One document matched: draft-wu-xrblock-rtcp-xr-quality-monitoring-02.txt
Differences from draft-wu-xrblock-rtcp-xr-quality-monitoring-01.txt
Network Working Group Q. Wu
Internet-Draft Huawei
Intended status: Standards Track G. Zorn
Expires: November 17, 2011 Network Zen
R. Schott
Deutsche Telekom Laboratories
K. Lee
China Telecom
May 16, 2011
RTCP XR Blocks for multimedia quality metric reporting
draft-wu-xrblock-rtcp-xr-quality-monitoring-02
Abstract
This document defines an RTCP XR Report Block and associated SDP
parameters that allows the reporting of multimedia quality metrics
for use in a range of RTP applications.
Status of this Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on November 17, 2011.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Standards Language . . . . . . . . . . . . . . . . . . . . 3
3. Applicability . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Synthetical Multimedia Quality Metrics Block . . . . . . . . . 4
4.1. Metric Block Structure . . . . . . . . . . . . . . . . . . 4
4.2. Definition of Fields in Multimedia Quality Metrics
Block . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
9.1. Normative References . . . . . . . . . . . . . . . . . . . 7
9.2. Informative References . . . . . . . . . . . . . . . . . . 8
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9
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1. Introduction
This draft 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 multimedia quality using
one of several standard metrics.
The metrics belong to the class of application level metrics defined
in [MONARCH] (work in progress).
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].
3. Applicability
The Multimedia Quality Metrics Report Block can be used in any real-
time AV application.
The factors that affect real-time AV application quality can be split
into two categories. The first category consists of transport-
dependent factors such as packet loss, delay and jitter (which also
translates into losses in the playback buffer). The factors in the
second category are application-specific factors that affect real
time application (e.g., video) quality and are sensitivity to network
errors. These factors can be but not limited to video codec and loss
recovery technique, coding bit rate, packetization scheme, and
content characteristics.
Compared with application-specific factors, the transport-dependent
factors sometimes are not sufficient to measure real time data
quality, since the ability to analyze the real time data in the
application layer provides quantifiable measurements for subscriber
Quality of Experience (QoE) that may not be captured in the
transmission layers or from the RTP layer down. In a typical
scenario, monitoring of the transmission layers can produce
statistics suggesting that quality is not an issue, such as the fact
that network jitter is not excessive. However, problems may occur in
the service layers leading to poor subscriber QoE. Therefore
monitoring using only network-level measurements may be insufficient
when application layer content quality is required.
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In order to provide accurate measures of real time application
quality when transporting real time contents across a network, the
synthentical multimedia quality Metrics is highly required which can
be conveyed in the RTCP XR packets[RFC3611] and may have the
following three benefits:
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
o Verifying the continued correct operation of an existing system
4. Synthetical Multimedia Quality Metrics Block
This block reports the multimedia application performance or quality
metrics beyond the information carried in the standard RTCP packet
format. Information is recorded about multimedia application QoE
metric which is expressed as a MOS ("Mean Opinion Score"), MOS is on
a scale from 1 to 5, in which 5 represents excellent and 1 represents
unacceptable. MOS scores are usually obtained using subjective
testing or using objective algorithm to estimate the multimedia
quality. However Subjective testing is not suitable for measuring
the multimedia quality since the results may vary from test to test.
Therefore using objective algorithm to calculate MOS scores is
recommended. ITU-T recommendation [G.1082][P.NAMS][P.NBAMS] defines
a methodology for verifying the performance of QoE estimation
algorithms for video and audio. Hence this document recommends
vendors and implementers to use International Telecommunication Union
(ITU)-specified methodologies to measure parameters when possible.
4.1. Metric Block Structure
The report block contents are dependent upon a series of flag bits
carried in the first part of the header. Not all parameters need to
be reported in each block. Flags indicate which are and which are
not reported. The fields corresponding to unreported parameters MUST
be present, but are set to zero. The receiver MUST ignore any
Perceptual Quality Metrics Block with a non-zero value in any field
flagged as unreported.
The Synthetical Multimedia Quality 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=TBD |I| tag | MC | block length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MOS Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4.2. Definition of Fields in Multimedia Quality Metrics Block
Block type (BT): 8 bits
The Perceptual Quality Metrics Block is identified by the constant
<SMQM>.
Interval Metric flag (I): 1 bit
This field is used to indicate whether the Basic Loss/Discard
metrics are Interval or Cumulative metrics, that is, whether the
reported values applies to the most recent measurement interval
duration between successive metrics reports (I=1) (the Interval
Duration) or to the accumulation period characteristic of
cumulative measurements (I=0) (the Cumulative Duration).
Measurement Identifier association (tag): 3 bits
This field is used to identify the Measurement Identifier block
[MEASIDENT] which describes this measurement.
MoS Class (MC): 4 bits
This field is used to indicate the MOS type to be reported. The
MOS type is defined as follows:
0000 MOS-A - Audio Quality MOS [G.107][P.564].
0001 MOS-V - Video Quality MOS [P.NAMS][P.NBAMS].
0010 MOS-AV - Audio-Video Quality MOS[P.NAMS][P.NBAMS].
0100~1111 - Reserved
Rsd.: 7 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
MUST be ignored by the receiver.
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SSRC of source: 32 bits
As defined in Section 4.1 of [RFC3611].
MOS Value: Variable Length
The estimated mean opinion score for Audio Qulity, Video Quality
or Audio-Video quality is defined as including the effects of
delay and other effects that would affect Audio-Video quality
[G.1082][P.NAMS][P.NBAMS]. It is expressed as an integer in the
range 10 to 50, corresponding to MOS x 10, as for MOS. A value of
127 indicates that this parameter is unavailable. Values other
than 127 and the valid range defined above MUST NOT be sent and
MUST be ignored by the receiving system.
5. SDP Signaling
One new parameter is defined for the six report blocks defined in
this document to be used with Session Description Protocol (SDP)
[RFC4566] using the Augmented Backus-Naur Form (ABNF) [RFC5234].
They have the following syntax within the "rtcp-xr" attribute
[RFC3611]:
rtcp-xr-attrib = "a=rtcp-xr:"
[xr-format *(SP xr-format)] CRLF
xr-format = multimedia-quality-metrics
multimedia-quality-metrics = "multimedia-quality-metrics"
["=" stat-flag *("," stat-flag)]
stat-flag = "Interval Metrics"
/"Cumulative metrics"
Refer to Section 5.1 of RFC 3611 [RFC3611] for a detailed description
and the full syntax of the "rtcp-xr" attribute.
6. IANA Considerations
New report block types for RTCP XR are subject to IANA registration.
For general guidelines on IANA allocations for RTCP XR, refer to
Section 6.2 of [RFC3611].
This document assigns one new block type value in the RTCP XR Block
Type Registry:
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Name: SMQM
Long Name: Synthetical Multimedia Quality Metric
Value <SMQM>
Reference: Section 4
This document also registers one new SDP [RFC4566] parameter for the
"rtcp-xr" attribute in the RTCP XR SDP Parameters Registry:
* "multimedia-quality-metrics"
The contact information for the registrations is:
Qin Wu
sunseawq@huawei.com
101 Software Avenue, Yuhua District
Nanjing, JiangSu 210012 China
7. Security Considerations
The new RTCP XR report blocks proposed in this document introduces no
new security considerations beyond those described in [RFC3611].
8. Acknowledgements
The authors would like to thank Bill Ver Steeg, David R Oran, Ali
Begen,Colin Perkins, Roni Even,Youqing Yang, Wenxiao Yu and Yinliang
Hu for their valuable comments and suggestions on this document.
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2250] Hoffman, D., Fernando, G., Goyal, V., and M. Civanlar,
"RTP Payload Format for MPEG1/MPEG2 Video", RFC 2250,
January 1998.
[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,
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November 2003.
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, July 2006.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
9.2. Informative References
[DSLF] Rahrer, T., Ed., Fiandra, Ed., and Wright, Ed., "Triple-
play Services Quality of Experience (QoE) Requirements",
DSL Forum Technical Report TR-126, December 2006.
[G.107] ITU-T, "The E Model, a computational model for use in
transmission planning", ITU-T Recommendation G.107,
April 2009.
[G.1082] ITU-T, "Measurement-based methods for improving the
robustness of IPTV performance", ITU-T
Recommendation G.1082, April 2009.
[IEEE] IEEE, "Human Perception of Jitter and Media
Synchronization", IEEE Journal on Selected Areas in
Communications Vol. 14, No. 1, January 1996.
[MEASIDENT]
Hunt, G. and A. Clark, "RTCP XR Measurement Identifier
Block", ID draft-ietf-avt-rtcp-xr-meas-identity-02,
May 2009.
[MONARCH] Wu, Q., "Monitoring Architectures for RTP",
ID draft-ietf-avtcore-monarch-00, April 2011.
[P.564] ITU-T, "Conformance testing for narrowband Voice over IP
transmission quality assessment models", ITU-T
Recommendation P.564, July 2006.
[P.NAMS] ITU-T, "Non-intrusive parametric model for the Assessment
of performance of Multimedia Streaming", ITU-T
Recommendation P.NAMS, November 2009.
[P.NBAMS] ITU-T, "non-intrusive bit-stream model for assessment of
performance of multimedia streaming", ITU-T
Recommendation P.NBAMS, November 2009.
[PMOL] Clark, A., "Framework for Performance Metric Development",
ID draft-ietf-pmol-metrics-framework-08, January 2011.
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Appendix A. Change Log
This version focuses on multimedia quality metrics and separated
other metrics block as independent documents.
Authors' Addresses
Qin Wu
Huawei
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
Email: sunseawq@huawei.com
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
Roland Schott
Deutsche Telekom Laboratories
Deutsche-Telekom-Allee 7
Darmstadt 64295
Germany
Email: Roland.Schott@telekom.de
Kai Lee
China Telecom
China Telecom Beijing Research Institute
Email: leekai@ctbri.com.cn
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