Network Working Group Q. Wu Internet-Draft Huawei Intended status: Standards Track G. Zorn Expires: March 18, 2012 Network Zen R. Schott Deutsche Telekom Laboratories K. Lee China Telecom September 15, 2011 RTCP XR Blocks for multimedia quality metric reporting draft-wu-xrblock-rtcp-xr-quality-monitoring-03 Abstract This document defines an RTCP XR Report Block and associated SDP parameters that allow the reporting of multimedia quality 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 March 18, 2012. Copyright Notice Copyright (c) 2011 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 carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must Wu, et al. Expires March 18, 2012 [Page 1] Internet-Draft RTCP XR Quality Report Blocks September 2011 include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 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 . . . . . . . . . . . . . . . . . . . . . . 8 A.1. draft-wu-xrblock-rtcp-xr-quality-monitoring-03 . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 Wu, et al. Expires March 18, 2012 [Page 2] Internet-Draft RTCP XR Quality Report Blocks September 2011 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. Wu, et al. Expires March 18, 2012 [Page 3] Internet-Draft RTCP XR Quality Report Blocks September 2011 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 these 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: Wu, et al. Expires March 18, 2012 [Page 4] Internet-Draft RTCP XR Quality Report Blocks September 2011 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| MC | Rsd.| 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 . 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). 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 for future definitions. If new MOS types are defined, they can be added by an update to this document. If the receiver does not understand the MOS type defined in this document it should discard this report. Rsd.:3 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. Wu, et al. Expires March 18, 2012 [Page 5] Internet-Draft RTCP XR Quality Report Blocks September 2011 SSRC of source: 32 bits As defined in Section 4.1 of [RFC3611]. MOS Value: 32 bits 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 report block defined in this document to be used with Session Description Protocol (SDP) [RFC4566] using the Augmented Backus-Naur Form (ABNF) [RFC5234]. It has 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: Wu, et al. Expires March 18, 2012 [Page 6] Internet-Draft RTCP XR Quality Report Blocks September 2011 Name: SMQM Long Name: Synthetical Multimedia Quality Metric Value 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. [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. [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, January 2008. Wu, et al. Expires March 18, 2012 [Page 7] Internet-Draft RTCP XR Quality Report Blocks September 2011 9.2. Informative References [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. [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. Appendix A. Change Log A.1. draft-wu-xrblock-rtcp-xr-quality-monitoring-03 The following are the major changes compared to previous version 02: o Remove the tag field. o Define MOS Value field as 32 bits integer value field. o Clear unused references. o Add text to MOS type field for clarification. o Other Editorial changes. Authors' Addresses Qin Wu Huawei 101 Software Avenue, Yuhua District Nanjing, Jiangsu 210012 China Email: sunseawq@huawei.com Wu, et al. Expires March 18, 2012 [Page 8] Internet-Draft RTCP XR Quality Report Blocks September 2011 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 Wu, et al. Expires March 18, 2012 [Page 9]