adaptations.

   The new block type provides metrics for actions taken by the receiver
   to mitigate the effect of packet loss and packet discard.
   Specifically, the first metric (On-Time Playout Duration) reports the
   duration of normal playout of data which the receiver obtained from
   the sender's stream.  A second metric (Loss Concealment Duration)
   reports the total time during which the receiver played out media
   data which was manufactured locally, because the sender's data for
   these periods was not available due to packet loss or discard.  A
   similar metric (Buffer Adjustment Concealment Duration) reports the
   duration of playout of locally-manufactured data replacing data
   unavailable due to adaptation of an adaptive de-jitter buffer.
   Further metrics (Playout Interrupt Count and Mean Playout Interrupt
   Size) report the number of times normal playout was interrupted, and
   the mean duration of these interruptions.

   Loss Concealment Duration and Buffer Adjustment Concealment Duration
   are reported separately because buffer adjustment is typically
   arranged to occur in silence periods so may have very little impact
   on user experience, whilst loss concealment may occur at any time.

   The metric belongs to the class of transport-related terminal metrics
   defined in Wu, et al. [I-D.ietf-avtcore-monarch].

1.3.  RTCP and RTCP XR Reports

   The use of RTCP for reporting is defined in Schulzrinne, et
   al. [RFC3550].  Friedman, Cacares & Clark [RFC3611] define an



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   extensible structure for reporting using an RTCP Extended Report
   (XR).  This draft defines a new Extended Report block that MUST be
   used as specified in RFC 3550 and RFC 3611.

1.4.  Performance Metrics Framework

   Clark & Claise [RFC6390] provides guidance on the definition and
   specification of performance metrics.  Wu, et
   al. [I-D.ietf-avtcore-monarch] provides guidelines for RTCP XR report
   block formats.  The report block defined in this document is in
   accordance with those guidelines.

1.5.  Applicability

   This metric is primarily applicable to audio applications of RTP.
   EDITOR'S NOTE: are there metrics for concealment of transport errors
   for video?

2.  Loss Concealment Block

2.1.  Report Block Structure


     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |    BT=<NLC>   | I |plc|  resv |       block length=5          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                         SSRC of Source                        |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                 On-time Playout Duration                      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                  Loss Concealment Duration                    |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |              Buffer Adjustment Concealment Duration           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |    Playout Interrupt Count    |  Mean Playout Interrupt Size  |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

         Figure 1: Structure of the Loss Concealment Metrics Block

2.2.  Definition of Fields in Loss Concealment Report Block

   Block type (BT): 8 bits

      A Loss Concealment Metrics Report Block is identified by the
      constant <NLC>.




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      [Note to RFC Editor: please replace <NLC> with the RTCP XR block
      type allocated by IANA for this block.]


   Interval Metric flag (I): 2 bits

      This field is used to indicate whether the delay metrics are
      sampled, interval or cumulative metrics, that is, whether the
      reported values applies to the most recent measurement interval
      duration between successive metrics reports (I=10) (the interval
      duration) or to the accumulation period characteristic of
      cumulative measurements (I=11) (the cumulative duration) or is a
      sampled instantaneous value (I=01) (sampled value).


   Packet Loss Concealment Method (plc): 2 bits

      This field is used to identify the packet loss concealment method
      in use at the receiver, according to the following scheme:

         00 = silence insertion

         01 = simple replay, no attenuation

         10 = simple replay, with attenuation

         11 = enhanced


   Reserved (resv): 4 bits

      These bits are reserved.  They MUST be set to zero by senders and
      SHOULD be ignored by receivers.


   block length: 16 bits

      The length of this report block in 32-bit words, minus one.  For
      the Loss Concealment block, the block length is equal to 5.


   SSRC of source: 32 bits

      As defined in Section 4.1 of RFC 3611.







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   On-time Playout Duration (ms): 32 bits

      'On-time' playout is the uninterrupted, in-sequence playout of
      valid decoded audio information originating from the remote
      endpoint.  This includes comfort noise during periods of remote
      talker silence if voice activity detection (VAD) is in use, and
      locally generated or regenerated tones and announcements.

      An equivalent definition is that on-time playout is playout of any
      signal other than those used for concealment.

      On-time playout duration MUST include both speech and silence
      intervals, whether VAD is used or not.  This duration is reported
      in millisecond units.

      If the measured value exceeds 0xFFFFFFFD, the value 0xFFFFFFFE
      SHOULD be reported to indicate an over-range measurement.  If the
      measurement is unavailable, the value 0xFFFFFFFF SHOULD be
      reported.


   Loss Concealment Duration (ms): 32 bits

      The duration, in milliseconds, of audio playout corresponding to
      loss-type concealment.

      Loss-type concealment is reactive insertion or deletion of samples
      in the audio playout stream due to effective frame loss at the
      audio decoder.  "Effective frame loss" is the event in which a
      frame of coded audio is simply not present at the audio decoder
      when required.  In this case, substitute audio samples are
      generally formed, at the decoder or elsewhere, to reduce audible
      impairment.

      If the measured value exceeds 0xFFFFFFFD, the value 0xFFFFFFFE
      SHOULD be reported to indicate an over-range measurement.  If the
      measurement is unavailable, the value 0xFFFFFFFF SHOULD be
      reported.


   Buffer Adjustment Concealment Duration (ms): 32 bits

      The duration, in milliseconds, of audio playout corresponding to
      buffer adjustment concealment, if known.

      If the measured value exceeds 0xFFFFFFFD, the value 0xFFFFFFFE
      SHOULD be reported to indicate an over-range measurement.  If the
      measurement is unavailable, the value 0xFFFFFFFF SHOULD be



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      reported.

      Buffer adjustment concealment is proactive or controlled insertion
      or deletion of samples in the audio playout stream due to jitter
      buffer adaptation, re-sizing or re-centering decisions within the
      endpoint.

      Because this insertion is controlled, rather than occurring
      randomly in response to losses, it is typically less audible than
      loss-type concealment.  For example, jitter buffer adaptation
      events may be constrained to occur during periods of talker
      silence, in which case only silence duration is affected, or
      sophisticated time-stretching methods for insertion/deletion
      during favorable periods in active speech may be employed.

      Concealment events which cannot be classified as buffer adjustment
      MUST be classified as loss concealment.


   Playout Interrupt Count: 16 bits

      The number of interruptions to normal playout which occurred
      during the reporting period.

      If the measured value exceeds 0xFFFD, the value 0xFFFE SHOULD be
      reported to indicate an over-range measurement.  If the
      measurement is unavailable, the value 0xFFFF SHOULD be reported.


   Mean Playout Interrupt Size (ms): 16 bits

      The mean duration, in ms, of interruptions to normal playout which
      occurred during the reporting period.

      If the measured value exceeds 0xFFFD, the value 0xFFFE SHOULD be
      reported to indicate an over-range measurement.  If the
      measurement is unavailable, the value 0xFFFF SHOULD be reported.


3.  SDP Signaling

   The use of the Session Description Protocol (SDP) [RFC4566] for
   signaling the use of XR blocks is described in RFC 3611.  XR blocks
   MAY be used without prior signaling.

   This section augments the SDP attribute "rtcp-xr" [RFC3611] by
   providing an additional value of "xr-format" to signal the use of the
   report block defined in this document.



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   rtcp-xr-attrib = "a=" "rtcp-xr" ":" [xr-format *(SP xr-format)] CRLF

   (defined in RFC 3611)

   xr-format =/ xr-conceal-block

   xr-conceal-block = "loss-conceal"

4.  IANA Considerations

   New block types for RTCP XR are subject to IANA registration.  For
   general guidelines on IANA considerations for RTCP XR, refer to RFC
   3611.

4.1.  New RTCP XR Block Type value

   This document assigns the block type value <NLC> in the IANA "RTCP XR
   Block Type Registry" to the "Loss Concealment Metrics Block".

   [Note to RFC Editor: please replace <NLC> with the RTCP XR block type
   assigned by IANA for this block.]

4.2.  New RTCP XR SDP Parameter

   This document also registers a new parameter "loss-conceal" in the
   "RTCP XR SDP Parameters Registry".

4.3.  Contact Information for Registrations


      The contact information for the registrations is:

      Alan Clark (alan.d.clark@telchemy.com)

      2905 Premiere Parkway, Suite 280
      Duluth, GA  30097
      USA

5.  Security Considerations

   It is believed that this proposed RTCP XR report block introduces no
   new security considerations beyond those described in RFC 3611.  This
   block does not provide per-packet statistics so the risk to
   confidentiality documented in Section 7, paragraph 3 of RFC 3611 does
   not apply.






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6.  Acknowledgements

   The authors gratefully acknowledge the comments and suggestions made
   by Bruce Adams, Philip Arden, Amit Arora, Bob Biskner, Kevin Connor,
   Claus Dahm, Randy Ethier, Roni Even, Jim Frauenthal, Albert Higashi,
   Tom Hock, Shane Holthaus, Paul Jones, Rajesh Kumar, Keith Lantz,
   Mohamed Mostafa, Amy Pendleton, Colin Perkins, Mike Ramalho, Ravi
   Raviraj, Albrecht Schwarz, Tom Taylor, and Hideaki Yamada.

7.  References

7.1.  Normative References

   [RFC2119]                   Bradner, S., "Key words for use in RFCs
                               to Indicate Requirement Levels", BCP 14,
                               RFC 2119, March 1997.

   [RFC3550]                   Schulzrinne, H., Casner, S., Frederick,
                               R., and V. Jacobson, "RTP: A Transport
                               Protocol for Real-Time Applications",
                               STD 64, RFC 3550, July 2003.

   [RFC3611]                   Friedman, T., Caceres, R., and A. Clark,
                               "RTP Control Protocol Extended Reports
                               (RTCP XR)", RFC 3611, November 2003.

   [RFC4566]                   Handley, M., Jacobson, V., and C.
                               Perkins, "SDP: Session Description
                               Protocol", RFC 4566, July 2006.

7.2.  Informative References

   [I-D.ietf-avtcore-monarch]  Wu, W., Hunt, G., and P. Arden,
                               "Guidelines for Use of the RTP Monitoring
                               Framework", draft-ietf-avtcore-monarch-17
                               (work in progress), June 2012.

   [RFC6390]                   Clark, A. and B. Claise, "Guidelines for
                               Considering New Performance Metric
                               Development", BCP 170, RFC 6390,
                               October 2011.










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Authors' Addresses

   Claire Bi
   Shanghai Research Institure of China Telecom Corporation Limited
   No.1835, South Pudong Road
   Shanghai  200122
   China

   EMail: bijy@sttri.com.cn


   Alan Clark
   Telchemy Incorporated
   2905 Premiere Parkway, Suite 280
   Duluth, GA  30097
   USA

   EMail: alan.d.clark@telchemy.com


   Geoff Hunt
   Unaffiliated

   EMail: r.geoff.hunt@gmail.com


   Qin Wu
   Huawei
   101 Software Avenue, Yuhua District
   Nanjing, Jiangsu  210012
   China

   EMail: sunseawq@huawei.com


   Glen Zorn (editor)
   Network Zen
   227/358 Thanon Sanphawut
   Bang Na, Bangkok  10260
   Thailand

   Phone: +66 (0) 90 920 1060
   EMail: glenzorn@gmail.com








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