Internet DRAFT - draft-ietf-xrblock-rtcp-xr-qoe
draft-ietf-xrblock-rtcp-xr-qoe
Network Working Group A. Clark
Internet-Draft Telchemy
Intended status: Standards Track Q. Wu
Expires: August 31, 2014 Huawei
R. Schott
Deutsche Telekom
G. Zorn
Network Zen
February 27, 2014
RTP Control Protocol (RTCP) Extended Report (XR) Blocks for MOS Metric
Reporting
draft-ietf-xrblock-rtcp-xr-qoe-17
Abstract
This document defines an RTP Control Protocol (RTCP) Extended Report
(XR) Block including two new segment types and associated SDP
parameters that allow the reporting of mean opinion score (MOS)
Metrics for use in a range of RTP applications.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 31, 2014.
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. MOS Metrics Report Block . . . . . . . . . . . . . . . . . 4
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
3. MoS Metrics Block . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Report Block Structure . . . . . . . . . . . . . . . . . . 6
3.2. Definition of Fields in MoS Metrics Block . . . . . . . . 7
3.2.1. Single Channel audio/video per SSRC Segment . . . . . 8
3.2.2. Multi-Channel audio per SSRC Segment . . . . . . . . . 9
4. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 11
4.1. SDP rtcp-xr-attrib Attribute Extension . . . . . . . . . . 11
4.2. Offer/Answer Usage . . . . . . . . . . . . . . . . . . . . 13
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
5.1. New RTCP XR Block Type value . . . . . . . . . . . . . . . 15
5.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 15
5.3. The SDP calgextmap Attribute . . . . . . . . . . . . . . . 15
5.4. New registry of calculation algorithms . . . . . . . . . . 16
6. Security Considerations . . . . . . . . . . . . . . . . . . . 17
7. Authors . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 17
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
9.1. Normative References . . . . . . . . . . . . . . . . . . . 18
9.2. Informative References . . . . . . . . . . . . . . . . . . 18
Appendix A. Metrics represented using RFC6390 Template . . . . . 20
Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 23
B.1. draft-ietf-xrblock-rtcp-xr-qoe-15 . . . . . . . . . . . . 23
B.2. draft-ietf-xrblock-rtcp-xr-qoe-14 . . . . . . . . . . . . 23
B.3. draft-ietf-xrblock-rtcp-xr-qoe-10 . . . . . . . . . . . . 23
B.4. draft-ietf-xrblock-rtcp-xr-qoe-09 . . . . . . . . . . . . 23
B.5. draft-ietf-xrblock-rtcp-xr-qoe-08 . . . . . . . . . . . . 23
B.6. draft-ietf-xrblock-rtcp-xr-qoe-07 . . . . . . . . . . . . 24
B.7. draft-ietf-xrblock-rtcp-xr-qoe-06 . . . . . . . . . . . . 24
B.8. draft-ietf-xrblock-rtcp-xr-qoe-04 . . . . . . . . . . . . 24
B.9. draft-ietf-xrblock-rtcp-xr-qoe-03 . . . . . . . . . . . . 24
B.10. draft-ietf-xrblock-rtcp-xr-qoe-02 . . . . . . . . . . . . 24
B.11. draft-ietf-xrblock-rtcp-xr-qoe-01 . . . . . . . . . . . . 24
B.12. draft-ietf-xrblock-rtcp-xr-qoe-00 . . . . . . . . . . . . 25
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 25
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1. Introduction
1.1. MOS Metrics Report Block
This document defines a new block type to augment those defined in
[RFC3611], for use in a range of RTP applications.
The new block type provides information on media quality using one of
several standard metrics (i.e. Mean Opinion Score(MOS)).
The metrics belong to the class of application level 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 document defines a new Extended Report block for
use with [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 guidelines for reporting
block format using RTCP XR. The XR block type described in this
document are in accordance with the guidelines in [RFC6390] and
[RFC6792].
1.4. Applicability
The MOS Metrics Report Block can be used in any application of RTP
for which QoE (Quality of Experience) measurement algorithms are
defined.
The factors that affect real-time audio/video application quality can
be split into two categories. The first category consists of
transport-specific factors such as packet loss, delay and jitter
(which also translates into losses in the playback buffer). The
factors in the second category consists of content and codec related
factors such as codec type and loss recovery technique, coding bit
rate, packetization scheme, and content characteristics
Transport-specific factors may be insufficient to infer real time
media quality as codec related parameters and the interaction between
transport problems and application layer protocols can have a
substantial effect on observed media quality. Media quality may be
measured using algorithm that directly compare input and output media
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streams, or may be estimated using algorithms that model the
interaction between media quality, protocol and encoded content.
Media quality is commonly expressed in terms of Mean Opinion Score
(MOS) however is also represented by a range of indexes and other
scores.
The measurement of media quality has a number of applications:
o Detecting problems with media delivery or encoding that is
impacting user perceived quality.
o Tuning the content encoder algorithm to satisfy real time data
quality requirements.
o Determining which system techniques to use in a given situation
and when to switch from one technique to another as system
parameters change (for example as discussed in [P.1082]).
o Pre-qualifying a network to assess its ability to deliver an
acceptable end-user perceived quality level.
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].
The terminology used is
Numeric formats X:Y
where 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. 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
3. MoS Metrics Block
Multimedia application MOS Metric is commonly expressed as a MOS
("Mean Opinion Score"), MOS is usually on a scale from 1 to 5, in
which 5 represents excellent and 1 represents unacceptable however
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can use other ranges (for example 0 to 10 ) . The term "MOS score"
originates from subjective testing, and is used to refer to the Mean
of a number of individual Opinion Scores. There is therefore a well
understood relationship between MOS and user experience, hence the
industry commonly uses MOS as the scale for objective test results.
Subjective tests can be used for measuring live network traffic
however the use of objective or algorithmic measurement techniques
allows much larger scale measurements to be made. Within the scope
of this document, MOS scores are obtained using objective or
estimation algorithms. ITU-T or ITU-R recommendations (e.g.,
[BS.1387-1],[G.107],[G.107.1],[P.862],[P.862.1],[P.862.2],[P.863],[P.
564],[G.1082],[P.1201.1],[P.1201.2],[P.1202.1],[P.1202.2]) define
methodologies for assessment of the performance of audio and video
streams. Other international and national standards organizations
such as EBU, ETSI, IEC and IEEE also define QoE algorithms and
methodologies, and the intent of this document is not to restrict its
use to ITU recommendations but to suggest that ITU recommendations be
used where they are defined.
This block reports the media quality in the form of a MOS range
(e.g., 1-5, 0-10, or 0-100, as specified by the calculation
algorithm) however does not report the MoS score that include
parameters outside the scope of the RTP stream, for example signaling
performance, mean time to repair (MTTR) or other factors that may
affect the overall user experience.
The MOS Metric reported in this block gives a numerical indication of
the perceived quality of the received media stream, which is
typically measured at the receiving end of the RTP stream. 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.
Senders MUST send this block in the same compound RTCP packet as the
measurement information block. Receivers MUST verify that the
measurement period is received in the same compound RTCP packet as
this Metrics Block. If not, this Metrics Block MUST be discarded.
3.1. Report Block Structure
The MOS Metrics Block has the following format:
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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=MMB | I | Reserved | Block Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
..................
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.2. Definition of Fields in MoS Metrics Block
Block type (BT): 8 bits
The MOS Metrics Block is identified by the constant <MMB>.
Interval Metric flag (I): 2 bits
This field is used to indicate whether the MOS Metrics are
Sampled, Interval or Cumulative [RFC6792]:
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.
I=00: Reserved
In this document, MOS Metrics MAY be reported for intervals or for
the duration of the media stream (cumulative). The value I=01,
indicating a sampled value, MUST NOT be sent, and MUST be
discarded when received.
Reserved: 6 bits
This field is reserved for future definition. In the absence of
such a definition, the bits in this field MUST be set to zero and
ignored by the receiver (See RFC6709 section 4.2).
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Block Length: 16 bits
The length of this report block in 32-bit words, minus one. For
the MOS Metrics Block, the block length is variable length.
SSRC of source: 32 bits
As defined in Section 4.1 of [RFC3611].
Segment i: 32 bits
There are two segment types defined in this document: single
stream Audio/Video per SSRC segment, multi-channel audio per SSRC
segment. Multi-channel audio per SSRC segment is used to deal
with the case where Multi-channel audios are carried in one RTP
stream while single channel Audio/Video per SSRC segment is used
to deal with the case where each media stream is identified by
SSRC and sent in separate RTP stream. The leftmost bit of the
segment determines its type. If the leftmost bit of the segment
is zero, then it is single channel segment. If the leftmost bit
is one, then it is multi-channel audio segment. Note that two
segment types can not be present in the same metric block.
3.2.1. Single Channel audio/video per SSRC Segment
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|S| CAID | PT | MOS Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Segment Type (S): 1 bit
This field is used to identify the segment type used in this
report block. A zero identifies this as a single channel Audio/
Video per SSRC segment. Single channel means there is only one
media stream carried in one RTP stream. The single channel Audio/
Video per SSRC segment can be used to report the MOS value
associated with the media stream identified by SSRC. If there are
multiple media streams and they want to use the single channel
Audio/Video per SSRC segment to report the MOS value, they should
be carried in the separate RTP streams with each identified by
different SSRC. In this case, multiple MOS Metrics Blocks are
required to report the MOS value corresponding to each media
stream using single channel Audio/Video per SSRC segment in the
same RTCP XR packet.
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Calculation Algorithm ID (CAID) : 8 bits
The 8-bit CAID is the session specific reference to the
calculation algorithm and associated qualifiers indicated in SDP
(see Section 4.1) and used to compute the MOS score for this
segment.
Payload Type (PT): 7 bits
MOS Metrics reporting depends on the payload format in use. This
field identifies the RTP payload type in use during the reporting
interval. The binding between RTP payload types and RTP payload
formats is configured via a signalling protocol, for example an
SDP offer/answer exchange. If the RTP payload type used is
changed during an RTP session, separate reports SHOULD be sent for
each RTP payload type, with corresponding measurement information
blocks indicating the time period to which they relate.
Note that the use of this Report Block with MPEG Transport streams
carried over RTP is undefined as each MPEG Transport stream may
use distinct audio or video codecs and the indication of the
encoding of these is within the MPEG Transport stream and does not
use RTP payloads.
MOS Value: 16 bits
The estimated Mean Opinion Score (MOS) for multimedia application
performance is defined as including the effects of delay, loss,
discard, jitter and other effects that would affect media quality.
This is a unsigned fixed-point 7:9 value representing the MOS,
allowing the MOS score up to 127 in the integer part. MOS ranges
are defined as part of the specification of the MOS estimation
algorithm (Calculation Algorithm in this document), and are
normally ranges like 1-5, 0-10, or 0-100. Two values are
reserved: A value of 0xFFFE indicates out of range and a value of
0xFFFF indicates that the measurement is unavailable. Values
outside of the range defined by the Calculation Algorithm, other
than the two reserved values, MUST NOT be sent and MUST be ignored
by the receiving system.
3.2.2. Multi-Channel audio per SSRC Segment
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|S| CAID | PT |CHID | MOS Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Segment Type (S): 1 bit
This field is used to identify the segment type used in this
report block. A one identifies this as a multi-channel audio
segment.
Calculation Algorithm ID (CAID) : 8 bits
The 8-bit CAID is the session specific reference to the
calculation algorithm and associated qualifiers indicated in SDP
(see Section 4.1) and used to compute the MOS score for this
segment.
Payload Type (PT): 7 bits
As defined in Section 3.2.1 of this document
Channel Identifier (CHID): 3 bits
If multiple channels of audio are carried in one RTP stream, each
channel of audio will be viewed as a independent channel(e.g.,
left channel audio, right channel audio). This field is used to
identify each channel carried in the same media stream. The
default Channel mapping follows static ordering rule described in
the section 4.1 of [RFC3551]. However there are some payload
formats that use different channel mappings, e.g., AC-3 audio over
RTP [RFC4184] only follow AC-3 channel order scheme defined in
[ATSC]. Enhanced AC-3 Audio over RTP [RFC4598] uses dynamic
channel transform mechanism. In order that the appropriate
channel mapping can be determined, MOS metrics reports need to be
tied to an RTP payload format, i.e., including the payload type of
the reported media according to [RFC6792] and using Payload Type
to determine the appropriate channel mapping.
MOS Value: 13 bits
The estimated Mean Opinion Score (MOS) for multimedia application
performance is defined as including the effects of delay, loss,
discard, jitter and other effects that would affect media quality.
This is a unsigned fixed-point 7:6 value representing the MOS,
allowing the MOS score up to 127 in the integer part. MOS ranges
are defined as part of the specification of the MOS estimation
algorithm (Calculation Algorithm in this document), and are
normally ranges like 1-5, 0-10, or 0-100. Two values are
reserved: A value of 0x1FFE indicates out of range and a value of
0x1FFF indicates that the measurement is unavailable. Values
outside of the range defined by the Calculation Algorithm, other
than the two reserved values, MUST NOT be sent and MUST be ignored
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by the receiving system.
4. SDP Signaling
[RFC3611]defines the use of SDP (Session Description Protocol)
[RFC4566] for signaling the use of XR blocks. However XR blocks MAY
be used without prior signaling (see section 5 of RFC3611).
4.1. SDP rtcp-xr-attrib Attribute Extension
This section augments the SDP [RFC4566] attribute "rtcp-xr" defined
in [RFC3611] by providing an additional value of "xr-format" to
signal the use of the report block defined in this document. Within
the "xr-format", the syntax element "calgextmap" is an attribute as
defined in [RFC4566] and used to signal the mapping of the local
identifier (CAID) in the segment extension defined in section 3.2 to
the calculation algorithm. Specific extensionattributes are defined
by the specification that defines a specific extension name; there
might be several.
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xr-format =/ xr-mos-block
xr-mos-block = "mos-metric" ["=" calgextmap *("," calgextmap)]
calgextmap = mapentry "=" extensionname [SP extentionattributes]
direction = "sendonly" / "recvonly" / "sendrecv" / "inactive"
mapentry = "calg:" 1*3 DIGIT ["/" direction]
; Values in the range 1-255 are valid
; if needed, 0 can be used to indicate that
; an algorithm is rejected
extensionname = "P564";ITU-T P.564 Compliant Algorithm [P.564]
/ "G107";ITU-T G.107 [G.107]
/ "G107_1";ITU-T G.107.1 [G.107.1]
/ "TS101_329";ETSI TS 101 329-5 Annex E [ ETSI]
/"JJ201_1 ";TTC JJ201.1 [TTC]
/"P1201_1";ITU-T P.1201.2 [P.1201.1]
/"P1201_2";ITU-T P.1201.2 [P.1201.2]
/"P1202_1";ITU-T P.1202.1 [P.1202.1]
/"P1202_2";ITU-T P.1202.2 [P.1202.2]
/"P.862.2";ITU-T P.862.2 [P.862.2]
/"P.863"; ITU-T P.863 [P.863]
/ non-ws-string
extensionattributes = mosref
/attributes-ext
mosref = "mosref=" ("l"; lower resolution
/"m"; middle resolution
/ "h";higher resolution
/ non-ws-string)
attributes-ext = non-ws-string
SP = <Define in RFC5234>
non-ws-string = 1*(%x21-FF)
Each local identifier (CAID)of calculation algorithm used in the
segment defined in the section 3.2 is mapped to a string using an
attribute of the form:
a=calg:<value> ["/"<direction>] <name> [<extensionattributes>]
where <name> is a calculation algorithm name, as above, <value> is
the local identifier (CAID)of the calculation algorithm associated
with the segment defined in this document and is an integer in the
valid range inclusive.
Example:
a=rtcp-xr:mos-metric=calg:1=G107,calg:2=P1202_1
A usable mapping MUST use IDs in the valid range, and each ID in this
range MUST be unique and used only once for each stream or each
channel in the stream.
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The mapping MUST be provided per media stream (in the media-level
section(s) of SDP, i.e., after an "m=" line).
The syntax element "mosref" is referred to the media resolution
relative reference and has three valules 'l','m','h'.(e.g.,
Narrowband (3.4kHz) Speech and Standard Definition (SD) or lower
Resolution Video have 'l' resolution, Super Wideband (>14kHz) Speech
or higher and High Definition (HD) or higher Resolution Video have
'h' Resolution, Wideband speech(7khz) and Video with resolution
between SD and HD has 'm' resolution). The MOS score reported in the
MOS metrics block might vary with the MOS reference; For example, MOS
values for narrowband, wideband, super wideband codecs occupy the
same range but SHOULD be reported in different value. For video
application, MOS scores for SD resolution, HD resolution video also
occupy the same ranges and SHOULD be reported in different value.
4.2. Offer/Answer Usage
When SDP is used in offer-answer context, the SDP Offer/Answer usage
defined in [RFC3611] applies. In the offer answer context, the
signaling described above might be used in three ways:
o asymmetric behavior (segment extensions sent in only one
direction),
o the offer of mutually exclusive alternatives, or
o the offer of more segments than can be sent in a single session.
A direction attribute MAY be included in a calgextmap; without it,
the direction implicitly inherits, of course, from the RTCP stream
direction.
Segment extensions, with their directions, MAY be signaled for an
"inactive" stream. An extension direction MUST be compatible with
the stream direction. If a segment extension in the SDP offer is
marked as "sendonly" and the answerer desires to receive it, the
extension MUST be marked as "recvonly" in the SDP answer. An
answerer that has no desire to receive the extension or does not
understand the extension SHOULD NOT include it in the SDP answer.
If a segment extension is marked as "recvonly" in the SDP offer and
the answerer desires to send it, the extension MUST be marked as
"sendonly" in the SDP answer. An answerer that has no desire to, or
is unable to, send the extension SHOULD NOT include it in the SDP
answer.
If a segment extension is offered as "sendrecv", explicitly or
implicitly, and asymmetric behavior is desired, the SDP MAY be
modified to modify or add direction qualifiers for that segment
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extension.
A mosref attribute and MOS type attribute MAY be included in an
calgextmap; without it, the mosref and most type attribute implicitly
inherits, of course, from the name attribute (e.g., P.1201.1
[P.1201.1] indicates lower resolution used while P.1201.2 [P.1201.2]
indicates higher resolution used) or payload type carried in the
segment extension (e.g.,EVRC-WB [RFC5188] indicates using Wideband
Codec). However not all payload types or MOS algorithm names
indicate resolution to be used and MOS type to be used. If an
answerer receives an offer with an mosref attribute value it doesn't
support (e.g.,the answerer only supports "l" and receives "h"from
offerer), the answer SHOULD reject the mosref attribute value offered
by the offerer.
If the answerer wishes to reject a mosref attribute offered by the
offerer, it sets identifiers associated with segment extensions in
the answer to the value in the range 4096-4351. The rejected answer
MUST contain 'mosref ' attribute whose value is the value of the SDP
offer.
Local identifiers in the valid range inclusive in an offer or answer
must not be used more than once per media section. A session update
MAY change the direction qualifiers of segment extensions under use.
A session update MAY add or remove segment extension(s). Identifiers
values in the valid range MUST NOT be altered (remapped).
If a party wishes to offer mutually exclusive alternatives, then
multiple segment extensions with the same identifier in the
(unusable) range 4096-4351 MAY be offered; the answerer SHOULD select
at most one of the offered extensions with the same identifier, and
remap it to a free identifier in the valid range, for that extension
to be usable. Note that two segment types defined in section 3 are
also two exclusive alternatives.
If more segment extensions are offered in the valid range, the
answerer SHOULD choose those that are desired, and place the offered
identifier value "as is" in the SDP answer.
Similarly, if more segment extensions are offered than can be fit in
the valid range, identifiers in the range 4096-4351 MAY be offered;
the answerer SHOULD choose those that are desired, and remap them to
a free identifier in the valid range.
Note that the range 4096-4351 for these negotiation identifiers is
deliberately restricted to allow expansion of the range of valid
identifiers in future. Segment extensions with an identifier outside
the valid range cannot, of course, be used.
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Example (port numbers, RTP profiles, payload IDs and rtpmaps, etc.
all omitted for brevity):
The offer:
a=rtcp-xr:mos-metric=calg:4906=P1201_l,calg:4906=P1202_l, calg:
4907=G107
The answerer is interested in transmission P.1202.1 on lower
resolution application, but doesn't support P.1201.1 on lower
resolution application at all. It is interested in transmission
G.107. It therefore adjusts the declarations:
a=rtcp-xr:mos-metric=calg:1=P1202_l,calg:2=G107
5. 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].
5.1. New RTCP XR Block Type value
This document assigns the block type value MMB in the IANA " RTP
Control Protocol Extended Reports (RTCP XR) Block Type Registry" to
the "MOS Metrics Block".
[Note to RFC Editor: please replace MMB with the IANA provided RTCP
XR block type for this block.]
5.2. New RTCP XR SDP Parameter
This document also registers a new parameter "mos-metric" in the "
RTP Control Protocol Extended Reports (RTCP XR) Session Description
Protocol (SDP) Parameters Registry".
5.3. The SDP calgextmap Attribute
This section contains the information required by [RFC4566] for an
SDP attribute.
o contact name, email address: RAI Area Directors
<rai-ads@tools.ietf.org>
o attribute name (as it will appear in SDP): calgextmap
o long-form attribute name in English: calculation algorithm map
definition
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o type of attribute (session level, media level, or both): both
o whether the attribute value is subject to the charset attribute:
not subject to the charset attribute
o a one-paragraph explanation of the purpose of the attribute: This
attribute defines the mapping from the local identifier (CAID) in
the segment extension defined in section 3.2 into the calculation
algorithm name as documented in specifications and appropriately
registered.
o a specification of appropriate attribute values for this
attribute: see RFC xxxx.
5.4. New registry of calculation algorithms
This document creates a new registry to be called "RTCP XR MOS Metric
block - multimedia application Calculation Algorithm" as a sub-
registry of the "RTP Control Protocol Extended Reports (RTCP XR)
Block Type Registry". This registry applies to the multimedia
session where each type of media are sent in a separate RTP stream
and also applies to the session where Multi-channel audios are
carried in one RTP stream. Policies for this new registry are as
follows:
o The information required to support this assignment is an
unambiguous definition of the new metric, covering the base
measurements and how they are processed to generate the reported
metric.
o The review process for the registry is "Specification Required" as
described in Section 4.1 of [RFC5226].
o Entries in the registry are identified by entry name and mapped to
the local identifier (CAID) in the segment extension defined in
section 3.2.
o Registration Template
The following information must be provided with each registration:
* Name: A string uniquely and unambiguously identifying the
Calculation algorithm for use in protocols.
* Name Description: A valid Description of the Calculation
algorithm name.
* Reference: The reference which defines the calculation
algorithm corresponding to the Name and Name Description.
* Type: The media type to which the calculation algorithm is
applied
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o Initial assignments are as follows:
Name Name Description Reference Type
========= =================================== ========== ====
P564 ITU-T P.564 Compliant Algorithm [P.564] Voice
G107 ITU-T G.107 [G.107] Voice
TS101_329 ETSI TS 101 329-5 Annex E [ETSI] Voice
JJ201_1 TTC JJ201.1 [TTC] Voice
G107_1 ITU-T G.107.1 [G.107.1] Voice
P862 ITU-T P.862 [P.862] Voice
P862_2 ITU-T P.862.2 [P.862.2] Voice
P863 ITU-T P.863 [P.863] Voice
P1201_1 ITU-T P.1201.1 [P.1201.1] Multimedia
P1201_2 ITU-T P.1201.2 [P.1201.2] Multimedia
P1202_1 ITU-T P.1202.1 [P.1202.1] Video
P1202_2 ITU-T P.1202.2 [P.1202.2] Video
6. Security Considerations
The new RTCP XR report blocks proposed in this document introduces no
new security considerations beyond those described in [RFC3611].
7. Authors
This draft merges ideas from two drafts addressing the MOS Metric
Reporting issue. The authors of these drafts are listed below (in
alphabetical order):
Alan Clark < alan.d.clark@telchemy.com >
Geoff Hunt < r.geoff.hunt@gmail.com >
Martin Kastner < martin.kastner@telchemy.com >
Qin Wu < sunseawq@huawei.com >
Roland Schott < roland.schott@telekom.de >
Glen Zorn < gwz@net-zen.net >
Kai Lee < leekai@ctbri.com.cn >
8. Acknowledgements
The authors gratefully acknowledge the comments and contributions
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, Bill Ver Steeg, David R
Oran, Ted Lemon,Benoit Claise, Pete Resnick, Ali Begen and Hideaki
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Yamada.
9. References
9.1. Normative References
[ATSC] U.S. Advanced Television Systems Committee (ATSC), "ATSC
Standard: Digital Audio Compression (AC-3), Revision B",
ATSC Doc A/52B, June 2005.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3550] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time
Applications", RFC 3550, July 2003.
[RFC3551] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and
Video Conferences with Minimal Control", RFC 3551,
July 2003.
[RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control
Protocol Extended Reports (RTCP XR)", RFC 3611,
November 2003.
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, July 2006.
[RFC5226] Narten, T., "Guidelines for Writing an IANA Considerations
Section in RFCs", RFC 5226, May 2008.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
[RFC6776] Wu, Q., "Measurement Identity and information Reporting
using SDES item and XR Block", RFC 6776, October 2012.
9.2. Informative References
[BS.1387-1]
ITU-R, "Method for objective measurements of perceived
audio quality", ITU-R Recommendation BS.1387-1, 2001.
[ETSI] ETSI, "Quality of Service (QoS) measurement
methodologies", ETSI TS 101 329-5 V1.1.1, November 2000.
[G.107] ITU-T, "The E Model, a computational model for use in
transmission planning", ITU-T Recommendation G.107,
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April 2009.
[G.107.1] ITU-T, "Wideband E-model", ITU-T Recommendation G.107.1,
December 2011.
[G.1082] ITU-T, "Measurement-based methods for improving the
robustness of IPTV performance", ITU-T
Recommendation G.1082, April 2009.
[P.1201.1]
ITU-T, "Parametric non-intrusive assessment of audiovisual
media streaming quality - lower resolution application
area", ITU-T Recommendation P.1201.1, October 2012.
[P.1201.2]
ITU-T, "Parametric non-intrusive assessment of audiovisual
media streaming quality - higher resolution application
area", ITU-T Recommendation P.1201.2, October 2012.
[P.1202.1]
ITU-T, "Parametric non-intrusive bitstream assessment of
video media streaming quality - lower resolution
application area", ITU-T Recommendation P.1202.1,
October 2012.
[P.1202.2]
ITU-T, "Parametric non-intrusive bitstream assessment of
video media streaming quality - higher resolution
application area", ITU-T Recommendation P.1202.2,
May 2013.
[P.564] ITU-T, "Conformance testing for narrowband Voice over IP
transmission quality assessment models", ITU-T
Recommendation P.564, July 2006.
[P.862] ITU-T, "Perceptual evaluation of speech quality (PESQ): An
objective method for end-to-end speech quality assessment
of narrow-band telephone networks and speech codecs",
ITU-T Recommendation P.862, Febuary 2001.
[P.862.1] ITU-T, "Mapping function for transforming P.862 raw result
scores to MOS-LQO", ITU-T Recommendation P.862.1,
November 2003.
[P.862.2] ITU-T, "Wideband extension to Recommendation P.862 for the
assessment of wideband telephone networks and speech
codecs", ITU-T Recommendation P.862.2, November 2007.
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[P.863] ITU-T, "Perceptual objective listening quality
assessment", ITU-T Recommendation P.863, January 2011.
[RFC4184] Link, B., Hager, T., and J. Flaks, "RTP Payload Format for
AC-3 Audio", RFC 4184, October 2005.
[RFC4598] Link, B., "Real-time Transport Protocol (RTP) Payload
Format for Enhanced AC-3 (E-AC-3) Audio", RFC 4598,
July 2006.
[RFC5188] Desineni, H. and Q. Xie, "RTP Payload Format for the
Enhanced Variable Rate Wideband Codec (EVRC-WB) and the
Media Subtype Updates for EVRC-B Codec", RFC 5188,
February 2008.
[RFC6390] Clark, A. and B. Claise, "Framework for Performance Metric
Development", RFC 6390, October 2011.
[RFC6792] Wu, Q., "Monitoring Architectures for RTP", RFC 6792,
November 2012.
[TTC] TTC 201.01 (Japan), "A method for speech quality
assessment for Voice over IP".
Appendix A. Metrics represented using RFC6390 Template
RFC EDITOR NOTE: please change XXXX in [RFCXXXX] by the new RFC
number, when assigned.
a. MOS Value Metric
* Metric Name: MOS in RTP
* Metric Description: The estimated Mean Opinion Score for
multimedia application performance of RTP stream is defined as
including the effects of delay,loss, discard,jitter and other
effects that would affect audio or video quality.
* Method of Measurement or Calculation: See section 3.2.1, MOS
value definition [RFCXXXX].
* Units of Measurement: See section 3.2.1, MOS value definition
[RFCXXXX].
* Measurement Point(s) with Potential Measurement Domain: See
section 3, 2nd paragraph [RFCXXXX].
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* Measurement Timing: See section 3, 3rd paragraph [RFCXXXX] for
measurement timing and section 3.1 [RFCXXXX] for Interval
Metric flag.
* Use and applications: See section 1.4 [RFCXXXX].
* Reporting model: See RFC3611.
b. Segment Type Metric
* Metric Name: Segment Type in RTP
* Metric Description: It is used to identify the segment type of
RTP stream used in this report block. For more details, see
section 3.2.1, Segment type definition.
* Method of Measurement or Calculation: See section 3.2.1,
Segment Type definition [RFCXXXX].
* Units of Measurement: See section 3.2.1, Segment Type
definition [RFCXXXX].
* Measurement Point(s) with Potential Measurement Domain: See
section 3, 2nd paragraph [RFCXXXX].
* Measurement Timing: See section 3, 3rd paragraph [RFCXXXX] for
measurement timing and section 3.1 [RFCXXXX] for Interval
Metric flag.
* Use and applications: See section 1.4 [RFCXXXX].
* Reporting model: See RFC3611.
c. Calculation Algorithm Identifier Metric
* Metric Name: RTP Stream Calculation Algorithm Identifier
* Metric Description: It is the local identifier of RTP Stream
calculation Algorithm associated with this segment in the
range 1-255 inclusive.
* Method of Measurement or Calculation: See section 3.2.1,
Calculation Algorithm ID definition [RFCXXXX].
* Units of Measurement: See section 3.2.1, Calg Algorithm ID
definition[RFCXXXX].
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* Measurement Point(s) with Potential Measurement Domain: See
section 3, 2nd paragraph [RFCXXXX].
* Measurement Timing: See section 3, 3rd paragraph [RFCXXXX] for
measurement timing and section 3.1 [RFCXXXX] for Interval
Metric flag.
* Use and applications: See section 1.4 [RFCXXXX].
* Reporting model: See RFC3611.
d. Payload Type Metric
* Metric Name: RTP Payload Type
* Metric Description: It is used to identify the format of the
RTP payload. For more details, see section 3.2.1, payload
type definition.
* Method of Measurement or Calculation: See section 3.2.1,
Payload type definition [RFCXXXX].
* Units of Measurement: See section 3.2.1, payload type
definition[RFCXXXX].
* Measurement Point(s) with Potential Measurement Domain: See
section 3, 2nd paragraph [RFCXXXX].
* Measurement Timing: See section 3, 3rd paragraph [RFCXXXX] for
measurement timing and section 3.1 [RFCXXXX] for Interval
Metric flag.
* Use and applications: See section 1.4 [RFCXXXX].
* Reporting model: See RFC3611.
e. Channel Identifier Metric
* Metric Name: Audio Channel Identifier in RTP
* Metric Description: It is used to identify each audio channel
carried in the same RTP stream. For more details, see section
3.2.2, channel identifier definition.
* Method of Measurement or Calculation: See section 3.2.2,
Channel Identifier definition [RFCXXXX].
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* Units of Measurement: See section 3.2.2, channel identifier
definition[RFCXXXX].
* Measurement Point(s) with Potential Measurement Domain: See
section 3, 2nd paragraph [RFCXXXX].
* Measurement Timing: See section 3, 3rd paragraph [RFCXXXX] for
measurement timing and section 3.1 [RFCXXXX] for Interval
Metric flag.
* Use and applications: See section 1.4 [RFCXXXX].
* Reporting model: See RFC3611.
Appendix B. Change Log
B.1. draft-ietf-xrblock-rtcp-xr-qoe-15
The following are the major changes compared to previous version:
o Some Editorial Changes.
B.2. draft-ietf-xrblock-rtcp-xr-qoe-14
The following are the major changes compared to previous version:
o Add some texts to address IESG review comments.
B.3. draft-ietf-xrblock-rtcp-xr-qoe-10
The following are the major changes compared to previous version:
o Replace QoE metrics with MoS metrics.
B.4. draft-ietf-xrblock-rtcp-xr-qoe-09
The following are the major changes compared to previous version:
o Address comments recieved from WGLC, PM-DIR Review and SDP review.
o Change an existing SDP attribute 'extmap' to new SDP attribute
'calgextmap' and add new SDP attribute registry.
o Add Reference to G.107.1, P.862.1, P.862.2 and P.863 for new
calculation algorithms.
o Add MoS type attribute to distinguish different MoS type.
o Other Editorial changes.
B.5. draft-ietf-xrblock-rtcp-xr-qoe-08
The following are the major changes compared to previous version:
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o Remove mostype attribute from SDP extension since it can inferred
from payload type.
o Clarify mosref attribute usage in the O/A.
B.6. draft-ietf-xrblock-rtcp-xr-qoe-07
The following are the major changes compared to previous version:
o Some editorial changes to get in line with burst gap related
draft.
o Add an appendix to apply RFC6390 template.
B.7. draft-ietf-xrblock-rtcp-xr-qoe-06
The following are the major changes compared to previous two
versions:
o A few Contact information update.
o A few Acknowledgement section update.
B.8. draft-ietf-xrblock-rtcp-xr-qoe-04
The following are the major changes compared to previous version:
o Split two references P.NAMS and P.NBAMS into four references.
o SDP signaling update.
o Add one example to explain User QoE evaluation for video stream
B.9. draft-ietf-xrblock-rtcp-xr-qoe-03
The following are the major changes compared to previous version:
o Add one new reference to support TTC JJ201.01.
o Update two references P.NAMS and P.NBAMS.
o Other Editorial changes based on comments applied to PDV and Delay
drafts.
B.10. draft-ietf-xrblock-rtcp-xr-qoe-02
The following are the major changes compared to previous version:
o Remove leftmost second bit since it is ueeless.
o Change 13bits MoS value field into 14 bits to increase MoS
precision.
o Fix some typo and make some editorial changes.
B.11. draft-ietf-xrblock-rtcp-xr-qoe-01
The following are the major changes compared to previous version:
o Remove layered support from the QoE Metric draft.
o Allocate 7 bits in the block header for payload type to indicate
what type of payload format is in use and add associated
definition of payload type.
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o Clarify using Payload Type to determine the appropriate channel
mapping in the definition of Channel Identifier.
B.12. draft-ietf-xrblock-rtcp-xr-qoe-00
The following are the major changes compared to previous version:
o Allocate one more bit in the single channel per SSC segment to get
alignment with the other two segment type.
Authors' Addresses
Alan Clark
Telchemy Incorporated
2905 Premiere Parkway, Suite 280
Duluth, GA 30097
USA
Email: alan.d.clark@telchemy.com
Qin Wu
Huawei
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
Email: sunseawq@huawei.com
Roland Schott
Deutsche Telekom
Heinrich-Hertz-Strasse 3-7
Darmstadt 64295
Germany
Email: Roland.Schott@telekom.de
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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
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