Internet Engineering Task Force A. Clark Internet-Draft Telchemy Incorporated Expires: 16th May 2008 A. Pendleton Nortel November 2007 RTCP XR - Video Metrics Report Blocks draft-ietf-avt-rtcpxr-video-02.txt 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 16th May 2008. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract This document defines extensions to the RTCP XR extended report packet type blocks to support the monitoring of video over IP for IPTV and videoconferencing endpoint reporting. Clark [Page 1] draft-ietf-avt-rtcpxr-video-02.txt 18th November 2007 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . 2 3. IP Video Metrics Report Block . . . . . . . . . . . . . . . 2 4. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5. Security Considerations . . . . . . . . . . . . . . . . . . 5 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . 5 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 8. Informative References . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . Intellectual Property and Copyright Statements . . . . . . . 1. Introduction This draft defines an RTCP XR block type for Quality of Service reporting for video over IP. It is intended to support both the identification of problems affecting performance and the collection of data that may be useful in optimizing system configuration. Video performance may be measured using zero (no) reference, partial (reduced) reference or full reference. The primary application of this draft is to support the reporting of real-time, in-service performance obtained using a zero or partial reference model however this approach could also be used to support the remote reporting of metrics from a full reference test. 2. Definitions This draft defines metrics related to IP Video performance. Video MOS scores have not been included in this draft however may be incorporated later if an industry standard method for computing such scores is defined. 3 Video Metrics Report Block 3.1 Block Description 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 | Reserved | block length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SSRC | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0 0 0| Program ID | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Clark [Page 2] draft-ietf-avt-rtcpxr-video-02.txt 18th November 2007 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Measurement Interval (ms) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Proportion Impaired I frames | Proportion Impaired BP frames | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Loss rate within I frames | Loss rate within BP frames | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Mean GoP Length (frames) | Max GoP Length (frames) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | EPSNR Threshold | Time below PSNR threshold | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Mean Video bit rate (bits/sec) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Round trip delay | A-V Delay (Video I/F) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Playout Interrupt Count | Mean Playout Interrupt Size | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Video Playout buffer size | Mean buffer level | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3.2 Metric definitions 3.2.1 Header The header comprises: (i) Block Type for this report block (ii) Reserved (set to 0xFF) (iii) Block length in words (set to 0x000C) (iv) SSRC of the received RTP stream that this report refers to (v) Program ID (PID) for the video stream (if MPEG Transport encapsulation is used) (vi) Reserved (set to 0xFFFF) 3.2.2 Measurement Interval The interval of time over which these metrics were measured, expressed in milliseconds. 3.2.3 Proportion of impaired I frames The proportion of I (intra-frame encoded) frames [4] that were impaired by packet loss or discard, expressed as a binary fraction. 3.2.4 Proportion of impaired BP frames The proportion of B and P (inter-frame encoded) frames [4] that were impaired by packet loss or discard, expressed as a binary fraction. 3.2.5 Loss rate within I frames The average packet loss/discard rate occurring within I frames, [4] expressed as a binary fraction. 3.2.6 Loss rate within BP frames The average packet loss/discard rate occurring within B and P [4] frames, expressed as a binary fraction. 3.2.7 Mean inter-I-frame gap (MIIF) Clark [Page 3] draft-ietf-avt-rtcpxr-video-02.txt 18th November 2007 The average interval between I frames expressed in terms of frames. If n(j) is the number of P and B frames between the jth and (j+1)th I frame then the mean inter-I-frame gap is MIIF(j) = ( MIIF(j-1) * 15 + n(j) ) / 16 The I frames occur at the start of Groups of Pictures (GoP) and may also be inserted during GoP's due to large scale changes in picture content (e.g. scene changes). This can result in bandwidth being larger than expected. 3.2.8 Max GoP Length (MGoP) The maximum GoP size (including the starting I frame and subsequent P and B frames) expressed in terms of frames. If m(j) comprises a count of the starting I frame and the subsequent frames (P, B or inserted I) prior to the I frame that forms the start of the next GoP, then the maximum GoP length is MGoP(j) = max( m(j), MGoP(j-1) ) A long GoP may result in lower bandwidth however will lead to increased error propagation and hence degraded performance. 3.2.9 Estimated PSNR (EPSNR) An estimate of the average Peak Signal to Noise Ratio, averaged over the duration of the measurement interval. This is expressed in unsigned 8:8 format and has the range 0.0 to 100.0. For typical high quality video streams this parameter would have a value in the range 35-45. The per frame PSNR value SHOULD be estimated by the decoder, based on the proportion of macroblocks within the frame that required concealment, the concealment algorithm used and quantization level. If a per-frame PSNR estimate is not available from the decoder then this value MAY be estimated from the proportion of packet loss per frame [4]. A value of 0xFFFF shall indicate that this parameter is not available. 3.2.10 EPSNR Threshold Threshold defined as the level below which quality is not acceptable A value of 0xFFFF shall indicate that this parameter is not available. 3.2.11 Proportion of time below EPSNR threshold The proportion of the measurement interval during which estimated PSNR was below the PSNR Threshold, expressed as a binary fraction. If the value of MOS Threshold is 0xFFFF then the value of this Clark [Page 4] draft-ietf-avt-rtcpxr-video-02.txt 18th November 2007 parameter is undefined. 3.2.12 Mean Video Bit Rate The average video bit rate [4] calculated over the measurement interval. This shall include RTP and MPEG Transport packet headers and payloads but shall exclude IP and UDP or TCP overhead. 3.2.13 Round Trip Delay The Round Trip Delay between the originating and terminating ends of this RTP stream, expressed in millseconds. In unicast or multicast applications this parameter may be set to "undefined" (0xFFFF). 3.2.14 A-V Delay The relative delay between decoded audio and video streams expressed in milliseconds [4]. 3.2.15 Playout Interrupt Count The number of interruptions or frame freezes that occurred during playout, due to either packet loss or buffer underrun [4]. 3.2.16 Mean Playout Interrupt Size The mean duration of interruptions in playout expressed in milliseconds. 3.2.17 Video Playout Buffer Size The available playout buffer size, expressed in milliseconds. 3.2.18 Mean Buffer Level The mean playout buffer size, expressed in milliseconds. 4. Summary This draft defines an RTCP XR report block for video quality reporting. This is intended for in-service monitoring of video streaming, IPTV and IP videoconferencing services to provide real time performance feedback and support performance management. 5. IANA Considerations The block type "mmm" will need to be replaced with an IANA assigned number within those allocated for RTCP XR report blocks (RFC 3611). 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 endpoints. As a result, any third party wishing to obtain this information should be properly authenticated and the Clark [Page 5] draft-ietf-avt-rtcpxr-video-02.txt 18th November 2007 information transferred securely. 7. Acknowledgments The authors would like to acknowledge Keith Lantz, Kaynam Hedayat, Satish Kumar for their helpful comments. 8. Informative References [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] ATIS-080008 QoS Metrics for Linear Broadcast IPTV. ATIS 2007 Authors' Addresses Alan Clark Telchemy Incorporated 2905 Premiere Parkway, Suite 280 Duluth, GA 30097 Email: alan@telchemy.com Amy Pendleton Nortel 2380 Performance Drive Richardson, TX 75081 Email: aspen@nortel.com Full Copyright Statement Copyright (C) The IETF Trust (2007). 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. 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. Intellectual Property Clark [Page 6] draft-ietf-avt-rtcpxr-video-02.txt 18th November 2007 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. 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. Acknowledgement Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Clark [Page 7]