draft-ietf-xrblock-rtcp-xr-concsec-00.txt   draft-ietf-xrblock-rtcp-xr-concsec-01.txt 
Audio/Video Transport Working Group G. Hunt Audio/Video Transport Working Group A. Clark
Internet-Draft Unaffiliated Internet-Draft Telchemy
Intended status: Standards Track A. Clark Intended status: Standards Track G. Zorn
Expires: December 14, 2012 Telchemy Expires: April 19, 2013 Network Zen
G. Zorn
Network Zen
C. Bi C. Bi
STTRI STTRI
Q. Wu Q. Wu
Huawei Huawei
June 12, 2012 October 16, 2012
RTCP XR Report Block for Concealed Seconds metric Reporting RTP Control Protocol (RTCP) Extended Report (XR) Block for Concealed
draft-ietf-xrblock-rtcp-xr-concsec-00.txt Seconds metric Reporting
draft-ietf-xrblock-rtcp-xr-concsec-01.txt
Abstract Abstract
This document defines an RTCP XR Report Block that allows the This document defines an RTP Control Protocol(RTCP) Extended Report
reporting of Concealed Seconds metrics primarily for audio (XR) Block that allows the reporting of Concealed Seconds metrics
applications of RTP. primarily 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 December 14, 2012. This Internet-Draft will expire on April 19, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2012 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
skipping to change at page 2, line 16 skipping to change at page 2, line 15
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Concealed Seconds Block . . . . . . . . . . . . . . . . . 3 1.1. Concealed Seconds Block . . . . . . . . . . . . . . . . . 3
1.2. RTCP and RTCP XR Reports . . . . . . . . . . . . . . . . . 3 1.2. RTCP and RTCP XR Reports . . . . . . . . . . . . . . . . . 3
1.3. Performance Metrics Framework . . . . . . . . . . . . . . 3 1.3. Performance Metrics Framework . . . . . . . . . . . . . . 3
1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 3 1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 4
2. Loss Concealment Block . . . . . . . . . . . . . . . . . . . . 5 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Report Block Structure . . . . . . . . . . . . . . . . . . 5 2.1. Standards Language . . . . . . . . . . . . . . . . . . . . 5
2.2. Definition of Fields in Concealed Seconds Metrics Block . 5 3. Loss Concealment Block . . . . . . . . . . . . . . . . . . . . 6
3. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 10 3.1. Report Block Structure . . . . . . . . . . . . . . . . . . 6
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 3.2. Definition of Fields in Concealed Seconds Metrics Block . 7
4.1. New RTCP XR Block Type value . . . . . . . . . . . . . . . 11 4. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 12
4.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 11 4.1. SDP rtcp-xr-attrib Attribute Extension . . . . . . . . . . 12
4.3. Contact information for registrations . . . . . . . . . . 11 4.2. Offer/Answer Usage . . . . . . . . . . . . . . . . . . . . 12
5. Security Considerations . . . . . . . . . . . . . . . . . . . 12 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 13 5.1. New RTCP XR Block Type value . . . . . . . . . . . . . . . 13
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14 5.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 13
7.1. Normative References . . . . . . . . . . . . . . . . . . . 14 5.3. Contact information for registrations . . . . . . . . . . 13
7.2. Informative References . . . . . . . . . . . . . . . . . . 14 6. Security Considerations . . . . . . . . . . . . . . . . . . . 14
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 15 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 15
A.1. draft-ietf-xrblock-rtcp-xr-concsec-00 . . . . . . . . . . 15 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17
9.1. Normative References . . . . . . . . . . . . . . . . . . . 17
9.2. Informative References . . . . . . . . . . . . . . . . . . 17
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 18
A.1. draft-ietf-xrblock-rtcp-xr-concsec-01 . . . . . . . . . . 18
A.2. draft-ietf-xrblock-rtcp-xr-concsec-00 . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction 1. Introduction
1.1. Concealed Seconds Block 1.1. Concealed Seconds Block
This draft defines a new block type to augment those defined in This draft defines a new block type to augment those defined in
[RFC3611], for use primarily in audio applications of RTP. [RFC3611], for use primarily in audio applications of RTP.
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 Concealment refers to playout of locally-generated signals used to
mask the impact of network impairments such as lost packets or to mask the impact of network impairments such as lost packets or to
reduce the audibility of jitter buffer adaptations. reduce the audibility of jitter buffer adaptations.
Editor's Note: For video application, the output at a receiver
should also be classified as either normal or concealed. Should
this paragraph be clear about this?
The new block type provides metrics for concealment. Specifically, The new block type provides metrics for concealment. Specifically,
the first metric (Unimpaired Seconds) reports the number of whole the first metric (Unimpaired Seconds) reports the number of whole
seconds occupied only with normal playout of data which the receiver seconds occupied only with normal playout of data which the receiver
obtained from the sender's stream. The second metric (Concealed obtained from the sender's stream. The second metric (Concealed
Seconds) reports the number of whole seconds during which the Seconds) reports the number of whole seconds during which the
receiver played out any locally-generated media data. A third metric receiver played out any locally-generated media data. A third metric
(Severely Concealed Seconds) reports the number of whole seconds (Severely Concealed Seconds (SCS)) reports the number of whole
during which the receiver played out locally-generated data for more seconds during which the receiver played out locally-generated data
than SCS Threshold (ms). for more than SCS Threshold (ms).
The metric belongs to the class of transport-related terminal metrics The metric belongs to the class of transport-related end system
defined in [MONARCH]. metrics defined in [MONARCH].
1.2. RTCP and RTCP XR Reports 1.2. RTCP and RTCP XR 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 defined an extensible structure for reporting using an RTCP Extended
Report (XR). This draft defines a new Extended Report block that Report (XR). This draft 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
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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 the guidelines in [RFC6390] and document are in accordance with the guidelines in [RFC6390] and
[MONARCH]. [MONARCH].
1.4. Applicability 1.4. Applicability
This metric is primarily applicable to audio applications of RTP. This metric is primarily applicable to audio applications of RTP.
EDITOR'S NOTE: are there metrics for concealment of transport errors EDITOR'S NOTE: are there metrics for concealment of transport errors
for video? for video?
2. Loss Concealment Block 2. Terminology
2.1. Standards Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
In addition, the following terms are defined:
Editor's Note: For Video loss concealment, at least the following
four methods are used,i.e., Frame freeze,inter-frame
extrapolation, interpolation, Noise insertation, should this
section consider giving definition of these four methods for video
loss concealment?
3. Loss Concealment Block
This sub-block provides a description of potentially audible This sub-block provides a description of potentially audible
impairments due to lost and discarded packets at the endpoint, impairments due to lost and discarded packets at the endpoint,
expressed on a time basis analogous to a traditional PSTN T1/E1 expressed on a time basis analogous to a traditional PSTN T1/E1
errored seconds metric. errored seconds metric.
Editor's Note: Should impairment also cover video application?
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 local clock. This local clock does NOT need to be declared by a local clock. This local 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 50ms
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 call, periods of time of less than 1000ms shall At the tail end of a session, periods of time of less than 1000ms
be incorporated into these counts if they exceed 500ms and shall be shall be incorporated into these counts if they exceed 500ms and
disregarded if they are less than 500ms. shall be disregarded if they are less than 500ms.
2.1. Report Block Structure 3.1. Report Block Structure
Loss Concealment metrics block Concealed Seconds 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 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=NLC | I |plc| rsv. | block length=4 | | BT=NCS | I |plc|Rserved| 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 1: Report Block Structure Figure 1: Report Block Structure
2.2. Definition of Fields in Concealed Seconds Metrics Block 3.2. 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 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 Delay metrics are This field is used to indicate whether the Concealed Seconds
Sampled, Interval or Cumulative metrics, that is, whether the metrics are Sampled, Interval or Cumulative metrics, that is,
reported values applies to the most recent measurement interval whether the reported values applies to the most recent measurement
duration between successive metrics reports (I=10) (the Interval interval duration between successive metrics reports (I=10) (the
Duration) or to the accumulation period characteristic of Interval Duration) or to the accumulation period characteristic of
cumulative measurements (I=11) (the Cumulative Duration) or is a cumulative measurements (I=11) (the Cumulative Duration) or is a
sampled instantaneous value (I=01) (Sampled Value). sampled instantaneous value (I=01) (Sampled Value).
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 = enhanced 3 = enhanced
Other values reserved Other values reserved
Editor's Note 1 : In the packet loss concealment
methods,"Enhanced" is defines as one new Packet loss
Concealment method? However it is not clear what this
packet loss concealment method looks like?
Editor's Note 2: For Video loss concealment, there are a
range of methods used, for example:
(i) Frame freeze In this case the impaired video frame
is not displayed and the previously displayed frame is
hence "frozen" for the duration of the loss event
(ii) Inter-frame extrapolation If an area of the video
frame is damaged by loss, the same area from the
previous frame(s) can be used to estimate what the
missing pixels would have been. This can work well in
a scene with no motion but can be very noticeable if
there is significant movement from one frame to
another. Simple decoders may simply re-use the pixels
that were in the missing area, more complex decoders
may try to use several frames to do a more complex
extrapolation.
(iii) Interpolation A decoder may use the undamaged
pixels in the image to estimate what the missing block
of image should have
(iv) Noise insertion A decoder may insert random pixel
values - which would generally be less noticeable than
a blank rectangle in the image.
Therefore more text required in the future draft to
discuss Techniques for Video Loss Concealment method in
this document.
Reserved (resv): 4 bits Reserved (resv): 4 bits
These bits are reserved. They SHOULD be set to zero by senders These bits are reserved. They SHOULD be set to zero by senders
and MUST be ignored by receivers. and MUST be ignored by receivers.
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 Delay block, the block length is equal to 4. the Delay 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 call must be classified as either OK occurred. Every second in a session must be classified as either
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 is used, shall be signal during periods of talker silence, if VAD [VAD] is used,
counted as unimpaired seconds. shall be counted as unimpaired seconds.
Editor's Note: It should be clear that VAD does not apply to
video.
If the measured value exceeds 0xFFFFFFFD, the value 0xFFFFFFFE If the measured value exceeds 0xFFFFFFFD, the value 0xFFFFFFFE
SHOULD be reported to indicate an over-range measurement. If the SHOULD be reported to indicate an over-range measurement. If the
measurement is unavailable, the value 0xFFFFFFFF SHOULD be measurement is unavailable, the value 0xFFFFFFFF SHOULD be
reported. 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.
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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. 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.
Editor's Note: In this document, two kind of concealments are
defined: a. Loss-type concealment b. Buffer Adjustment-type
concealment Loss-type concealment is applicable to both audio
and video. However Buffer Adjustment-type concealment is
usually applied to audio. Should this section be clear about
this?
However, an implementation SHOULD include buffer-type concealment However, an implementation SHOULD include buffer-type concealment
in counts of Concealed Seconds and Severely Concealed Seconds if in counts of Concealed Seconds and Severely Concealed Seconds if
the event occurs at an 'inopportune' moment, with an emergency or the event occurs at an 'inopportune' moment, with an emergency or
large, immediate adaptation during active speech, or for large, immediate adaptation during active speech, or for
unsophisticated adaptation during speech without regard for the unsophisticated adaptation during speech without regard for the
underlying signal, in which cases the assumption of low-audibility underlying signal, in which cases the assumption of low-audibility
cannot hold. In other words, jitter buffer adaptation events cannot hold. In other words, jitter buffer adaptation events
which may be presumed to be audible SHOULD be included in which may be presumed to be audible SHOULD be included in
Concealed Seconds and Severely Concealed Seconds counts. Concealed Seconds and Severely Concealed Seconds counts.
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A Severely Concealed Second is defined as a non-overlapping period A Severely Concealed Second is defined as a non-overlapping period
of 1000 ms during which the cumulative amount of time that has of 1000 ms 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.
If the measured value exceeds 0xFFFD, the value 0xFFFE SHOULD be If the measured value exceeds 0xFFFD, the value 0xFFFE SHOULD 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 SHOULD be reported. measurement is unavailable, the value 0xFFFF SHOULD be reported.
RESERVED: 8 bits Reserved: 8 bits
These bits are reserved. They SHOULD be set to zero by senders These bits are reserved. They SHOULD be set to zero by senders
and MUST be ignored by receivers. and MUST be ignored by receivers.
SCS Threshold: 8 bits SCS Threshold: 8 bits
The SCS Threshold defines the amount of time corresponding to lost The SCS Threshold defines the amount of time corresponding to lost
or discarded frames that must occur within a one second period in or discarded frames that must occur within a one second period in
order for the second to be classified as a Severely Concealed order for the second to be classified as a Severely Concealed
Second. This is expressed in milliseconds and hence can represent Second. This is expressed in milliseconds and hence can represent
a range of 0.1 to 25.5 percent loss or discard. a range of 0.1 to 25.5 percent loss or discard.
A default threshold of 50ms (5% effective frame loss per second) A default threshold of 50ms (5% effective frame loss per second)
is suggested. is suggested.
3. SDP Signaling 4. 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.
4.1. SDP rtcp-xr-attrib Attribute Extension
This section augments the SDP [RFC4566] attribute "rtcp-xr" defined This section augments the SDP [RFC4566] attribute "rtcp-xr" defined
in [RFC3611] by providing an additional value of "xr-format" to in [RFC3611] by providing an additional value of "xr-format" to
signal the use of the report block defined in this document. signal the use of the report block defined in this document.
The SDP attribute for the block has an additional optional paremeter, The SDP attribute for the block has an additional optional paremeter,
"thresh", used to supply a value for the SCS Threshold parameter. If "thresh", used to supply a value for the SCS Threshold parameter. If
this parameter is present, the RTP system receiving the SDP SHOULD this parameter is present, the RTP system receiving the SDP SHOULD
use this value for the current session. If the parameter is not use this value for the current session. If the parameter is not
present, the RTP system SHOULD use a locally configured value. present, the RTP system SHOULD use a locally configured value.
rtcp-xr-attrib = "a=" "rtcp-xr" ":" [xr-format *(SP xr-format)] CRLF
(defined in [RFC3611])
xr-format =/ xr-conc-sec-block xr-format =/ xr-conc-sec-block
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 = <as defined in Section 3.4 of [RFC5234]>
4. IANA Considerations 4.2. Offer/Answer Usage
When SDP is used in offer-answer context, the SDP Offer/Answer usage
defined in [RFC3611] applies.
5. 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].
4.1. New RTCP XR Block Type value 5.1. New RTCP XR Block Type value
This document assigns the block type value NJB in the IANA "RTCP XR This document assigns the block type value NJB in the IANA "RTCP XR
Block Type Registry" to the "Concealed Seconds Metrics Block". Block Type Registry" to the "Concealed Seconds Metrics Block".
[Note to RFC Editor: please replace NCS with the IANA provided RTCP [Note to RFC Editor: please replace NCS with the IANA provided RTCP
XR block type for this block.] XR block type for this block.]
4.2. New RTCP XR SDP Parameter 5.2. New RTCP XR SDP Parameter
This document also registers a new parameter "conc-sec" in the "RTCP This document also registers a new parameter "conc-sec" in the "RTCP
XR SDP Parameters Registry". XR SDP Parameters Registry".
4.3. Contact information for registrations 5.3. Contact information for registrations
The contact information for the registrations is: The contact information for the registrations is:
Alan Clark (alan.d.clark@telchemy.com) Alan Clark (alan.d.clark@telchemy.com)
2905 Premiere Parkway, Suite 280 2905 Premiere Parkway, Suite 280
Duluth, GA 30097 Duluth, GA 30097
USA USA
5. Security Considerations 6. Security Considerations
It is believed that this proposed RTCP XR report block introduces no It is believed that this proposed RTCP XR report block introduces no
new security considerations beyond those described in [RFC3611]. new security considerations beyond those described in [RFC3611].
This block does not provide per-packet statistics so the risk to This block does not provide per-packet statistics so the risk to
confidentiality documented in Section 7, paragraph 3 of [RFC3611] confidentiality documented in Section 7, paragraph 3 of [RFC3611]
does not apply. does not apply.
6. Acknowledgements 7. Contributors
The authors gratefully acknowledge the comments and contributions Geoff Hunt wrote the initial draft of this document.
made by Bruce Adams, Philip Arden, Amit Arora, Bob Biskner, Kevin
Connor, Claus Dahm, Randy Ethier, Roni Even, Jim Frauenthal, Albert
Higashi, Tom Hock, Shane Holthaus, Paul Jones, Rajesh Kumar, Keith
Lantz, Mohamed Mostafa, Amy Pendleton, Colin Perkins, Mike Ramalho,
Ravi Raviraj, Albrecht Schwarz, Tom Taylor, and Hideaki Yamada.
7. References 8. Acknowledgements
7.1. Normative References The authors gratefully acknowledge reviews and feedback provided by
Bruce Adams, Philip Arden, Amit Arora, Bob Biskner, Kevin Connor,
Claus Dahm, Randy Ethier, Roni Even, Jim Frauenthal, Albert Higashi,
Tom Hock, Shane Holthaus, Paul Jones, Rajesh Kumar, Keith Lantz,
Mohamed Mostafa, Amy Pendleton, Colin Perkins, Mike Ramalho, Ravi
Raviraj, Albrecht Schwarz, Tom Taylor, and Hideaki Yamada.
9. References
9.1. 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", March 1997.
[RFC3550] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time [RFC3550] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time
Applications", RFC 3550, July 2003. Applications", 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)", 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", July 2006.
7.2. Informative References 9.2. Informative References
[MONARCH] Hunt, G., "Monitoring Architectures for RTP", [MONARCH] Hunt, G., "Monitoring Architectures for RTP",
ID draft-ietf-avtcore-monarch-04, August 2011. ID draft-ietf-avtcore-monarch-22, September 2012.
[RFC6390] Clark, A. and B. Claise, "Framework for Performance Metric [RFC6390] Clark, A. and B. Claise, "Framework for Performance Metric
Development", RFC 6390, October 2011. Development", RFC 6390, October 2011.
[VAD] "http://en.wikipedia.org/wiki/Voice_activity_detection".
Appendix A. Change Log Appendix A. 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.
A.1. draft-ietf-xrblock-rtcp-xr-concsec-00 A.1. draft-ietf-xrblock-rtcp-xr-concsec-01
The following are the major changes to previous version :
o Outdated references update.
o Add Editor's notes to point out where to require more texts for
video loss concealment support
o Other Editorial changes.
A.2. draft-ietf-xrblock-rtcp-xr-concsec-00
The following are the major changes to previous version : The following are the major changes to previous version :
o Updated references. o Updated references.
o Allocate two bits for interval metric flag and 32 bit for SSRC o Allocate two bits for interval metric flag and 32 bit for SSRC
o Other editorial changes to get in line with MONARCH and MeasID o Other editorial changes to get in line with MONARCH and MeasID
draft. draft.
Authors' Addresses Authors' Addresses
Geoff Hunt
Unaffiliated
Email: r.geoff.hunt@gmail.com
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
 End of changes. 42 change blocks. 
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