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Versions: (draft-clark-xrblock-rtcp-xr-qoe) 00 01 02 03 06 07 08 09 10 11 12 13 14 15 16 17 RFC 7266

Network Working Group                                           A. Clark
Internet-Draft                                                  Telchemy
Intended status: Standards Track                                   Q. Wu
Expires: July 11, 2014                                            Huawei
                                                               R. Schott
                                                        Deutsche Telekom
                                                                 G. Zorn
                                                             Network Zen
                                                        January 9, 2014


 RTP Control Protocol (RTCP) Extended Report (XR) Blocks for MOS Metric
                               Reporting
                   draft-ietf-xrblock-rtcp-xr-qoe-13

Abstract

   This document defines an RTP Control Protocol (RTCP) Extended Report
   (XR) Block including two new segment types and associated SDP
   parameters that allow the reporting of MOS Metrics for use in a range
   of RTP applications.

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 July 11, 2014.

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



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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 . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1.  MOS Metrics Report Block . . . . . . . . . . . . . . . . .  4
     1.2.  RTCP and RTCP XR Reports . . . . . . . . . . . . . . . . .  4
     1.3.  Performance Metrics Framework  . . . . . . . . . . . . . .  4
     1.4.  Applicability  . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  5
     2.1.  Standards Language . . . . . . . . . . . . . . . . . . . .  5
   3.  MOS Metrics Block  . . . . . . . . . . . . . . . . . . . . . .  6
     3.1.  Metric Block Structure . . . . . . . . . . . . . . . . . .  6
     3.2.  Definition of Fields in MOS Metrics Block  . . . . . . . .  7
       3.2.1.  Single Channel audio/video per SSRC Segment . . . . .  8
       3.2.2.  Multi-Channel audio per SSRC Segment . . . . . . . . .  9
   4.  SDP Signaling  . . . . . . . . . . . . . . . . . . . . . . . . 10
     4.1.  SDP rtcp-xr-attrib Attribute Extension . . . . . . . . . . 10
     4.2.  Offer/Answer Usage . . . . . . . . . . . . . . . . . . . . 12
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 14
     5.1.  New RTCP XR Block Type value . . . . . . . . . . . . . . . 14
     5.2.  New RTCP XR SDP Parameter  . . . . . . . . . . . . . . . . 14
     5.3.  The SDP calgextmap Attribute . . . . . . . . . . . . . . . 14
     5.4.  New registry of calculation algorithms . . . . . . . . . . 15
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 16
   7.  Authors  . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
   8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 16
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 17
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 17
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 17
   Appendix A.  Metrics represented using RFC6390 Template  . . . . . 20
   Appendix B.  Change Log  . . . . . . . . . . . . . . . . . . . . . 22
     B.1.  draft-ietf-xrblock-rtcp-xr-qoe-10  . . . . . . . . . . . . 22
     B.2.  draft-ietf-xrblock-rtcp-xr-qoe-09  . . . . . . . . . . . . 23
     B.3.  draft-ietf-xrblock-rtcp-xr-qoe-08  . . . . . . . . . . . . 23
     B.4.  draft-ietf-xrblock-rtcp-xr-qoe-07  . . . . . . . . . . . . 23
     B.5.  draft-ietf-xrblock-rtcp-xr-qoe-06  . . . . . . . . . . . . 23
     B.6.  draft-ietf-xrblock-rtcp-xr-qoe-04  . . . . . . . . . . . . 23
     B.7.  draft-ietf-xrblock-rtcp-xr-qoe-03  . . . . . . . . . . . . 23
     B.8.  draft-ietf-xrblock-rtcp-xr-qoe-02  . . . . . . . . . . . . 24
     B.9.  draft-ietf-xrblock-rtcp-xr-qoe-01  . . . . . . . . . . . . 24
     C.9.  draft-ietf-xrblock-rtcp-xr-qoe-01  . . . . . . . . . . . . 24



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     B.10. draft-ietf-xrblock-rtcp-xr-qoe-00  . . . . . . . . . . . . 24
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 24

















































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1.  Introduction

1.1.  MOS Metrics Report Block

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

   The new block type provides information on media quality using one of
   several standard metrics (i.e. Mean Opinion Score(MOS)).

   The metrics belong to the class of application level metrics defined
   in [RFC6792].

1.2.  RTCP and RTCP XR Reports

   The use of RTCP for reporting is defined in [RFC3550].  RFC3611
   defined an extensible structure for reporting using an RTCP Extended
   Report (XR).  This document defines a new Extended Report block for
   use with [RFC3550] and [RFC3611].

1.3.  Performance Metrics Framework

   The Performance Metrics Framework [RFC6390] provides guidance on the
   definition and specification of performance metrics.  The RTP
   Monitoring Architectures [RFC6792] provides guidelines for reporting
   block format using RTCP XR.  The XR block type described in this
   document are in accordance with the guidelines in [RFC6390] and
   [RFC6792].

1.4.  Applicability

   The MOS Metrics Report Block can be used in any application of RTP
   for which QoE (Quality of Experience) measurement algorithms are
   defined.

   The factors that affect real-time audio/video application quality can
   be split into two categories.  The first category consists of
   transport-specific factors such as packet loss, delay and jitter
   (which also translates into losses in the playback buffer).  The
   factors in the second category consists of content and codec related
   factors such as codec type and loss recovery technique, coding bit
   rate, packetization scheme, and content characteristics

   Transport-specific factors may be insufficient to infer real time
   media quality as codec related parameters and the interaction
   between transport problems and application layer protocols can
   have a substantial effect on observed media quality. Media quality
   may be measured using algorithm that directly compare input and
   output media streams, or may be estimated using algorithms that



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   model the interaction between media quality, protocol and encoded
   content. Media quality is commonly expressed in terms of Mean
   Opinion Scores (MOS) however is also represented by a range of
   indexes and other scores.

   The measurement of media quality has a number of applications:

   o  Detecting problems with media delivery or encoding that is
      impacting user perceived quality.
   o  Tuning the content encoder algorithm to satisfy real time data
      quality requirements.
   o  Determining which system techniques to use in a given situation
      and when to switch from one technique to another as system
      parameters change (for example as discussed in [P.1082]).
   o  Pre-qualifying a network to assess its ability to deliver an
      acceptable end-user perceived quality level.


2.  Terminology

2.1.  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].

   The terminology used is

      Numeric formats S X:Y

         where S indicates a two's complement signed representation, X
         the number of bits prior to the decimal place and Y the number
         of bits after the decimal place.
         Hence 8:8 represents an unsigned number in the range 0.0 to
         255.996 with a granularity of 0.0039.  S7:8 would represent the
         range -127.996 to +127.996. 0:16 represents a proper binary
         fraction with range
         0.0 to 1 - 1/65536 = 0.9999847
         though note that use of flag values at the top of the numeric
         range slightly reduces this upper limit.  For example, if the
         16- bit values 0xfffe and 0xffff are used as flags for "over-
         range" and "unavailable" conditions, a 0:16 quantity has range
         0.0 to 1 - 3/65536 = 0.9999542

3.  MOS Metrics Block

   Multimedia application MOS Metric is commonly expressed as a MOS
   ("Mean Opinion Score"), MOS is usually on a scale from 1 to 5, in
   which 5 represents excellent and 1 represents unacceptable however


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   can use other ranges (for example 1 to 11).  The term "MOS score"
   originates from subjective testing, and is used to refer to the
   Mean of a number of individual Opinion Scores.  There is therefore
   a well understood relationship between MOS and user experience,
   hence the industry commonly uses MOS as the scale for objective
   test results.  Subjective tests can be used for measuring live
   network traffic however the use of objective or algorithmic
   measurement techniques allows much large scale measurements to
   be made.  Within the scope of this document, MOS scores are
   obtained using objective or estimation algorithms.
   ITU-T or ITU-R recommendations (e.g., [BS.1387-1], [G.107],
   [G.107.1], [P.862], [P.862.1], [P.862.2], [P.863], [P.564],
   [P.1201.1], [P.1201.2], [P.1202.1], [P.1202.2]) define
   methodologies for assessment of the performance of audio and
   video streams.  Other international and national standards
   organizations such as EBU, ETSI, IEC and IEEE also define
   QoE algorithms and methodologies, and the intent of this document
   is not to restrict its use to ITU recommendations but to suggest
   that ITU recommendations be used where they are defined.

   This block reports media quality in the form of a 1-5 MOS range
   however does not report QoE scores that include parameters
   outside the scope of the RTP stream, for example signaling
   performance, MTTR or other factors that may affect the overall
   user experience.

   The MOS Metric reported in this block gives a numerical indication
   of the perceived quality of the received media stream, which is
   typically measured at the receiving end of the RTP stream.
   Instances of this Metrics Block refer by Synchronization source
   (SSRC) to the separate auxiliary Measurement Information block
   [RFC6776] which describes measurement periods in use (see RFC6776
   section 4.2).

   This Metrics Block relies on the measurement period in the
   Measurement Information block indicating the span of the report.
   Senders MUST send this block in the same compound RTCP packet as the
   measurement information block.  Receivers MUST verify that the
   measurement period is received in the same compound RTCP packet as
   this Metrics Block.  If not, this Metrics Block MUST be discarded.

3.1.  Metric Block Structure

   The MOS Metrics Block has the following format:







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       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=MMB    | I |  Reserved |       Block Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        SSRC of source                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          Segment  1                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          Segment 2                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ..................
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          Segment n                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

3.2.  Definition of Fields in MOS Metrics Block

   Block type (BT): 8 bits

      The MOS Metrics Block is identified by the constant <MMB>.

   Interval Metric flag (I): 2 bits

      This field is used to indicate whether the MOS Metrics are
      Sampled, Interval or Cumulative [RFC6792]:

         I=10: Interval Duration - the reported value applies to the
         most recent measurement interval duration between successive
         metrics reports.
         I=11: Cumulative Duration - the reported value applies to the
         accumulation period characteristic of cumulative measurements.
         I=01: Sampled Value - the reported value is a sampled
         instantaneous value.
         I=00: Reserved

      In this document, MOS Metrics MAY be reported for intervals or
      for the duration of the media stream (cumulative) however it
      is not recommended that sampled values are used.

   Reserved: 6 bits

      This field is reserved for future definition.  In the absence of
      such a definition, the bits in this field MUST be set to zero and
      ignored by the receiver (See RFC6709 section 4.2).

   Block Length: 16 bits

      The length of this report block in 32-bit words, minus one.  For
      the MOS Metrics Block, the block length is variable length.


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   SSRC of source: 32 bits

      As defined in Section 4.1 of [RFC3611].

   Segment i: 32 bits

      There are two segment types defined in this document: single
      stream Audio/Video per SSRC segment, multi-channel audio per SSRC
      segment.  Multi-channel audio per SSRC segment is used to deal
      with the case where Multi-channel audios are carried in one RTP
      stream while single channel Audio/Video per SSRC segment is used
      to deal with the case where each media stream is identified by
      SSRC and sent in separate RTP stream.  The leftmost bit of the
      segment determines its type.  If the leftmost bit of the segment
      is zero, then it is single channel segment.  If the leftmost bit
      is one, then it is multi-channel audio segment.  Note that two
      segment types can not be present in the same metric block.


3.2.1.  Single Channel audio/video per SSRC Segment

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |S|     CAID      |    PT       |           MOS Value           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Segment Type (S): 1 bit

      This field is used to identify the segment type used in this
      report block.  A zero identifies this as a single channel Audio/
      Video per SSRC segment.  Single channel means there is only one
      media stream carried in one RTP stream.  The single channel Audio/
      Video per SSRC segment can be used to report the MOS value
      associated with the media stream identified by SSRC.  If there are
      multiple media streams and they want to use the single channel
      Audio/Video per SSRC segment to report the MOS value, they should
      be carried in the separate RTP streams with each identified by
      different SSRC.  In this case, multiple MOS Metrics Blocks are
      required to report the MOS value corresponding to each media
      stream using single channel Audio/Video per SSRC segment in the
      same RTCP XR packet.

   Calculation Algorithm ID (CAID) : 8 bits

      The 8-bit CAID is the session specific reference to the
      calculation algorithm and associated qualifiers indicated in SDP
      (see Section 4.1) and used to compute QoE scores for this segment




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   Payload Type (PT): 7 bits

      MOS Metrics reporting depends on the payload format in use.  This
      field identifies the RTP payload type in use during the reporting
      interval.  The binding between RTP payload types and RTP payload
      formats is configured via a signalling protocol, for example an
      SDP offer/answer exchange.  If the RTP payload type used is
      changed during an RTP session, separate reports SHOULD be sent for
      each RTP payload type, with corresponding measurement information
      blocks indicating the time period to which they relate.

      Note that the use of this Report Block with MPEG Transport streams
      carried over RTP is undefined as each MPEG Transport stream may
      use distinct audio or video codecs and the indication of the
      encoding of these is within the MPEG Transport stream and does not
      use RTP payloads.

   MOS Value: 16 bits

      The estimated Mean Opinion Score for multimedia application
      performance is defined as including the effects of delay,loss,
      discard, jitter and other effects that would affect media quality.
      A 1-5 MOS score is multiplied by 10 and then represented in the
      8:8 format. If the measured value is over range, the value
      0xFFFE MUST be reported.  If the measurement is unavailable, the
      value 0xFFFF MUST be reported. Values other than 0xFFFE, 0xFFFF
      and the valid range defined above MUST NOT be sent and MUST be
      ignored by the receiving system.


3.2.2.  Multi-Channel audio per SSRC Segment

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |S|     CAID      |    PT       |CHID |        MOS Value        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Segment Type (S): 1 bit

      This field is used to identify the segment type used in this
      report block.  A one identifies this as a multi-channel audio
      segment.

   Calculation Algorithm ID (CAID) : 8 bits

      The 8-bit CAID is the session specific reference to the
      calculation algorithm and associated qualifiers indicated in SDP
      (see Section 4.1) and used to compute QoE scores for this segment

   Payload Type (PT): 7 bits

      As defined in Section 3.2.1 of this document.

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   Channel Identifier (CHID): 3 bits

      If multiple channels of audio are carried in one RTP stream, each
      channel of audio will be viewed as a independent channel(e.g.,
      left channel audio, right channel audio).  This field is used to
      identify each channel carried in the same media stream.  The
      default Channel mapping follows static ordering rule described in
      the section 4.1 of [RFC3551].  However there are some payload
      formats that use different channel mappings, e.g., AC-3 audio over
      RTP [RFC4184] only follow AC-3 channel order scheme defined in
      [ATSC].  Enhanced AC-3 Audio over RTP [RFC4598] uses dynamic
      channel transform mechanism.  In order that the appropriate
      channel mapping can be determined, MOS metrics reports need to be
      tied to an RTP payload format, i.e., including the payload type of
      the reported media according to [RFC6792] and using Payload Type
      to determine the appropriate channel mapping.

   MOS Value: 13 bits

      The estimated Mean Opinion Score for multimedia application
      performance includes the effects of delay,loss, discard, jitter
      and other effects that would affect multimedia quality.
      The estimated MOS value is multiplied by 10 and expressed in
      6:7 format.  If the measured value is over range, the value
      0x1FFE MUST be reported to indicate an over-range measurement.
      If the measurement is unavailable, the value 0x1FFF MUST be
      reported.  Values other than 0x1FFE, 0x1FFF and the valid range
      defined above MUST NOT be sent and MUST be ignored by the
      receiving system.



4.  SDP Signaling

   [RFC3611] defines the use of SDP (Session Description Protocol)
   [RFC4566] for signaling the use of XR blocks.  However XR blocks MAY
   be used without prior signaling (see section 5 of RFC3611).

4.1.  SDP rtcp-xr-attrib Attribute Extension

   This section augments the SDP [RFC4566] attribute "rtcp-xr" defined
   in [RFC3611] by providing an additional value of "xr-format" to
   signal the use of the report block defined in this document.  Within
   the "xr-format", the syntax element "calgextmap" is an attribute as
   defined in [RFC4566] and used to signal the mapping of the local
   identifier (CAID) in the segment extension defined in section 3.2 to
   the calculation algorithm.  Specific extensionattributes are defined
   by the specification that defines a specific extension name; there
   might be several.

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   xr-format =/ xr-mos-block
   xr-mos-block = "mos-metrics" ["=" extmap *("," calgextmap)]
   calgextmap =  mapentry "=" extensionname [SP extentionattributes]
   direction = "sendonly" / "recvonly" / "sendrecv" / "inactive"
   mapentry =  "calg:" 1*3 DIGIT ["/" direction]
                          ; Values in the range 1-255 are valid
                          ; if needed, 0 can be used to indicate that
                          ; an algorithm is rejected
   extensionname = "P564";ITU-T P.564 Compliant Algorithm [P.564]
                 / "G107";ITU-T G.107 [G.107]
                 / "G107_1";ITU-T G.107.1 [G.107.1]
                 / "TS101_329";ETSI TS 101 329-5 Annex E [ ETSI]
                 /"JJ201_1 ";TTC JJ201.1 [TTC]
                 /"P1201_1";ITU-T P.1201.2 [P.1201.1]
                 /"P1201_2";ITU-T P.1201.2 [P.1201.2]
                 /"P1202_1";ITU-T P.1202.1 [P.1202.1]
                 /"P1202_2";ITU-T P.1202.2 [P.1202.2]
                 /"P.862.2";ITU-T P.862.2 [P.862.2]
                 /"P.863"; ITU-T P.863 [P.863]
                 / non-ws-string
   extensionattributes = mosref
                       /attributes-ext
   mosref =  "mosref=" ("l"; lower resolution
                        /"m"; middle resolution
                        / "h";higher resolution
                       / non-ws-string)
   attributes-ext = non-ws-string
   SP = <Define in RFC5234>
   non-ws-string  = 1*(%x21-FF)


   Each local identifier (CAID)of calculation algorithm used in the
   segment defined in the section 3.2 is mapped to a string using an
   attribute of the form:

   a=calgextmap:<value> ["/"<direction>] <name> [<extensionattributes>]

   where <name> is a calculation algorithm name, as above, <value> is
   the local identifier (CAID)of the calculation algorithm associated
   with the segment defined in this document and is an integer in the
   valid range inclusive.

   Example:
   a=rtcp-xr:mos-metrics=calg:1=G107,calg:2=P1202_1

   A usable mapping MUST use IDs in the valid range, and each ID in this
   range MUST be unique and used only once for each stream or each
   channel in the stream.



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   The mapping MUST be provided per media stream (in the media-level
   section(s) of SDP, i.e., after an "m=" line).

   The syntax element "mosref" is referred to the media resolution
   relative reference and has three valules 'l','m','h'.(e.g.,
   Narrowband (3.4kHz) Speech and StandardDefinition (SD) or lower
   Resolution Video have 'l' resolution, Super Wideband (>14kHz) Speech
   or higher and High Definition (HD) or higher Resolution Video have
   'h' Resolution, Wideband speech(7khz) and Video with resolution
   between SD and HD has 'm' resolution).  MOS scores reported in the
   mos metrics block might vary with the MOS reference; For example, MOS
   values for narrowband, wideband, super wideband codecs occupy the
   same range but SHOULD be reported in different value.  For video
   application, MOS scores for SD resolution, HD resolution video also
   occupy the same ranges and SHOULD be reported in different value.

4.2.  Offer/Answer Usage

   When SDP is used in offer-answer context, the SDP Offer/Answer
   usage defined in [RFC3611] applies.  In the offer answer
   context, the signaling described above might be used in
   three ways:

   o  asymmetric behavior (segment extensions sent in only one
      direction),
   o  the offer of mutually exclusive alternatives, or
   o  the offer of more segments than can be sent in a single session.

   A direction attribute MAY be included in a calgextmap; without it,
   the direction implicitly inherits, of course, from the RTCP stream
   direction.

   Segment extensions, with their directions, MAY be signaled for an
   "inactive" stream.  It is an error to use an extension direction
   incompatible with the stream direction (e.g., a "sendonly" attribute
   for a "recvonly" stream).

   If an segment extension is offered as "sendrecv", explicitly or
   implicitly, and asymmetric behavior is desired, the SDP MAY be
   modified to modify or add direction qualifiers for that segment
   extension.

   A mosref attribute and mos type attribute MAY be included in an
   calgextmap; without it, the mosref and most type attribute implicitly
   inherits, of course, from the name attribute (e.g., P.1201.1
   [P.1201.1] indicates lower resolution used while P.1201.2 [P.1201.2]
   indicates higher resolution used) or payload type carried in the
   segment extension (e.g.,EVRC-WB [RFC5188] indicates using Wideband
   Codec).  However not all payload types or MOS algorithm names
   indicate resolution to be used and mos type to be used.

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   If an answerer receives an offer with an mosref attribute value it
   doesn't support (e.g.,the answerer only supports "l" and receives
   "h"from offerer), the answer SHOULD reject the mosref attribute value
   offered by the offerer.

   If the answerer wishes to reject a mosref attribute offered by the
   offerer, it sets identifiers associated with segment extensions in
   the answer to the value in the range 4096-4351.  The rejected answer
   MUST contain 'mosref ' attribute whose value is the value of the SDP
   offer.

   Local identifiers in the valid range inclusive in an offer or answer
   must not be used more than once per media section.  A session update
   MAY change the direction qualifiers of segment extensions under use.
   A session update MAY add or remove segment extension(s).  Identifiers
   values in the valid range MUST NOT be altered (remapped).

   If a party wishes to offer mutually exclusive alternatives, then
   multiple segment extensions with the same identifier in the
   (unusable) range 4096-4351 MAY be offered; the answerer SHOULD select
   at most one of the offered extensions with the same identifier, and
   remap it to a free identifier in the valid range, for that extension
   to be usable.  Note that two segment types defined in section 3 are
   also two exclusive alternatives.

   If more segment extensions are offered in the valid range, the
   answerer SHOULD choose those that are desired, and place the offered
   identifier value "as is" in the SDP answer.

   Similarly, if more segment extensions are offered than can be fit in
   the valid range, identifiers in the range 4096-4351 MAY be offered;
   the answerer SHOULD choose those that are desired, and remap them to
   a free identifier in the valid range.

   Note that the range 4096-4351 for these negotiation identifiers is
   deliberately restricted to allow expansion of the range of valid
   identifiers in future.  Segment extensions with an identifier outside
   the valid range cannot, of course, be used.

   Example (port numbers, RTP profiles, payload IDs and rtpmaps, etc.
   all omitted for brevity):

   The offer:

   a=rtcp-xr:mos-metrics=calg:4906=P1201_l,calg:4906=P1202_l,
     calg:4907=G107

   The answerer is interested in transmission P.1202.1 on lower
   resolution application, but doesn't support P.1201.1 on lower
   resolution application at all.  It is interested in transmission
   G.107.  It therefore adjusts the declarations:


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   a=rtcp-xr:mos-metrics=calg:1=P1202_l,calg:2=G107


5.  IANA Considerations

   New block types for RTCP XR are subject to IANA registration.  For
   general guidelines on IANA considerations for RTCP XR, refer to
   [RFC3611].

5.1.  New RTCP XR Block Type value

   This document assigns the block type value MMB in the IANA " RTP
   Control Protocol Extended Reports (RTCP XR) Block Type Registry" to
   the "MOS Metrics Block".

   [Note to RFC Editor: please replace MMB with the IANA provided RTCP
   XR block type for this block.]

5.2.  New RTCP XR SDP Parameter

   This document also registers a new parameter "mos-metrics" in the "
   RTP Control Protocol Extended Reports (RTCP XR) Session Description
   Protocol (SDP) Parameters Registry".

5.3.  The SDP calgextmap Attribute

   This section contains the information required by [RFC4566] for an
   SDP attribute.
   o  contact name, email address:

                            Qin Wu
                            sunseawq@huawei.com

   o  attribute name (as it will appear in SDP): calgextmap
   o  long-form attribute name in English: calculation algorithm map
      definition
   o  type of attribute (session level, media level, or both): both
   o  whether the attribute value is subject to the charset attribute:
      not subject to the charset attribute
   o  a one-paragraph explanation of the purpose of the attribute: This
      attribute defines the mapping from the local identifier (CAID) in
      the segment extension defined in section 3.2 into the calculation
      algorithm name as documented in specifications and appropriately
      registered.
   o  a specification of appropriate attribute values for this
      attribute: see RFC xxxx.

5.4.  New registry of calculation algorithms



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   This document creates a new registry to be called "RTCP XR MOS Metric
   block - multimedia application Calculation Algorithm" as a sub-
   registry of the "RTP Control Protocol Extended Reports (RTCP XR)
   Block Type Registry".  This registry applies to the multimedia
   session where each type of media are sent in a separate RTP stream
   and also applies to the session where Multi-channel audios are
   carried in one RTP stream.  Policies for this new registry are as
   follows:

   o  The information required to support this assignment is an
      unambiguous definition of the new metric, covering the base
      measurements and how they are processed to generate the reported
      metric.

   o  The review process for the registry is "Specification Required" as
      described in Section 4.1 of [RFC5226].

   o  Entries in the registry are identified by entry name and mapped to
      the local identifier (CAID) in the segment extension defined in
      section 3.2.

   o  Registration Template

      The following information must be provided with each registration:
      *  Name: A string uniquely and unambiguously identifying the
         Calculation algorithm for use in protocols.
      *  Name Description: A valid Description of the Calculation
         algorithm name.
      *  Reference: The reference which defines the calculation
         algorithm corresponding to the Name and Name Description.

      *  Type: The media type to which the calculation algorithm is
         applied

   o  Initial assignments are as follows:

Name             Name Description                  Reference    Type
=========   ===================================   ==========    ====
P564       ITU-T P.564 Compliant Algorithm        [P.564]        Voice
G107       ITU-T G.107                            [G.107]        Voice
TS101_329  ETSI TS 101 329-5 Annex E              [ETSI]         Voice
JJ201_1    TTC JJ201.1                            [TTC]          Voice
G107_1     ITU-T G.107.1                          [G.107.1]      Voice
P862       ITU-T P.862                            [P.862]        Voice
P862_2     ITU-T P.862.2                          [P.862.2]      Voice
P863       ITU-T P.863                            [P.863]        Voice
P1201_1    ITU-T P.1201.1                     [P.1201.1]      Multimedia
P1201_2    ITU-T P.1201.2                     [P.1201.2]      Multimedia
P1202_1    ITU-T P.1202.1                     [P.1202.1]         Video
P1202_2    ITU-T P.1202.2                     [P.1202.2]         Video


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6.  Security Considerations

   The new RTCP XR report blocks proposed in this document introduces no
   new security considerations beyond those described in [RFC3611].


7.  Authors

   This draft merges ideas from two drafts addressing the MOS Metric
   Reporting issue.  The authors of these drafts are listed below (in
   alphabetical order):

      Alan Clark < alan.d.clark@telchemy.com >
      Geoff Hunt < r.geoff.hunt@gmail.com >
      Martin Kastner < martin.kastner@telchemy.com >
      Kai Lee < leekai@ctbri.com.cn >
      Roland Schott < roland.schott@telekom.de >
      Qin Wu < sunseawq@huawei.com >
      Glen Zorn < gwz@net-zen.net >


8.  Acknowledgements

   The authors gratefully acknowledge the comments and contributions
   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, Bill Ver Steeg, David R
   Oran, Ali Begen and Hideaki Yamada.


9.  References

9.1.  Normative References

   [ATSC]     U.S. Advanced Television Systems Committee (ATSC), "ATSC
              Standard: Digital Audio Compression (AC-3), Revision B",
              ATSC Doc A/52B, June 2005.

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

   [RFC3550]  Schulzrinne, H., "RTP: A Transport Protocol for Real-Time
              Applications", RFC 3550, July 2003.

   [RFC3551]  Schulzrinne, H. and S. Casner, "RTP Profile for Audio and
              Video Conferences with Minimal Control", RFC 3551,
              July 2003.

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   [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.

   [RFC5226]  Narten, T., "Guidelines for Writing an IANA Considerations
              Section in RFCs", RFC 5226, May 2008.

   [RFC5234]  Crocker, D. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234, January 2008.

   [RFC6776]  Wu, Q., "Measurement Identity and information Reporting
              using SDES item and XR Block", RFC 6776, October 2012.

9.2.  Informative References

   [BS.1387] ITU-R, "Method for objective measurements of perceived
              audio quality], ITU-R Recommendation BS.1387-1, 2001

   [ETSI]     ETSI, "Quality of Service (QoS) measurement
              methodologies", ETSI TS 101 329-5 V1.1.1, November 2000.

   [G.107]    ITU-T, "The E Model, a computational model for use in
              transmission planning", ITU-T Recommendation G.107,
              April 2009.

   [G.107.1]  ITU-T, "Wideband E-model", ITU-T Recommendation G.107.1,
              December 2011.

   [G.1082]   ITU-T, "Measurement-based methods for improving the
              robustness of IPTV performance", ITU-T
              Recommendation G.1082, April 2009.

   [P.1201.1]
              ITU-T, "Parametric non-intrusive assessment of audiovisual
              media streaming quality - lower resolution application
              area", ITU-T Recommendation P.1201.1, October 2012.

   [P.1201.2]
              ITU-T, "Parametric non-intrusive assessment of audiovisual
              media streaming quality - higher resolution application
              area", ITU-T Recommendation P.1201.2, October 2012.

   [P.1202.1]
              ITU-T, "Parametric non-intrusive bitstream assessment of
              video media streaming quality - lower resolution
              application area", ITU-T Recommendation P.1202.1,
              October 2012.


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   [P.1202.2]
              ITU-T, "Parametric non-intrusive bitstream assessment of
              video media streaming quality - higher resolution
              application area", ITU-T Recommendation P.1202.2,
              May 2013.

   [P.564]    ITU-T, "Conformance testing for narrowband Voice over IP
              transmission quality assessment models", ITU-T
              Recommendation P.564, July 2006.

   [P.862]    ITU-T, "Perceptual evaluation of speech quality (PESQ): An
              objective method for end-to-end speech quality assessment
              of narrow-band telephone networks and speech codecs",
              ITU-T Recommendation P.862, Febuary 2001.

   [P.862.1]  ITU-T, "Mapping function for transforming P.862 raw result
              scores to MOS-LQO", ITU-T Recommendation P.862.1,
              November 2003.

   [P.862.2]  ITU-T, "Wideband extension to Recommendation P.862 for the
              assessment of wideband telephone networks and speech
              codecs", ITU-T Recommendation P.862.2, November 2007.

   [P.863]    ITU-T, "Perceptual objective listening quality
              assessment", ITU-T Recommendation P.863, January 2011.

   [RFC4184]  Link, B., Hager, T., and J. Flaks, "RTP Payload Format for
              AC-3 Audio", RFC 4184, October 2005.

   [RFC4598]  Link, B., "Real-time Transport Protocol (RTP) Payload
              Format for Enhanced AC-3 (E-AC-3) Audio", RFC 4598,
              July 2006.

   [RFC5188]  Desineni, H. and Q. Xie, "RTP Payload Format for the
              Enhanced Variable Rate Wideband Codec (EVRC-WB) and the
              Media Subtype Updates for EVRC-B Codec", RFC 5188,
              February 2008.

   [RFC6390]  Clark, A. and B. Claise, "Framework for Performance Metric
              Development", RFC 6390, October 2011.

   [RFC6792]  Wu, Q., "Monitoring Architectures for RTP", RFC 6792,
              November 2012.

   [TTC]      TTC 201.01 (Japan), "A method for speech quality
              assessment for Voice over IP".






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Appendix A.  Metrics represented using RFC6390 Template

   RFC EDITOR NOTE: please change XXXX in [RFCXXXX] by the new RFC
   number, when assigned.

   a.  MOS Value Metric

       *  Metric Name: MOS

       *  Metric Description: The estimated Mean Opinion Score for
          multimedia application performance is defined as including the
          effects of delay,loss, discard,jitter and other effects that
          would affect audio or video quality.

       *  Method of Measurement or Calculation: See section 3.2.1, MOS
          value definition [RFCXXXX].

       *  Units of Measurement: See section 3.2.1, MOS value definition
          [RFCXXXX].

       *  Measurement Point(s) with Potential Measurement Domain: See
          section 3, 2nd paragraph [RFCXXXX].

       *  Measurement Timing: See section 3, 3rd paragraph [RFCXXXX] for
          measurement timing and section 3.1 [RFCXXXX] for Interval
          Metric flag.

       *  Use and applications: See section 1.4 [RFCXXXX].

       *  Reporting model: See RFC3611.

   b.  Segment Type Metric

       *  Metric Name: Segment Type

       *  Metric Description: It is used to identify the segment type
          used in this report block.  For more details, see section
          3.2.1, Segment type definition.

       *  Method of Measurement or Calculation: See section 3.2.1,
          Segment Type definition [RFCXXXX].

       *  Units of Measurement: See section 3.2.1, Segment Type
          definition [RFCXXXX].

       *  Measurement Point(s) with Potential Measurement Domain: See
          section 3, 2nd paragraph [RFCXXXX].

       *  Measurement Timing: See section 3, 3rd paragraph [RFCXXXX] for
          measurement timing and section 3.1 [RFCXXXX] for Interval
          Metric flag.

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       *  Use and applications: See section 1.4 [RFCXXXX].

       *  Reporting model: See RFC3611.

   c.  Calculation Algorithm Identifier Metric

       *  Metric Name: Calculation Algorithm Identifier

       *  Metric Description: It is the local identifier of calculation
          Algorithm associated with this segment in the range 1-255
          inclusive.

       *  Method of Measurement or Calculation: See section 3.2.1,
          Calculation Algorithm ID definition [RFCXXXX].

       *  Units of Measurement: See section 3.2.1, Calg Algorithm ID
          definition[RFCXXXX].

       *  Measurement Point(s) with Potential Measurement Domain: See
          section 3, 2nd paragraph [RFCXXXX].

       *  Measurement Timing: See section 3, 3rd paragraph [RFCXXXX] for
          measurement timing and section 3.1 [RFCXXXX] for Interval
          Metric flag.

       *  Use and applications: See section 1.4 [RFCXXXX].

       *  Reporting model: See RFC3611.

   d.  Payload Type Metric

       *  Metric Name: Payload Type

       *  Metric Description: It is used to identify the format of the
          RTP payload.  For more details, see section 3.2.1, payload
          type definition.

       *  Method of Measurement or Calculation: See section 3.2.1,
          Payload type definition [RFCXXXX].

       *  Units of Measurement: See section 3.2.1, payload type
          definition[RFCXXXX].

       *  Measurement Point(s) with Potential Measurement Domain: See
          section 3, 2nd paragraph [RFCXXXX].

       *  Measurement Timing: See section 3, 3rd paragraph [RFCXXXX] for
          measurement timing and section 3.1 [RFCXXXX] for Interval
          Metric flag.

       *  Use and applications: See section 1.4 [RFCXXXX].


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       *  Reporting model: See RFC3611.

   e.  Channel Identifier Metric

       *  Metric Name: Payload Type

       *  Metric Description: It is used to identify each channel
          carried in the same media stream.  For more details, see
          section 3.2.2, channel identifier definition.

       *  Method of Measurement or Calculation: See section 3.2.2,
          Channel Identifier definition [RFCXXXX].

       *  Units of Measurement: See section 3.2.2, channel identifier
          definition[RFCXXXX].

       *  Measurement Point(s) with Potential Measurement Domain: See
          section 3, 2nd paragraph [RFCXXXX].

       *  Measurement Timing: See section 3, 3rd paragraph [RFCXXXX] for
          measurement timing and section 3.1 [RFCXXXX] for Interval
          Metric flag.

       *  Use and applications: See section 1.4 [RFCXXXX].

       *  Reporting model: See RFC3611.

Appendix B.  Change Log

B.1.   draft-ietf-xrblock-rtcp-xr-qoe-13

   o  Incorporated comments from Gen Art review
   o  Amended SDP description in 4.1
   o  Overall clean up

B.2.  draft-ietf-xrblock-rtcp-xr-qoe-10

   The following are the major changes compared to previous version:

   o  Replace QoE metrics with MOS metrics.

B.3.  draft-ietf-xrblock-rtcp-xr-qoe-09

   The following are the major changes compared to previous version:
   o  Address comments recieved from WGLC, PM-DIR Review and SDP review.
   o  Change an existing SDP attribute 'extmap' to new SDP attribute
      'calgextmap' and add new SDP attribute registry.
   o  Add Reference to G.107.1, P.862.1, P.862.2 and P.863 for new
      calculation algorithms.
   o  Add MOS type attribute to distinguish different MOS type.
   o  Other Editorial changes.

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B.4.  draft-ietf-xrblock-rtcp-xr-qoe-08

   The following are the major changes compared to previous version:
   o  Remove mostype attribute from SDP extension since it can inferred
      from payload type.
   o  Clarify mosref attribute usage in the O/A.

B.5.  draft-ietf-xrblock-rtcp-xr-qoe-07

   The following are the major changes compared to previous version:
   o  Some editorial changes to get in line with burst gap related
      draft.
   o  Add an appendix to apply RFC6390 template.

B.6.  draft-ietf-xrblock-rtcp-xr-qoe-06

   The following are the major changes compared to previous two
   versions:
   o  A few Contact information update.
   o  A few Acknowledgement section update.

B.7.  draft-ietf-xrblock-rtcp-xr-qoe-04

   The following are the major changes compared to previous version:
   o  Split two references P.NAMS and P.NBAMS into four references.
   o  SDP signaling update.
   o  Add one example to explain User QoE evaluation for video stream

B.8.  draft-ietf-xrblock-rtcp-xr-qoe-03

   The following are the major changes compared to previous version:
   o  Add one new reference to support TTC JJ201.01.
   o  Update two references P.NAMS and P.NBAMS.
   o  Other Editorial changes based on comments applied to PDV and Delay
      drafts.

B.9.  draft-ietf-xrblock-rtcp-xr-qoe-02

   The following are the major changes compared to previous version:
   o  Remove leftmost second bit since it is ueeless.
   o  Change 13bits MOS value field into 14 bits to increase MOS
      precision.
   o  Fix some typo and make some editorial changes.

B.10.  draft-ietf-xrblock-rtcp-xr-qoe-01

   The following are the major changes compared to previous version:
   o  Remove layered support from the QoE Metric draft.
   o  Allocate 7 bits in the block header for payload type to indicate
      what type of payload format is in use and add associated
      definition of payload type.
   o  Clarify using Payload Type to determine the appropriate channel
      mapping in the definition of Channel Identifier.


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B.11.  draft-ietf-xrblock-rtcp-xr-qoe-00

   The following are the major changes compared to previous version:
   o  Allocate one more bit in the single channel per SSC segment to get
      alignment with the other two segment type.


Authors' Addresses

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

   Email: alan.d.clark@telchemy.com


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

   Email: sunseawq@huawei.com

   Roland Schott
   Deutsche Telekom
   Heinrich-Hertz-Strasse 3-7
   Darmstadt  64295
   Germany

   Email: Roland.Schott@telekom.de


   Glen Zorn
   Network Zen
   77/440 Soi Phoomjit, Rama IV Road
   Phra Khanong, Khlong Toie
   Bangkok  10110
   Thailand

   Phone: +66 (0) 87 502 4274
   Email: gwz@net-zen.net









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