Internet Engineering Task Force (IETF) J. Tong

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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RFC 7380 RTCP XR TS Decodability November 2014

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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RFC 7380 RTCP XR TS Decodability November 2014

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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RFC 7380 RTCP XR TS Decodability November 2014

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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RFC 7380 RTCP XR TS Decodability November 2014

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 <[email protected]>

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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RFC 7380 RTCP XR TS Decodability November 2014

[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: [email protected]

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

EMail: [email protected]

Roni Even
Huawei
14 David Hamelech
Tel Aviv 64953
Israel

EMail: [email protected]

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

EMail: [email protected]

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

EMail: [email protected]

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