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rfc:rfc6990

Internet Engineering Task Force (IETF) R. Huang Request for Comments: 6990 Q. Wu Category: Standards Track Huawei ISSN: 2070-1721 H. Asaeda

                                                                  NICT
                                                               G. Zorn
                                                           Network Zen
                                                           August 2013
 RTP Control Protocol (RTCP) Extended Report (XR) Block for MPEG-2
Transport Stream (TS) Program Specific Information (PSI) Independent
             Decodability Statistics Metrics Reporting

Abstract

 An MPEG-2 Transport Stream (TS) is a standard container format used
 in the transmission and storage of multimedia data.  Unicast/
 multicast MPEG-2 TS over RTP is widely deployed in IPTV systems.
 This document defines an RTP Control Protocol (RTCP) Extended Report
 (XR) block that allows the reporting of MPEG-2 TS decodability
 statistics metrics related to transmissions of MPEG-2 TS over RTP.
 The metrics specified in the RTCP XR block are not dependent on
 Program Specific Information (PSI) carried in MPEG-2 TS.

Status of This Memo

 This is an Internet Standards Track document.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 Internet Standards is available in Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc6990.

Huang, et al. Standards Track [Page 1] RFC 6990 RTCP XR TS Decodability August 2013

Copyright Notice

 Copyright (c) 2013 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
 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.  MPEG-2 Transport Stream Decodability Metrics  . . . . . .   3
   1.2.  RTCP and RTCP Extended Reports  . . . . . . . . . . . . .   3
   1.3.  Performance Metrics Framework . . . . . . . . . . . . . .   3
   1.4.  Applicability . . . . . . . . . . . . . . . . . . . . . .   4
 2.  Standards Language  . . . . . . . . . . . . . . . . . . . . .   4
 3.  MPEG-2 TS PSI-Independent Decodability Statistics Metrics
     Block . . . . . . . . . . . . . . . . . . . . . . . . . . . .   4
 4.  SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . .   8
   4.1.  SDP rtcp-xr Attribute Extension . . . . . . . . . . . . .   8
   4.2.  Offer/Answer Usage  . . . . . . . . . . . . . . . . . . .   8
 5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   5.1.  New RTCP XR Block Type Value  . . . . . . . . . . . . . .   8
   5.2.  New RTCP XR SDP Parameter . . . . . . . . . . . . . . . .   9
   5.3.  Contact Information for Registrations . . . . . . . . . .   9
 6.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
 7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
 8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
   8.1.  Normative References  . . . . . . . . . . . . . . . . . .   9
   8.2.  Informative References  . . . . . . . . . . . . . . . . .  10

Huang, et al. Standards Track [Page 2] RFC 6990 RTCP XR TS Decodability August 2013

1. Introduction

1.1. MPEG-2 Transport Stream Decodability Metrics

 The European Telecommunications Standards Institute (ETSI) has
 defined a set of syntax and information consistency tests and
 corresponding indicators [ETSI] that are recommended for the
 monitoring of MPEG-2 Transport Streams [ISO-IEC.13818-1.2013].  The
 tests and corresponding indicators are grouped according to priority:
 o  First priority - Necessary for decodability (basic monitoring)
 o  Second priority - Recommended for continuous or periodic
    monitoring
 o  Third priority - Recommended for application-dependent monitoring
 This memo is based on information consistency tests and resulting
 indicators defined by ETSI [ETSI] and defines a new block type to
 augment those defined in [RFC3611] for use with MPEG-2 Transport
 Stream (TS) [ISO-IEC.13818-1.2013].  The new block type supports
 reporting of the number of occurrences of each PSI-independent
 indicator in the first and second priorities; third priority
 indicators are not supported.

1.2. RTCP and RTCP Extended 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 document defines a new Extended Report block for
 use with [RFC3550] and [RFC3611].

1.3. Performance Metrics Framework

 "Guidelines for Considering New Performance Metric Development"
 [RFC6390] provides guidance on the definition and specification of
 performance metrics.  "Guidelines for Use of the RTP Monitoring
 Framework" [RFC6792] provides guidance on the reporting block format
 using RTCP XR.  The new report block described in this memo is in
 compliance with the monitoring architecture specified in [RFC6792]
 and the performance metrics framework [RFC6390].

Huang, et al. Standards Track [Page 3] RFC 6990 RTCP XR TS Decodability August 2013

1.4. Applicability

 This block type allows a count of MPEG-2 Transport Stream quality
 metrics that are measured in accordance with ETSI TR 101290 [ETSI] to
 be reported by an endpoint.  These metrics are useful for identifying
 bitstream packetization and transport stream encoding problems that
 may affect the user's perception of a video service delivered over
 RTP.

2. 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. MPEG-2 TS PSI-Independent Decodability Statistics Metrics Block

 ETSI TR 101290 [ETSI] generally defines metrics related to error
 events while this document contains counts of those metrics defined
 in [ETSI].  The block defined in this document reports MPEG-2 TS PSI-
 independent decodability statistics metrics beyond the information
 carried in the standard RTCP packet format, which are measured at the
 receiving end of the RTP stream.  It contains counts of eight metrics
 defined in ETSI TR 101290 [ETSI].  Information is reported about
 basic monitoring parameters necessary to ensure that the TS can be
 decoded, including:
 o  Transport Stream Synchronization Losses
 o  Sync byte errors
 o  Continuity count errors
 and continuous monitoring parameters necessary to ensure the
 continuous decoding, including:
 o  Transport errors
 o  Program Clock Reference (PCR) errors
 o  PCR repetition errors
 o  PCR discontinuity indicator errors
 o  PCR accuracy errors
 o  Presentation Time Stamp (PTS) errors

Huang, et al. Standards Track [Page 4] RFC 6990 RTCP XR TS Decodability August 2013

 The other parameters are ignored since they do not apply to all
 MPEG-2 implementations.  For further information on these parameters,
 see [ETSI].  Note that when the report of this block spans across
 more than one measurement interval [RFC6776], the count of the
 metrics (e.g., Sync byte errors and PCR errors) defined in [ETSI] may
 reflect a problem in the current or previous measurement interval.
 The MPEG-2 TS PSI-Independent Decodability Statistics Metrics Block
 has the following format:
  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=22     |    Reserved   |         Block Length          |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                     SSRC of Source                            |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |          begin_seq            |             end_seq           |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                      TS_sync_loss_count                       |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                      Sync_byte_error_count                    |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                  Continuity_count_error_count                 |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                      Transport_error_count                    |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                        PCR_error_count                        |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                   PCR_repetition_error_count                  |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |            PCR_discontinuity_indicator_error_count            |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                     PCR_accuracy_error_count                  |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                       PTS_error_count                         |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 Block Type (BT): 8 bits
    The MPEG-2 TS PSI-Independent Decodability Statistics Metrics
    Block is identified by the constant 22.
 Reserved: 8 bits
    These bits are reserved.  They MUST be set to zero by senders and
    ignored by receivers (see [RFC6709] Section 4.2).

Huang, et al. Standards Track [Page 5] RFC 6990 RTCP XR TS Decodability August 2013

 Block Length: 16 bits
    The constant 11, in accordance with the definition of this field
    in Section 3 of RFC 3611.  The block MUST be discarded if the
    block length is set to a different value.
 Synchronization source (SSRC) of Source: 32 bits
    As defined in Section 4.1 of RFC 3611.
 begin_seq: 16 bits
    The RTP sequence number corresponding to the start of the
    measurement period, as defined in Section 4.1 of RFC 3611.
 end_seq: 16 bits
    The RTP sequence number corresponding to the end of the
    measurement period, as defined in Section 4.1 of RFC 3611.
 TS_sync_loss_count: 32 bits
    A count of the number of TS_sync_loss errors that occurred in the
    above sequence number interval.  A TS_sync_loss error occurs when
    there are two or more consecutive incorrect sync bytes within the
    MPEG-2 TS, as defined in Section 5.2.1 of [ETSI].
 Sync_byte_error_count: 32 bits
    A count of the number of Sync_byte_errors that occurred in the
    above sequence number interval.  A sync byte error occurs when the
    sync byte is not equal to 0x47 in any TS packet contained in the
    MPEG-2 TS, as defined in Section 5.2.1 of [ETSI].
 Continuity_count_error_count: 32 bits
    A count of the number of Continuity_count_errors that occurred in
    the above sequence number interval.  A Continuity_count_error
    occurs when any of the following faults happen within the MPEG-2
    TS -- incorrect packet order, a packet occurs more than twice, or
    a packet is lost, as defined in Section 5.2.1 of [ETSI].

Huang, et al. Standards Track [Page 6] RFC 6990 RTCP XR TS Decodability August 2013

 Transport_error_count: 32 bits
    A count of the number of Transport_errors that occurred in the
    above sequence number interval.  A Transport_error occurs when an
    erroneous TS packet cannot be corrected within the MPEG-2 TS, as
    defined in Section 5.2.2 of [ETSI].
 PCR_error_count: 32 bits
    A count of the number of PCR_errors that occurred in the above
    sequence number interval.  A PCR_error occurs if the primary clock
    reference (PCR) is not seen for more than 100 ms within the MPEG-2
    TS, as defined in Section 5.2.2 of [ETSI].  The time interval
    between two consecutive PCR values should be no more than 40 ms.
 PCR_repetition_error_count: 32 bits
    A count of the number of PCR_repetition_errors that occurred in
    the above sequence number interval.  A PCR_repetition_error occurs
    when the time interval between two consecutive PCR values is more
    than 40 ms within the MPEG-2 TS, as defined in Section 5.2.2 of
    [ETSI].
 PCR_discontinuity_indicator_error_count: 32 bits
    A count of the number of PCR_discontinuity_indicator_errors that
    occurred in the above sequence number interval.  A
    PCR_discontinuity_indicator_error occurs if the time interval
    between two consecutive PCR values is more than 100 ms within the
    MPEG-2 TS, as defined in Section 5.2.2 of [ETSI].
 PCR_accuracy_error_count: 32 bits
    A count of the number of PCR_accuracy_errors that occurred in the
    above sequence number interval.  A PCR_accuracy_error occurs when
    the PCR accuracy of the selected program is outside the range of
    +/-500 ns within the MPEG-2 TS, as defined in Section 5.2.2 of
    [ETSI].

Huang, et al. Standards Track [Page 7] RFC 6990 RTCP XR TS Decodability August 2013

 PTS_error_count: 32 bits
    A count of the number of PTS_errors that occurred in the above
    sequence number interval.  A PTS_error occurs when the PTS
    repetition is more than 700 ms within the MPEG-2 TS, as defined in
    Section 5.2.2 of [ETSI].  Note that the PTS is contained in the
    MPEG-2 TS and is used to aid the decoder in presenting the program
    on time, at the correct speed, and synchronized.

4. SDP Signaling

 RFC 3611 defines the use of the Session Description Protocol (SDP)
 [RFC4566] for signaling the use of RTCP XR blocks.  However, XR
 blocks MAY be used without prior signaling (see Section 5 of RFC
 3611).

4.1. SDP rtcp-xr Attribute Extension

 This session augments the SDP attribute "rtcp-xr" defined in
 Section 5.1 of RFC 3611 by providing an additional value of
 "xr-format" to signal the use of the report block defined in this
 document.  The ABNF [RFC5234] syntax is as follows.
 xr-format =/  xr-tpid-block
 xr-tpid-block = "ts-psi-indep-decodability"

4.2. Offer/Answer Usage

 When SDP is used in Offer/Answer context, the SDP Offer/Answer usage
 defined in [RFC3611] for unilateral "rtcp-xr" attribute parameters
 applies.  For detailed usage of Offer/Answer for unilateral
 parameters, refer to Section 5.2 of [RFC3611].

5. 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 RFC 3611.

5.1. New RTCP XR Block Type Value

 This document assigns the block type value 22 in the IANA "RTP
 Control Protocol Extended Reports (RTCP XR) Block Type Registry" to
 the "MPEG-2 Transport Stream PSI-Independent Decodability Statistics
 Metrics Block".

Huang, et al. Standards Track [Page 8] RFC 6990 RTCP XR TS Decodability August 2013

5.2. New RTCP XR SDP Parameter

 This document also registers the new parameter "ts-psi-
 indep-decodability" in the "RTP Control Protocol Extended Reports
 (RTCP XR) Session Description Protocol (SDP) Parameters Registry".

5.3. Contact Information for Registrations

 The contact information for registrations is:
 Qin Wu (sunseawq@huawei.com)
 101 Software Avenue, Yuhua District
 Nanjing, Jiangsu  210012
 China

6. Security Considerations

 There might be some relationship between reported error counters and
 contractual Service Level Agreements (SLAs); hence, an attack (e.g.,
 RTP endpoints reporting false data, or an attacker in the path
 modifying the data being reported) might deliberately corrupt these
 error counters, resulting in financial implications for the network
 operator (either as a result of unneeded performance metrics, or
 penalty charges for SLA failure).
 A solution to prevent such an attack is to apply an authentication
 and integrity protection framework for the RTCP XR block.  This can
 be accomplished using the RTP profile that combines Secure RTP
 [RFC3711] and the Audio-Visual Profile with Feedback (AVPF) into
 Secure AVPF (SAVPF) [RFC5124].
 Besides this, the RTCP XR block in this document introduces no new
 security considerations beyond those described in [RFC3611].

7. Acknowledgements

 Thanks to Ray van Brandenburg, Claire Bi, Colin Perkins, Roni Even,
 Dan Romascanu, Ali Begen, Alexey Melnikov, Bert Wijnen, Gonzalo
 Camarillo, Benoit Claise, and Alan Clark for useful reviews and
 suggestions.

8. References

8.1. Normative References

 [ETSI]     ETSI, "Digital Video Broadcasting (DVB); Measurement
            guidelines for DVB systems", Technical Report TR 101 290,
            2001.

Huang, et al. Standards Track [Page 9] RFC 6990 RTCP XR TS Decodability August 2013

 [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119, March 1997.
 [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, November
            2003.
 [RFC3711]  Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
            Norrman, "The Secure Real-time Transport Protocol (SRTP)",
            RFC 3711, March 2004.
 [RFC4566]  Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
            Description Protocol", RFC 4566, July 2006.
 [RFC5124]  Ott, J. and E. Carrara, "Extended Secure RTP Profile for
            Real-time Transport Control Protocol (RTCP)-Based Feedback
            (RTP/SAVPF)", RFC 5124, February 2008.
 [RFC5234]  Crocker, D. and P. Overell, "Augmented BNF for Syntax
            Specifications: ABNF", STD 68, RFC 5234, January 2008.

8.2. Informative References

 [ISO-IEC.13818-1.2013]
            International Organization for Standardization,
            "Information technology - Generic coding of moving
            pictures and associated audio information: Systems", ISO
            International Standard 13818-1, May 2013.
 [RFC6390]  Clark, A. and B. Claise, "Guidelines for Considering New
            Performance Metric Development", BCP 170, RFC 6390,
            October 2011.
 [RFC6709]  Carpenter, B., Aboba, B., and S. Cheshire, "Design
            Considerations for Protocol Extensions", RFC 6709,
            September 2012.
 [RFC6776]  Clark, A. and Q. Wu, "Measurement Identity and Information
            Reporting Using a Source Description (SDES) Item and an
            RTCP Extended Report (XR) Block", RFC 6776, October 2012.
 [RFC6792]  Wu, Q., Hunt, G., and P. Arden, "Guidelines for Use of the
            RTP Monitoring Framework", RFC 6792, November 2012.

Huang, et al. Standards Track [Page 10] RFC 6990 RTCP XR TS Decodability August 2013

Authors' Addresses

 Rachel Huang
 Huawei
 101 Software Avenue, Yuhua District
 Nanjing  210012
 China
 EMail: rachel.huang@huawei.com
 Qin Wu
 Huawei
 101 Software Avenue, Yuhua District
 Nanjing, Jiangsu  210012
 China
 EMail: bill.wu@huawei.com
 Hitoshi Asaeda
 National Institute of Information and Communications Technology
 4-2-1 Nukui-Kitamachi
 Koganei, Tokyo  184-8795
 Japan
 EMail: asaeda@nict.go.jp
 Glen Zorn
 Network Zen
 227/358 Thanon Sanphawut
 Bang Na, Bangkok  10260
 Thailand
 Phone: +66 (0) 8-1000-4155
 EMail: glenzorn@gmail.com

Huang, et al. Standards Track [Page 11]

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