draft-ietf-xrblock-rtcp-xr-loss-conceal-12.txt   rfc7294.txt 
Audio/Video Transport Working Group A. Clark Internet Engineering Task Force (IETF) A. Clark
Internet-Draft Telchemy Request for Comments: 7294 Telchemy
Intended status: Standards Track G. Zorn Category: Standards Track G. Zorn
Expires: October 13, 2014 Network Zen ISSN: 2070-1721 Network Zen
C. Bi C. Bi
STTRI STTRI
Q. Wu, Ed. Q. Wu
Huawei Huawei
April 11, 2014 July 2014
RTCP XR Report Block for Concealment metrics Reporting on Audio RTP Control Protocol (RTCP) Extended Report (XR) Blocks
Applications for Concealment Metrics Reporting on Audio Applications
draft-ietf-xrblock-rtcp-xr-loss-conceal-12.txt
Abstract Abstract
This document defines two RTCP XR Report Blocks that allows the This document defines two RTP Control Protocol (RTCP) Extended Report
reporting of concealment metrics for audio applications of RTP. (XR) blocks that allow the reporting of concealment metrics for audio
applications of RTP.
Status of this Memo
This Internet-Draft is submitted in full conformance with the Status of This Memo
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering This is an Internet Standards Track document.
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
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Internet Standards is available in Section 2 of RFC 5741.
This Internet-Draft will expire on October 13, 2014. 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/rfc7294.
Copyright Notice Copyright Notice
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document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Loss Concealment and Concealment Seconds Metrics 1.1. Loss Concealment and Concealed Seconds Metrics
Reporting Block . . . . . . . . . . . . . . . . . . . . . 3 Blocks . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2. RTCP and RTCP XR Reports . . . . . . . . . . . . . . . . . 4 1.2. RTCP and RTCP Extended Reports . . . . . . . . . . . . . 3
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 . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Standards Language . . . . . . . . . . . . . . . . . . . . 5 2.1. Standards Language . . . . . . . . . . . . . . . . . . . 4
2.2. Notations . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2. Notations . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Loss Concealment Block . . . . . . . . . . . . . . . . . . . . 6 3. Loss Concealment Metrics Block . . . . . . . . . . . . . . . 5
3.1. Report Block Structure . . . . . . . . . . . . . . . . . . 6 3.1. Report Block Structure . . . . . . . . . . . . . . . . . 5
3.2. Definition of Fields in Loss Concealment Metrics Block . . 6 3.2. Definition of Fields in Loss Concealment Metrics Block . 5
4. Concealment Seconds Block . . . . . . . . . . . . . . . . . . 11 4. Concealed Seconds Metrics Block . . . . . . . . . . . . . . . 9
4.1. Report Block Structure . . . . . . . . . . . . . . . . . . 11 4.1. Report Block Structure . . . . . . . . . . . . . . . . . 10
4.2. Definition of Fields in Concealed Seconds Metrics Block . 12 4.2. Definition of Fields in Concealed Seconds Metrics Block . 10
5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 16 5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 14
5.1. SDP rtcp-xr-attrib Attribute Extension . . . . . . . . . . 16 5.1. SDP rtcp-xr-attrib Attribute Extension . . . . . . . . . 14
5.2. Offer/Answer Usage . . . . . . . . . . . . . . . . . . . . 16 5.2. Offer/Answer Usage . . . . . . . . . . . . . . . . . . . 14
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
6.1. New RTCP XR Block Type values . . . . . . . . . . . . . . 17 6.1. New RTCP XR Block Type Values . . . . . . . . . . . . . . 14
6.2. New RTCP XR SDP Parameters . . . . . . . . . . . . . . . . 17 6.2. New RTCP XR SDP Parameters . . . . . . . . . . . . . . . 15
6.3. Contact information for registrations . . . . . . . . . . 17 6.3. Contact Information for Registrations . . . . . . . . . . 15
7. Security Considerations . . . . . . . . . . . . . . . . . . . 18 7. Security Considerations . . . . . . . . . . . . . . . . . . . 15
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 19 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 15
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 20 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
10.1. Normative References . . . . . . . . . . . . . . . . . . . 21 10.1. Normative References . . . . . . . . . . . . . . . . . . 16
10.2. Informative References . . . . . . . . . . . . . . . . . . 21 10.2. Informative References . . . . . . . . . . . . . . . . . 16
Appendix A. Metrics represented using RFC6390 Template . . . . . 22 Appendix A. Metrics Represented Using the Template from RFC 6390 17
Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 29
B.1. draft-ietf-xrblock-rtcp-xr-loss-conceal-11 . . . . . . . . 29
B.2. draft-ietf-xrblock-rtcp-xr-loss-conceal-09 . . . . . . . . 29
B.3. draft-ietf-xrblock-rtcp-xr-loss-conceal-07 . . . . . . . . 29
B.4. draft-ietf-xrblock-rtcp-xr-loss-conceal-06 . . . . . . . . 29
B.5. draft-ietf-xrblock-rtcp-xr-loss-conceal-05 . . . . . . . . 29
B.6. draft-ietf-xrblock-rtcp-xr-loss-conceal-04 . . . . . . . . 29
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 31
1. Introduction 1. Introduction
1.1. Loss Concealment and Concealment Seconds Metrics Reporting Block 1.1. Loss Concealment and Concealed Seconds Metrics Blocks
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.
Concealment refers to playout of locally-generated signals used to 'Concealed' refers to playout of locally generated signals used to
mask the impact of network impairments or to reduce the audibility of mask the impact of network impairments or to reduce the audibility of
jitter buffer adaptations. jitter buffer adaptations.
This draft defines two new concealment related block types to augment This document defines two new concealment-related block types to
those defined in [RFC3611] for use in a range of RTP applications. augment those defined in [RFC3611] for use in a range of RTP
These two block types extend packet loss concealment mechanism applications. These two block types extend the packet loss
defined in section 4.7.6 of RFC3611. concealment mechanism defined in Section 4.7.6 of [RFC3611].
The first block type provides metrics for actions taken by the The first block type, the Loss Concealment Metrics Block, provides
receiver to mitigate the effect of packet loss and packet discard. metrics for actions taken by the receiver to mitigate the effect of
Specifically, the first metric (On-Time Playout Duration) reports the packet loss and packet discard. Specifically, the first metric
duration of normal playout of data which the receiver obtained from (On-Time Playout Duration) reports the duration of normal playout of
the sender's stream. A second metric (Loss Concealment Duration) data that the receiver obtained from the sender's stream. A second
reports the total time during which the receiver played out media metric (Loss Concealment Duration) reports the total time during
data which was manufactured locally, because the sender's data for which the receiver played out media data that was manufactured
these periods was not available due to packet loss or discard. A locally, because the sender's data for these periods was not
similar metric (Buffer Adjustment Concealment Duration) reports the available due to packet loss or discard. A similar metric (Buffer
duration of playout of locally-manufactured data replacing data which Adjustment Concealment Duration) reports the duration of playout of
is unavailable due to adaptation of an adaptive de-jitter buffer. locally manufactured data replacing data that is unavailable due to
Further metrics (Playout Interrupt Count and Mean Playout Interrupt adaptation of an adaptive de-jitter buffer. Further metrics (Playout
Size) report the number of times normal playout was interrupted, and Interrupt Count and Mean Playout Interrupt Size) report the number of
the mean duration of these interruptions. times normal playout was interrupted and the mean duration of these
interruptions.
Loss Concealment Duration and Buffer Adjustment Concealment Duration Loss Concealment Duration and Buffer Adjustment Concealment Duration
are reported separately because buffer adjustment is typically are reported separately because buffer adjustment is typically
arranged to occur in silence periods so may have very little impact arranged to occur in silence periods, so it may have very little
on user experience, whilst loss concealment may occur at any time. impact on user experience, whilst loss concealment may occur at any
time.
The second block type provides metrics for concealment seconds, which The second block type, the Concealed Seconds Metrics Block, provides
are measured at the receiving end of the RTP stream. Specifically, metrics for Concealed Seconds, which are measured at the receiving
the first metric (Unimpaired Seconds) reports the number of whole end of the RTP stream. Specifically, the first metric (Unimpaired
seconds occupied only with normal playout of data which the receiver Seconds) reports the number of whole seconds occupied only with
obtained from the sender's stream. The second metric (Concealed normal playout of data that the receiver obtained from the sender's
Seconds) reports the number of whole seconds during which the stream. The second metric (Concealed Seconds) reports the number of
receiver played out any locally-generated media data. A third whole seconds during which the receiver played out any locally
metric, Severely Concealed Seconds (SCS), reports the number of whole generated media data. A third metric, Severely Concealed Seconds
seconds during which the receiver played out locally-generated data (SCSs), reports the number of whole seconds during which the receiver
for more than SCS Threshold. played out locally generated data to conceal a lost or discarded
frame percentage in excess of the configured SCS Threshold.
These metrics belongs to the class of transport-related terminal These metrics belongs to the class of transport-related terminal
metrics defined in [RFC6792]. metrics defined in [RFC6792].
1.2. RTCP and RTCP XR Reports 1.2. RTCP and RTCP Extended Reports
The use of RTCP for reporting is defined in [RFC3550]. [RFC3611] The use of RTCP for reporting is defined in [RFC3550]. [RFC3611]
defined an extensible structure for reporting using an RTCP Extended defines an extensible structure for reporting using an RTCP Extended
Report (XR). This draft defines a new Extended Report block that Report (XR). This document defines a new Extended Report block that
MUST be used as defined in [RFC3550] and [RFC3611]. MUST be used as defined in [RFC3550] and [RFC3611].
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 Framework [RFC6792] provides guidelines for reporting
block format using RTCP XR. The Metrics Block described in this block format using RTCP XR. The metrics blocks 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 applicable to audio applications of RTP and the These metrics are applicable to audio applications of RTP and the
audio component of Audio/Video applications in which the packet loss audio component of audio/video applications in which the packet loss
concealment machinery is contained at the receiving end to mitigate concealment machinery is contained at the receiving end to mitigate
the impact of network impairments to user's perception of media the impact of network impairments to user's perception of media
quality. 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 RFC 2119 [RFC2119].
2.2. Notations 2.2. Notations
This report block makes use of binary fractions. The terminology The report blocks in this document make use of binary fractions. The
used is following terminology is used:
Numeric formats S X:Y Numeric formats S X:Y
where S indicates a two's complement signed representation, X where S indicates a two's complement signed representation, X
the number of bits prior to the decimal place and Y the number the number of bits prior to the decimal place, and Y the number
of bits after the decimal place. of bits after the decimal place.
Hence 8:8 represents an unsigned number in the range 0.0 to Hence, 8:8 represents an unsigned number in the range 0.0 to
255.996 with a granularity of 0.0039. S7:8 would represent the 255.996 with a granularity of 0.0039. S7:8 would represent the
range -127.996 to +127.996. 0:16 represents a proper binary range -127.996 to +127.996. 0:16 represents a proper binary
fraction with range fraction with range
0.0 to 1 - 1/65536 = 0.9999847 0.0 to 1 - 1/65536 = 0.9999847
though note that use of flag values at the top of the numeric though note that use of flag values at the top of the numeric
range slightly reduces this upper limit. For example, if the range slightly reduces this upper limit. For example, if the
16- bit values 0xfffe and 0xffff are used as flags for "over- 16-bit values 0xFFFE and 0xFFFF are used as flags for "over-
range" and "unavailable" conditions, a 0:16 quantity has range range" and "unavailable" conditions, a 0:16 quantity has range
0.0 to 1 - 3/65536 = 0.9999542 0.0 to 1 - 3/65536 = 0.9999542
3. Loss Concealment Block 3. Loss Concealment Metrics Block
The metrics block described here are intended to be used as described The Loss Concealment Metrics Block is intended to be used as
in this section, in conjunction with information from the Measurement described in this section, in conjunction with information from the
Information block [RFC6776]. Instances of this Metrics Block refer Measurement Information Block [RFC6776]. Instances of this metrics
by Synchronization source (SSRC) to the separate auxiliary block refer by synchronization source (SSRC) to the separate
Measurement Information block [RFC6776] which describes measurement auxiliary Measurement Information Block [RFC6776], which describes
periods in use (see [RFC6776] section 4.2). This Metrics Block measurement periods in use (see [RFC6776], Section 4.2). This
relies on the measurement period in the Measurement Information block metrics block relies on the measurement period in the Measurement
indicating the span of the report and SHOULD be sent in the same Information Block indicating the span of the report and SHOULD be
compound RTCP packet as the measurement information block. If the sent in the same compound RTCP packet as the Measurement Information
measurement period is not received in the same compound RTCP packet Block. If the measurement period is not received in the same
as this Metrics Block, this metrics block MUST be discarded. compound RTCP packet as this metrics block, this metrics block MUST
be discarded.
3.1. Report Block Structure 3.1. Report Block Structure
Loss Concealment Metrics Block The structure of the Loss Concealment Metrics Block is as follows.
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=6 | | BT=30 | I |plc| resv | block length=6 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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 | Reserved. | | Playout Interrupt Count | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mean Playout Interrupt Size | | Mean Playout Interrupt Size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Report Block Structure Figure 1: Loss Concealment Metrics Block
3.2. Definition of Fields in Loss Concealment Metrics 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 Block is identified by the constant 30.
constant NLC.
[Note to RFC Editor: please replace NLC with the IANA provided
RTCP XR block type for this block.]
Interval Metric flag (I): 2 bit Interval Metric flag (I): 2 bits
This field is used to indicate whether the Loss Concealment This field is used to indicate whether the loss concealment
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 ( Not allowed in this block). instantaneous value (not allowed in this block).
I=00: Reserved value- this value is reserved for future use. I=00: Reserved value - this value is reserved for future use.
In this document, Loss Concealment Metrics can only be measured In this document, Loss Concealment metrics can only be measured
over definite intervals, and cannot be sampled. Senders MUST NOT over definite intervals and cannot be sampled. Senders MUST NOT
use the values I=00 or I=01. If a block is received with I=00 or use the values I=00 or I=01. If a block is received with I=00 or
I=01, the receiver MUST discard the block. I=01, the receiver MUST discard the block.
Packet Loss Concealment Method (plc): 2 bits Packet Loss Concealment Method (plc): 2 bits
This field is used to identify the packet loss concealment method This field is used to identify the packet loss concealment method
in use at the receiver, according to the following code: in use at the receiver, according to the following code:
bits 014-015 bits 014-015
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 are reserved.
Note that the enhancement method (plc =3 ) for packet loss Note that the enhancement method (plc=3) for packet loss
concealment offers an improved audio quality and a better concealment offers an improved audio quality and better robustness
robustness against packet losses [G.711] and is equivalent to against packet losses [G.711] and is equivalent to "enhanced" in
enhanced in section 4.7.6 of [RFC3611]. Section 4.7.6 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 6. the Loss Concealment Metrics Block, the block length is equal to
6.
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: 32 bits On-Time Playout Duration: 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 [VAD] is used, and locally generated or talker silence, if Voice Activity Detection (VAD) [VAD] is used,
regenerated tones and announcements. and locally generated or 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 is expressed in units of RTP timestamp On-time playout duration is expressed in units of RTP timestamp
and MUST include both speech and silence intervals, whether VAD is and MUST include both speech and silence intervals, whether VAD is
used or not. used or not.
Two values are reserved: A value of 0xFFFFFFFE indicates out of Two values are reserved: a value of 0xFFFFFFFE indicates out of
range (that is, a measured value exceeding 0xFFFFFFFD) and a value range (that is, a measured value exceeding 0xFFFFFFFD), and a
of 0xFFFFFFFF indicates that the measurement is unavailable. value of 0xFFFFFFFF indicates that the measurement is unavailable.
Loss Concealment Duration: 32 bits Loss Concealment Duration: 32 bits
The duration, expressed in units of RTP timestamp, of audio The duration, expressed in units of RTP timestamp, of audio
playout corresponding to Loss-type concealment. playout corresponding to Loss-Type concealment.
Loss-type concealment is reactive insertion or deletion of samples Loss-Type concealment is reactive insertion or deletion of samples
in the audio playout stream due to effective frame loss at the in the audio playout stream due to effective frame loss at the
audio decoder. "Effective frame loss" is the event in which a audio decoder. Effective frame loss is the event in which a frame
frame of coded audio is simply not present at the audio decoder of coded audio is simply not present at the audio decoder when
when required. In this case, substitute audio samples are required. In this case, substitute audio samples are generally
generally formed, at the decoder or elsewhere, to reduce audible formed, at the decoder or elsewhere, to reduce audible impairment.
impairment.
Two values are reserved: A value of 0xFFFFFFFE indicates out of Two values are reserved: a value of 0xFFFFFFFE indicates out of
range (that is, a measured value exceeding 0xFFFFFFFD) and a value range (that is, a measured value exceeding 0xFFFFFFFD), and a
of 0xFFFFFFFF indicates that the measurement is unavailable. value of 0xFFFFFFFF indicates that the measurement is unavailable.
Buffer Adjustment Concealment Duration: 32 bits Buffer Adjustment Concealment Duration: 32 bits
The duration, expressed in units of RTP timestamp, of audio The duration, expressed in units of RTP timestamp, of audio
playout corresponding to Buffer Adjustment-type concealment, if playout corresponding to Buffer Adjustment-Type concealment, if
known. known.
Buffer Adjustment-type concealment is proactive or controlled Buffer Adjustment-Type concealment is proactive or controlled
insertion or deletion of samples in the audio playout stream due insertion or deletion of samples in the audio playout stream due
to jitter buffer adaptation, re-sizing or re-centering decisions to jitter buffer adaptation, re-sizing decisions, or re-centering
within the endpoint. decisions within the endpoint.
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 that cannot be classified as Buffer Adjustment-
Adjustment-type MUST be classified as Loss-type. Type MUST be classified as Loss-Type.
Two values are reserved: A value of 0xFFFFFFFE indicates out of Two values are reserved: a value of 0xFFFFFFFE indicates out of
range (that is, a measured value exceeding 0xFFFFFFFD) and a value range (that is, a measured value exceeding 0xFFFFFFFD), and a
of 0xFFFFFFFF indicates that the measurement is unavailable. value of 0xFFFFFFFF indicates that the measurement is unavailable.
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 that occurred during
during the reporting period. the reporting period.
Two values are reserved: A value of 0xFFFE indicates out of range Two values are reserved: a value of 0xFFFE indicates out of range
(that is, a measured value exceeding 0xFFFD) and a value of 0xFFFF (that is, a measured value exceeding 0xFFFD), and a value of
indicates that the measurement is unavailable. 0xFFFF indicates that the measurement is unavailable.
Reserved (resv): 16 bits Reserved: 16 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).
Mean Playout Interrupt Size: 32 bits Mean Playout Interrupt Size: 32 bits
The mean duration, expressed in units of RTP timestamp, of The mean duration, expressed in units of RTP timestamp, of
interruptions to normal playout which occurred during the interruptions to normal playout that occurred during the reporting
reporting period. period.
Two values are reserved: A value of 0xFFFFFFFE indicates out of Two values are reserved: a value of 0xFFFFFFFE indicates out of
range (that is, a measured value exceeding 0xFFFFFFFD) and a value range (that is, a measured value exceeding 0xFFFFFFFD), and a
of 0xFFFFFFFF indicates that the measurement is unavailable. value of 0xFFFFFFFF indicates that the measurement is unavailable.
4. Concealment Seconds Block 4. Concealed Seconds Metrics Block
This sub-block described here is intended to be used as described in The Concealed Seconds Metrics Block is intended to be used as
this section, in conjunction with information from the Measurement described in this section, in conjunction with information from the
Information block [RFC6776] and provides a description of potentially Measurement Information Block [RFC6776]. It provides a description
audible impairments due to lost and discarded packets at the of potentially audible impairments due to lost and discarded packets
endpoint, expressed on a time basis analogous to a traditional PSTN at the endpoint, expressed on a time basis analogous to a traditional
T1/E1 errored seconds metric. Instances of this Metrics Block refer Public Switched Telephone Network (PSTN) T1/E1 errored seconds
by Synchronization source (SSRC) to the separate auxiliary metric. Instances of this metrics block refer by synchronization
Measurement Information block [RFC6776] which describes measurement source (SSRC) to the separate auxiliary Measurement Information Block
periods in use (see [RFC6776] section 4.2). This Metrics Block [RFC6776] that describes measurement periods in use (see [RFC6776],
relies on the measurement period in the Measurement Information block Section 4.2). This metrics block relies on the measurement period in
indicating the span of the report and SHOULD be sent in the same the Measurement Information Block indicating the span of the report
compound RTCP packet as the measurement information block. If the and SHOULD be sent in the same compound RTCP packet as the
measurement period is not received in the same compound RTCP packet Measurement Information Block. If the measurement period is not
as this Metrics Block, this metrics block MUST be discarded. received in the same compound RTCP packet as this metrics block, this
metrics block MUST be discarded.
The following metrics are based on successive one second intervals as The following metrics are based on successive one-second intervals as
declared by a RTP clock. This RTP clock does not need to be declared by an RTP clock. This RTP clock does not need to be
synchronized to any external time reference. The starting time of synchronized to any external time reference. The starting time of
this clock is unspecified. Note that this implies that the same loss this clock is unspecified. Note that this implies that the same loss
pattern could result in slightly different count values, depending on pattern could result in slightly different count values, depending on
where the losses occur relative to the particular one-second where the losses occur relative to the particular one-second
demarcation points. For example, two loss events occurring 50ms demarcation points. For example, two loss events occurring 50 ms
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 one second boundaries used. on the particular one-second 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 one second At the tail end of a session, periods of time of less than one second
shall be incorporated into these counts if they exceed 500ms and shall be incorporated into these counts if they exceed 500 ms and
shall be disregarded if they are less than 500ms. shall be disregarded if they are less than 500 ms.
4.1. Report Block Structure 4.1. Report Block Structure
Concealed Seconds Metrics Block The structure of the Concealed Seconds Metrics Block is as follows.
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=31 | I |plc| resv | block length=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of Source | | SSRC of Source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Unimpaired Seconds | | Unimpaired Seconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Concealed Seconds | | Concealed Seconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Severely Concealed Seconds | RESERVED | SCS Threshold | | Severely Concealed Seconds | Reserved | SCS Threshold |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Report Block Structure Figure 2: Concealed Seconds Metrics Block
4.2. Definition of Fields in Concealed Seconds Metrics Block 4.2. Definition of Fields in Concealed Seconds Metrics Block
Block type (BT): 8 bits Block type (BT): 8 bits
A Concealed Seconds Metrics Report Block is identified by the A Concealed Seconds Metrics Block is identified by the constant
constant NCS. 31.
[Note to RFC Editor: please replace NCS with the IANA provided
RTCP XR block type for this block.]
Interval Metric flag (I): 2 bit Interval Metric flag (I): 2 bits
This field is used to indicate whether the Concealment Seconds This field is used to indicate whether the Concealed 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 (Not allowed in this block). instantaneous value (Not allowed in this block).
I=00: Reserved value- this value is reserved for future use. I=00: Reserved value - this value is reserved for future use.
In this document, Concealment Seconds Metrics can only be measured In this document, Concealed Seconds metrics can only be measured
over definite intervals, and cannot be sampled. Senders MUST NOT over definite intervals and cannot be sampled. Senders MUST NOT
use the values I=00 or I=01. If a block is received with I=00 or use the values I=00 or I=01. If a block is received with I=00 or
I=01, the receiver MUST discard the block. I=01, the receiver MUST discard the block.
Packet Loss Concealment Method (plc): 2 bits Packet Loss Concealment Method (plc): 2 bits
This field is used to identify the packet loss concealment method This field is used to identify the packet loss concealment method
in use at the receiver, according to the following code: in use at the receiver, according to the following code:
bits 014-015 bits 014-015
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 are reserved.
Note that the enhancement method (plc =3 ) for packet loss Note that the enhancement method (plc=3) for packet loss
concealment offers an improved audio quality and a better concealment offers an improved audio quality and 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 4.7.6 of [RFC3611]. "enhanced" in Section 4.7.6 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 Concealed Seconds Metrics 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 one An Unimpaired Second is defined as a continuous period of one
second during which no frame loss or discard due to late arrival second during which no frame loss or discard due to late arrival
has occurred. Every second in a session must be classified as has occurred. Every second in a session must be classified as
either OK or Concealed. either 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 is used, shall be signals during periods of talker silence, if VAD is used, shall be
counted as unimpaired seconds. counted as Unimpaired Seconds.
Two values are reserved: A value of 0xFFFFFFFE indicates out of Two values are reserved: a value of 0xFFFFFFFE indicates out of
range (that is, a measured value exceeding 0xFFFFFFFD) and a value range (that is, a measured value exceeding 0xFFFFFFFD), and a
of 0xFFFFFFFF indicates that the measurement is unavailable. value of 0xFFFFFFFF indicates that the measurement is unavailable.
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 one second A Concealed Second is defined as a continuous period of one second
during which any frame loss or discard due to late arrival has during which any frame loss or discard due to late arrival has
occurred. occurred.
Equivalently, a concealed second is one in which some Loss-type Equivalently, a Concealed Second is one in which some Loss-Type
concealment has occurred. Buffer adjustment-type concealment concealment has occurred. Buffer Adjustment-Type concealment
SHOULD NOT cause Concealed Seconds to be incremented, with the SHOULD NOT cause Concealed Seconds to be incremented, with the
following exception. An implementation MAY cause Concealed following exception. An implementation MAY cause Concealed
Seconds to be incremented for 'emergency' buffer adjustments made Seconds to be incremented for 'emergency' buffer adjustments made
during talkspurts. during talkspurts.
Loss-type concealment is reactive insertion or deletion of samples Loss-Type concealment is reactive insertion or deletion of samples
in the audio playout stream due to effective frame loss at the in the audio playout stream due to effective frame loss at the
audio decoder. "Effective frame loss" is the event in which a audio decoder. "Effective frame loss" is the event in which a
frame of coded audio is simply not present at the audio decoder frame of coded audio is simply not present at the audio decoder
when required. In this case, substitute audio samples are when required. In this case, substitute audio samples are
generally formed, at the decoder or elsewhere, to reduce audible generally formed, at the decoder or elsewhere, to reduce audible
impairment. impairment.
Buffer Adjustment-type concealment is proactive or controlled Buffer Adjustment-Type concealment is proactive or controlled
insertion or deletion of samples in the audio playout stream due insertion or deletion of samples in the audio playout stream due
to jitter buffer adaptation, re-sizing or re-centering decisions to jitter buffer adaptation, re-sizing decisions, or re-centering
within the endpoint. decisions within the endpoint.
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. For during favorable periods in active speech may be employed. For
these reasons, buffer adjustment-type concealment MAY be exempted these reasons, Buffer Adjustment-Type concealment MAY be exempted
from inclusion in calculations of Concealed Seconds and Severely from inclusion in calculations of Concealed Seconds and Severely
Concealed Seconds. Concealed Seconds.
However, an implementation SHOULD include buffer-type concealment However, an implementation SHOULD include Buffer Adjustment-Type
in counts of Concealed Seconds and Severely Concealed Seconds if concealment in counts of Concealed Seconds and Severely Concealed
the event occurs at an 'inopportune' moment, with an emergency or Seconds if the event occurs at an 'inopportune' moment, such as an
large, immediate adaptation during active speech, or for emergency or large, immediate adaptation during active speech or
unsophisticated adaptation during speech without regard for the an unsophisticated adaptation during speech without regard for the
underlying signal, in which cases the assumption of low-audibility underlying signal. In these cases, the assumption of low
cannot hold. In other words, jitter buffer adaptation events audibility cannot hold. In other words, jitter buffer adaptation
which may be presumed to be audible SHOULD be included in events that may be presumed to be audible SHOULD be included in
Concealed Seconds and Severely Concealed Seconds counts. Concealed Seconds and Severely Concealed Seconds counts.
Concealment events which cannot be classified as Buffer Concealment events that cannot be classified as Buffer Adjustment-
Adjustment- type MUST be classified as Loss-type. Type MUST be classified as Loss-Type.
For clarification, the count of Concealed Seconds MUST include the For clarification, the count of Concealed Seconds MUST include the
count of Severely Concealed Seconds. count of Severely Concealed Seconds.
Two values are reserved: A value of 0xFFFFFFFE indicates out of Two values are reserved: a value of 0xFFFFFFFE indicates out of
range (that is, a measured value exceeding 0xFFFFFFFD) and a value range (that is, a measured value exceeding 0xFFFFFFFD), and a
of 0xFFFFFFFF indicates that the measurement is unavailable. value of 0xFFFFFFFF indicates that the measurement is unavailable.
Severely Concealed Seconds: 16 bits Severely Concealed Seconds: 16 bits
A count of the number of Severely Concealed Seconds. A count of the number of Severely Concealed Seconds.
A Severely Concealed Second is defined as a non-overlapping period A Severely Concealed Second is defined as a non-overlapping period
of one second during which the cumulative amount of time that has of one second during which the cumulative amount of time that has
been subject to frame loss or discard due to late arrival, exceeds been subject to frame loss or discard due to late arrival exceeds
the SCS Threshold. the SCS Threshold.
Two values are reserved: A value of 0xFFFE indicates out of range Two values are reserved: a value of 0xFFFE indicates out of range
(that is, a measured value exceeding 0xFFFD) and a value of 0xFFFF (that is, a measured value exceeding 0xFFFD), and a value of
indicates that the measurement is unavailable. 0xFFFF indicates that the measurement is unavailable.
Reserved: 8 bits Reserved: 8 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).
SCS Threshold: 8 bits SCS Threshold: 8 bits
The SCS Threshold is defined as the percentage of packets The SCS Threshold is defined as the percentage of packets
corresponding to lost or discarded frames that must occur within a corresponding to lost or discarded frames that must occur within a
one second period in order for the second to be classified as a one second period in order for the second to be classified as a
Severely Concealed Second. This is expressed in numeric format Severely Concealed Second. This is expressed in numeric format
0:8 and hence can represent a range of 0 to 99.6 percent loss or 0:8 and hence can represent a range of 0 to 99.6 percent loss or
discard. discard.
A default threshold of 5% effective frame loss (50ms effective A default threshold of 5 percent effective frame loss (50 ms
frame loss ) per second is suggested. This corresponds to an SCS effective frame loss ) per second is suggested. This corresponds
Threshold in hexadecimal of 0x0D. to an SCS Threshold in hexadecimal of 0x0D.
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
two report blocks defined in this document. the two report blocks defined in this document.
xr-format =/ xr-conceal-block xr-format =/ xr-conceal-block
/ 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 = <as defined in Section 3 of [RFC5234]> DIGIT = <as defined in Section 3 of [RFC5234]>
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. Note that "thresh" is declared by the defined in [RFC3611] applies. Note that "thresh" is declared by the
offer. 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 "RTP Control This document assigns two block type values in the IANA "RTP Control
Protocol Extended Reports (RTCP XR) Block Type Registry ": Protocol Extended Reports (RTCP XR) Block Type Registry" under the
subregistry "RTCP XR Block Type":
Name: LCB Name: LCB
Long Name: Loss Concealment Block Long Name: Loss Concealment Metrics Block
Value <NLC> Value 30
Reference: Section 3.1 Reference: Section 3.1
Name: CSB Name: CSB
Long Name: Concealment Seconds Block Long Name: Concealed Seconds Metrics Block
Value <NCS> Value 31
Reference: Section 4.1 Reference: Section 4.1
[Note to RFC Editor: please replace <NLC> and <NCS> with the RTCP XR
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 "RTP Control This document also registers two new parameters in the "RTP Control
Protocol Extended Reports (RTCP XR) Session Description Protocol Protocol Extended Reports (RTCP XR) Session Description Protocol
(SDP) Parameters Registry": (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:
RAI Area Directors RAI Area Directors
rai-ads@tools.ietf.org rai-ads@tools.ietf.org
7. Security Considerations 7. Security Considerations
It is believed that this proposed RTCP XR report block introduces no It is believed that the RTCP XR blocks defined in this document
new security considerations beyond those described in [RFC3611]. introduce no new security considerations beyond those described in
This block does not provide per-packet statistics so the risk to [RFC3611]. These blocks do not provide per-packet statistics, so the
confidentiality documented in Section 7, paragraph 3 of [RFC3611] risk to confidentiality documented in Section 7, Paragraph 3 of
does not apply. [RFC3611] does not apply.
8. Contributors 8. Contributors
Geoff Hunt wrote the initial draft of this document. Geoff Hunt wrote the initial version of this document.
9. Acknowledgements 9. Acknowledgements
The authors gratefully acknowledge reviews and feedback provided by The authors gratefully acknowledge reviews and feedback provided by
Bruce Adams, Philip Arden, Amit Arora, Bob Biskner, Kevin Connor, Bruce Adams, Philip Arden, Amit Arora, Bob Biskner, Kevin Connor,
Claus Dahm, Randy Ethier, Roni Even, Jim Frauenthal, Albert Higashi, Alissa Cooper, Claus Dahm, Randy Ethier, Roni Even, Adrian Farrel,
Tom Hock, Shane Holthaus, Paul Jones, Rajesh Kumar, Keith Lantz, Jim Frauenthal, Albert Higashi, Tom Hock, Shane Holthaus, Paul Jones,
Mohamed Mostafa, Amy Pendleton, Colin Perkins, Mike Ramalho, Ravi Rajesh Kumar, Keith Lantz, Alfred C. Morton, Mohamed Mostafa, Amy
Raviraj, Albrecht Schwarz, Tom Taylor, Hideaki Yamada ,Alissa Pendleton, Colin Perkins, Mike Ramalho, Ravi Raviraj, Pete Resnick,
Cooper,Meral Shirazipour and ,MORTON, ALFRED C (AL),Adrian Farrel and Albrecht Schwarz, Meral Shirazipour, Tom Taylor, and Hideaki Yamada.
Pete Resnick.
10. References 10. References
10.1. Normative References 10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3550] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Applications", RFC 3550, July 2003. Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, July 2003.
[RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control [RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control
Protocol Extended Reports (RTCP XR)", November 2003. Protocol Extended Reports (RTCP XR)", RFC 3611, November
2003.
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", July 2006. Description Protocol", RFC 4566, July 2006.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 5234, January 2008. Specifications: ABNF", STD 68, RFC 5234, January 2008.
[RFC6776] Wu, Q., "Measurement Identity and information Reporting [RFC6776] Clark, A. and Q. Wu, "Measurement Identity and Information
using SDES item and XR Block", RFC 6776, August 2012. Reporting Using a Source Description (SDES) Item and an
RTCP Extended Report (XR) Block", RFC 6776, October 2012.
10.2. Informative References 10.2. Informative References
[RFC6390] Clark, A. and B. Claise, "Framework for Performance Metric [G.711] ITU-T, "Pulse Code Modulation (PCM) of Voice Frequencies",
Development", RFC 6390, October 2011. ITU-T Recommendation G.711, 1988.
[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 [RFC6709] Carpenter, B., Aboba, B., and S. Cheshire, "Design
Considerations for Protocol Extensions", RFC 6709, Considerations for Protocol Extensions", RFC 6709,
September 2012. September 2012.
[RFC6792] Hunt, G., "Monitoring Architectures for RTP", RFC 6792, [RFC6792] Wu, Q., Hunt, G., and P. Arden, "Guidelines for Use of the
November 2012. RTP Monitoring Framework", RFC 6792, November 2012.
[VAD] "http://en.wikipedia.org/wiki/Voice_activity_detection".
Appendix A. Metrics represented using RFC6390 Template [VAD] Wikipedia, "Voice activity detection", January 2014,
<http://en.wikipedia.org/w/
index.php?title=Voice_activity_detection&oldid=593287643>.
RFC EDITOR NOTE: please change XXXX in [RFCXXXX] by the new RFC Appendix A. Metrics Represented Using the Template from RFC 6390
number, when assigned.
a. On-time Playout Duration Metric a. On-Time Playout Duration Metric
* Metric Name: On-time Playout Duration * Metric Name: On-Time Playout Duration
* Metric Description: 'On-time' playout is the uninterrupted, * Metric Description: 'On-time playout' is the uninterrupted,
in-sequence playout of valid decoded audio information in-sequence playout of valid decoded audio information
originating from the remote endpoint. On-time playout originating from the remote endpoint. On-time playout
Duration is playout duration of any signal other than those duration is playout duration of any signal other than those
used for concealment used for concealment.
* Method of Measurement or Calculation: See section 3. 2, On- * Method of Measurement or Calculation: See Section 3.2, On-Time
time Playout Duration definition [RFCXXXX]. Playout Duration definition.
* Units of Measurement: See section 3.2, On-time Playout * Units of Measurement: See Section 3.2, On-Time Playout
Duration definition [RFCXXXX]. Duration definition.
* Measurement Point(s) with Potential Measurement Domain: See * Measurement Point(s) with Potential Measurement Domain: See
section 1.1, 3rd paragraph [RFCXXXX]. Section 1.1, 3rd paragraph.
* Measurement Timing: See section 3, 1st paragraph [RFCXXXX] for * Measurement Timing: See Section 3, 1st paragraph for
measurement timing and section 3.2 [RFCXXXX] for Interval measurement timing and Section 3.2 for Interval Metric flag.
Metric flag.
* Use and applications: See section 1.4 [RFCXXXX]. * Use and Applications: See Section 1.4.
* Reporting model: See RFC3611. * Reporting Model: See RFC 3611.
b. Loss Concealment Duration Metric b. Loss Concealment Duration Metric
* Metric Name: Loss Concealment Duration * Metric Name: Loss Concealment Duration
* Metric Description: The duration of audio playout * Metric Description: The duration of audio playout
corresponding to Loss-type concealment. corresponding to Loss-Type concealment.
* Method of Measurement or Calculation: See section 3.2, Loss * Method of Measurement or Calculation: See Section 3.2, Loss
Concealment Duration definition [RFCXXXX]. Concealment Duration definition.
* Units of Measurement: See section 3.2, Loss Concealment * Units of Measurement: See Section 3.2, Loss Concealment
Duration definition [RFCXXXX]. Duration definition.
* Measurement Point(s) with Potential Measurement Domain: See * Measurement Point(s) with Potential Measurement Domain: See
section 1.1, 3rd paragraph [RFCXXXX]. Section 1.1, 3rd paragraph.
* Measurement Timing: See section 3, 1st paragraph [RFCXXXX] for * Measurement Timing: See Section 3, 1st paragraph for
measurement timing and section 3. 2 [RFCXXXX] for Interval measurement timing and Section 3.2 for Interval Metric flag.
Metric flag.
* Use and applications: See section 1.4 [RFCXXXX]. * Use and Applications: See Section 1.4.
* Reporting model: See RFC3611. * Reporting Model: See RFC 3611.
c. Buffer Adjustment Concealment Duration Metric c. Buffer Adjustment Concealment Duration Metric
* Metric Name: Buffer Adjustment Concealment Duration * Metric Name: Buffer Adjustment Concealment Duration
* Metric Description: The duration of audio playout * Metric Description: The duration of audio playout
corresponding to Buffer Adjustment-type concealment. corresponding to Buffer Adjustment-Type concealment.
* Method of Measurement or Calculation: See section 3. 2, Buffer * Method of Measurement or Calculation: See Section 3.2, Buffer
Adjustment Concealment Duration definition [RFCXXXX]. Adjustment Concealment Duration definition.
* Units of Measurement: See section 3.2, Buffer Adjustment * Units of Measurement: See Section 3.2, Buffer Adjustment
Concealment Duration definition [RFCXXXX]. Concealment Duration definition.
* Measurement Point(s) with Potential Measurement Domain: See * Measurement Point(s) with Potential Measurement Domain: See
section 1.1, 3rd paragraph [RFCXXXX]. Section 1.1, 3rd paragraph.
* Measurement Timing: See section 3, 1st paragraph [RFCXXXX] for * Measurement Timing: See Section 3, 1st paragraph for
measurement timing and section 3.2 [RFCXXXX] for Interval measurement timing and Section 3.2 for Interval Metric flag.
Metric flag.
* Use and applications: See section 1.4 [RFCXXXX]. * Use and Applications: See Section 1.4.
* Reporting model: See RFC3611. * Reporting Model: See RFC 3611.
d. Playout Interrupt Count Metric d. Playout Interrupt Count Metric
* Metric Name: Playout Interrupt Count * Metric Name: Playout Interrupt Count
* Metric Description: The number of interruptions to normal * Metric Description: The number of interruptions to normal
playout which occurred during the reporting period. playout that occurred during the reporting period.
* Method of Measurement or Calculation: See section 3. 2, * Method of Measurement or Calculation: See Section 3.2, Playout
Playout Interrupt Count definition [RFCXXXX]. Interrupt Count definition.
* Units of Measurement: See section 3.2, Playout Interrupt Count * Units of Measurement: See Section 3.2, Playout Interrupt Count
definition [RFCXXXX]. definition.
* Measurement Point(s) with Potential Measurement Domain: See * Measurement Point(s) with Potential Measurement Domain: See
section 1.1, 3rd paragraph [RFCXXXX]. Section 1.1, 3rd paragraph.
* Measurement Timing: See section 3, 1st paragraph [RFCXXXX] for * Measurement Timing: See Section 3, 1st paragraph for
measurement timing and section 3.2 [RFCXXXX] for Interval measurement timing and Section 3.2 for Interval Metric flag.
Metric flag.
* Use and applications: See section 1.4 [RFCXXXX]. * Use and Applications: See Section 1.4.
* Reporting model: See RFC3611. * Reporting Model: See RFC 3611.
e. Mean Playout Interrupt Size Metric e. Mean Playout Interrupt Size Metric
* Metric Name: Mean Playout Interrupt Size * Metric Name: Mean Playout Interrupt Size
* Metric Description: The mean duration of interruptions to * Metric Description: The mean duration of interruptions to
normal playout which occurred during the reporting period. normal playout that occurred during the reporting period.
* Method of Measurement or Calculation: See section 3. 2, * Method of Measurement or Calculation: See Section 3.2, Playout
Playout Interrupt Count definition [RFCXXXX]. Interrupt Count definition.
* Units of Measurement: See section 3.2, Playout Interrupt Count * Units of Measurement: See Section 3.2, Playout Interrupt Count
definition [RFCXXXX]. definition.
* Measurement Point(s) with Potential Measurement Domain: See * Measurement Point(s) with Potential Measurement Domain: See
section 1.1, 3rd paragraph [RFCXXXX]. Section 1.1, 3rd paragraph.
* Measurement Timing: See section 3, 1st paragraph [RFCXXXX] for * Measurement Timing: See Section 3, 1st paragraph for
measurement timing and section 3.2 [RFCXXXX] for Interval measurement timing and Section 3.2 for Interval Metric flag.
Metric flag.
* Use and applications: See section 1.4 [RFCXXXX]. * Use and Applications: See Section 1.4.
* Reporting model: See RFC3611. * Reporting Model: See RFC 3611.
f. Unimpaired Seconds Metric f. Unimpaired Seconds Metric
* Metric Name: Unimpaired Seconds * Metric Name: Unimpaired Seconds
* Metric Description: A count of the number of unimpaired * Metric Description: A count of the number of Unimpaired
Seconds that have occurred. Seconds that have occurred.
* Method of Measurement or Calculation: See section 4. 2, * Method of Measurement or Calculation: See Section 4.2,
Unimpaired Seconds definition [RFCXXXX]. Unimpaired Seconds definition.
* Units of Measurement: See section 4.2, Unimpaired Seconds * Units of Measurement: See Section 4.2, Unimpaired Seconds
definition [RFCXXXX]. definition.
* Measurement Point(s) with Potential Measurement Domain: See * Measurement Point(s) with Potential Measurement Domain: See
section 1.1, 5th paragraph [RFCXXXX]. Section 1.1, 5th paragraph.
* Measurement Timing: See section 4, 1st paragraph [RFCXXXX] for * Measurement Timing: See Section 4, 1st paragraph for
measurement timing and section 4.2 paragraph [RFCXXXX] for measurement timing and Section 4.2 paragraph for Interval
Interval Metric flag. Metric flag.
* Use and applications: See section 1.4 [RFCXXXX]. * Use and Applications: See Section 1.4.
* Reporting model: See RFC3611. * Reporting Model: See RFC 3611.
g. Concealed Seconds Metric g. Concealed Seconds Metric
* Metric Name: Concealed Seconds * Metric Name: Concealed Seconds
* Metric Description: A count of the number of Concealed Seconds * Metric Description: A count of the number of Concealed Seconds
that have occurred. that have occurred.
* Method of Measurement or Calculation: See section 4. 2, * Method of Measurement or Calculation: See Section 4.2,
Concealed Seconds definition [RFCXXXX]. Concealed Seconds definition.
* Units of Measurement: See section 4.2, Concealed Seconds * Units of Measurement: See Section 4.2, Concealed Seconds
definition [RFCXXXX]. definition.
* Measurement Point(s) with Potential Measurement Domain: See * Measurement Point(s) with Potential Measurement Domain: See
section 1.1, 5th paragraph [RFCXXXX]. Section 1.1, 5th paragraph.
* Measurement Timing: See section 4, 1st paragraph [RFCXXXX] for * Measurement Timing: See Section 4, 1st paragraph for
measurement timing and section 4.2 [RFCXXXX] for Interval measurement timing and Section 4.2 for Interval Metric flag.
Metric flag.
* Use and applications: See section 1.4 [RFCXXXX]. * Use and Applications: See Section 1.4.
* Reporting model: See RFC3611. * Reporting Model: See RFC 3611.
h. Severely Concealed Seconds Metric h. Severely Concealed Seconds Metric
* Metric Name: Severely Concealed Seconds * Metric Name: Severely Concealed Seconds
* Metric Description: A count of the number of Severely * Metric Description: A count of the number of Severely
Concealed Seconds that have occurred. Concealed Seconds that have occurred.
* Method of Measurement or Calculation: See section 4. 2, * Method of Measurement or Calculation: See Section 4.2,
Severely Concealed Seconds definition [RFCXXXX]. Severely Concealed Seconds definition.
* Units of Measurement: See section 4.2, Severely Concealed * Units of Measurement: See Section 4.2, Severely Concealed
Seconds definition [RFCXXXX]. Seconds definition.
* Measurement Point(s) with Potential Measurement Domain: See * Measurement Point(s) with Potential Measurement Domain: See
section 1.1, 5th paragraph [RFCXXXX]. Section 1.1, 5th paragraph.
* Measurement Timing: See section 4, 1st paragraph [RFCXXXX] for * Measurement Timing: See Section 4, 1st paragraph for
measurement timing and section 4.2 [RFCXXXX] for Interval measurement timing and Section 4.2 for Interval Metric flag.
Metric flag.
* Use and applications: See section 1.4 [RFCXXXX]. * Use and Applications: See Section 1.4.
* Reporting model: See RFC3611. * Reporting Model: See RFC 3611.
i. SCS Threshold Metric i. SCS Threshold Metric
* Metric Name: SCS Threshold * Metric Name: SCS Threshold
* Metric Description: The amount of time corresponding to lost * Metric Description: The amount of time corresponding to lost
or discarded frames that must occur within a one second period or discarded frames that must occur within a one-second period
in order for the second to be classified as a Severely in order for the second to be classified as a Severely
Concealed Second. Concealed Second.
* Method of Measurement or Calculation: See section 4. 2, SCS * Method of Measurement or Calculation: See Section 4.2, SCS
Threshold definition [RFCXXXX]. Threshold definition.
* Units of Measurement: See section 4.2, SCS Threshold * Units of Measurement: See Section 4.2, SCS Threshold
definition [RFCXXXX]. definition.
* Measurement Point(s) with Potential Measurement Domain: See * Measurement Point(s) with Potential Measurement Domain: See
section 1.1, 5th paragraph [RFCXXXX]. Section 1.1, 5th paragraph.
* Measurement Timing: See section 4, 1st paragraph [RFCXXXX] for
measurement timing and section 4.2 [RFCXXXX] for Interval
Metric flag.
* Use and applications: See section 1.4 [RFCXXXX].
* Reporting model: See RFC3611.
Appendix B. Change Log
Note to the RFC-Editor: please remove this section prior to
publication as an RFC.
B.1. draft-ietf-xrblock-rtcp-xr-loss-conceal-11
The following are the major changes to previous version :
o Address comments recieved in Gen-Art Review and OPS-DIR Review.
B.2. draft-ietf-xrblock-rtcp-xr-loss-conceal-09
The following are the major changes to previous version :
o Only Version Number changes.
B.3. draft-ietf-xrblock-rtcp-xr-loss-conceal-07
The following are the major changes to previous version :
o Change units for threshold and units used for reporting in loss
concealment block and concealment seconds block.
o Change 16bit "Mean Playout Interrupt Size" into 32bits.
B.4. 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.5. draft-ietf-xrblock-rtcp-xr-loss-conceal-05
The following are the major changes to previous version :
o Add text to clarify the definition of enhanced method.
o Add appendix to apply RFC6390 template to the metrics.
B.6. draft-ietf-xrblock-rtcp-xr-loss-conceal-04
The following are the major changes to previous version : * Measurement Timing: See Section 4, 1st paragraph for
measurement timing and Section 4.2 for Interval Metric flag.
o Merge Concealment Seconds draft into this draft (i.e.,Loss * Use and Applications: See Section 1.4.
Concealment draft).
o Updated references. * Reporting Model: See RFC 3611.
Authors' Addresses Authors' Addresses
Alan Clark Alan Clark
Telchemy Incorporated Telchemy Incorporated
2905 Premiere Parkway, Suite 280 2905 Premiere Parkway, Suite 280
Duluth, GA 30097 Duluth, GA 30097
USA USA
Email: alan.d.clark@telchemy.com EMail: alan.d.clark@telchemy.com
Glen Zorn Glen Zorn
Network Zen Network Zen
77/440 Soi Phoomjit, Rama IV Road 77/440 Soi Phoomjit, Rama IV Road
Phra Khanong, Khlong Toie Phra Khanong, Khlong Toie
Bangkok 10110 Bangkok 10110
Thailand Thailand
Phone: +66 (0) 87 502 4274 Phone: +66 (0) 87 502 4274
Email: gwz@net-zen.net EMail: gwz@net-zen.net
Claire Bi Claire Bi
Shanghai Research Institure of China Telecom Corporation Limited Shanghai Research Institute of China Telecom Corporation Limited
No.1835,South Pudong Road No. 1835, South Pudong Road
Shanghai 200122 Shanghai 200122
China China
Email: bijy@sttri.com.cn EMail: bijy@sttri.com.cn
Qin Wu (editor) Qin Wu
Huawei Huawei
101 Software Avenue, Yuhua District 101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012 Nanjing, Jiangsu 210012
China China
Email: sunseawq@huawei.com EMail: sunseawq@huawei.com
 End of changes. 192 change blocks. 
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