Audio/Video Transport Working Group A. Clark
Internet-Draft Telchemy
Intended status: Standards Track G. Zorn
Expires: October 13, 2014 Network Zen
C. Bi
STTRI
Q. Wu, Ed.
Huawei
April 11, 2014
RTCP XR Report Block for Concealment metrics Reporting on Audio
Applications
draft-ietf-xrblock-rtcp-xr-loss-conceal-12.txt
Abstract
This document defines two RTCP XR Report Blocks that allows the
reporting of concealment metrics for audio applications of RTP.
Status of this Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on October 13, 2014.
Copyright Notice
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include Simplified BSD License text as described in Section 4.e of
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Loss Concealment and Concealment Seconds Metrics
Reporting Block . . . . . . . . . . . . . . . . . . . . . 3
1.2. RTCP and RTCP XR Reports . . . . . . . . . . . . . . . . . 4
1.3. Performance Metrics Framework . . . . . . . . . . . . . . 4
1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Standards Language . . . . . . . . . . . . . . . . . . . . 5
2.2. Notations . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Loss Concealment Block . . . . . . . . . . . . . . . . . . . . 6
3.1. Report Block Structure . . . . . . . . . . . . . . . . . . 6
3.2. Definition of Fields in Loss Concealment Metrics Block . . 6
4. Concealment Seconds Block . . . . . . . . . . . . . . . . . . 11
4.1. Report Block Structure . . . . . . . . . . . . . . . . . . 11
4.2. Definition of Fields in Concealed Seconds Metrics Block . 12
5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 16
5.1. SDP rtcp-xr-attrib Attribute Extension . . . . . . . . . . 16
5.2. Offer/Answer Usage . . . . . . . . . . . . . . . . . . . . 16
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
6.1. New RTCP XR Block Type values . . . . . . . . . . . . . . 17
6.2. New RTCP XR SDP Parameters . . . . . . . . . . . . . . . . 17
6.3. Contact information for registrations . . . . . . . . . . 17
7. Security Considerations . . . . . . . . . . . . . . . . . . . 18
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 19
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 20
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
10.1. Normative References . . . . . . . . . . . . . . . . . . . 21
10.2. Informative References . . . . . . . . . . . . . . . . . . 21
Appendix A. Metrics represented using RFC6390 Template . . . . . 22
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
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1. Introduction
1.1. Loss Concealment and Concealment Seconds Metrics Reporting Block
At any instant, the audio output at a receiver may be classified as
either 'normal' or 'concealed'. 'Normal' refers to playout of audio
payload received from the remote end, and also includes locally
generated signals such as announcements, tones and comfort noise.
Concealment refers to playout of locally-generated signals used to
mask the impact of network impairments or to reduce the audibility of
jitter buffer adaptations.
This draft defines two new concealment related block types to augment
those defined in [RFC3611] for use in a range of RTP applications.
These two block types extend packet loss concealment mechanism
defined in section 4.7.6 of RFC3611.
The first block type provides metrics for actions taken by the
receiver to mitigate the effect of packet loss and packet discard.
Specifically, the first metric (On-Time Playout Duration) reports the
duration of normal playout of data which the receiver obtained from
the sender's stream. A second metric (Loss Concealment Duration)
reports the total time during which the receiver played out media
data which was manufactured locally, because the sender's data for
these periods was not available due to packet loss or discard. A
similar metric (Buffer Adjustment Concealment Duration) reports the
duration of playout of locally-manufactured data replacing data which
is unavailable due to adaptation of an adaptive de-jitter buffer.
Further metrics (Playout Interrupt Count and Mean Playout Interrupt
Size) report the number of times normal playout was interrupted, and
the mean duration of these interruptions.
Loss Concealment Duration and Buffer Adjustment Concealment Duration
are reported separately because buffer adjustment is typically
arranged to occur in silence periods so may have very little impact
on user experience, whilst loss concealment may occur at any time.
The second block type provides metrics for concealment seconds, which
are measured at the receiving end of the RTP stream. Specifically,
the first metric (Unimpaired Seconds) reports the number of whole
seconds occupied only with normal playout of data which the receiver
obtained from the sender's stream. The second metric (Concealed
Seconds) reports the number of whole seconds during which the
receiver played out any locally-generated media data. A third
metric, Severely Concealed Seconds (SCS), reports the number of whole
seconds during which the receiver played out locally-generated data
for more than SCS Threshold.
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These metrics belongs to the class of transport-related terminal
metrics defined in [RFC6792].
1.2. RTCP and RTCP XR Reports
The use of RTCP for reporting is defined in [RFC3550]. [RFC3611]
defined an extensible structure for reporting using an RTCP Extended
Report (XR). This draft defines a new Extended Report block that
MUST be used as defined in [RFC3550] and [RFC3611].
1.3. Performance Metrics Framework
The Performance Metrics Framework [RFC6390] provides guidance on the
definition and specification of performance metrics. The RTP
Monitoring Architectures [RFC6792] provides guideline for reporting
block format using RTCP XR. The Metrics Block described in this
document are in accordance with those guidelines.
1.4. Applicability
These metrics are applicable to audio applications of RTP and the
audio component of Audio/Video applications in which the packet loss
concealment machinery is contained at the receiving end to mitigate
the impact of network impairments to user's perception of media
quality.
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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 RFC2119 [RFC2119].
2.2. Notations
This report block makes use of binary fractions. The terminology
used is
Numeric formats S X:Y
where S indicates a two's complement signed representation, X
the number of bits prior to the decimal place and Y the number
of bits after the decimal place.
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
range -127.996 to +127.996. 0:16 represents a proper binary
fraction with range
0.0 to 1 - 1/65536 = 0.9999847
though note that use of flag values at the top of the numeric
range slightly reduces this upper limit. For example, if the
16- bit values 0xfffe and 0xffff are used as flags for "over-
range" and "unavailable" conditions, a 0:16 quantity has range
0.0 to 1 - 3/65536 = 0.9999542
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3. Loss Concealment Block
The metrics block described here are intended to be used as described
in this section, in conjunction with information from the Measurement
Information block [RFC6776]. Instances of this Metrics Block refer
by Synchronization source (SSRC) to the separate auxiliary
Measurement Information block [RFC6776] which describes measurement
periods in use (see [RFC6776] section 4.2). This Metrics Block
relies on the measurement period in the Measurement Information block
indicating the span of the report and SHOULD be sent in the same
compound RTCP packet as the measurement information block. If the
measurement period is not received in the same compound RTCP packet
as this Metrics Block, this metrics block MUST be discarded.
3.1. Report Block Structure
Loss Concealment Metrics Block
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BT=NLC | I |plc| rsv. | block length=6 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of Source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| On-time Playout Duration |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Loss Concealment Duration |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Buffer Adjustment Concealment Duration |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Playout Interrupt Count | Reserved. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mean Playout Interrupt Size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Report Block Structure
3.2. Definition of Fields in Loss Concealment Metrics Block
Block type (BT): 8 bits
A Loss Concealment Metrics Report Block is identified by the
constant NLC.
[Note to RFC Editor: please replace NLC with the IANA provided
RTCP XR block type for this block.]
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Interval Metric flag (I): 2 bit
This field is used to indicate whether the Loss Concealment
metrics are Sampled, Interval or Cumulative metrics:
I=10: Interval Duration - the reported value applies to the
most recent measurement interval duration between successive
metrics reports.
I=11: Cumulative Duration - the reported value applies to the
accumulation period characteristic of cumulative measurements.
I=01: Sampled Value - the reported value is a sampled
instantaneous value ( Not allowed in this block).
I=00: Reserved value- this value is reserved for future use.
In this document, Loss Concealment Metrics can only be measured
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
I=01, the receiver MUST discard the block.
Packet Loss Concealment Method (plc): 2 bits
This field is used to identify the packet loss concealment method
in use at the receiver, according to the following code:
bits 014-015
0 = silence insertion
1 = simple replay, no attenuation
2 = simple replay, with attenuation
3 = enhancement
Other values reserved
Note that the enhancement method (plc =3 ) for packet loss
concealment offers an improved audio quality and a better
robustness against packet losses [G.711] and is equivalent to
enhanced in section 4.7.6 of [RFC3611].
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Reserved (resv): 4 bits
These bits are reserved. They MUST be set to zero by senders and
ignored by receivers (See [RFC6709] section 4.2).
block length: 16 bits
The length of this report block in 32-bit words, minus one. For
the Loss Concealment Block, the block length is equal to 6.
SSRC of source: 32 bits
As defined in Section 4.1 of [RFC3611].
On-time Playout Duration: 32 bits
'On-time' playout is the uninterrupted, in-sequence playout of
valid decoded audio information originating from the remote
endpoint. This includes comfort noise during periods of remote
talker silence, if VAD [VAD] is used, and locally generated or
regenerated tones and announcements.
An equivalent definition is that on-time playout is playout of any
signal other than those used for concealment.
On-time playout duration is expressed in units of RTP timestamp
and MUST include both speech and silence intervals, whether VAD is
used or not.
Two values are reserved: A value of 0xFFFFFFFE indicates out of
range (that is, a measured value exceeding 0xFFFFFFFD) and a value
of 0xFFFFFFFF indicates that the measurement is unavailable.
Loss Concealment Duration: 32 bits
The duration, expressed in units of RTP timestamp, of audio
playout corresponding to Loss-type concealment.
Loss-type concealment is reactive insertion or deletion of samples
in the audio playout stream due to effective frame loss at the
audio decoder. "Effective frame loss" is the event in which a
frame of coded audio is simply not present at the audio decoder
when required. In this case, substitute audio samples are
generally formed, at the decoder or elsewhere, to reduce audible
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impairment.
Two values are reserved: A value of 0xFFFFFFFE indicates out of
range (that is, a measured value exceeding 0xFFFFFFFD) and a value
of 0xFFFFFFFF indicates that the measurement is unavailable.
Buffer Adjustment Concealment Duration: 32 bits
The duration, expressed in units of RTP timestamp, of audio
playout corresponding to Buffer Adjustment-type concealment, if
known.
Buffer Adjustment-type concealment is proactive or controlled
insertion or deletion of samples in the audio playout stream due
to jitter buffer adaptation, re-sizing or re-centering decisions
within the endpoint.
Because this insertion is controlled, rather than occurring
randomly in response to losses, it is typically less audible than
loss-type concealment. For example, jitter buffer adaptation
events may be constrained to occur during periods of talker
silence, in which case only silence duration is affected, or
sophisticated time-stretching methods for insertion/deletion
during favorable periods in active speech may be employed.
Concealment events which cannot be classified as Buffer
Adjustment-type MUST be classified as Loss-type.
Two values are reserved: A value of 0xFFFFFFFE indicates out of
range (that is, a measured value exceeding 0xFFFFFFFD) and a value
of 0xFFFFFFFF indicates that the measurement is unavailable.
Playout Interrupt Count: 16 bits
The number of interruptions to normal playout which occurred
during the reporting period.
Two values are reserved: A value of 0xFFFE indicates out of range
(that is, a measured value exceeding 0xFFFD) and a value of 0xFFFF
indicates that the measurement is unavailable.
Reserved (resv): 16 bits
These bits are reserved. They MUST be set to zero by senders and
ignored by receivers (See [RFC6709] section 4.2).
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Mean Playout Interrupt Size: 32 bits
The mean duration, expressed in units of RTP timestamp, of
interruptions to normal playout which occurred during the
reporting period.
Two values are reserved: A value of 0xFFFFFFFE indicates out of
range (that is, a measured value exceeding 0xFFFFFFFD) and a value
of 0xFFFFFFFF indicates that the measurement is unavailable.
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4. Concealment Seconds Block
This sub-block described here is intended to be used as described in
this section, in conjunction with information from the Measurement
Information block [RFC6776] and provides a description of potentially
audible impairments due to lost and discarded packets at the
endpoint, expressed on a time basis analogous to a traditional PSTN
T1/E1 errored seconds metric. Instances of this Metrics Block refer
by Synchronization source (SSRC) to the separate auxiliary
Measurement Information block [RFC6776] which describes measurement
periods in use (see [RFC6776] section 4.2). This Metrics Block
relies on the measurement period in the Measurement Information block
indicating the span of the report and SHOULD be sent in the same
compound RTCP packet as the measurement information block. If the
measurement period is not 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
declared by a RTP clock. This RTP clock does not need to be
synchronized to any external time reference. The starting time of
this clock is unspecified. Note that this implies that the same loss
pattern could result in slightly different count values, depending on
where the losses occur relative to the particular one-second
demarcation points. For example, two loss events occurring 50ms
apart could result in either one concealed second or two, depending
on the particular one second boundaries used.
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
shall be incorporated into these counts if they exceed 500ms and
shall be disregarded if they are less than 500ms.
4.1. Report Block Structure
Concealed Seconds Metrics Block
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BT=NCS | I |plc|Rserved| block length=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of Source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Unimpaired Seconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Concealed Seconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Severely Concealed Seconds | RESERVED | SCS Threshold |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Report Block Structure
4.2. Definition of Fields in Concealed Seconds Metrics Block
Block type (BT): 8 bits
A Concealed Seconds Metrics Report Block is identified by the
constant NCS.
[Note to RFC Editor: please replace NCS with the IANA provided
RTCP XR block type for this block.]
Interval Metric flag (I): 2 bit
This field is used to indicate whether the Concealment Seconds
Metrics are Sampled, Interval or Cumulative metrics:
I=10: Interval Duration - the reported value applies to the
most recent measurement interval duration between successive
metrics reports.
I=11: Cumulative Duration - the reported value applies to the
accumulation period characteristic of cumulative measurements.
I=01: Sampled Value - the reported value is a sampled
instantaneous value (Not allowed in this block).
I=00: Reserved value- this value is reserved for future use.
In this document, Concealment Seconds Metrics can only be measured
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
I=01, the receiver MUST discard the block.
Packet Loss Concealment Method (plc): 2 bits
This field is used to identify the packet loss concealment method
in use at the receiver, according to the following code:
bits 014-015
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0 = silence insertion
1 = simple replay, no attenuation
2 = simple replay, with attenuation
3 = enhancement
Other values reserved
Note that the enhancement method (plc =3 ) for packet loss
concealment offers an improved audio quality and a better
robustness against packet losses [G.711] and is equivalent to
enhanced in section 4.7.6 of [RFC3611].
Reserved (resv): 4 bits
These bits are reserved. They MUST be set to zero by senders and
ignored by receivers (See [RFC6709] section 4.2).
Block Length: 16 bits
The length of this report block in 32-bit words, minus one. For
the Concealment Seconds Block, the block length is equal to 4.
SSRC of source: 32 bits
As defined in Section 4.1 of [RFC3611].
Unimpaired Seconds: 32 bits
A count of the number of unimpaired Seconds that have occurred.
An unimpaired Second is defined as a continuous period of one
second during which no frame loss or discard due to late arrival
has occurred. Every second in a session must be classified as
either OK or Concealed.
Normal playout of comfort noise or other silence concealment
signal during periods of talker silence, if VAD is used, shall be
counted as unimpaired seconds.
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Two values are reserved: A value of 0xFFFFFFFE indicates out of
range (that is, a measured value exceeding 0xFFFFFFFD) and a value
of 0xFFFFFFFF indicates that the measurement is unavailable.
Concealed Seconds: 32 bits
A count of the number of Concealed Seconds that have occurred.
A Concealed Second is defined as a continuous period of one second
during which any frame loss or discard due to late arrival has
occurred.
Equivalently, a concealed second is one in which some Loss-type
concealment has occurred. Buffer adjustment-type concealment
SHOULD NOT cause Concealed Seconds to be incremented, with the
following exception. An implementation MAY cause Concealed
Seconds to be incremented for 'emergency' buffer adjustments made
during talkspurts.
Loss-type concealment is reactive insertion or deletion of samples
in the audio playout stream due to effective frame loss at the
audio decoder. "Effective frame loss" is the event in which a
frame of coded audio is simply not present at the audio decoder
when required. In this case, substitute audio samples are
generally formed, at the decoder or elsewhere, to reduce audible
impairment.
Buffer Adjustment-type concealment is proactive or controlled
insertion or deletion of samples in the audio playout stream due
to jitter buffer adaptation, re-sizing or re-centering decisions
within the endpoint.
Because this insertion is controlled, rather than occurring
randomly in response to losses, it is typically less audible than
loss-type concealment. For example, jitter buffer adaptation
events may be constrained to occur during periods of talker
silence, in which case only silence duration is affected, or
sophisticated time-stretching methods for insertion/deletion
during favorable periods in active speech may be employed. For
these reasons, buffer adjustment-type concealment MAY be exempted
from inclusion in calculations of Concealed Seconds and Severely
Concealed Seconds.
However, an implementation SHOULD include buffer-type concealment
in counts of Concealed Seconds and Severely Concealed Seconds if
the event occurs at an 'inopportune' moment, with an emergency or
large, immediate adaptation during active speech, or for
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unsophisticated adaptation during speech without regard for the
underlying signal, in which cases the assumption of low-audibility
cannot hold. In other words, jitter buffer adaptation events
which may be presumed to be audible SHOULD be included in
Concealed Seconds and Severely Concealed Seconds counts.
Concealment events which cannot be classified as Buffer
Adjustment- type MUST be classified as Loss-type.
For clarification, the count of Concealed Seconds MUST include the
count of Severely Concealed Seconds.
Two values are reserved: A value of 0xFFFFFFFE indicates out of
range (that is, a measured value exceeding 0xFFFFFFFD) and a value
of 0xFFFFFFFF indicates that the measurement is unavailable.
Severely Concealed Seconds: 16 bits
A count of the number of Severely Concealed Seconds.
A Severely Concealed Second is defined as a non-overlapping period
of one second during which the cumulative amount of time that has
been subject to frame loss or discard due to late arrival, exceeds
the SCS Threshold.
Two values are reserved: A value of 0xFFFE indicates out of range
(that is, a measured value exceeding 0xFFFD) and a value of 0xFFFF
indicates that the measurement is unavailable.
Reserved: 8 bits
These bits are reserved. They MUST be set to zero by senders and
ignored by receivers (See [RFC6709] section 4.2).
SCS Threshold: 8 bits
The SCS Threshold is defined as the percentage of packets
corresponding to lost or discarded frames that must occur within a
one second period in order for the second to be classified as a
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
discard.
A default threshold of 5% effective frame loss (50ms effective
frame loss ) per second is suggested. This corresponds to an SCS
Threshold in hexadecimal of 0x0D.
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5. SDP Signaling
[RFC3611] defines the use of SDP (Session Description Protocol)
[RFC4566] for signaling the use of XR blocks. XR blocks MAY be used
without prior signaling.
5.1. SDP rtcp-xr-attrib Attribute Extension
This section augments the SDP attribute "rtcp-xr" [RFC3611] by
providing two additional values of "xr-format" to signal the use of
two report blocks defined in this document.
xr-format =/ xr-conceal-block
/ xr-conc-sec-block
xr-conceal-block = "loss-conceal"
xr-conc-sec-block = "conc-sec" ["=" thresh]
thresh = 1*DIGIT ; threshold for SCS (ms)
DIGIT = <as defined in Section 3 of [RFC5234]>
5.2. 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
offer.
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6. IANA Considerations
New block types for RTCP XR are subject to IANA registration. For
general guidelines on IANA considerations for RTCP XR, refer to
[RFC3611].
6.1. New RTCP XR Block Type values
This document assigns two block type values in the IANA "RTP Control
Protocol Extended Reports (RTCP XR) Block Type Registry ":
Name: LCB
Long Name: Loss Concealment Block
Value <NLC>
Reference: Section 3.1
Name: CSB
Long Name: Concealment Seconds Block
Value <NCS>
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
This document also registers two new parameters in the "RTP Control
Protocol Extended Reports (RTCP XR) Session Description Protocol
(SDP) Parameters Registry":
o "loss-conceal"
o "conc-sec"
6.3. Contact information for registrations
The contact information for the registrations is:
RAI Area Directors
rai-ads@tools.ietf.org
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7. Security Considerations
It is believed that this proposed RTCP XR report block introduces no
new security considerations beyond those described in [RFC3611].
This block does not provide per-packet statistics so the risk to
confidentiality documented in Section 7, paragraph 3 of [RFC3611]
does not apply.
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8. Contributors
Geoff Hunt wrote the initial draft of this document.
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9. Acknowledgements
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, Hideaki Yamada ,Alissa
Cooper,Meral Shirazipour and ,MORTON, ALFRED C (AL),Adrian Farrel and
Pete Resnick.
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10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", March 1997.
[RFC3550] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time
Applications", RFC 3550, July 2003.
[RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control
Protocol Extended Reports (RTCP XR)", November 2003.
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", July 2006.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 5234, January 2008.
[RFC6776] Wu, Q., "Measurement Identity and information Reporting
using SDES item and XR Block", RFC 6776, August 2012.
10.2. Informative References
[RFC6390] Clark, A. and B. Claise, "Framework for Performance Metric
Development", RFC 6390, October 2011.
[RFC6709] Carpenter, B., Aboba, B., and S. Cheshire, "Design
Considerations for Protocol Extensions", RFC 6709,
September 2012.
[RFC6792] Hunt, G., "Monitoring Architectures for RTP", RFC 6792,
November 2012.
[VAD] "http://en.wikipedia.org/wiki/Voice_activity_detection".
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Appendix A. Metrics represented using RFC6390 Template
RFC EDITOR NOTE: please change XXXX in [RFCXXXX] by the new RFC
number, when assigned.
a. On-time Playout Duration Metric
* Metric Name: On-time Playout Duration
* Metric Description: 'On-time' playout is the uninterrupted,
in-sequence playout of valid decoded audio information
originating from the remote endpoint. On-time playout
Duration is playout duration of any signal other than those
used for concealment
* Method of Measurement or Calculation: See section 3. 2, On-
time Playout Duration definition [RFCXXXX].
* Units of Measurement: See section 3.2, On-time Playout
Duration definition [RFCXXXX].
* Measurement Point(s) with Potential Measurement Domain: See
section 1.1, 3rd paragraph [RFCXXXX].
* Measurement Timing: See section 3, 1st paragraph [RFCXXXX] for
measurement timing and section 3.2 [RFCXXXX] for Interval
Metric flag.
* Use and applications: See section 1.4 [RFCXXXX].
* Reporting model: See RFC3611.
b. Loss Concealment Duration Metric
* Metric Name: Loss Concealment Duration
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* Metric Description: The duration of audio playout
corresponding to Loss-type concealment.
* Method of Measurement or Calculation: See section 3.2, Loss
Concealment Duration definition [RFCXXXX].
* Units of Measurement: See section 3.2, Loss Concealment
Duration definition [RFCXXXX].
* Measurement Point(s) with Potential Measurement Domain: See
section 1.1, 3rd paragraph [RFCXXXX].
* Measurement Timing: See section 3, 1st paragraph [RFCXXXX] for
measurement timing and section 3. 2 [RFCXXXX] for Interval
Metric flag.
* Use and applications: See section 1.4 [RFCXXXX].
* Reporting model: See RFC3611.
c. Buffer Adjustment Concealment Duration Metric
* Metric Name: Buffer Adjustment Concealment Duration
* Metric Description: The duration of audio playout
corresponding to Buffer Adjustment-type concealment.
* Method of Measurement or Calculation: See section 3. 2, Buffer
Adjustment Concealment Duration definition [RFCXXXX].
* Units of Measurement: See section 3.2, Buffer Adjustment
Concealment Duration definition [RFCXXXX].
* Measurement Point(s) with Potential Measurement Domain: See
section 1.1, 3rd paragraph [RFCXXXX].
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* Measurement Timing: See section 3, 1st paragraph [RFCXXXX] for
measurement timing and section 3.2 [RFCXXXX] for Interval
Metric flag.
* Use and applications: See section 1.4 [RFCXXXX].
* Reporting model: See RFC3611.
d. Playout Interrupt Count Metric
* Metric Name: Playout Interrupt Count
* Metric Description: The number of interruptions to normal
playout which occurred during the reporting period.
* Method of Measurement or Calculation: See section 3. 2,
Playout Interrupt Count definition [RFCXXXX].
* Units of Measurement: See section 3.2, Playout Interrupt Count
definition [RFCXXXX].
* Measurement Point(s) with Potential Measurement Domain: See
section 1.1, 3rd paragraph [RFCXXXX].
* Measurement Timing: See section 3, 1st paragraph [RFCXXXX] for
measurement timing and section 3.2 [RFCXXXX] for Interval
Metric flag.
* Use and applications: See section 1.4 [RFCXXXX].
* Reporting model: See RFC3611.
e. Mean Playout Interrupt Size Metric
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* Metric Name: Mean Playout Interrupt Size
* Metric Description: The mean duration of interruptions to
normal playout which occurred during the reporting period.
* Method of Measurement or Calculation: See section 3. 2,
Playout Interrupt Count definition [RFCXXXX].
* Units of Measurement: See section 3.2, Playout Interrupt Count
definition [RFCXXXX].
* Measurement Point(s) with Potential Measurement Domain: See
section 1.1, 3rd paragraph [RFCXXXX].
* Measurement Timing: See section 3, 1st paragraph [RFCXXXX] for
measurement timing and section 3.2 [RFCXXXX] for Interval
Metric flag.
* Use and applications: See section 1.4 [RFCXXXX].
* Reporting model: See RFC3611.
f. Unimpaired Seconds Metric
* Metric Name: Unimpaired Seconds
* Metric Description: A count of the number of unimpaired
Seconds that have occurred.
* Method of Measurement or Calculation: See section 4. 2,
Unimpaired Seconds definition [RFCXXXX].
* Units of Measurement: See section 4.2, Unimpaired Seconds
definition [RFCXXXX].
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* Measurement Point(s) with Potential Measurement Domain: See
section 1.1, 5th paragraph [RFCXXXX].
* Measurement Timing: See section 4, 1st paragraph [RFCXXXX] for
measurement timing and section 4.2 paragraph [RFCXXXX] for
Interval Metric flag.
* Use and applications: See section 1.4 [RFCXXXX].
* Reporting model: See RFC3611.
g. Concealed Seconds Metric
* Metric Name: Concealed Seconds
* Metric Description: A count of the number of Concealed Seconds
that have occurred.
* Method of Measurement or Calculation: See section 4. 2,
Concealed Seconds definition [RFCXXXX].
* Units of Measurement: See section 4.2, Concealed Seconds
definition [RFCXXXX].
* Measurement Point(s) with Potential Measurement Domain: See
section 1.1, 5th paragraph [RFCXXXX].
* 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.
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h. Severely Concealed Seconds Metric
* Metric Name: Severely Concealed Seconds
* Metric Description: A count of the number of Severely
Concealed Seconds that have occurred.
* Method of Measurement or Calculation: See section 4. 2,
Severely Concealed Seconds definition [RFCXXXX].
* Units of Measurement: See section 4.2, Severely Concealed
Seconds definition [RFCXXXX].
* Measurement Point(s) with Potential Measurement Domain: See
section 1.1, 5th paragraph [RFCXXXX].
* 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.
i. SCS Threshold Metric
* Metric Name: SCS Threshold
* Metric Description: The amount of time corresponding to lost
or discarded frames that must occur within a one second period
in order for the second to be classified as a Severely
Concealed Second.
* Method of Measurement or Calculation: See section 4. 2, SCS
Threshold definition [RFCXXXX].
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* Units of Measurement: See section 4.2, SCS Threshold
definition [RFCXXXX].
* Measurement Point(s) with Potential Measurement Domain: See
section 1.1, 5th paragraph [RFCXXXX].
* 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.
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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 :
o Merge Concealment Seconds draft into this draft (i.e.,Loss
Concealment draft).
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o Updated references.
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Authors' Addresses
Alan Clark
Telchemy Incorporated
2905 Premiere Parkway, Suite 280
Duluth, GA 30097
USA
Email: alan.d.clark@telchemy.com
Glen Zorn
Network Zen
77/440 Soi Phoomjit, Rama IV Road
Phra Khanong, Khlong Toie
Bangkok 10110
Thailand
Phone: +66 (0) 87 502 4274
Email: gwz@net-zen.net
Claire Bi
Shanghai Research Institure of China Telecom Corporation Limited
No.1835,South Pudong Road
Shanghai 200122
China
Email: bijy@sttri.com.cn
Qin Wu (editor)
Huawei
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
Email: sunseawq@huawei.com
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