RFC 7380 PROPOSED STANDARD RTCP · VIDEO · MONITORING
RTP Control Protocol (RTCP) Extended Report (XR) Block for MPEG2 Transport Stream (TS) Program Specific Information (PSI) Decodability Statistics Metrics Reporting
A new RTCP report block that counts PSI errors in MPEG2 transport streams, so IPTV receivers can say how decodable a stream is.
RFC EDITOR
Tong, J., Bi, C., Ed., Even, R., Wu, Q., Ed., and R. Huang, "RTP Control Protocol (RTCP) Extended Report (XR) Block for MPEG2 Transport Stream (TS) Program Specific Information (PSI) Decodability Statistics Metrics Reporting", RFC 7380, DOI 10.17487/RFC7380, November 2014, <https://www.rfc-editor.org/info/rfc7380>.
BIBTEX
@misc{rfc7380,
series = {Request for Comments},
number = 7380,
howpublished = {RFC 7380},
publisher = {RFC Editor},
doi = {10.17487/RFC7380},
url = {https://www.rfc-editor.org/info/rfc7380},
author = {J. Tong and C. Bi and R. Even and Q. Wu and R. Huang},
title = {{RTP Control Protocol (RTCP) Extended Report (XR) Block for MPEG2 Transport Stream (TS) Program Specific Information (PSI) Decodability Statistics Metrics Reporting}},
pagetotal = 11,
year = 2014,
month = nov,
} RFC text
Contents
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.
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
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
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
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].
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].
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.
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].
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>.
[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>.
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
AI ELI5
On this page
PROBLEMMPEG2 Transport Streams carried over RTP are widely used in IPTV, but RTCP had no way to report whether the Program Specific Information inside a stream was healthy enough to decode.
MECHANISMThe RFC defines an RTCP XR block (block type 32) that carries seven 16-bit counters taken from ETSI TR 101 290 tests: PAT, PAT2, PMT, PMT2, PID, CRC and CAT errors over a range of RTP sequence numbers.
WHY IT MATTERSOperators and monitoring tools can now collect PSI error counts from receivers alongside other RTCP data. It supplements the PSI-independent metrics of RFC 6990.
§1Why Report PSI Decodability
An MPEG2 Transport Stream (TS) is a standard container format for multimedia data, and sending it over RTP is widely deployed in IPTV systems. This RFC defines a new RTCP Extended Report (XR) block that reports decodability statistics related to the Program Specific Information (PSI) carried in the TS.
The metrics come from a set of tests published by ETSI (ETSI TR 101 290), which groups indicators by priority: first priority is necessary for decodability, second priority is recommended for continuous or periodic monitoring, and third priority is for application-dependent monitoring. This block reports occurrence counts for the first and second priority PSI indicators only. Third priority indicators are not supported.
Think of a TV signal as a book with a table of contents. This RFC gives receivers a way to report how often the table of contents was broken.
§2Where the Block Fits
RTCP reporting is defined in RFC 3550, and RFC 3611 defines the extensible XR report structure. This document adds one more block type to that structure. It also supplements the PSI-Independent Decodability Statistics Metrics Block from RFC 6990, and follows the Performance Metrics Framework (RFC 6390) and the RTP monitoring guidelines (RFC 6792).
The metrics apply to any RTP application that uses the MPEG2 TS format, for example MPEG4 over MPEG2 TS over RTP. They can help measure content stream or TS quality by checking TS header information, and can reveal packetization problems that may affect what users see. They may also help verify that an existing system management tool still works correctly.
The report rides along with the normal status messages that video senders and receivers already swap. It just adds one more kind of note.
§3The Block Layout
The block is measured at the receiving end of the RTP stream. It has a block type (BT) of 32, a reserved byte, a block length of 6, the SSRC of the source, begin_seq and end_seq, and then seven 16-bit counters followed by 16 reserved bits.
The block length MUST be the constant 6, and a block with any other value MUST be discarded. Reserved bits MUST be set to zero by senders and ignored by receivers. The SSRC, begin_seq and end_seq fields are defined as in Section 4.1 of RFC 3611; every count covers the sequence number interval they delimit.
The report is a small form with a fixed number of boxes. There is a box for who it is about, the range of packets it covers, and seven counting boxes.
| Field | Name | Size | Value | Description |
|---|---|---|---|---|
BT | BT | 1 byte | 32 | Block type. |
RESERVED-1 | Reserved | 1 byte | Set to zero by senders, ignored by receivers. | |
BLOCK-LENGTH | Block length | 2 bytes | 6 | The constant 6. |
SSRC | SSRC of source | 4 bytes | As defined in RFC 3611. | |
BEGIN-SEQ | begin_seq | 2 bytes | Start of the sequence number interval. | |
END-SEQ | end_seq | 2 bytes | End of the sequence number interval. | |
PAT | PAT_error_count | 2 bytes | PAT errors in the interval. | |
PAT2 | PAT_error_2_count | 2 bytes | PAT2 errors in the interval. | |
PMT | PMT_error_count | 2 bytes | PMT errors in the interval. | |
PMT2 | PMT_error_2_count | 2 bytes | PMT2 errors in the interval. | |
PID | PID_error_count | 2 bytes | PID errors in the interval. | |
CRC | CRC_error_count | 2 bytes | CRC errors in the interval. | |
CAT | CAT_error_count | 2 bytes | CAT errors in the interval. | |
RESERVED-2 | Reserved | 2 bytes | Set to zero by senders, ignored by receivers. |
§4The Seven Counters
Five counters cover basic monitoring needed to decode the stream: PAT_error_count, PAT_error_2_count, PMT_error_count, PMT_error_2_count and PID_error_count. Two cover continuous monitoring: CRC_error_count and CAT_error_count.
- A PAT error occurs when a packet with PID 0x0000 does not occur at least every 0.5 seconds, does not contain table_id 0x00, or has a non-zero scrambling control field. The PAT lists every program in the stream, so if it is missing no programs can be decoded.
- A PMT error occurs when a packet with table_id 0x02 does not occur at least every 0.5 seconds on the PID referred to in the PAT, or when scrambling control is not 00.
- A PID error occurs when no data stream is present for a given PID, which may be caused by multiplexing or demultiplexing and then remultiplexing.
- A CRC error means data corruption in any of the CAT, PAT, PMT, NIT, EIT, BAT, SDT or TOT tables.
- A CAT error occurs when a packet with PID 0x0001 carries a table_id other than 0x01, or when scrambling is employed and no CAT is present.
The PAT2 and PMT2 counters are replacements and improvements on the PAT and PMT counters, so they are preferred in future implementations. If PAT_error_2_count or PMT_error_2_count is available (not 0xFFFF), receivers MUST ignore the older counter. Any measurement that is unavailable MUST be reported as 0xFFFF.
Each counter is a tally of one kind of mistake, like a missing table of contents or a corrupted page. If a counter cannot be measured, the report says so with a special all-ones number.
§5Signaling with SDP
RFC 3611 defines how the Session Description Protocol signals use of XR blocks, though XR blocks MAY be used without prior signaling. This RFC adds a new value for the rtcp-xr attribute: xr-format =/ xr-tpd-block, where xr-tpd-block = "ts-psi-decodability".
Offer/Answer usage follows the unilateral parameter rules in Section 5.2 of RFC 3611, and usage outside Offer/Answer follows Section 5.3 of RFC 3611.
Before the report is sent, two sides can tell each other they understand it by using a short agreed name, ts-psi-decodability.
§6IANA Registrations
The RFC assigns block type value 32, named "MPEG2 Transport Stream PSI Decodability Statistics Metrics Block", in the RTCP XR Block Type subregistry. It also registers the parameter ts-psi-decodability in the RTCP XR SDP Parameters subregistry. The contact for both registrations is the RAI Area Directors.
The number 32 and the name were written into the official list so nobody else uses them for something different.
§7Security Considerations
The block introduces no new security considerations beyond those described in RFC 3611 and RFC 6990.
This new report does not add any new safety worries beyond what the older reports already have.
§8References
[ETSI]ETSI, "Digital Video Broadcasting (DVB); Measurement guidelines for DVB systems", ETSI TR 101 290, June 2014.
[RFC3550]RFC 3550Schulzrinne, H., "RTP: A Transport Protocol for Real-Time Applications", RFC 3550, July 2003.July 2003[RFC3611]RFC 3611Friedman, T., Caceres, R., and A. Clark, "RTP Control Protocol Extended Reports (RTCP XR)", RFC 3611, November 2003.November 2003[RFC6390]RFC 6390Clark, A. and B. Claise, "Guidelines for Considering New Performance Metric Development", BCP 170, RFC 6390, October 2011.October 2011[RFC6792]RFC 6792Wu, Q., Hunt, G., and P. Arden, "Guidelines for Use of the RTP Monitoring Framework", RFC 6792, November 2012.November 2012[RFC6990]RFC 6990Wu, 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.August 2013