AVT Working Group Alan Clark Internet Draft Telchemy Geoff Hunt BT Intended status: Standards Track October 26, 2008 Expires: April 28, 2008 RTCP XR Report Block for QoE Metrics Reporting draft-ietf-avt-rtcp-xr-qoe-00 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on April 28, 2009. Copyright Notice Copyright (C) The IETF Trust (2008). Abstract This document defines an RTCP XR Report Block that allows the reporting of QoE metrics for use in voice, audio and video services. Terminology 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 [1]. Clark & Hunt [Page 1] RTCP XR QoE Metrics October 2008 1. Introduction 1.1. QoE Metrics Report Block This draft defines a new block types to augment those defined in RFC3611 for use in reporting QoE metrics. QoE metrics consider the impact of a range of transmission and payload (content) related impairments on the quality of a service from the user viewpoint. 1.2. RTCP and RTCP XR Reports The use of RTCP for reporting is defined in RFC3550 [2]. RFC3611 [3] defined an extensible structure for reporting using an RTCP Extended Report (XR). This draft defines a new Extended Report block that MUST be used as defined in RFC3550 and RFC3611. 1.3 Performance Metrics Framework The Performance Metrics Framework [9] provides guidance on the definition and specification of performance metrics. Metrics described in this draft either reference external definitions or define metrics generally in accordance with the guidelines in [9]. 1.4 Applicability This memo applies to any application of RTP for which QoE measurement algorithms are defined. 2. Definitions 2.1 QoE Metrics A QoE ("Quality of Experience") metric is intended to provide a measure that is indicative of the user's view of a service. This is commonly expressed as a MOS ("Mean Opinion Score") which usually (but not always) is a 1.0-5.0 numerical scale in which a 1.0 represents "Unacceptable" and 5.0 represents "Excellent". True MOS scores are obtained using subjective testing, and tend vary from test to test. Subjective testing is also not suitable for measuring the quality of operational services and hence it is common practice to use objective algorithms to estimate subjective quality. During the development of such QoE algorithms, there is extensive comparison against both subjective test data and data from other "trusted" objective test tools. ITU-T Recommendation P.564 defines a methodology for verifying the performance of QoE estimation algorithms for Voice over IP services. There is standardization work underway related to Clark & Hunt [Page 2] RTCP XR QoE Metrics October 2008 QoE metrics for video and audio. The continuous progression of work in this area means that new algorithms may be defined in the future, hence this memo does make provision for new algorithms. Implementors are advised that IPR disclosures have been made in respect of most known QoE estimation algorithms and they should check the IPR disclosure databases and policies of the relevant standards organizations (for example ITU and ETSI). 2.2 Channel Certain types of encoder (for example stereo audio codecs) incorporate multiple audio or video channels into a single encoded stream which is then packetized and carried in RTP or MPEG Transport. Within the scope of this memo, the term "channel" applies to this definition only - if multiple audio or video streams are carried either in separate RTP sessions (identified by an SSRC) or MPEG Transport program streams (identified by a PID) then the Measurement Identifier block MUST be used to identify the stream to which metrics apply. 3. QoE Metrics Block 3.1 Report Block Structure 0 1 2 3 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BT=N |I|Tag | | block length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Chan |Dir| Type | Calc alg | QoE Metric | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ .......... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Chan |Dir| Type | Calc alg | QoE Metric | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3.2 Definition of Fields in QoE Metric Report Block block type (BT): 8 bits A Basic Loss/Discard Report Block is identified by the constant NWRX. [Note to RFC Editor: please replace NWRX with the IANA provided RTCP XR block type for this block.] 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 Clark & Hunt [Page 3] RTCP XR QoE Metrics October 2008 duration between successive metrics reports (I=1) (the Interval Duration) or to the accumulation period characteristic of cumulative measurements (I=0) (the Cumulative Duration). Numerical values for both these intervals are provided in the Measurement Identifier block referenced by the tag field below. Measurement Identifier association (tag): 3 bits This field is used to identify the Measurement Identifier block which describes this measurement. The relevant Measurement Identifier block has the same tag value as the Basic Loss/Discard block. Note that there may be more than one Measurement Identifier block per RTCP packet. Block length: 16 bits The length if this report block in 32-bit words minus one. Channel The channel number of the audio or video stream to which this metric applies Direction Type 0000 MOS-LQ - Estimated Listening Quality MOS 0001 MOS-CQ - Estimated Conversational Quality MOS 0010 RLQ - Listening Quality R Factor 0011 RCQ - Conversational Quality R Factorv 0100 MOS-V - Video Quality MOS 0101 PSNR - Peak Signal to Noise Ratio 0110 MOS-A - Audio Quality MOS 0111 - 1111 - Reserved Calculation Algorithm 0 - P.564 [5] (Voice) 1 - G.107 / ETSI TS 101 329-5 Annex E [6,7] (Voice) 2 - TTC JJ201.01 [8] (Japan) 3-254 - Reserved 255 - Indicated via SDP QoE Metric A 8:8 integer scaled representation of the QoE metric value. This allows values in the range 0.0 to 255.996 to be represented. 4. SDP Signaling RFC3611 [3] defines the use of SDP (Session Description Protocol) Clark & Hunt [Page 4] RTCP XR QoE Metrics October 2008 [4] for signaling the use of XR blocks. XR blocks MAY be used without prior signaling. This section augments the SDP [4] attribute "rtcp-xr" defined in RFC3611[3] by providing a "xr-format" to signal the use of the report block defined in this document. rtcp-xr-attrib = "a=" "rtcp-xr" ":" [xr-format *(SP xr-format)] CRLF (defined in RFC3611) xr-format = xr-format / qoe-metrics qoe-metrics = "qoe-metrics" [EQUAL word] DIGIT = %x30-39 format-ext = non-ws-string non-ws-string = 1*(%x21-FF) CRLF = %d13.10 5. IANA Considerations This document creates a new block type within the IANA "RTCP XR Block Type Registry" called the QoE Metrics, and a new [new-xrblock] parameter within the "RTCP XR SDP Parameters Registry". 6. Security Considerations RTCP reports can contain sensitive information since they can provide information about the nature and duration of a session established between two or more endpoints. 7. Contributors 8. References Normative [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Schulzrinne, H., Casner, S., Frederick, R. and V. Jacobson, "RTP: A Transport Protocol for Real-Time Applications", STD 64, RFC 3550, July 2003. [3] Friedman, T., Caceres, R., and A. Clark, "RTP Control Protocol Extended Reports (RTCP XR)", RFC 3611, November 2003. [4] Handley, M. and V. Jacobson, "SDP: Session Description Protocol", RFC 4566, July 2006. Clark & Hunt [Page 5] RTCP XR QoE Metrics October 2008 [5] ITU-T Recommendation P.564, Conformance testing for narrowband Coice over IP transmission quality assessment models [6] ITU-T Recommendation G.107, The E Model, a computational model for use in transmission planning [7] ETSI TS 101 329-5, QoS Measurement for Voice over IP [8] TTC 201.01 (Japan) A method for speech quality assessment for Coice over IP Informative [9] Clark, A. "Framework for Performance Metric Development draft-ietf-pmol-perf-metrics-framework-00.txt Author's Addresses Alan Clark Telchemy Incorporated 2905 Premiere Parkway, Suite 280 Duluth, GA 30097 USA Email: alan.d.clark@telchemy.com Geoff Hunt BT Orion 1 PP9 Adastral Park Martlesham Heath Ipswich, Suffolk IP4 2TH United Kingdom Email: geoff.hunt@bt.com Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Clark & Hunt [Page 6] RTCP XR QoE Metrics October 2008 Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Clark & Hunt [Page 7]