RTCP XR Report Block for TS Decodability Statistics Metric reporting
draft-huang-avt-rtcp-xr-decodability-00

Abstract

This document defines an RTCP XR Report Block that allows the reporting of Decodability Statistics Metric used for Transport Stream.

Status of this Memo

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Table of Contents

1.  Introduction
2.  Terminology
    2.1.  Standards Language
    2.2.  Acronyms
3.  TR 101 290 Decodability Statistics Metric Report Block
4.  SDP Signaling
5.  IANA Considerations
6.  Security Considerations
7.  References
    7.1.  Normative References
    7.2.  Informative References
§  Authors' Addresses

1.  Introduction

This draft defines a new block type to augment those defined in [RFC3611] (Friedman, T., Caceres, R., and A. Clark, “RTP Control Protocol Extended Reports (RTCP XR),” November 2003.) for use in Transport Stream. The new block type supports the reporting of consistency of Transport Stream [ETSI] (ETSI, “Digital Video Broadcasting (DVB); Measurement guidelines for DVB systems,” 2001.). This new block type can be useful for identifying the existence, and characterising the severity, of a packet transport problem which may affect users' perception of a service delivered over RTP, also useful for Verifying the continued correct operation of an existing system management and providing accurate measures of Transport Stream quality for operators.

The metric is applicable to any other types of RTP application that use TS standard format for transmission and storage of audio, video, and data.

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 (Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” March 1997.) [RFC2119].

In addition, the following terms are defined:

2.2.  Acronyms

SSRC

Synchronization Source (Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson, “RTP: A Transport Protocol for Real-Time Applications,” July 2003.) [RFC3550]

TS

Transport Stream (International Organization for Standardization, “Information technology - Generic coding of moving pictures and associated audio information: Systems,” October 2007.) [ISO‑IEC.13818‑1.2007]

3.  TR 101 290 Decodability Statistics Metric Report Block

This block reports decodability statistics metric beyond the information carried in the standard RTCP packet format. Information is recorded about the number of Transport Stream Synchronization Losses, Sync byte errors, Continuity count errors, Transport errors, Program Clock Reference (PCR) errors, PCR repetition errors, PCR discontinuity indicator errors, and Presentation Time Stamp (PTS) errors [ETSI] (ETSI, “Digital Video Broadcasting (DVB); Measurement guidelines for DVB systems,” 2001.). Such information can be useful for network management and video quality monitoring.

Note that this is not only applicable to MPEG-2 RTP streams [RFC2250] (Hoffman, D., Fernando, G., Goyal, V., and M. Civanlar, “RTP Payload Format for MPEG1/MPEG2 Video,” January 1998.),but also applicable to any other video codec using Transport Stream as input.

The report block contents are dependent upon a series of flag bits carried in the first part of the header. Not all parameters need to be reported in each block. Flags indicate which are and which are not reported. The fields corresponding to unreported parameters MUST be present, but are set to zero. The receiver MUST ignore any Decodability Metrics Block with a non-zero value in any field flagged as unreported.

The 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=TBD    |L|B|C|T|P|S|rvd|         block length          |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        SSRC of source                         |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|          begin_seq            |             end_seq           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|       Number of packets       |         Number of TSs         |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|             Transport Stream Synchronization Losses           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                      Sync byte errors                         |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                  Continuity count errors                      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                      Transport errors                         |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                         PCR errors                            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                   PCR repetition errors                       |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|            PCR discontinuity indicator errors                 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                         PTS errors                            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

block type (BT): 8 bits

A TR 101 290 decodability metrics report block is identified by the constant <TDM>.

Transport Stream Synchronization Loss flag (L): 1 bit

Bit set to 1 if the Transport Stream Synchronization Loss field contains a report, 0 otherwise.

Sync byte error flag (B): 1 bit

Bit set to 1 if the Sync byte error field contains a report, 0 otherwise.

Continuity count error flag (C): 1 bit

Bit set to 1 if the Continuity count error field contains a report, 0 otherwise.

Transport error flag (T): 1 bit

Bit set to 1 if the Transport error field contains a report, 0 otherwise.

PCR related error flag (P): 1 bit

Bit set to 1 if the PCR error field, PCR repetition error field and PCR discontinuity indicator error fields contain a report, 0 otherwise.

PTS error flag (S): 1 bit

Bit set to 1 if the PTS error field contains a report, 0 otherwise.

rvd: 2 bits

This field is reserved for future definition. In the absence of such a definition, the bits in this field MUST be set to zero and MUST be ignored by the receiver.

block length: 16 bits

The constant 10, in accordance with the definition of this field in Section 3 of RFC 3611 (Friedman, T., Caceres, R., and A. Clark, “RTP Control Protocol Extended Reports (RTCP XR),” November 2003.) [RFC3611].

SSRC of source: 32 bits

As defined in Section 4.1 of [RFC3611] (Friedman, T., Caceres, R., and A. Clark, “RTP Control Protocol Extended Reports (RTCP XR),” November 2003.).

begin_seq: 16 bits

As defined in Section 4.1 of [RFC3611] (Friedman, T., Caceres, R., and A. Clark, “RTP Control Protocol Extended Reports (RTCP XR),” November 2003.).

end_seq: 16 bits

As defined in Section 4.1 of [RFC3611] (Friedman, T., Caceres, R., and A. Clark, “RTP Control Protocol Extended Reports (RTCP XR),” November 2003.).

Number of Packets: 16 bits

Number of RTP packets in the above sequence number interval.

Number of TSs: 16 bits

Number of Transport Streams in the above sequence number interval.

Transport Stream Synchronization Losses: 32 bits

Number of Transport Stream Synchronization Losses in the above sequence number interval.

Sync byte errors: 32 bits

Number of Transport sync byte errors in the above sequence number interval.

Continuity count error: 32 bits

Number of Transport Continuity count errors in the above sequence number interval.

Transport errors: 32 bits

Number of Transport errors in the above sequence number interval.

PCR errors: 32 bits

Number of PCR errors in the above sequence number interval.

PCR repetition errors: 32 bits

Number of Transport PCR repetition errors in the above sequence number interval.

PCR discontinuity indicator errors: 32 bits

Number of PCR discontinuity indicator errors in the above sequence number interval.

PTS errors: 32 bits

Number of PTS errors in the above sequence number interval.

4.  SDP Signaling

One new parameters are defined for the one report blocks defined in this document to be used with Session Description Protocol (SDP) [RFC4566] (Handley, M., Jacobson, V., and C. Perkins, “SDP: Session Description Protocol,” July 2006.) using the Augmented Backus-Naur Form (ABNF) [RFC5234] (Crocker, D. and P. Overell, “Augmented BNF for Syntax Specifications: ABNF,” January 2008.). They have the following syntax within the "rtcp-xr" attribute [RFC3611] (Friedman, T., Caceres, R., and A. Clark, “RTP Control Protocol Extended Reports (RTCP XR),” November 2003.):

rtcp-xr-attrib =  "a=rtcp-xr:"
                  [xr-format *(SP xr-format)] CRLF

   xr-format = decodability-metrics

      decodability-metrics = "decodability-metrics"
                            ["=" stat-flag *("," stat-flag)]
         stat-flag = "TS Synchronization Loss "
                   / "Sync byte error "
                   / "Continuity count error "
                  / "Transport error"
                  / "PCR related error"
                  / "PTS error"

Refer to Section 5.1 of RFC 3611 (Friedman, T., Caceres, R., and A. Clark, “RTP Control Protocol Extended Reports (RTCP XR),” November 2003.) [RFC3611] for a detailed description and the full syntax of the "rtcp-xr" attribute.

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 (Friedman, T., Caceres, R., and A. Clark, “RTP Control Protocol Extended Reports (RTCP XR),” November 2003.) [RFC3611].

This document assigns one new block type values in the RTCP XR Block Type Registry:

Name:

TDM

Long Name:

TR 101 290 Decodability Metrics

Value

<TDM>

Reference:

section 3

This document also registers one SDP [RFC4566] (Handley, M., Jacobson, V., and C. Perkins, “SDP: Session Description Protocol,” July 2006.) parameters for the "rtcp-xr" attribute in the RTCP XR SDP Parameters Registry:

• “decodability-metrics”

The contact information for the registrations is:

Rachel Huang
Rachel@huawei.com
101 Software Avenue, Yuhua District
Nanjing, JiangSu 210012 China

6.  Security Considerations

TBC

7.  References

7.1. Normative References

7.2. Informative References

Authors' Addresses