draft-ietf-xrblock-rtcp-xr-qoe-15.txt   draft-ietf-xrblock-rtcp-xr-qoe-16.txt 
Network Working Group A. Clark Network Working Group A. Clark
Internet-Draft Telchemy Internet-Draft Telchemy
Intended status: Standards Track Q. Wu Intended status: Standards Track Q. Wu
Expires: August 17, 2014 Huawei Expires: August 30, 2014 Huawei
R. Schott R. Schott
Deutsche Telekom Deutsche Telekom
G. Zorn G. Zorn
Network Zen Network Zen
February 13, 2014 February 26, 2014
RTP Control Protocol (RTCP) Extended Report (XR) Blocks for MOS Metric RTP Control Protocol (RTCP) Extended Report (XR) Blocks for MOS Metric
Reporting Reporting
draft-ietf-xrblock-rtcp-xr-qoe-15 draft-ietf-xrblock-rtcp-xr-qoe-16
Abstract Abstract
This document defines an RTP Control Protocol (RTCP) Extended Report This document defines an RTP Control Protocol (RTCP) Extended Report
(XR) Block including two new segment types and associated SDP (XR) Block including two new segment types and associated SDP
parameters that allow the reporting of mean opinion score (MOS) parameters that allow the reporting of mean opinion score (MOS)
Metrics for use in a range of RTP applications. Metrics for use in a range of RTP applications.
Status of this Memo Status of this Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 17, 2014. This Internet-Draft will expire on August 30, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. MOS Metrics Report Block . . . . . . . . . . . . . . . . . 4 1.1. MOS Metrics Report Block . . . . . . . . . . . . . . . . . 4
1.2. RTCP and RTCP XR Reports . . . . . . . . . . . . . . . . . 4 1.2. RTCP and RTCP XR Reports . . . . . . . . . . . . . . . . . 4
1.3. Performance Metrics Framework . . . . . . . . . . . . . . 4 1.3. Performance Metrics Framework . . . . . . . . . . . . . . 4
1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 4 1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Standards Language . . . . . . . . . . . . . . . . . . . . 5 2.1. Standards Language . . . . . . . . . . . . . . . . . . . . 5
3. MoS Metrics Block . . . . . . . . . . . . . . . . . . . . . . 5 3. MoS Metrics Block . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Metric Block Structure . . . . . . . . . . . . . . . . . . 6 3.1. Report Block Structure . . . . . . . . . . . . . . . . . . 6
3.2. Definition of Fields in MoS Metrics Block . . . . . . . . 7 3.2. Definition of Fields in MoS Metrics Block . . . . . . . . 7
3.2.1. Single Channel audio/video per SSRC Segment . . . . . 8 3.2.1. Single Channel audio/video per SSRC Segment . . . . . 8
3.2.2. Multi-Channel audio per SSRC Segment . . . . . . . . . 9 3.2.2. Multi-Channel audio per SSRC Segment . . . . . . . . . 9
4. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 10 4. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 11
4.1. SDP rtcp-xr-attrib Attribute Extension . . . . . . . . . . 11 4.1. SDP rtcp-xr-attrib Attribute Extension . . . . . . . . . . 11
4.2. Offer/Answer Usage . . . . . . . . . . . . . . . . . . . . 12 4.2. Offer/Answer Usage . . . . . . . . . . . . . . . . . . . . 13
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
5.1. New RTCP XR Block Type value . . . . . . . . . . . . . . . 14 5.1. New RTCP XR Block Type value . . . . . . . . . . . . . . . 15
5.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 14 5.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 15
5.3. The SDP calgextmap Attribute . . . . . . . . . . . . . . . 15 5.3. The SDP calgextmap Attribute . . . . . . . . . . . . . . . 15
5.4. New registry of calculation algorithms . . . . . . . . . . 15 5.4. New registry of calculation algorithms . . . . . . . . . . 16
6. Security Considerations . . . . . . . . . . . . . . . . . . . 16 6. Security Considerations . . . . . . . . . . . . . . . . . . . 17
7. Authors . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 7. Authors . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 17 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 17
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
9.1. Normative References . . . . . . . . . . . . . . . . . . . 17 9.1. Normative References . . . . . . . . . . . . . . . . . . . 18
9.2. Informative References . . . . . . . . . . . . . . . . . . 18 9.2. Informative References . . . . . . . . . . . . . . . . . . 18
Appendix A. Metrics represented using RFC6390 Template . . . . . 19 Appendix A. Metrics represented using RFC6390 Template . . . . . 20
Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 22 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 23
B.1. draft-ietf-xrblock-rtcp-xr-qoe-15 . . . . . . . . . . . . 22 B.1. draft-ietf-xrblock-rtcp-xr-qoe-15 . . . . . . . . . . . . 23
B.2. draft-ietf-xrblock-rtcp-xr-qoe-14 . . . . . . . . . . . . 22 B.2. draft-ietf-xrblock-rtcp-xr-qoe-14 . . . . . . . . . . . . 23
B.3. draft-ietf-xrblock-rtcp-xr-qoe-10 . . . . . . . . . . . . 22 B.3. draft-ietf-xrblock-rtcp-xr-qoe-10 . . . . . . . . . . . . 23
B.4. draft-ietf-xrblock-rtcp-xr-qoe-09 . . . . . . . . . . . . 23 B.4. draft-ietf-xrblock-rtcp-xr-qoe-09 . . . . . . . . . . . . 23
B.5. draft-ietf-xrblock-rtcp-xr-qoe-08 . . . . . . . . . . . . 23 B.5. draft-ietf-xrblock-rtcp-xr-qoe-08 . . . . . . . . . . . . 23
B.6. draft-ietf-xrblock-rtcp-xr-qoe-07 . . . . . . . . . . . . 23 B.6. draft-ietf-xrblock-rtcp-xr-qoe-07 . . . . . . . . . . . . 24
B.7. draft-ietf-xrblock-rtcp-xr-qoe-06 . . . . . . . . . . . . 23 B.7. draft-ietf-xrblock-rtcp-xr-qoe-06 . . . . . . . . . . . . 24
B.8. draft-ietf-xrblock-rtcp-xr-qoe-04 . . . . . . . . . . . . 23 B.8. draft-ietf-xrblock-rtcp-xr-qoe-04 . . . . . . . . . . . . 24
B.9. draft-ietf-xrblock-rtcp-xr-qoe-03 . . . . . . . . . . . . 23 B.9. draft-ietf-xrblock-rtcp-xr-qoe-03 . . . . . . . . . . . . 24
B.10. draft-ietf-xrblock-rtcp-xr-qoe-02 . . . . . . . . . . . . 24 B.10. draft-ietf-xrblock-rtcp-xr-qoe-02 . . . . . . . . . . . . 24
B.11. draft-ietf-xrblock-rtcp-xr-qoe-01 . . . . . . . . . . . . 24 B.11. draft-ietf-xrblock-rtcp-xr-qoe-01 . . . . . . . . . . . . 24
B.12. draft-ietf-xrblock-rtcp-xr-qoe-00 . . . . . . . . . . . . 24 B.12. draft-ietf-xrblock-rtcp-xr-qoe-00 . . . . . . . . . . . . 25
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 24 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 25
1. Introduction 1. Introduction
1.1. MOS Metrics Report Block 1.1. MOS Metrics Report Block
This document defines a new block type to augment those defined in This document defines a new block type to augment those defined in
[RFC3611], for use in a range of RTP applications. [RFC3611], for use in a range of RTP applications.
The new block type provides information on media quality using one of The new block type provides information on media quality using one of
several standard metrics (i.e. Mean Opinion Score(MOS)). several standard metrics (i.e. Mean Opinion Score(MOS)).
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factors such as codec type and loss recovery technique, coding bit factors such as codec type and loss recovery technique, coding bit
rate, packetization scheme, and content characteristics rate, packetization scheme, and content characteristics
Transport-specific factors may be insufficient to infer real time Transport-specific factors may be insufficient to infer real time
media quality as codec related parameters and the interaction between media quality as codec related parameters and the interaction between
transport problems and application layer protocols can have a transport problems and application layer protocols can have a
substantial effect on observed media quality. Media quality may be substantial effect on observed media quality. Media quality may be
measured using algorithm that directly compare input and output media measured using algorithm that directly compare input and output media
streams, or may be estimated using algorithms that model the streams, or may be estimated using algorithms that model the
interaction between media quality, protocol and encoded content. interaction between media quality, protocol and encoded content.
Media quality is commonly expressed in terms of Mean Opinion Scores Media quality is commonly expressed in terms of Mean Opinion Score
(MOS) however is also represented by a range of indexes and other (MOS) however is also represented by a range of indexes and other
scores. scores.
The measurement of media quality has a number of applications: The measurement of media quality has a number of applications:
o Detecting problems with media delivery or encoding that is o Detecting problems with media delivery or encoding that is
impacting user perceived quality. impacting user perceived quality.
o Tuning the content encoder algorithm to satisfy real time data o Tuning the content encoder algorithm to satisfy real time data
quality requirements. quality requirements.
o Determining which system techniques to use in a given situation o Determining which system techniques to use in a given situation
and when to switch from one technique to another as system and when to switch from one technique to another as system
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range slightly reduces this upper limit. For example, if the range slightly reduces this upper limit. For example, if the
16- bit values 0xfffe and 0xffff are used as flags for "over- 16- bit values 0xfffe and 0xffff are used as flags for "over-
range" and "unavailable" conditions, a 0:16 quantity has range range" and "unavailable" conditions, a 0:16 quantity has range
0.0 to 1 - 3/65536 = 0.9999542 0.0 to 1 - 3/65536 = 0.9999542
3. MoS Metrics Block 3. MoS Metrics Block
Multimedia application MOS Metric is commonly expressed as a MOS Multimedia application MOS Metric is commonly expressed as a MOS
("Mean Opinion Score"), MOS is usually on a scale from 1 to 5, in ("Mean Opinion Score"), MOS is usually on a scale from 1 to 5, in
which 5 represents excellent and 1 represents unacceptable however which 5 represents excellent and 1 represents unacceptable however
can use other ranges (for example 1 to 11). The term "MOS score" can use other ranges (for example 0 to 10 ) . The term "MOS score"
originates from subjective testing, and is used to refer to the Mean originates from subjective testing, and is used to refer to the Mean
of a number of individual Opinion Scores. There is therefore a well of a number of individual Opinion Scores. There is therefore a well
understood relationship between MOS and user experience, hence the understood relationship between MOS and user experience, hence the
industry commonly uses MOS as the scale for objective test results. industry commonly uses MOS as the scale for objective test results.
Subjective tests can be used for measuring live network traffic Subjective tests can be used for measuring live network traffic
however the use of objective or algorithmic measurement techniques however the use of objective or algorithmic measurement techniques
allows much larger scale measurements to be made. Within the scope allows much larger scale measurements to be made. Within the scope
of this document, MOS scores are obtained using objective or of this document, MOS scores are obtained using objective or
estimation algorithms. ITU-T or ITU-R recommendations (e.g., 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][G. [BS.1387-1],[G.107],[G.107.1],[P.862],[P.862.1],[P.862.2],[P.863],[P.
1082][P.1201.1][P.1201.2][P.1202.1][P.1202.2]) define methodologies 564],[G.1082],[P.1201.1],[P.1201.2],[P.1202.1],[P.1202.2]) define
for assessment of the performance of audio and video streams. Other methodologies for assessment of the performance of audio and video
international and national standards organizations such as EBU, ETSI, streams. Other international and national standards organizations
IEC and IEEE also define QoE algorithms and methodologies, and the such as EBU, ETSI, IEC and IEEE also define QoE algorithms and
intent of this document is not to restrict its use to ITU methodologies, and the intent of this document is not to restrict its
recommendations but to suggest that ITU recommendations be used where use to ITU recommendations but to suggest that ITU recommendations be
they are defined. used where they are defined.
This block reports media quality in the form of a 1-5 MOS range This block reports the media quality in the form of a 1-5 MOS range
however does not report QoE scores that include parameters outside however does not report the MoS score that include parameters outside
the scope of the RTP stream, for example signaling performance, MTTR the scope of the RTP stream, for example signaling performance, mean
or other factors that may affect the overall user experience. time to repair (MTTR) or other factors that may affect the overall
user experience.
The MOS Metric reported in this block gives a numerical indication of The MOS Metric reported in this block gives a numerical indication of
the perceived quality of the received media stream, which is the perceived quality of the received media stream, which is
typically measured at the receiving end of the RTP stream. Instances typically measured at the receiving end of the RTP stream. Instances
of this Metrics Block refer by Synchronization source (SSRC) to the of this Metrics Block refer by Synchronization source (SSRC) to the
separate auxiliary Measurement Information block [RFC6776] which separate auxiliary Measurement Information block [RFC6776] which
describes measurement periods in use (see RFC6776 section 4.2). describes measurement periods in use (see RFC6776 section 4.2).
This Metrics Block relies on the measurement period in the This Metrics Block relies on the measurement period in the
Measurement Information block indicating the span of the report. Measurement Information block indicating the span of the report.
Senders MUST send this block in the same compound RTCP packet as the Senders MUST send this block in the same compound RTCP packet as the
measurement information block. Receivers MUST verify that the measurement information block. Receivers MUST verify that the
measurement period is received in the same compound RTCP packet as measurement period is received in the same compound RTCP packet as
this Metrics Block. If not, this Metrics Block MUST be discarded. this Metrics Block. If not, this Metrics Block MUST be discarded.
3.1. Metric Block Structure 3.1. Report Block Structure
The MOS Metrics Block has the following format: The MOS Metrics Block has the following format:
0 1 2 3 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 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 | | BT=MMB | I | Reserved | Block Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of source | | SSRC of source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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be carried in the separate RTP streams with each identified by be carried in the separate RTP streams with each identified by
different SSRC. In this case, multiple MOS Metrics Blocks are different SSRC. In this case, multiple MOS Metrics Blocks are
required to report the MOS value corresponding to each media required to report the MOS value corresponding to each media
stream using single channel Audio/Video per SSRC segment in the stream using single channel Audio/Video per SSRC segment in the
same RTCP XR packet. same RTCP XR packet.
Calculation Algorithm ID (CAID) : 8 bits Calculation Algorithm ID (CAID) : 8 bits
The 8-bit CAID is the session specific reference to the The 8-bit CAID is the session specific reference to the
calculation algorithm and associated qualifiers indicated in SDP calculation algorithm and associated qualifiers indicated in SDP
(see Section 4.1) and used to compute QoE scores for this segment. (see Section 4.1) and used to compute the MOS score for this
segment.
Payload Type (PT): 7 bits Payload Type (PT): 7 bits
MOS Metrics reporting depends on the payload format in use. This MOS Metrics reporting depends on the payload format in use. This
field identifies the RTP payload type in use during the reporting field identifies the RTP payload type in use during the reporting
interval. The binding between RTP payload types and RTP payload interval. The binding between RTP payload types and RTP payload
formats is configured via a signalling protocol, for example an formats is configured via a signalling protocol, for example an
SDP offer/answer exchange. If the RTP payload type used is SDP offer/answer exchange. If the RTP payload type used is
changed during an RTP session, separate reports SHOULD be sent for changed during an RTP session, separate reports SHOULD be sent for
each RTP payload type, with corresponding measurement information each RTP payload type, with corresponding measurement information
blocks indicating the time period to which they relate. blocks indicating the time period to which they relate.
Note that the use of this Report Block with MPEG Transport streams Note that the use of this Report Block with MPEG Transport streams
carried over RTP is undefined as each MPEG Transport stream may carried over RTP is undefined as each MPEG Transport stream may
use distinct audio or video codecs and the indication of the use distinct audio or video codecs and the indication of the
encoding of these is within the MPEG Transport stream and does not encoding of these is within the MPEG Transport stream and does not
use RTP payloads. use RTP payloads.
MOS Value: 16 bits MOS Value: 16 bits
The estimated Mean Opinion Score for multimedia application The estimated Mean Opinion Score (MOS) for multimedia application
performance is defined as including the effects of delay,loss, performance is defined as including the effects of delay, loss,
discard, jitter and other effects that would affect media quality. discard, jitter and other effects that would affect media quality.
A 1-5 MOS score is multiplied by 10 and then represented in the This is a unsigned fixed-point 7:9 value representing the MOS,
7:9 format. A value of 0xFFFE is a flag indicating that the allowing the MOS score up to 127 in the integer part. MOS ranges
measured value is out of range. A value of 0xFFFF is a flag are defined as part of the specification of the MOS estimation
indicating that the measurement is unavailable. Values other than algorithm (Calculation Algorithm in this document), and are
0xFFFE, 0xFFFF and the valid range defined above MUST NOT be sent normally ranges like 1-5, 0-10, or 0-100. Two values are
and MUST be ignored by the receiving system. reserved: A value of 0xFFFE indicates out of range and a value of
0xFFFF indicates that the measurement is unavailable. Values
outside of the range defined by the Calculation Algorithm, other
than the two reserved values, MUST NOT be sent and MUST be ignored
by the receiving system.
3.2.2. Multi-Channel audio per SSRC Segment 3.2.2. Multi-Channel audio per SSRC Segment
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|S| CAID | PT |CHID | MOS Value | |S| CAID | PT |CHID | MOS Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Segment Type (S): 1 bit Segment Type (S): 1 bit
This field is used to identify the segment type used in this This field is used to identify the segment type used in this
report block. A one identifies this as a multi-channel audio report block. A one identifies this as a multi-channel audio
segment. segment.
Calculation Algorithm ID (CAID) : 8 bits Calculation Algorithm ID (CAID) : 8 bits
The 8-bit CAID is the session specific reference to the The 8-bit CAID is the session specific reference to the
calculation algorithm and associated qualifiers indicated in SDP calculation algorithm and associated qualifiers indicated in SDP
(see Section 4.1) and used to compute QoE scores for this segment. (see Section 4.1) and used to compute the MOS score for this
segment.
Payload Type (PT): 7 bits Payload Type (PT): 7 bits
As defined in Section 3.2.1 of this document As defined in Section 3.2.1 of this document
Channel Identifier (CHID): 3 bits Channel Identifier (CHID): 3 bits
If multiple channels of audio are carried in one RTP stream, each If multiple channels of audio are carried in one RTP stream, each
channel of audio will be viewed as a independent channel(e.g., channel of audio will be viewed as a independent channel(e.g.,
left channel audio, right channel audio). This field is used to left channel audio, right channel audio). This field is used to
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RTP [RFC4184] only follow AC-3 channel order scheme defined in RTP [RFC4184] only follow AC-3 channel order scheme defined in
[ATSC]. Enhanced AC-3 Audio over RTP [RFC4598] uses dynamic [ATSC]. Enhanced AC-3 Audio over RTP [RFC4598] uses dynamic
channel transform mechanism. In order that the appropriate channel transform mechanism. In order that the appropriate
channel mapping can be determined, MOS metrics reports need to be channel mapping can be determined, MOS metrics reports need to be
tied to an RTP payload format, i.e., including the payload type of tied to an RTP payload format, i.e., including the payload type of
the reported media according to [RFC6792] and using Payload Type the reported media according to [RFC6792] and using Payload Type
to determine the appropriate channel mapping. to determine the appropriate channel mapping.
MOS Value: 13 bits MOS Value: 13 bits
The estimated Mean Opinion Score for multimedia application The estimated Mean Opinion Score (MOS) for multimedia application
performance includes the effects of delay,loss, discard, jitter performance is defined as including the effects of delay, loss,
and other effects that would affect multimedia quality. The discard, jitter and other effects that would affect media quality.
estimated MOS value is multiplied by 10 and expressed in 7:6 This is a unsigned fixed-point 7:6 value representing the MOS,
format. A value of 0x1FFE is a flag indicating that the measured allowing the MOS score up to 127 in the integer part. MOS ranges
value is out of range. A value of 0x1FFF is a flag indicating are defined as part of the specification of the MOS estimation
that the measurement is unavailable. Values other than 0x1FFE, algorithm (Calculation Algorithm in this document), and are
0x1FFF and the valid range defined above MUST NOT be sent and MUST normally ranges like 1-5, 0-10, or 0-100. Two values are
be ignored by the receiving system. reserved: A value of 0x1FFE indicates out of range and a value of
0x1FFF indicates that the measurement is unavailable. Values
outside of the range defined by the Calculation Algorithm, other
than the two reserved values, MUST NOT be sent and MUST be ignored
by the receiving system.
4. SDP Signaling 4. SDP Signaling
[RFC3611]defines the use of SDP (Session Description Protocol) [RFC3611]defines the use of SDP (Session Description Protocol)
[RFC4566] for signaling the use of XR blocks. However XR blocks MAY [RFC4566] for signaling the use of XR blocks. However XR blocks MAY
be used without prior signaling (see section 5 of RFC3611). be used without prior signaling (see section 5 of RFC3611).
4.1. SDP rtcp-xr-attrib Attribute Extension 4.1. SDP rtcp-xr-attrib Attribute Extension
This section augments the SDP [RFC4566] attribute "rtcp-xr" defined This section augments the SDP [RFC4566] attribute "rtcp-xr" defined
in [RFC3611] by providing an additional value of "xr-format" to in [RFC3611] by providing an additional value of "xr-format" to
signal the use of the report block defined in this document. Within signal the use of the report block defined in this document. Within
the "xr-format", the syntax element "calgextmap" is an attribute as the "xr-format", the syntax element "calgextmap" is an attribute as
defined in [RFC4566] and used to signal the mapping of the local defined in [RFC4566] and used to signal the mapping of the local
identifier (CAID) in the segment extension defined in section 3.2 to identifier (CAID) in the segment extension defined in section 3.2 to
the calculation algorithm. Specific extensionattributes are defined the calculation algorithm. Specific extensionattributes are defined
by the specification that defines a specific extension name; there by the specification that defines a specific extension name; there
might be several. might be several.
xr-format =/ xr-mos-block xr-format =/ xr-mos-block
xr-mos-block = "mos-metrics" ["=" calgextmap *("," calgextmap)] xr-mos-block = "mos-metric" ["=" calgextmap *("," calgextmap)]
calgextmap = mapentry "=" extensionname [SP extentionattributes] calgextmap = mapentry "=" extensionname [SP extentionattributes]
direction = "sendonly" / "recvonly" / "sendrecv" / "inactive" direction = "sendonly" / "recvonly" / "sendrecv" / "inactive"
mapentry = "calg:" 1*3 DIGIT ["/" direction] mapentry = "calg:" 1*3 DIGIT ["/" direction]
; Values in the range 1-255 are valid ; Values in the range 1-255 are valid
; if needed, 0 can be used to indicate that ; if needed, 0 can be used to indicate that
; an algorithm is rejected ; an algorithm is rejected
extensionname = "P564";ITU-T P.564 Compliant Algorithm [P.564] extensionname = "P564";ITU-T P.564 Compliant Algorithm [P.564]
/ "G107";ITU-T G.107 [G.107] / "G107";ITU-T G.107 [G.107]
/ "G107_1";ITU-T G.107.1 [G.107.1] / "G107_1";ITU-T G.107.1 [G.107.1]
/ "TS101_329";ETSI TS 101 329-5 Annex E [ ETSI] / "TS101_329";ETSI TS 101 329-5 Annex E [ ETSI]
skipping to change at page 12, line 4 skipping to change at page 12, line 40
/ non-ws-string) / non-ws-string)
attributes-ext = non-ws-string attributes-ext = non-ws-string
SP = <Define in RFC5234> SP = <Define in RFC5234>
non-ws-string = 1*(%x21-FF) non-ws-string = 1*(%x21-FF)
Each local identifier (CAID)of calculation algorithm used in the Each local identifier (CAID)of calculation algorithm used in the
segment defined in the section 3.2 is mapped to a string using an segment defined in the section 3.2 is mapped to a string using an
attribute of the form: attribute of the form:
a=calg:<value> ["/"<direction>] <name> [<extensionattributes>] a=calg:<value> ["/"<direction>] <name> [<extensionattributes>]
where <name> is a calculation algorithm name, as above, <value> is where <name> is a calculation algorithm name, as above, <value> is
the local identifier (CAID)of the calculation algorithm associated the local identifier (CAID)of the calculation algorithm associated
with the segment defined in this document and is an integer in the with the segment defined in this document and is an integer in the
valid range inclusive. valid range inclusive.
Example: Example:
a=rtcp-xr:mos-metrics=calg:1=G107,calg:2=P1202_1 a=rtcp-xr:mos-metric=calg:1=G107,calg:2=P1202_1
A usable mapping MUST use IDs in the valid range, and each ID in this 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 range MUST be unique and used only once for each stream or each
channel in the stream. channel in the stream.
The mapping MUST be provided per media stream (in the media-level The mapping MUST be provided per media stream (in the media-level
section(s) of SDP, i.e., after an "m=" line). section(s) of SDP, i.e., after an "m=" line).
The syntax element "mosref" is referred to the media resolution The syntax element "mosref" is referred to the media resolution
relative reference and has three valules 'l','m','h'.(e.g., relative reference and has three valules 'l','m','h'.(e.g.,
Narrowband (3.4kHz) Speech and Standard Definition (SD) or lower Narrowband (3.4kHz) Speech and Standard Definition (SD) or lower
Resolution Video have 'l' resolution, Super Wideband (>14kHz) Speech Resolution Video have 'l' resolution, Super Wideband (>14kHz) Speech
or higher and High Definition (HD) or higher Resolution Video have or higher and High Definition (HD) or higher Resolution Video have
'h' Resolution, Wideband speech(7khz) and Video with resolution 'h' Resolution, Wideband speech(7khz) and Video with resolution
between SD and HD has 'm' resolution). MOS scores reported in the between SD and HD has 'm' resolution). The MOS score reported in the
mos metrics block might vary with the MOS reference; For example, MOS MOS metrics block might vary with the MOS reference; For example, MOS
values for narrowband, wideband, super wideband codecs occupy the values for narrowband, wideband, super wideband codecs occupy the
same range but SHOULD be reported in different value. For video same range but SHOULD be reported in different value. For video
application, MOS scores for SD resolution, HD resolution video also application, MOS scores for SD resolution, HD resolution video also
occupy the same ranges and SHOULD be reported in different value. occupy the same ranges and SHOULD be reported in different value.
4.2. Offer/Answer Usage 4.2. Offer/Answer Usage
When SDP is used in offer-answer context, the SDP 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 defined in [RFC3611] applies. In the offer answer context, the
signaling described above might be used in three ways: signaling described above might be used in three ways:
skipping to change at page 13, line 5 skipping to change at page 13, line 42
A direction attribute MAY be included in a calgextmap; without it, A direction attribute MAY be included in a calgextmap; without it,
the direction implicitly inherits, of course, from the RTCP stream the direction implicitly inherits, of course, from the RTCP stream
direction. direction.
Segment extensions, with their directions, MAY be signaled for an Segment extensions, with their directions, MAY be signaled for an
"inactive" stream. An extension direction MUST be compatible with "inactive" stream. An extension direction MUST be compatible with
the stream direction. If a segment extension in the SDP offer is the stream direction. If a segment extension in the SDP offer is
marked as "sendonly" and the answerer desires to receive it, the marked as "sendonly" and the answerer desires to receive it, the
extension MUST be marked as "recvonly" in the SDP answer. An extension MUST be marked as "recvonly" in the SDP answer. An
answerer that has no desire to receive the extension or does not answerer that has no desire to receive the extension or does not
understand the extension SHOULD NOT include it from the SDP answer. understand the extension SHOULD NOT include it in the SDP answer.
If a segment extension is marked as "recvonly" in the SDP offer and If a segment extension is marked as "recvonly" in the SDP offer and
the answerer desires to send it, the extension MUST be marked as the answerer desires to send it, the extension MUST be marked as
"sendonly" in the SDP answer. An answerer that has no desire to, or "sendonly" in the SDP answer. An answerer that has no desire to, or
is unable to, send the extension SHOULD NOT include it from the SDP is unable to, send the extension SHOULD NOT include it in the SDP
answer. answer.
If a segment extension is offered as "sendrecv", explicitly or If a segment extension is offered as "sendrecv", explicitly or
implicitly, and asymmetric behavior is desired, the SDP MAY be implicitly, and asymmetric behavior is desired, the SDP MAY be
modified to modify or add direction qualifiers for that segment modified to modify or add direction qualifiers for that segment
extension. extension.
A mosref attribute and mos type attribute MAY be included in an A mosref attribute and MOS type attribute MAY be included in an
calgextmap; without it, the mosref and most type attribute implicitly calgextmap; without it, the mosref and most type attribute implicitly
inherits, of course, from the name attribute (e.g., P.1201.1 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] [P.1201.1] indicates lower resolution used while P.1201.2 [P.1201.2]
indicates higher resolution used) or payload type carried in the indicates higher resolution used) or payload type carried in the
segment extension (e.g.,EVRC-WB [RFC5188] indicates using Wideband segment extension (e.g.,EVRC-WB [RFC5188] indicates using Wideband
Codec). However not all payload types or MOS algorithm names Codec). However not all payload types or MOS algorithm names
indicate resolution to be used and mos type to be used. If an indicate resolution to be used and MOS type to be used. If an
answerer receives an offer with an mosref attribute value it doesn't answerer receives an offer with an mosref attribute value it doesn't
support (e.g.,the answerer only supports "l" and receives "h"from support (e.g.,the answerer only supports "l" and receives "h"from
offerer), the answer SHOULD reject the mosref attribute value offered offerer), the answer SHOULD reject the mosref attribute value offered
by the offerer. by the offerer.
If the answerer wishes to reject a mosref attribute offered by the If the answerer wishes to reject a mosref attribute offered by the
offerer, it sets identifiers associated with segment extensions in offerer, it sets identifiers associated with segment extensions in
the answer to the value in the range 4096-4351. The rejected answer 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 MUST contain 'mosref ' attribute whose value is the value of the SDP
offer. offer.
skipping to change at page 14, line 22 skipping to change at page 15, line 10
Note that the range 4096-4351 for these negotiation identifiers is Note that the range 4096-4351 for these negotiation identifiers is
deliberately restricted to allow expansion of the range of valid deliberately restricted to allow expansion of the range of valid
identifiers in future. Segment extensions with an identifier outside identifiers in future. Segment extensions with an identifier outside
the valid range cannot, of course, be used. the valid range cannot, of course, be used.
Example (port numbers, RTP profiles, payload IDs and rtpmaps, etc. Example (port numbers, RTP profiles, payload IDs and rtpmaps, etc.
all omitted for brevity): all omitted for brevity):
The offer: The offer:
a=rtcp-xr:mos-metrics=calg:4906=P1201_l,calg:4906=P1202_l, calg: a=rtcp-xr:mos-metric=calg:4906=P1201_l,calg:4906=P1202_l, calg:
4907=G107 4907=G107
The answerer is interested in transmission P.1202.1 on lower The answerer is interested in transmission P.1202.1 on lower
resolution application, but doesn't support P.1201.1 on lower resolution application, but doesn't support P.1201.1 on lower
resolution application at all. It is interested in transmission resolution application at all. It is interested in transmission
G.107. It therefore adjusts the declarations: G.107. It therefore adjusts the declarations:
a=rtcp-xr:mos-metrics=calg:1=P1202_l,calg:2=G107 a=rtcp-xr:mos-metric=calg:1=P1202_l,calg:2=G107
5. IANA Considerations 5. IANA Considerations
New block types for RTCP XR are subject to IANA registration. For New block types for RTCP XR are subject to IANA registration. For
general guidelines on IANA considerations for RTCP XR, refer to general guidelines on IANA considerations for RTCP XR, refer to
[RFC3611]. [RFC3611].
5.1. New RTCP XR Block Type value 5.1. New RTCP XR Block Type value
This document assigns the block type value MMB in the IANA " RTP This document assigns the block type value MMB in the IANA " RTP
Control Protocol Extended Reports (RTCP XR) Block Type Registry" to Control Protocol Extended Reports (RTCP XR) Block Type Registry" to
the "MOS Metrics Block". the "MOS Metrics Block".
[Note to RFC Editor: please replace MMB with the IANA provided RTCP [Note to RFC Editor: please replace MMB with the IANA provided RTCP
XR block type for this block.] XR block type for this block.]
5.2. New RTCP XR SDP Parameter 5.2. New RTCP XR SDP Parameter
This document also registers a new parameter "mos-metrics" in the " This document also registers a new parameter "mos-metric" in the "
RTP Control Protocol Extended Reports (RTCP XR) Session Description RTP Control Protocol Extended Reports (RTCP XR) Session Description
Protocol (SDP) Parameters Registry". Protocol (SDP) Parameters Registry".
5.3. The SDP calgextmap Attribute 5.3. The SDP calgextmap Attribute
This section contains the information required by [RFC4566] for an This section contains the information required by [RFC4566] for an
SDP attribute. SDP attribute.
o contact name, email address: ietf o contact name, email address: RAI Area Directors
<rai-ads@tools.ietf.org>
o attribute name (as it will appear in SDP): calgextmap o attribute name (as it will appear in SDP): calgextmap
o long-form attribute name in English: calculation algorithm map o long-form attribute name in English: calculation algorithm map
definition definition
o type of attribute (session level, media level, or both): both o type of attribute (session level, media level, or both): both
o whether the attribute value is subject to the charset attribute: o whether the attribute value is subject to the charset attribute:
not subject to the charset attribute not subject to the charset attribute
o a one-paragraph explanation of the purpose of the attribute: This o a one-paragraph explanation of the purpose of the attribute: This
attribute defines the mapping from the local identifier (CAID) in attribute defines the mapping from the local identifier (CAID) in
the segment extension defined in section 3.2 into the calculation the segment extension defined in section 3.2 into the calculation
algorithm name as documented in specifications and appropriately algorithm name as documented in specifications and appropriately
registered. registered.
o a specification of appropriate attribute values for this o a specification of appropriate attribute values for this
attribute: see RFC xxxx. attribute: see RFC xxxx.
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