draft-ietf-xrblock-rtcp-xr-loss-conceal-05.txt   draft-ietf-xrblock-rtcp-xr-loss-conceal-06.txt 
Audio/Video Transport Working Group A. Clark Audio/Video Transport Working Group A. Clark
Internet-Draft Telchemy Internet-Draft Telchemy
Intended status: Standards Track G. Zorn, Ed. Intended status: Standards Track G. Zorn, Ed.
Expires: September 26, 2013 Network Zen Expires: December 20, 2013 Network Zen
C. Bi C. Bi
STTRI STTRI
Q. Wu, Ed. Q. Wu, Ed.
Huawei Huawei
March 25, 2013 June 18, 2013
RTCP XR Report Block for Concealment metrics Reporting on Audio RTCP XR Report Block for Concealment metrics Reporting on Audio
Applications Applications
draft-ietf-xrblock-rtcp-xr-loss-conceal-05.txt draft-ietf-xrblock-rtcp-xr-loss-conceal-06.txt
Abstract Abstract
This document defines two RTCP XR Report Blocks that allows the This document defines two RTCP XR Report Blocks that allows the
reporting of loss concealment metrics for audio applications of RTP. reporting of concealment metrics for audio applications of RTP.
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 26, 2013. This Internet-Draft will expire on December 20, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Loss Concealment and Concealment Seconds Metrics 1.1. Loss Concealment and Concealment Seconds Metrics
Reporting Block . . . . . . . . . . . . . . . . . . . . . 3 Reporting Block . . . . . . . . . . . . . . . . . . . . . 3
1.2. RTCP and RTCP XR Reports . . . . . . . . . . . . . . . . . 4 1.2. RTCP and RTCP XR Reports . . . . . . . . . . . . . . . . . 4
1.3. Performance Metrics Framework . . . . . . . . . . . . . . 4 1.3. Performance Metrics Framework . . . . . . . . . . . . . . 4
1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 4 1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Standards Language . . . . . . . . . . . . . . . . . . . . 5 2.1. Standards Language . . . . . . . . . . . . . . . . . . . . 5
3. Loss Concealment Block . . . . . . . . . . . . . . . . . . . . 6 3. Loss Concealment Block . . . . . . . . . . . . . . . . . . . . 6
3.1. Report Block Structure . . . . . . . . . . . . . . . . . . 6 3.1. Report Block Structure . . . . . . . . . . . . . . . . . . 6
3.2. Definition of Fields in Loss Concealment Report Block . . 6 3.2. Definition of Fields in Loss Concealment Metrics Block . . 6
4. Concealment Seconds Block . . . . . . . . . . . . . . . . . . 10 4. Concealment Seconds Block . . . . . . . . . . . . . . . . . . 10
4.1. Report Block Structure . . . . . . . . . . . . . . . . . . 10 4.1. Report Block Structure . . . . . . . . . . . . . . . . . . 10
4.2. Definition of Fields in Concealed Seconds Metrics Block . 11 4.2. Definition of Fields in Concealed Seconds Metrics Block . 11
5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 15 5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 15
5.1. SDP rtcp-xr-attrib Attribute Extension . . . . . . . . . . 15 5.1. SDP rtcp-xr-attrib Attribute Extension . . . . . . . . . . 15
5.2. Offer/Answer Usage . . . . . . . . . . . . . . . . . . . . 15 5.2. Offer/Answer Usage . . . . . . . . . . . . . . . . . . . . 15
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
6.1. New RTCP XR Block Type values . . . . . . . . . . . . . . 16 6.1. New RTCP XR Block Type values . . . . . . . . . . . . . . 16
6.2. New RTCP XR SDP Parameters . . . . . . . . . . . . . . . . 16 6.2. New RTCP XR SDP Parameters . . . . . . . . . . . . . . . . 16
6.3. Contact information for registrations . . . . . . . . . . 16 6.3. Contact information for registrations . . . . . . . . . . 16
7. Security Considerations . . . . . . . . . . . . . . . . . . . 17 7. Security Considerations . . . . . . . . . . . . . . . . . . . 17
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 18 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 18
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 19 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 19
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 20 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 20
10.1. Normative References . . . . . . . . . . . . . . . . . . . 20 10.1. Normative References . . . . . . . . . . . . . . . . . . . 20
10.2. Informative References . . . . . . . . . . . . . . . . . . 20 10.2. Informative References . . . . . . . . . . . . . . . . . . 20
Appendix A. Metrics represented using RFC6390 Template . . . . . 21 Appendix A. Metrics represented using RFC6390 Template . . . . . 21
Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 28 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 28
B.1. draft-ietf-xrblock-rtcp-xr-loss-conceal-05 . . . . . . . . 28 B.1. draft-ietf-xrblock-rtcp-xr-loss-conceal-06 . . . . . . . . 28
B.2. draft-ietf-xrblock-rtcp-xr-loss-conceal-04 . . . . . . . . 28 B.2. draft-ietf-xrblock-rtcp-xr-loss-conceal-05 . . . . . . . . 28
B.3. draft-ietf-xrblock-rtcp-xr-loss-conceal-04 . . . . . . . . 28
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 29 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 29
1. Introduction 1. Introduction
1.1. Loss Concealment and Concealment Seconds Metrics Reporting Block 1.1. Loss Concealment and Concealment Seconds Metrics Reporting Block
At any instant, the audio output at a receiver may be classified as At any instant, the audio output at a receiver may be classified as
either 'normal' or 'concealed'. 'Normal' refers to playout of audio either 'normal' or 'concealed'. 'Normal' refers to playout of audio
payload received from the remote end, and also includes locally payload received from the remote end, and also includes locally
generated signals such as announcements, tones and comfort noise. generated signals such as announcements, tones and comfort noise.
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1.3. Performance Metrics Framework 1.3. Performance Metrics Framework
The Performance Metrics Framework [RFC6390] provides guidance on the The Performance Metrics Framework [RFC6390] provides guidance on the
definition and specification of performance metrics. The RTP definition and specification of performance metrics. The RTP
Monitoring Architectures [RFC6792] provides guideline for reporting Monitoring Architectures [RFC6792] provides guideline for reporting
block format using RTCP XR. The Metrics Block described in this block format using RTCP XR. The Metrics Block described in this
document are in accordance with those guidelines. document are in accordance with those guidelines.
1.4. Applicability 1.4. Applicability
These metrics are only applicable to audio applications of RTP. These metrics are applicable to audio applications of RTP and the
audio component of Audio/Video applications in which the packet loss
concealment machinery is contained at the receiving end to mitigate
the impact of network impairments to user's perception of media
quality.
2. Terminology 2. Terminology
2.1. Standards Language 2.1. Standards Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC2119 [RFC2119]. document are to be interpreted as described in RFC2119 [RFC2119].
3. Loss Concealment Block 3. Loss Concealment Block
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Measurement Information block [RFC6776] which describes measurement Measurement Information block [RFC6776] which describes measurement
periods in use (see [RFC6776] section 4.2). This Metrics Block periods in use (see [RFC6776] section 4.2). This Metrics Block
relies on the measurement period in the Measurement Information block relies on the measurement period in the Measurement Information block
indicating the span of the report and SHOULD be sent in the same indicating the span of the report and SHOULD be sent in the same
compound RTCP packet as the measurement information block. If the compound RTCP packet as the measurement information block. If the
measurement period is not received in the same compound RTCP packet measurement period is not received in the same compound RTCP packet
as this Metrics Block, this metrics block MUST be discarded. as this Metrics Block, this metrics block MUST be discarded.
3.1. Report Block Structure 3.1. Report Block Structure
Loss Concealment metrics block Loss Concealment Metrics Block
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BT=NLC | I |plc| rsv. | block length=5 | | BT=NLC | I |plc| rsv. | block length=5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of Source | | SSRC of Source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| On-time Playout Duration | | On-time Playout Duration |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Loss Concealment Duration | | Loss Concealment Duration |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Buffer Adjustment Concealment Duration | | Buffer Adjustment Concealment Duration |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Playout Interrupt Count | Mean Playout Interrupt Size | | Playout Interrupt Count | Mean Playout Interrupt Size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Report Block Structure Figure 1: Report Block Structure
3.2. Definition of Fields in Loss Concealment Report Block 3.2. Definition of Fields in Loss Concealment Metrics Block
Block type (BT): 8 bits Block type (BT): 8 bits
A Loss Concealment Metrics Report Block is identified by the A Loss Concealment Metrics Report Block is identified by the
constant NLC. constant NLC.
[Note to RFC Editor: please replace NLC with the IANA provided [Note to RFC Editor: please replace NLC with the IANA provided
RTCP XR block type for this block.] RTCP XR block type for this block.]
Interval Metric flag (I): 2 bit Interval Metric flag (I): 2 bit
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0 = silence insertion 0 = silence insertion
1 = simple replay, no attenuation 1 = simple replay, no attenuation
2 = simple replay, with attenuation 2 = simple replay, with attenuation
3 = enhancement 3 = enhancement
Other values reserved Other values reserved
Note that the enhancment method (plc =3 )for packet loss Note that the enhancement method (plc =3 )for packet loss
concealment offers an improved audio quality and or a better concealment offers an improved audio quality and or a better
robustness against packet losses [G.711] and is equivalent to robustness against packet losses [G.711] and is equivalent to
enhanced in section 4.7.1 of [RFC3611], enhanced in section 4.7.1 of [RFC3611],
Reserved (resv): 4 bits Reserved (resv): 4 bits
These bits are reserved. They MUST be set to zero by senders and These bits are reserved. They MUST be set to zero by senders and
ignored by receivers (See [RFC6709] section 4.2). ignored by receivers (See [RFC6709] section 4.2).
block length: 16 bits block length: 16 bits
The length of this report block in 32-bit words, minus one. For The length of this report block in 32-bit words, minus one. For
the Loss Concealment block, the block length is equal to 5. the Loss Concealment Block, the block length is equal to 5.
SSRC of source: 32 bits SSRC of source: 32 bits
As defined in Section 4.1 of [RFC3611]. As defined in Section 4.1 of [RFC3611].
On-time Playout Duration (ms): 32 bits On-time Playout Duration (ms): 32 bits
'On-time' playout is the uninterrupted, in-sequence playout of 'On-time' playout is the uninterrupted, in-sequence playout of
valid decoded audio information originating from the remote valid decoded audio information originating from the remote
endpoint. This includes comfort noise during periods of remote endpoint. This includes comfort noise during periods of remote
talker silence, if VAD is used, and locally generated or talker silence, if VAD [VAD] is used, and locally generated or
regenerated tones and announcements. regenerated tones and announcements.
An equivalent definition is that on-time playout is playout of any An equivalent definition is that on-time playout is playout of any
signal other than those used for concealment. signal other than those used for concealment.
On-time playout duration MUST include both speech and silence On-time playout duration MUST include both speech and silence
intervals, whether VAD is used or not. This duration is reported intervals, whether VAD is used or not. This duration is reported
in millisecond units. in millisecond units.
If the measured value exceeds 0xFFFFFFFD, the value 0xFFFFFFFE If the measured value exceeds 0xFFFFFFFD, the value 0xFFFFFFFE
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Because this insertion is controlled, rather than occurring Because this insertion is controlled, rather than occurring
randomly in response to losses, it is typically less audible than randomly in response to losses, it is typically less audible than
loss-type concealment. For example, jitter buffer adaptation loss-type concealment. For example, jitter buffer adaptation
events may be constrained to occur during periods of talker events may be constrained to occur during periods of talker
silence, in which case only silence duration is affected, or silence, in which case only silence duration is affected, or
sophisticated time-stretching methods for insertion/deletion sophisticated time-stretching methods for insertion/deletion
during favorable periods in active speech may be employed. during favorable periods in active speech may be employed.
Concealment events which cannot be classified as Buffer Concealment events which cannot be classified as Buffer
Adjustment- type MUST be classified as Loss-type. Adjustment-type MUST be classified as Loss-type.
Playout Interrupt Count: 16 bits Playout Interrupt Count: 16 bits
The number of interruptions to normal playout which occurred The number of interruptions to normal playout which occurred
during the reporting period. during the reporting period.
If the measured value exceeds 0xFFFD, the value 0xFFFE MUST be If the measured value exceeds 0xFFFD, the value 0xFFFE MUST be
reported to indicate an over-range measurement. If the reported to indicate an over-range measurement. If the
measurement is unavailable, the value 0xFFFF MUST be reported. measurement is unavailable, the value 0xFFFF MUST be reported.
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The mean duration, in ms, of interruptions to normal playout which The mean duration, in ms, of interruptions to normal playout which
occurred during the reporting period. occurred during the reporting period.
If the measured value exceeds 0xFFFD, the value 0xFFFE MUST be If the measured value exceeds 0xFFFD, the value 0xFFFE MUST be
reported to indicate an over-range measurement. If the reported to indicate an over-range measurement. If the
measurement is unavailable, the value 0xFFFF MUST be reported. measurement is unavailable, the value 0xFFFF MUST be reported.
4. Concealment Seconds Block 4. Concealment Seconds Block
This sub-block described here are intended to be used as described in This sub-block described here is intended to be used as described in
this section, in conjunction with information from the Measurement this section, in conjunction with information from the Measurement
Information block [RFC6776] and provides a description of potentially Information block [RFC6776] and provides a description of potentially
audible impairments due to lost and discarded packets at the audible impairments due to lost and discarded packets at the
endpoint, expressed on a time basis analogous to a traditional PSTN endpoint, expressed on a time basis analogous to a traditional PSTN
T1/E1 errored seconds metric. Instances of this Metrics Block refer T1/E1 errored seconds metric. Instances of this Metrics Block refer
by Synchronization source (SSRC) to the separate auxiliary by Synchronization source (SSRC) to the separate auxiliary
Measurement Information block [RFC6776] which describes measurement Measurement Information block [RFC6776] which describes measurement
periods in use (see [RFC6776] section 4.2). This Metrics Block periods in use (see [RFC6776] section 4.2). This Metrics Block
relies on the measurement period in the Measurement Information block relies on the measurement period in the Measurement Information block
indicating the span of the report and SHOULD be sent in the same indicating the span of the report and SHOULD be sent in the same
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apart could result in either one concealed second or two, depending apart could result in either one concealed second or two, depending
on the particular 1000 ms boundaries used. on the particular 1000 ms boundaries used.
The seconds in this sub-block are not necessarily calendar seconds. The seconds in this sub-block are not necessarily calendar seconds.
At the tail end of a session, periods of time of less than 1000ms At the tail end of a session, periods of time of less than 1000ms
shall be incorporated into these counts if they exceed 500ms and shall be incorporated into these counts if they exceed 500ms and
shall be disregarded if they are less than 500ms. shall be disregarded if they are less than 500ms.
4.1. Report Block Structure 4.1. Report Block Structure
Concealed Seconds metrics block Concealed Seconds Metrics Block
0 1 2 3 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 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=NCS | I |plc|Rserved| block length=4 | | BT=NCS | I |plc|Rserved| block length=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of Source | | SSRC of Source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Unimpaired Seconds | | Unimpaired Seconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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A Concealed Seconds Metrics Report Block is identified by the A Concealed Seconds Metrics Report Block is identified by the
constant NCS. constant NCS.
[Note to RFC Editor: please replace NCS with the IANA provided [Note to RFC Editor: please replace NCS with the IANA provided
RTCP XR block type for this block.] RTCP XR block type for this block.]
Interval Metric flag (I): 2 bit Interval Metric flag (I): 2 bit
This field is used to indicate whether the Concealment Seconds This field is used to indicate whether the Concealment Seconds
metrics are Sampled, Interval or Cumulative metrics: Metrics are Sampled, Interval or Cumulative metrics:
I=10: Interval Duration - the reported value applies to the I=10: Interval Duration - the reported value applies to the
most recent measurement interval duration between successive most recent measurement interval duration between successive
metrics reports. metrics reports.
I=11: Cumulative Duration - the reported value applies to the I=11: Cumulative Duration - the reported value applies to the
accumulation period characteristic of cumulative measurements. accumulation period characteristic of cumulative measurements.
I=01: Sampled Value - the reported value is a sampled I=01: Sampled Value - the reported value is a sampled
instantaneous value. instantaneous value.
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enhanced in section 4.7.1 of [RFC3611], enhanced in section 4.7.1 of [RFC3611],
Reserved (resv): 4 bits Reserved (resv): 4 bits
These bits are reserved. They MUST be set to zero by senders and These bits are reserved. They MUST be set to zero by senders and
ignored by receivers (See [RFC6709] section 4.2). ignored by receivers (See [RFC6709] section 4.2).
Block Length: 16 bits Block Length: 16 bits
The length of this report block in 32-bit words, minus one. For The length of this report block in 32-bit words, minus one. For
the Concealment Seconds block, the block length is equal to 4. the Concealment Seconds Block, the block length is equal to 4.
SSRC of source: 32 bits SSRC of source: 32 bits
As defined in Section 4.1 of [RFC3611]. As defined in Section 4.1 of [RFC3611].
Unimpaired Seconds: 32 bits Unimpaired Seconds: 32 bits
A count of the number of unimpaired Seconds that have occurred. A count of the number of unimpaired Seconds that have occurred.
An unimpaired Second is defined as a continuous period of 1000ms An unimpaired Second is defined as a continuous period of 1000ms
during which no frame loss or discard due to late arrival has during which no frame loss or discard due to late arrival has
occurred. Every second in a session must be classified as either occurred. Every second in a session must be classified as either
OK or Concealed. OK or Concealed.
Normal playout of comfort noise or other silence concealment Normal playout of comfort noise or other silence concealment
signal during periods of talker silence, if VAD [VAD] is used, signal during periods of talker silence, if VAD is used, shall be
shall be counted as unimpaired seconds. counted as unimpaired seconds.
If the measured value exceeds 0xFFFFFFFD, the value 0xFFFFFFFE If the measured value exceeds 0xFFFFFFFD, the value 0xFFFFFFFE
MUST be reported to indicate an over-range measurement. If the MUST be reported to indicate an over-range measurement. If the
measurement is unavailable, the value 0xFFFFFFFF MUST be reported. measurement is unavailable, the value 0xFFFFFFFF MUST be reported.
Concealed Seconds: 32 bits Concealed Seconds: 32 bits
A count of the number of Concealed Seconds that have occurred. A count of the number of Concealed Seconds that have occurred.
A Concealed Second is defined as a continuous period of 1000ms A Concealed Second is defined as a continuous period of 1000ms
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5. SDP Signaling 5. SDP Signaling
[RFC3611] defines the use of SDP (Session Description Protocol) [RFC3611] defines the use of SDP (Session Description Protocol)
[RFC4566] for signaling the use of XR blocks. XR blocks MAY be used [RFC4566] for signaling the use of XR blocks. XR blocks MAY be used
without prior signaling. without prior signaling.
5.1. SDP rtcp-xr-attrib Attribute Extension 5.1. SDP rtcp-xr-attrib Attribute Extension
This section augments the SDP attribute "rtcp-xr" [RFC3611] by This section augments the SDP attribute "rtcp-xr" [RFC3611] by
providing two additional values of "xr-format" to signal the use of providing two additional values of "xr-format" to signal the use of
the report block defined in this document. two report blocks defined in this document.
xr-format =/ xr-conceal-block xr-format =/ xr-conceal-block
xr-format =/ xr-conc-sec-block / xr-conc-sec-block
xr-conceal-block = "loss-conceal" xr-conceal-block = "loss-conceal"
xr-conc-sec-block = "conc-sec" ["=" thresh] xr-conc-sec-block = "conc-sec" ["=" thresh]
thresh = 1*DIGIT ; threshold for SCS (ms) thresh = 1*DIGIT ; threshold for SCS (ms)
DIGIT = %x30-39 DIGIT = %x30-39
5.2. Offer/Answer Usage 5.2. Offer/Answer Usage
When SDP is used in offer-answer context, the SDP Offer/Answer usage When SDP is used in offer-answer context, the SDP Offer/Answer usage
defined in [RFC3611] applies. defined in [RFC3611] applies. Note that "thresh" is declared by the
offer.
6. IANA Considerations 6. IANA Considerations
New block types for RTCP XR are subject to IANA registration. For New block types for RTCP XR are subject to IANA registration. For
general guidelines on IANA considerations for RTCP XR, refer to general guidelines on IANA considerations for RTCP XR, refer to
[RFC3611]. [RFC3611].
6.1. New RTCP XR Block Type values 6.1. New RTCP XR Block Type values
This document assigns two block type values in the IANA "RTCP XR This document assigns two block type values in the IANA "RTP Control
Block Type Registry": Protocol Extended Reports (RTCP XR) Block Type Registry ":
Name: NLC Name: LCB
Long Name: Loss Concealment Block Long Name: Loss Concealment Block
Value <NLC> Value <LCB>
Reference: Section 3.1 Reference: Section 3.1
Name: NCS Name: CSB
Long Name: Concealment Seconds Block Long Name: Concealment Seconds Block
Value <NCS> Value <CSB>
Reference: Section 4.1 Reference: Section 4.1
[Note to RFC Editor: please replace <NLC> and <NCS> with the RTCP XR [Note to RFC Editor: please replace <NLC> and <NCS> with the RTCP XR
block type assigned by IANA for this block.] block type assigned by IANA for this block.]
6.2. New RTCP XR SDP Parameters 6.2. New RTCP XR SDP Parameters
This document also registers two new parameters in the "RTCP XR SDP This document also registers two new parameters in the "RTP Control
Parameters Registry": Protocol Extended Reports (RTCP XR) Session Description Protocol
(SDP) Parameters Registry":
o "loss-conceal" o "loss-conceal"
o "conc-sec" o "conc-sec"
6.3. Contact information for registrations 6.3. Contact information for registrations
The contact information for the registrations is: The contact information for the registrations is:
Qin Wu (sunseawq@huawei.com) Qin Wu (sunseawq@huawei.com)
skipping to change at page 28, line 10 skipping to change at page 28, line 10
* Use and applications: See section 1.4 [RFCXXXX]. * Use and applications: See section 1.4 [RFCXXXX].
* Reporting model: See RFC3611. * Reporting model: See RFC3611.
Appendix B. Change Log Appendix B. Change Log
Note to the RFC-Editor: please remove this section prior to Note to the RFC-Editor: please remove this section prior to
publication as an RFC. publication as an RFC.
B.1. draft-ietf-xrblock-rtcp-xr-loss-conceal-05 B.1. draft-ietf-xrblock-rtcp-xr-loss-conceal-06
The following are the major changes to previous version :
o Comments in the WGLC are addressed in this version.
B.2. draft-ietf-xrblock-rtcp-xr-loss-conceal-05
The following are the major changes to previous version : The following are the major changes to previous version :
o Add text to clarify the definition of enhanced method. o Add text to clarify the definition of enhanced method.
o Add appendix to apply RFC6390 template to the metrics. o Add appendix to apply RFC6390 template to the metrics.
B.2. draft-ietf-xrblock-rtcp-xr-loss-conceal-04 B.3. draft-ietf-xrblock-rtcp-xr-loss-conceal-04
The following are the major changes to previous version : The following are the major changes to previous version :
o Merge Concealment Seconds draft into this draft (i.e.,Loss o Merge Concealment Seconds draft into this draft (i.e.,Loss
Concealment draft). Concealment draft).
o Updated references. o Updated references.
Authors' Addresses Authors' Addresses
 End of changes. 30 change blocks. 
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