





Internet Engineering Task Force (IETF)                           J. Tong
Request for Comments: 7380                                    C. Bi, Ed.
Category: Standards Track                                  China Telecom
ISSN: 2070-1721                                                  R. Even
                                                              Q. Wu, Ed.
                                                                R. Huang
                                                                  Huawei
                                                           November 2014


    RTP Control Protocol (RTCP) Extended Report (XR) Block for MPEG2
 Transport Stream (TS) Program Specific Information (PSI) Decodability
                      Statistics Metrics Reporting

Abstract

   An MPEG2 Transport Stream (TS) is a standard container format used in
   the transmission and storage of multimedia data.  Unicast/multicast
   MPEG2 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 MPEG2 TS decodability statistics metrics
   related to transmissions of MPEG2 TS over RTP.  The metrics specified
   in the RTCP XR block are related to Program Specific Information
   (PSI) carried in MPEG 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/rfc7380.













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Copyright Notice

   Copyright (c) 2014 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. MPEG2 Transport Stream Decodability Metrics ................3
      1.2. RTCP and RTCP XR Reports ...................................3
      1.3. Performance Metrics Framework ..............................3
      1.4. Applicability ..............................................3
   2. Terminology .....................................................4
      2.1. Standards Language .........................................4
   3. MPEG2 TS PSI Decodability Statistics Metrics Block ..............4
   4. SDP Signaling ...................................................8
      4.1. SDP rtcp-xr-attrib Attribute Extension .....................8
      4.2. Offer/Answer Usage .........................................8
      4.3. Usage Outside of Offer/Answer ..............................8
   5. IANA Considerations .............................................9
      5.1. New RTCP XR Block Type Value ...............................9
      5.2. New RTCP XR SDP Parameter ..................................9
      5.3. Contact Information for Registrations ......................9
   6. Security Considerations .........................................9
   7. References ......................................................9
      7.1. Normative References .......................................9
      7.2. Informative References ....................................10
  Authors' Addresses .................................................11













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1.  Introduction

1.1.  MPEG2 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 MPEG2 Transport Streams [ISO-IEC.13818-1.2007].  The
   tests and corresponding indicators are grouped according to priority:

   First priority:  Necessary for decodability (basic monitoring)

   Second priority:  Recommended for continuous or periodic monitoring

   Third priority:  Recommended for application-dependent monitoring

   This memo defines a new block type for use with MPEG2 Transport
   Streams [ISO-IEC.13818-1.2007] to augment those defined in [RFC3611].
   The new block type supports reporting of the number of occurrences of
   each Program Specific Information (PSI) indicator in the first and
   second priorities listed in Sections 5.2.1 and 5.2.2, respectively,
   of [ETSI].  The third priority indicators are not supported.  The
   metrics defined here supplement information from the PSI-Independent
   Decodability Statistics Metrics Block [RFC6990].

1.2.  RTCP and RTCP XR Reports

   The use of RTCP for reporting is defined in [RFC3550].  [RFC3611]
   defines 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

   The Performance Metrics Framework [RFC6390] provides guidance on the
   definition and specification of performance metrics.  The RTP
   Monitoring Architectures [RFC6792] provides guidelines for RTCP XR
   block formats.  The new report block described in this memo is in
   compliance with the monitoring architecture specified in [RFC6792]
   and the Performance Metrics Framework [RFC6390].

1.4.  Applicability

   These metrics are applicable to any type of RTP application that uses
   the MPEG2 TS standard format for multimedia data, for example, MPEG4
   over MPEG2 TS over RTP.  This new block type can be useful for
   measuring content stream or TS quality by checking TS header
   information [ETSI] and identifying the existence (and characterizing



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   the severity) of bitstream packetization problems that may affect
   users' perception of a service delivered over RTP.  It may also be
   useful for verifying the continued correct operation of an existing
   system management tool.

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.  MPEG2 TS PSI Decodability Statistics Metrics Block

   ETSI TR 101 290 [ETSI] generally defines indicators related to error
   events whereas the XR block defined in this document contains counts
   of occurrences of the [ETSI] indicators.  The block defined in this
   document reports MPEG2 TS PSI decodability statistics metrics beyond
   the information carried in the standard RTCP packet format and PSI-
   Independent Decodability Statistics Metrics Block [RFC6990], which
   are measured at the receiving end of the RTP stream.  It contains
   counts of seven metrics defined in ETSI TR 101 290 [ETSI].
   Information is reported about basic monitoring parameters necessary
   to ensure that the TS can be decoded, including:

   o  Program Association Table (PAT) errors

   o  PAT2 errors

   o  Program Map Table (PMT) errors

   o  PMT2 errors

   o  Packet Identifier (PID) errors

   Information is also reported about continuous monitoring parameters
   necessary to ensure continuous decoding, including:

   o  Cyclic Redundancy Check (CRC) errors

   o  Conditional Access Table (CAT) errors

   In these parameters, PAT2 errors and PMT2 errors are actually
   replacements for and improvements on PAT errors and PMT errors,
   respectively, and are therefore preferred in future implementations.
   In addition, measurement results for some of these parameters (e.g.,
   PAT errors or PMT errors) may be different based on whether



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   scrambling is employed.  The other parameters defined in Section 5 of
   [ETSI] are ignored since they do not apply to all MPEG2
   implementations.  For further detailed information on these
   parameters, see [ETSI].

   The MPEG2 TS PSI Decodability 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=32    |    Reserved   |         block length          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     SSRC of source                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          begin_seq            |             end_seq           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        PAT_error_count        |      PAT_error_2_count        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        PMT_error_count        |      PMT_error_2_count        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       PID_error_count         |      CRC_error_count          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        CAT_error_count        |        Reserved               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   block type (BT): 8 bits

      The MPEG2 TS PSI Decodability Metrics Block is identified by the
      constant 32;.

   Reserved: 8 bits

      These bits are reserved.  They MUST be set to zero by senders
      ignored by receivers (see Section 4.2 of [RFC6709]).

   block length: 16 bits

      The constant 6, in accordance with the definition of this field in
      Section 3 of [RFC3611].  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 [RFC3611].

   begin_seq: 16 bits

      As defined in Section 4.1 of [RFC3611].



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   end_seq: 16 bits

      As defined in Section 4.1 of [RFC3611].

   PAT_error_count: 16 bits

      A count of the number of PAT errors that occurred in the above
      sequence number interval.  The Program Association Table (PAT) is
      the only packet with Packet Identifier (PID) 0x0000.  A PAT error
      occurs when (1) a packet with PID 0x0000 does not occur at least
      every 0.5 seconds, (2) a packet with PID 0x0000 does not contain
      table_id 0x00 (i.e., a PAT), or (3) the Scrambling_control_field
      in the TS packet header is not 00 for a packet with PID 0x0000.
      See Section 5.2.1 of [ETSI].  Every program within the MPEG TS
      stream is listed in the PAT; if it is missing, then no programs
      can be decoded.

      The measured value is an unsigned value.  If the measurement is
      unavailable, then the value 0xFFFF MUST be reported.  NOTE 1 of
      the table in Section 5.2.1 of [ETSI] recommends using
      PAT_error_2_count.  Upon reception, if PAT_error_2_count is
      available (that is, other than 0xFFFF), then receivers MUST ignore
      PAT_error_count.

   PAT_error_2_count: 16 bits

      A count of the number of PAT2 errors that occurred in the above
      sequence number interval.  A PAT2 error occurs when (1) a packet
      with PID 0x0000 containing table_id 0x00 does not occur at least
      every 0.5 seconds, (2) a packet with PID 0x0000 contains a table
      with a table_id other than 0x00, or (3) the
      Scrambling_control_field in the TS packet header is not 00 for a
      packet with PID 0x0000.  See Section 5.2.1 of [ETSI].

      The measured value is an unsigned value.  If the measurement is
      unavailable, then the value 0xFFFF MUST be reported.

   PMT_error_count: 16 bits

      A count of the number of PMT errors that occurred in the above
      sequence number interval.  A PMT_error occurs when (1) a packet
      containing a table with table_id 0x02 (i.e., a PMT) does not occur
      at least every 0.5 seconds on the PID that is referred to in the
      PAT or (2) the Scrambling_control_field in the TS packet header is
      not 00 for all packets with PID containing a table with table_id
      0x02 (i.e., a PMT).  See Section 5.2.1 of [ETSI].





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      The measured value is an unsigned value.  If the measurement is
      unavailable, the value 0xFFFF MUST be reported.  NOTE 2 of the
      table in Section 5.2.1 of [ETSI] recommends using
      PMT_error_2_count.  Upon reception, if PMT_error_2_count is
      available (that is, other than 0xFFFF), then receivers MUST ignore
      PMT_error_count.

   PMT_error_2_count: 16 bits

      A count of the number of PMT2 errors that occurred in the above
      sequence number interval.  A PMT2_error occurs when (1) a packet
      containing table_id 0x02 (i.e., a PMT) does not occur at least
      every 0.5 seconds on each program_map_PID that is referred to in
      the PAT or (2) the Scrambling_control_field in the TS packet
      header is not 00 for all packets containing a table with table_id
      0x02 (i.e., a PMT) on each program_map_PID that is referred to in
      the PAT.  See Section 5.2.1 of [ETSI].

      The measured value is an unsigned value.  If the measurement is
      unavailable, then the value 0xFFFF MUST be reported.

   PID_error_count: 16 bits

      A count of the number of PID errors that occurred in the above
      sequence number interval.  A PID error occurs when no data stream
      is present corresponding to a given PID.  This may be caused by
      multiplexing or demultiplexing, then remultiplexing.  See
      Section 5.2.1 of [ETSI].

      The measured value is an unsigned value.  If the measurement is
      unavailable, then the value 0xFFFF MUST be reported.

   CRC_error_count: 16 bits

      A count of the number of CRC errors that occurred in the above
      sequence number interval.  A CRC_error occurs if data corruption
      occurred in any of the following tables -- CAT, PAT, PMT, Network
      Information Table (NIT), Event Information Table (EIT), Bouquet
      Association Table (BAT), Service Description Table (SDT), or Time
      Offset Table (TOT), as defined in Section 5.2.2 of [ETSI].

      The measured value is an unsigned value.  If the measurement is
      unavailable, then the value 0xFFFF MUST be reported.








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   CAT_error_count: 16 bits

      A count of the number of CAT errors that occurred in the above
      sequence number interval.  A CAT_error occurs when (1) a packet
      with PID 0x0001 contains a table with a table_id other than 0x01
      (i.e., not a CAT) or (2) a packet does not contain a table with
      table_id = 0x01 (i.e., a CAT) when scrambling is employed (i.e.,
      the Scrambling_control_field is set as a value other than 00).
      See Section 5.2.2 of [ETSI].

      The measured value is an unsigned value.  If the measurement is
      unavailable, then the value 0xFFFF MUST be reported.

   Reserved: 16 bits

      These bits are reserved.  They MUST be set to zero by senders
      ignored by receivers (see Section 4.2 of [RFC6709]).

4.  SDP Signaling

   [RFC3611] 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
   [RFC3611]).

4.1.  SDP rtcp-xr-attrib Attribute Extension

   This session augments the SDP attribute "rtcp-xr" defined in
   Section 5.1 of [RFC3611] 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-tpd-block

   xr-tpd-block = "ts-psi-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].

4.3.  Usage Outside of Offer/Answer

   For usage outside of Offer/Answer, refer to Section 5.3 of [RFC3611].





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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 [RFC3611].

5.1.  New RTCP XR Block Type Value

   This document assigns the block type value 32 "MPEG2 Transport Stream
   PSI Decodability Statistics Metrics Block" in the "RTCP XR Block
   Type" subregistry of the IANA "RTP Control Protocol Extended Reports
   (RTCP XR) Block Type Registry".

5.2.  New RTCP XR SDP Parameter

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

5.3.  Contact Information for Registrations

   The contact information for the registrations is:

   RAI Area Directors <rai-ads@tools.ietf.org>

6.  Security Considerations

   This proposed RTCP XR block introduces no new security considerations
   beyond those described in [RFC3611] and [RFC6990].

7.  References

7.1.  Normative References

   [ETSI]     ETSI, "Digital Video Broadcasting (DVB); Measurement
              guidelines for DVB systems", ETSI TR 101 290, June 2014.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC3550]  Schulzrinne, H., "RTP: A Transport Protocol for Real-Time
              Applications", RFC 3550, July 2003,
              <http://www.rfc-editor.org/info/rfc3550>.






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   [RFC3611]  Friedman, T., Caceres, R., and A. Clark, "RTP Control
              Protocol Extended Reports (RTCP XR)", RFC 3611, November
              2003, <http://www.rfc-editor.org/info/rfc3611>.

   [RFC4566]  Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
              Description Protocol", RFC 4566, July 2006,
              <http://www.rfc-editor.org/info/rfc4566>.

   [RFC5234]  Crocker, D. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234, January 2008,
              <http://www.rfc-editor.org/info/rfc5234>.

7.2.  Informative References

   [ISO-IEC.13818-1.2007]
              ISO/IEC, "Information technology - Generic coding of
              moving pictures and associated audio information - Part 1:
              Systems", ISO International Standard 13818-1, 2013.

   [RFC6390]  Clark, A. and B. Claise, "Guidelines for Considering New
              Performance Metric Development", BCP 170, RFC 6390,
              October 2011, <http://www.rfc-editor.org/info/rfc6390>.

   [RFC6709]  Carpenter, B., Aboba, B., and S. Cheshire, "Design
              Considerations for Protocol Extensions", RFC 6709,
              September 2012, <http://www.rfc-editor.org/info/rfc6709>.

   [RFC6792]  Wu, Q., Hunt, G., and P. Arden, "Guidelines for Use of the
              RTP Monitoring Framework", RFC 6792, November 2012,
              <http://www.rfc-editor.org/info/rfc6792>.

   [RFC6990]  Wu, Q., "RTP Control Protocol (RTCP) Extended Report (XR)
              Block for MPEG2 Transport Stream (TS) Program Specific
              Information (PSI) Independent Decodability Statistics
              Metrics reporting", RFC 6990, May 2013,
              <http://www.rfc-editor.org/info/rfc6990>.















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Authors' Addresses

   Jiangang Tong
   Shanghai Research Institute of China Telecom Corporation Limited
   No. 1835, South Pudong Road
   Shanghai  200122
   China

   EMail: tongjg@sttri.com.cn


   Claire Bi (editor)
   Shanghai Research Institure of China Telecom Corporation Limited
   No. 1835, South Pudong Road
   Shanghai  200122
   China

   EMail: bijy@sttri.com.cn


   Roni Even
   Huawei
   14 David Hamelech
   Tel Aviv  64953
   Israel

   EMail: roni.even@mail01.huawei.com


   Qin Wu (editor)
   Huawei
   101 Software Avenue, Yuhua District
   Nanjing, Jiangsu  210012
   China

   EMail: bill.wu@huawei.com


   Rachel Huang
   Huawei
   101 Software Avenue, Yuhua District
   Nanjing, Jiangsu  210012
   China

   EMail: rachel.huang@huawei.com






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