Audio/Video Transport Working Group G. Hunt Internet-Draft Unaffiliated Intended status: Standards Track A. Clark Expires: December 14, 2012 Telchemy G. Zorn Network Zen C. Bi STTRI Q. Wu Huawei June 12, 2012 RTCP XR Report Block for Loss Concealment metric Reporting draft-ietf-xrblock-rtcp-xr-loss-conceal-00.txt Abstract This document defines an RTCP XR Report Block that allows the reporting of Loss Concealment metrics primarily for audio applications of RTP. 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 December 14, 2012. Copyright Notice Copyright (c) 2012 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 Hunt, et al. Expires December 14, 2012 [Page 1] Internet-Draft RTCP XR Loss Concealment June 2012 carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must 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 1.1. Loss Concealment Report Block . . . . . . . . . . . . . . 3 1.2. RTCP and RTCP XR Reports . . . . . . . . . . . . . . . . . 3 1.3. Performance Metrics Framework . . . . . . . . . . . . . . 4 1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 4 2. Loss Concealment Block . . . . . . . . . . . . . . . . . . . . 5 2.1. Report Block Structure . . . . . . . . . . . . . . . . . . 5 2.2. Definition of Fields in Loss Concealment Report Block . . 5 3. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 9 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 4.1. New RTCP XR Block Type value . . . . . . . . . . . . . . . 10 4.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 10 4.3. Contact information for registrations . . . . . . . . . . 10 5. Security Considerations . . . . . . . . . . . . . . . . . . . 11 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 7.1. Normative References . . . . . . . . . . . . . . . . . . . 13 7.2. Informative References . . . . . . . . . . . . . . . . . . 13 Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 14 A.1. draft-ietf-xrblock-rtcp-xr-loss-conceal-00 . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15 Hunt, et al. Expires December 14, 2012 [Page 2] Internet-Draft RTCP XR Loss Concealment June 2012 1. Introduction 1.1. Loss Concealment Report Block This draft defines a new block type to augment those defined in [RFC3611], for use in a range of RTP applications. At any instant, the audio output at a receiver may be classified as either 'normal' or 'concealed'. 'Normal' refers to playout of audio payload received from the remote end, and also includes locally generated signals such as announcements, tones and comfort noise. Concealment refers to playout of locally-generated signals used to mask the impact of network impairments or to reduce the audibility of jitter buffer adaptations. The new block type provides metrics for actions taken by the receiver to mitigate the effect of packet loss and packet discard. Specifically, the first metric (On-Time Playout Duration) reports the duration of normal playout of data which the receiver obtained from the sender's stream. A second metric (Loss Concealment Duration) reports the total time during which the receiver played out media data which was manufactured locally, because the sender's data for these periods was not available due to packet loss or discard. A similar metric (Buffer Adjustment Concealment Duration) reports the duration of playout of locally-manufactured data replacing data which is unavailable due to adaptation of an adaptive de-jitter buffer. Further metrics (Playout Interrupt Count and Mean Playout Interrupt Size) report the number of times normal playout was interrupted, and the mean duration of these interruptions. Loss Concealment Duration and Buffer Adjustment Concealment Duration are reported separately because buffer adjustment is typically arranged to occur in silence periods so may have very little impact on user experience, whilst loss concealment may occur at any time. The metric belongs to the class of transport-related terminal metrics defined in [MONARCH] (work in progress). 1.2. RTCP and RTCP XR Reports The use of RTCP for reporting is defined in [RFC3550]. [RFC3611] 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]. Hunt, et al. Expires December 14, 2012 [Page 3] Internet-Draft RTCP XR Loss Concealment June 2012 1.3. Performance Metrics Framework The Performance Metrics Framework [RFC6390] provides guidance on the definition and specification of performance metrics. The RTP Monitoring Architectures [MONARCH] provides guideline for reporting block format using RTCP XR. The Metrics Block described in this document are in accordance with the guidelines in [RFC6390] and [MONARCH]. 1.4. Applicability This metric is primarily applicable to audio applications of RTP. EDITOR'S NOTE: are there metrics for concealment of transport errors for video? Hunt, et al. Expires December 14, 2012 [Page 4] Internet-Draft RTCP XR Loss Concealment June 2012 2. Loss Concealment Block 2.1. Report Block Structure Loss Concealment metrics block 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=NLC | I |plc| rsv. | block length=5 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SSRC of Source | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | On-time Playout Duration | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Loss Concealment Duration | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Buffer Adjustment Concealment Duration | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Playout Interrupt Count | Mean Playout Interrupt Size | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: Report Block Structure 2.2. Definition of Fields in Loss Concealment Report Block Block type (BT): 8 bits A Loss Concealment Metrics Report Block is identified by the constant NLC. [Note to RFC Editor: please replace NLC with the IANA provided RTCP XR block type for this block.] Interval Metric flag (I): 2 bit This field is used to indicate whether the Delay metrics are Sampled, Interval or Cumulative metrics, that is, whether the reported values applies to the most recent measurement interval duration between successive metrics reports (I=10) (the Interval Duration) or to the accumulation period characteristic of cumulative measurements (I=11) (the Cumulative Duration) or is a sampled instantaneous value (I=01) (Sampled Value). Hunt, et al. Expires December 14, 2012 [Page 5] Internet-Draft RTCP XR Loss Concealment June 2012 Packet Loss Concealment Method (plc): 2 bits This field is used to identify the packet loss concealment method in use at the receiver, according to the following code: bits 014-015 0 = silence insertion 1 = simple replay, no attenuation 2 = simple replay, with attenuation 3 = enhanced Other values reserved Reserved (resv): 4 bits These bits are reserved. They SHOULD be set to zero by senders and MUST be ignored by receivers. block length: 16 bits The length of this report block in 32-bit words, minus one. For the Delay block, the block length is equal to 5. SSRC of source: 32 bits As defined in Section 4.1 of [RFC3611]. On-time Playout Duration (ms): 32 bits 'On-time' playout is the uninterrupted, in-sequence playout of valid decoded audio information originating from the remote endpoint. This includes comfort noise during periods of remote talker silence, if VAD is used, and locally generated or regenerated tones and announcements. An equivalent definition is that on-time playout is playout of any signal other than those used for concealment. On-time playout duration MUST include both speech and silence intervals, whether VAD is used or not. This duration is reported Hunt, et al. Expires December 14, 2012 [Page 6] Internet-Draft RTCP XR Loss Concealment June 2012 in millisecond units. If the measured value exceeds 0xFFFFFFFD, the value 0xFFFFFFFE SHOULD be reported to indicate an over-range measurement. If the measurement is unavailable, the value 0xFFFFFFFF SHOULD be reported. Loss Concealment Duration (ms): 32 bits The duration, in milliseconds, of audio playout corresponding to Loss-type concealment. Loss-type concealment is reactive insertion or deletion of samples in the audio playout stream due to effective frame loss at the audio decoder. "Effective frame loss" is the event in which a frame of coded audio is simply not present at the audio decoder when required. In this case, substitute audio samples are generally formed, at the decoder or elsewhere, to reduce audible impairment. If the measured value exceeds 0xFFFFFFFD, the value 0xFFFFFFFE SHOULD be reported to indicate an over-range measurement. If the measurement is unavailable, the value 0xFFFFFFFF SHOULD be reported. Buffer Adjustment Concealment Duration (ms): 32 bits The duration, in milliseconds, of audio playout corresponding to Buffer Adjustment-type concealment, if known. If the measured value exceeds 0xFFFFFFFD, the value 0xFFFFFFFE SHOULD be reported to indicate an over-range measurement. If the measurement is unavailable, the value 0xFFFFFFFF SHOULD be reported. Buffer Adjustment-type concealment is proactive or controlled insertion or deletion of samples in the audio playout stream due to jitter buffer adaptation, re-sizing or re-centering decisions within the endpoint. Because this insertion is controlled, rather than occurring randomly in response to losses, it is typically less audible than loss-type concealment. For example, jitter buffer adaptation events may be constrained to occur during periods of talker silence, in which case only silence duration is affected, or sophisticated time-stretching methods for insertion/deletion Hunt, et al. Expires December 14, 2012 [Page 7] Internet-Draft RTCP XR Loss Concealment June 2012 during favorable periods in active speech may be employed. Concealment events which cannot be classified as Buffer Adjustment- type MUST be classified as Loss-type. Playout Interrupt Count: 16 bits The number of interruptions to normal playout which occurred during the reporting period. If the measured value exceeds 0xFFFD, the value 0xFFFE SHOULD be reported to indicate an over-range measurement. If the measurement is unavailable, the value 0xFFFF SHOULD be reported. Mean Playout Interrupt Size (ms): 16 bits The mean duration, in ms, of interruptions to normal playout which occurred during the reporting period. If the measured value exceeds 0xFFFD, the value 0xFFFE SHOULD be reported to indicate an over-range measurement. If the measurement is unavailable, the value 0xFFFF SHOULD be reported. Hunt, et al. Expires December 14, 2012 [Page 8] Internet-Draft RTCP XR Loss Concealment June 2012 3. SDP Signaling [RFC3611] defines the use of SDP (Session Description Protocol) [RFC4566] for signaling the use of XR blocks. XR blocks MAY be used without prior signaling. This section augments the SDP [RFC4566] attribute "rtcp-xr" defined in [RFC3611] by providing an additional value of "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-conceal-block xr-conceal-block = "loss-conceal" Hunt, et al. Expires December 14, 2012 [Page 9] Internet-Draft RTCP XR Loss Concealment June 2012 4. IANA Considerations New block types for RTCP XR are subject to IANA registration. For general guidelines on IANA considerations for RTCP XR, refer to [RFC3611]. 4.1. New RTCP XR Block Type value This document assigns the block type value NJB in the IANA "RTCP XR Block Type Registry" to the "Loss Concealment Metrics Block". [Note to RFC Editor: please replace NLC with the IANA provided RTCP XR block type for this block.] 4.2. New RTCP XR SDP Parameter This document also registers a new parameter "loss-conceal" in the "RTCP XR SDP Parameters Registry". 4.3. Contact information for registrations The contact information for the registrations is: Alan Clark (alan.d.clark@telchemy.com) 2905 Premiere Parkway, Suite 280 Duluth, GA 30097 USA Hunt, et al. Expires December 14, 2012 [Page 10] Internet-Draft RTCP XR Loss Concealment June 2012 5. Security Considerations It is believed that this proposed RTCP XR report block introduces no new security considerations beyond those described in [RFC3611]. This block does not provide per-packet statistics so the risk to confidentiality documented in Section 7, paragraph 3 of [RFC3611] does not apply. Hunt, et al. Expires December 14, 2012 [Page 11] Internet-Draft RTCP XR Loss Concealment June 2012 6. Acknowledgements The authors gratefully acknowledge the comments and contributions made by Bruce Adams, Philip Arden, Amit Arora, Bob Biskner, Kevin Connor, Claus Dahm, Randy Ethier, Roni Even, Jim Frauenthal, Albert Higashi, Tom Hock, Shane Holthaus, Paul Jones, Rajesh Kumar, Keith Lantz, Mohamed Mostafa, Amy Pendleton, Colin Perkins, Mike Ramalho, Ravi Raviraj, Albrecht Schwarz, Tom Taylor, and Hideaki Yamada. Hunt, et al. Expires December 14, 2012 [Page 12] Internet-Draft RTCP XR Loss Concealment June 2012 7. References 7.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", March 1997. [RFC3550] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time Applications", RFC 3550, July 2003. [RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control Protocol Extended Reports (RTCP XR)", November 2003. [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session Description Protocol", July 2006. 7.2. Informative References [MONARCH] Hunt, G., "Monitoring Architectures for RTP", ID draft-ietf-avtcore-monarch-04, August 2011. [RFC6390] Clark, A. and B. Claise, "Framework for Performance Metric Development", RFC 6390, October 2011. Hunt, et al. Expires December 14, 2012 [Page 13] Internet-Draft RTCP XR Loss Concealment June 2012 Appendix A. Change Log Note to the RFC-Editor: please remove this section prior to publication as an RFC. A.1. draft-ietf-xrblock-rtcp-xr-loss-conceal-00 The following are the major changes to previous version : o Changed BNF for SDP following Christian Groves' and Tom Taylor's comments (4th and 5th May 2009). o Updated references. Hunt, et al. Expires December 14, 2012 [Page 14] Internet-Draft RTCP XR Loss Concealment June 2012 Authors' Addresses Geoff Hunt Unaffiliated Email: r.geoff.hunt@gmail.com Alan Clark Telchemy Incorporated 2905 Premiere Parkway, Suite 280 Duluth, GA 30097 USA Email: alan.d.clark@telchemy.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 Claire Bi Shanghai Research Institure of China Telecom Corporation Limited No.1835,South Pudong Road Shanghai 200122 China Email: bijy@sttri.com.cn Qin Wu Huawei 101 Software Avenue, Yuhua District Nanjing, Jiangsu 210012 China Email: sunseawq@huawei.com Hunt, et al. Expires December 14, 2012 [Page 15]