Internet DRAFT - draft-ietf-xrblock-rtcp-xr-decodability
draft-ietf-xrblock-rtcp-xr-decodability
Network Working Group R. Huang
Internet-Draft Q. Wu
Intended status: Standards Track Huawei
Expires: December 2, 2013 H. Asaeda
NICT
G. Zorn
Network Zen
May 31, 2013
RTP Control Protocol (RTCP) Extended Report (XR) Block for MPEG2
Transport Stream (TS) Program Specific Information (PSI) Independent
Decodability Statistics Metrics reporting
draft-ietf-xrblock-rtcp-xr-decodability-12
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 not dependent on Program specific
information carried in MPEG TS.
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
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This Internet-Draft will expire on December 2, 2013.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
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(http://trustee.ietf.org/license-info) in effect on the date of
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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 Independent Decodability Statistics Metrics
Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 7
4.1. SDP rtcp-xr-attrib 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 . . . . . . . . . . . . . . . . 8
5.3. Contact information for registrations . . . . . . . . . . 8
6. Security Considerations . . . . . . . . . . . . . . . . . . . 9
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9
8.1. Normative References . . . . . . . . . . . . . . . . . . . 9
8.2. Informative References . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10
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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:
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 MPEG2 Transport
Stream (TS) [ISO-IEC.13818-1.2007]. The new block type supports
reporting of the number of occurrences of each Program Specific
Information (PSI) Independent indicator in the first and second
priorities; third priority indicators are not supported.
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 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 guideline for 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].
1.4. Applicability
This block type allows a counts of MPEG 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.
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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 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 MPEG2 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
The other parameters are ignored since they do not apply to all MPEG2
implementations. For further information on these parameters, see
[ETSI]. Note that when the report of this block spans across more
than one measurement intervals [RFC6776], the count of the metrics
(e.g., Sync byte errors, PCR errors )defined in [ETSI] may reflect a
problem in the current or previous measurement interval.
The MPEG2 TS PSI Independent Decodability Metrics Block has the
following format:
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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=MTPID | 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 MPEG2 TS PSI Independent Decodability Metrics Block is
identified by the constant <MTPID>.
Reserved: 8 bits
These bits are reserved. They MUST be set to zero by senders and
ignored by receivers (See [RFC6709] section 4.2).
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.
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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 TS stream, 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 TS stream, 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 TS
stream - incorrect packet order, a packet occurs more than twice
or a packet is lost,as defined in the section 5.2.1 of [ETSI].
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
erroneous TS packet can not be corrected within the MPEG TS
stream. as defined in the 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 100ms within the MPEG TS
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stream, as defined in the section 5.2.2 of [ETSI]. The time
interval between two consecutive PCR values should be no more than
40ms.
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_repeition_error occurs
when the time interval between two consecutive PCR values is more
than 40ms within the MPEG TS stream,as defined in the 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 100ms within the
MPEG TS stream, as defined in the 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
+/-500ns within the MPEG TS stream,as defined in the section 5.2.2
of [ETSI].
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 700ms within the MPEG TS stream, as
defined in the section 5.2.2 of[ETSI]. Note that the PTS is
contained in the MPEG-2 TS stream 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 SDP (Session Description Protocol)
[RFC4566] for signaling the use of RTCP XR blocks. However XR blocks
MAY be used without prior signaling (See section 5 of RFC3611).
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4.1. SDP rtcp-xr-attrib 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.
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
parameter, 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 MTPID in the IANA " RTP
Control Protocol Extended Reports (RTCP XR) Block Type Registry " to
the "MPEG2 Transport Stream PSI Independent Decodability Statistics
Metrics Block".
[Note to RFC Editor: please replace MPITD with the IANA provided RTCP
XR block type for this block.]
5.2. New RTCP XR SDP Parameter
This document also registers a 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 the registrations is:
Qin Wu
sunseawq@huawei.com
101 Software Avenue, Yuhua District
Nanjing, JiangSu 210012 China
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6. Security Considerations
There might be some relationship between reported error counters and
contractual Service Level Agreements (SLA)s and hence an attack
(e.g., RTP endpoints report fake information, or an attacker in the
path modifies the data being reported ) may deliberately corrupt
these error counters fields and will result in financial implications
for the network operator (either as a result of un-needed Performance
metrics, or penalty charges for SLA failure).
A solution to prevent such attack is to apply an authentication and
integrity protection framework for the RTCP XR report block. This
can be accomplished using the RTP profile that combines Secure RTP
[RFC3711] and AVPF into SAVPF [RFC5124].
Besides this, the proposed RTCP XR report block in this document
introduces no other new security considerations beyond those
described in [RFC3611].
7. Acknowledgements
Thanks to Ray van Brandenburg, Claire Bi, Colin Perkin, Roni Even,
Dan Romascanu, Ali Begen and Alan Clark for useful review 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.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, 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)", 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.
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[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.
8.2. Informative References
[ISO-IEC.13818-1.2007]
International Organization for Standardization,
"Information technology - Generic coding of moving
pictures and associated audio information: Systems",
ISO International Standard 13818-1, October 2007.
[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] Wu, Q., "Measurement Identity and information Reporting
using SDES item and XR Block", RFC 6776, August 2012.
[RFC6792] Wu, Q., Hunt, G., and P. Arden, "Guidelines for Use of the
RTP Monitoring Framework", RFC 6792, November 2012.
Authors' Addresses
Rachel Huang
Huawei
101 Software Avenue, Yuhua District
Nanjing 210012
China
Email: rachel.huang@huawei.com
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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) 909-201060
Email: glenzorn@gmail.com
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