RTCP XR Report Block for TS Decodability Statistics Metric reporting
draft-huang-xrblock-rtcp-xr-decodability-04

Abstract

Transport Stream is a standard container format used in the transmission and storage of multimedia data. Unicast/Multicast/Broadcast MPEG-TS over RTP is widely adopted in the IPTV deployment. This document defines an RTCP XR Report Block that allows the reporting of decodability statistics metrics related to transmissions of MPEG-TS over RTP.

Status of This Memo

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Table of Contents

• 1. Introduction
• 2. Terminology
• 2.1. Standards Language
• 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] for use with Transport Stream (TS) [ISO-IEC.13818-1.2007]. The new block type supports reporting on the consistency of important elements in the transport stream. 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 problem which 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.

The new report block is in compliance with the monitoring architecture specified in [MONARCH] and the Performance Metrics Framework [RFC6390]. The metric is applicable to any type of RTP application that uses TS standard format for container of multimedia data, for example MPEG4 TS content over RTP.

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. TR 101 290 Decodability Statistics Metric Report Block

 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    |       rvd     |         block length          |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                     SSRC of source                           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|          begin_seq            |             end_seq           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                         Number of TSs                         |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                      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            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                       PTS_error_count                         |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

This block reports decodability statistics metrics beyond the information carried in the standard RTCP packet format. It defines eight metrics based on ETSI TR 101 290. ETSI TR 101 290 focuses on what kind of de-codability errors occur and specifies over 30 measurements split into three different priorities, depending on how drastically they affect content stream[ETSI] . The parameters from priority 1 or 2 are either considered necessary to ensure decodability or recommended for continuous monitoring. The parameters from priority 3 are not applied to every MPEG-TS implememtation and regarded as application dependent monitoring specific. However ETSI TR_101_290 does not specify how many de-codability errrors happen when the client receives a sequence of consecutive RTP packets. The metrics defined in this block are used to deal with this issue. It accommodates three basic monitoring parameters in priority 1 to ensure that the TS can be decoded and report the number of TS_sync_losses, Sync_byte_errors, Continuity_count_errors; It also accommodates 5 continuous monitoring parameters in priority 2 and report the number of Transport_errors, PCR_errors, PCR_repetition_errors, PCR_discontinuity_indicator_errors, and PTS_errors [ETSI]. The other parameters are ignored since they are not applied to all the MPEG implantations.

The Decodability Metrics Block has the following format:

block type (BT): 8 bits

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

rvd: 8 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 SHOULD be ignored by the receiver.

block length: 16 bits

The constant 11, in accordance with the definition of this field in Section 3 of RFC 3611 [RFC3611].

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].

Number of TSs: 32 bits

Number of TS in the above sequence number interval.

TS_sync_loss_count: 32 bits

Number of TS_sync_loss errors in the above sequence number interval.

Sync_byte_error_count: 32 bits

Number of sync_byte_errors in the above sequence number interval.

Continuity_count_error_count: 32 bits

Number of Continuity_count_errors in the above sequence number interval.

Transport_error_count: 32 bits

Number of Transport_errors in the above sequence number interval.

PCR_error_count: 32 bits

Number of PCR_errors in the above sequence number interval.

PCR_repetition_error_count: 32 bits

Number of PCR_repetition_errors in the above sequence number interval.

PCR_discontinuity_indicator_error_count: 32 bits

Number of PCR_discontinuity_indicator_errors in the above sequence number interval.

PTS_error_count: 32 bits

Number of PTS_errors in the above sequence number interval.

4. SDP Signaling

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

   xr-format = decodability-metrics

      decodability-metrics = "decodability-metrics" 

One new parameter is defined for the report block defined in this document to be used with Session Description Protocol (SDP) [RFC4566] using the Augmented Backus-Naur Form (ABNF) [RFC5234]. It has the following syntax within the "rtcp-xr" attribute [RFC3611]: RFC 3611 [RFC3611] for a detailed description and the full syntax of the "rtcp-xr" attribute.

5. IANA Considerations

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

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].

This document assigns one new block type value in the RTCP XR Block Type Registry: [RFC4566] parameters for the "rtcp-xr" attribute in the RTCP XR SDP Parameter Registry:

The contact information for the registrations is:

• Name:

  TDM

  Long Name:

  TR 101 290 Decodability Metrics

  Value

  <TDM>

  Reference:

  section 3
  
  

This document also registers one SDP

• • “decodability-metrics”

6. Security Considerations

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

7. References

7.1. Normative References

7.2. Informative References

Authors' Addresses