One document matched: draft-wu-avt-rtcp-xr-quality-monitoring-01.txt
Differences from draft-wu-avt-rtcp-xr-quality-monitoring-00.txt
Network Working Group Q. Wu
Internet-Draft Huawei
Intended status: Standards Track G. Zorn
Expires: January 10, 2011 Network Zen
July 9, 2010
RTP Control Protocol Extended Reports (RTCP XR) Report Blocks for Real-
time Video Quality Monitoring
draft-wu-avt-rtcp-xr-quality-monitoring-01
Abstract
This document defines a set of RTP Control Protocol Extended Reports
(RTCP XR) Report Blocks and associated SDP parameters allowing the
report of video quality metrics, primarily for video applications of
RTP.
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 January 10, 2011.
Copyright Notice
Copyright (c) 2010 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
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
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Standards Language . . . . . . . . . . . . . . . . . . . . 4
2.2. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 4
4. RTP Flows Synchronization Delay Report Block . . . . . . . . . 5
5. Audio-Video Synchronization Report Block . . . . . . . . . . . 6
6. Video Statistics Summary Report Block . . . . . . . . . . . . 7
7. TR 101 290 Decodability Metrics Report Block . . . . . . . . . 10
8. Video Stream Metrics Report Block . . . . . . . . . . . . . . 13
8.1. Packet Loss and Discard Metrics . . . . . . . . . . . . . 15
8.2. Burst Metrics . . . . . . . . . . . . . . . . . . . . . . 16
8.3. Delay Metrics . . . . . . . . . . . . . . . . . . . . . . 17
8.4. Configuration Parameter Metrics . . . . . . . . . . . . . 17
8.5. Jitter Buffer Parameters . . . . . . . . . . . . . . . . . 18
9. Perceptual Quality Metrics Report Block . . . . . . . . . . . 18
10. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 21
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22
12. Security Considerations . . . . . . . . . . . . . . . . . . . 24
13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 24
14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 24
14.1. Normative References . . . . . . . . . . . . . . . . . . . 24
14.2. Informative References . . . . . . . . . . . . . . . . . . 25
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 25
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1. Introduction
Along with the wide deployment of broadband access and the
development of new IPTV services (e.g., broadcast video, video on
demand), there is increasing interest in monitoring and managing
networks and applications that deliver real-time applications over
IP, to ensure that all end users obtain acceptable video/audio
quality. The main drives come from operators, since offering
performance monitoring capability can help diagnose network
impairments, facilitate in root cause analysis and aid in verifying
compliance with service level agreements (SLAs) between Internet
Service Providers (ISPs) and content providers.
The factors that affect real-time application quality can be split
into two categories. The first category consists of network-
dependent factors such as packet loss, delay and jitter (which also
translates into losses in the playback buffer). The factors in the
second category are application-specific factors that affect video
quality and its sensitivity to network errors. These factors can be
but not limited to video codec and loss recovery technique, coding
bit rate, packetization scheme, and content characteristics.
Compared with application-specific factors, the network-dependent
factors sometimes are not sufficient to measure video quality, since
the ability to analyze the video in the application layer provides
quantifiable measurements for subscriber Quality of Experience (QoE)
that may not be captured in the transmission layers or from the RTP
layer down. In a typical scenario, monitoring of the transmission
layers can produce statistics suggesting that quality is not an
issue, such as the fact that network jitter is not excessive.
However, problems may occur in the service layers leading to poor
subscriber QoE. Therefore monitoring using only network-level
measurements may be insufficient when application layer video quality
is required.
In order to provide accurate measures of video quality for operators
when transporting video across a network, conveying video quality
metrics in RTCP XR packets [RFC3611] has the following three
benefits:
* Tuning the video encoder algorithm to satisfy video quality
requirements
* Determining which system techniques to use in a given situation
and when to switch from one technique to another as system
parameters change
* Verifying the continued correct operation of an existing system
RFC 3611 [RFC3611] defines seven report block formats for network
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management and quality monitoring. However, there are no block types
specifically designed for conveying video quality metrics. This
document focuses on specifying new report block types used to convey
video-specific quality metrics.
The report block types defined in this document fall into two
categories. The first category consists of synchronization
information on received RTP packets. The report blocks in the second
category convey metrics relating to packet receipts defined in RFC
3611 [RFC3611] that are summary in nature but include data that is
more detailed, or of a different type, than that conveyed in existing
RTCP packets.
Six report block formats are defined by this document. Of these, two
are synchronization information blocks:
* RTP Flows Synchronization Delay Report Block
* Audio-Video Synchronization Report Block
The other four are summary metrics blocks:
* Statistics Summary Report Block
* TR 101 290 Decodability Metrics Block [ETSI]
* Video Stream Metrics Report Block
* Perceptual Quality Metrics 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].
2.2. Acronyms
SSRC
Synchronization Source [RFC3550]
TS
Transport Stream [ISO-IEC.13818-1.2007]
3. Applicability
All the report blocks defined in this document could be used by
dedicated network monitoring applications. As specified in RFC 3611
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[RFC3611], for such an application it might be appropriate to allow
more than 5% of RTP data bandwidth to be used for RTCP packets, thus
allowing proportionately larger and more detailed report blocks.
The Audio-Video Synchronization Report Block Section 5 has been
defined for video conferencing applications. Such applications can
use this report block to monitor A/V component synchronization to
ensure satisfactory QoE. Tighter tolerances than typically used have
been recommended for such applications.
The Flows Synchronization Delay Report Block has been defined
primarily for layered or multi-description video coding applications.
When joining a layered video session in such an application, a
receiver may not synchronize playout across the multimedia session
until RTCP SR packets have been received on all of the component RTP
sessions. This report block can be used to ensure synchronization
between different media layers for the same multimedia session.
The Stream Metrics Report Block and Statistics Summary Report Block
can be applied to any real time video application, while the TR 101
290 Decodability Metrics Report Block and Perceptual Quality Metrics
Report Block can be used in any real-time AV application [ETSI].
4. RTP Flows Synchronization Delay Report Block
This block reports synchronization delay between RTP sessions of the
same video stream sent using Multi-Session Transmission
[I-D.ietf-avt-rtp-svc] beyond the information carried in the standard
RTCP packet format. Information is recorded about session bandwidth
and synchronization delay.
The RTP Flows Synchronization Delay Report Block has the following
format:
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=TBD | Reserved | Block length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of Sender |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Session Bandwidth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Initial Synchronization Delay |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Block type (BT): 8 bits
The Statistics Summary Report Block is identified by the constant
<RFSD>.
Reserved: 8 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
MUST be ignored by the receiver.
Block length: 16 bits
The constant 3, in accordance with the definition of this field in
Section 3 of RFC 3611 [RFC3611].
SSRC of Sender: 32 bits
The SSRC of the RTP data packet source being reported upon by this
report block. (Section 4.1 of [RFC3611]).
Session Bandwidth: 32 bits
This field indicates the maximum bandwidth allocated to each RTP
Session. The value in this field represents the bandwidth
allocation per RTP Session in kilobits per second, with values in
the range 0 <= BW < 65536.
Initial Synchronization Delay: 32 bits
The average delay, expressed in units of 1/65536 seconds, between
the RTCP packets received on all of the components RTP sessions
and the beginning of session [I-D.ietf-avt-rapid-rtp-sync]. The
value is calculated as follows:
Initial Synchronization Delay = max((the time interval between
receiving the first RTP packet with synchronization metadata
and the start of a session), (the time interval between
receiving the first RTCP packet in the RTP session with the
longest RTCP reporting interval and the start of a session)).
5. Audio-Video Synchronization Report Block
This block reports the audio-video synchronization requirements
between audio and video components beyond the information carried in
the standard RTCP packet format. Information is recorded about
tolerant audio lead video time and tolerant audio lag video time.
The Audio-Video Synchronization Report 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=TBD |L| Reserved | Block length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Audio Lead Video | Audio Lag Video |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Block type (BT): 8 bits
The Statistics Summary Report Block is identified by the constant
<AVS>.
Audio Lead/Lag Video flag (L): 1 bit
Bit set to 1 if Audio Lead Video field contains a report, 0 if
Audio Lag Video field contains a report.
Reserved: 7 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
MUST be ignored by the receiver.
Block length: 16 bits
The constant 2, in accordance with the definition of this field in
Section 3 of RFC 3611 [RFC3611].
SSRC of source: 32 bits
As defined in Section 4.1 of RFC 3611 [RFC3611].
Audio Lead Video time: 16 bits
This field indicates the tolerant audio lead video time in
milliseconds [DSLF]. This value is calculated based on the
interarrival time between previous video RTP packet and the next
first audio RTP packet and timestamps of both previous video RTP
packet and the next first audio packet.
Audio Lag Video time: 16 bits
This field indicates the tolerant audio lag video time in
milliseconds [DSLF]. This value is calculated based on the
interarrival time between previous video RTP packet and the next
first audio RTP packet and timestamps of both previous video RTP
packet and the next first audio packet.
6. Video Statistics Summary Report Block
This block reports statistics beyond the information carried in the
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Statistics Summary Report Block RTCP packet specified in the section
4.6 of RFC 3611 [RFC3611]. Information is recorded about lost frame
packets, duplicated frame packets, lost layered component packets,
duplicated layered component packets. Such information can be useful
for network management and video quality monitoring.
The report block contents are dependent upon a series of flag bits
carried in the first part of the header. Not all parameters need to
be reported in each block. Flags indicate which parameters are
reported and which are not. The fields corresponding to unreported
parameters MUST be present, but are set to zero. The receiver MUST
ignore any Video Statistics Summary Report Block with a non-zero
value in any field flagged as unreported.
The Video Statistics Summary Report Block has the following format:
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=TBD |L|D|FT | LT |P| block length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| begin_seq | end_seq |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| lost_frames |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| dup frames |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| lost_layered component packets |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| dup layered component_packets |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| lost_partial frame packets |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| dup partial frame_packets |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Block type (BT): 8 bits
The Video Statistics Summary Report Block is identified by the
constant <VSS>.
loss report flag (L): 1 bit
Bit set to 1 if the lost_frame packets field, the
lost_layered_component field or the lost partial frame packets
field contains a report, 0 otherwise.
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duplicate report flag (D): 1 bit
Bit set to 1 of the dup_frame packets field, the
dup_layered_component packets field or the dup partial frame
packets field contains a report, 0 otherwise.
Frame type indicator (FT): 2 bits
This field is used to indicate the frame type to be reported.
Bits set to 01 if the lost_frames field or dup_frames field
contain a I_frame report, 10 if the lost_frames field and
dup_frames field contain a P frame report, 11 if the lost_frames
field and dup_frames field contain a B frame report, 00 otherwise.
Layer Type indicator (LT): 3 bits
This field is used to indicate the layer type of layered video to
be reported. LT is set to 001 if the loss_component_packet field
and dup_component packet contain the base layer packet in SVC
[I-D.ietf-avt-rtp-svc], 010 if the loss_component packet field and
dup_component packet contain enhancement layer 1 packet in SVC,
011 if the loss_component packet field and dup_component packet
contain the enhancement layer 2 packet, 000 otherwise.
P: 1 bit
Bit set to 1 if the lost_partial frame packets field or the
dup_partial_frame packets field contains a report, 0 otherwise.
Block length: 16 bits
The constant 8, in accordance with the definition of this field in
Section 3 of RFC 3611 [RFC3611].
SSRC of source: 32 bits
As defined in Section 4.1 of RFC 3611 [RFC3611].
begin_seq: 16 bits
As defined in Section 4.1 of RFC 3611 [RFC3611].
end_seq: 16 bits
As defined in Section 4.1 of RFC 3611 [RFC3611].
lost_frames: 32 bits
Number of lost_frames in the above sequence number interval.
dup_frames: 32 bits
Number of dup_frames in the above sequence number interval.
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lost_layered component packets: 32 bits
Number of lost_component packets in the above sequence number
interval.
dup_layered component packets: 32 bits
Number of dup_component packets in the above sequence number
interval.
lost_partial frame packets: 32 bits
Number of lost_partial frame packets in the above sequence number
interval.
dup_partial frame packets: 32 bits
Number of dup_partial frame packets in the above sequence number
interval.
7. TR 101 290 Decodability Metrics Report Block
This block reports decodability metrics statistics beyond the
information carried in the standard RTCP packet format. Information
is recorded about the number of Transport Stream Synchronization
Losses, Sync byte errors, Continuity count errors, Transport errors,
Program Clock Reference (PCR) errors, PCR repetition errors, PCR
discontinuity indicator errors, and Presentation Time Stamp (PTS)
errors [ETSI]. Such information can be useful for network management
and video quality monitoring.
Note that this is only applicable to MPEG-2 RTP streams [RFC2250].
and not to any other video codec.
The report block contents are dependent upon a series of flag bits
carried in the first part of the header. Not all parameters need to
be reported in each block. Flags indicate which are and which are
not reported. The fields corresponding to unreported parameters MUST
be present, but are set to zero. The receiver MUST ignore any
Decodability Metrics Block with a non-zero value in any field flagged
as unreported.
The Decodability 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=TBD |L|B|C|T|P|S|rvd| block length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| begin_seq | end_seq |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Number of packets | Number of TSs |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transport Stream Synchronization Losses |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sync byte errors |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Continuity count errors |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transport errors |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PCR errors |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PCR repetition errors |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PCR discontinuity indicator errors |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PTS errors |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
block type (BT): 8 bits
A TR 101 290 decodability metrics report block is identified by
the constant <TDM>.
Transport Stream Synchronization Loss flag (L): 1 bit
Bit set to 1 if the Transport Stream Synchronization Loss field
contains a report, 0 otherwise.
Sync byte error flag (B): 1 bit
Bit set to 1 if the Sync byte error field contains a report, 0
otherwise.
Continuity count error flag (C): 1 bit
Bit set to 1 if the Continuity count error field contains a
report, 0 otherwise.
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Transport error flag (T): 1 bit
Bit set to 1 if the Transport error field contains a report, 0
otherwise.
PCR related error flag (P): 1 bit
Bit set to 1 if the PCR error field, PCR repetition error field
and PCR discontinuity indicator error fields contain a report, 0
otherwise.
PTS error flag (S): 1 bit
Bit set to 1 if the PTS error field contains a report, 0
otherwise.
rvd: 2 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
MUST be ignored by the receiver.
block length: 16 bits
The constant 10, in accordance with the definition of this field
in Section 3 of RFC 3611 [RFC3611].
SSRC of source: 32 bits
As defined in Section 4.1 of [RFC3611].
begin_seq: 16 bits
As defined in Section 4.1 of [RFC3611].
end_seq: 16 bits
As defined in Section 4.1 of [RFC3611].
Number of Packets: 16 bits
Number of RTP packets in the above sequence number interval.
Number of TSs: 16 bits
Number of Transport Streams in the above sequence number interval.
Transport Stream Synchronization Losses: 32 bits
Number of Transport Stream Synchronization Losses in the above
sequence number interval.
Sync byte errors: 32 bits
Number of Transport sync byte errors in the above sequence number
interval.
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Continuity count error: 32 bits
Number of Transport Continuity count errors in the above sequence
number interval.
Transport errors: 32 bits
Number of Transport errors in the above sequence number interval.
PCR errors: 32 bits
Number of PCR errors in the above sequence number interval.
PCR repetition errors: 32 bits
Number of Transport PCR repetition errors in the above sequence
number interval.
PCR discontinuity indicator errors: 32 bits
Number of PCR discontinuity indicator errors in the above sequence
number interval.
PTS errors: 32 bits
Number of PTS errors in the above sequence number interval.
8. Video Stream Metrics Report Block
The Video Stream Metrics Report Block provides metrics for monitoring
the quality of video stream. This metrics includes Loss and discard
metrics, Burst metrics, Delay metrics for I-Frame packets, B-Frame
packets and P-Frame packets, Configuration parameter metrics. The
block reports separately on packets lost on the IP channel, and those
that have been received but then discarded by the receiving jitter
buffer. It also reports on the combined effect of losses and
discards, as both have equal effect on video quality.
In order to properly assess the quality of a video stream, it is
desirable to consider the degree of burstiness of packet loss RFC
3357 [RFC3357]. Following the one-way loss pattern sample metrics
discussed in [RFC3357], a measure of the spacing between consecutive
network packet loss or error events, is a "loss distance". The loss
distance metric captures the spacing between the loss periods. The
duration of a loss or error event (e.g. and how many packets are lost
in that duration) is a "loss period", the loss period metric captures
the frequency and length (burstiness) of loss once it starts. Delay
reports include the transit delay between RTP end points and the end
system processing delays, both of which contribute to the user
perceived delay.
Implementations MUST provide values for all the fields defined here.
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For certain metrics, if the value is undefined or unknown, then the
specified default or unknown field value MUST be provided.
The block is encoded as six 32-bit words:
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=TBD |FT | reserved | block length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Loss rate | Discard rate | Loss Period |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Loss Distance | Max Loss Duration |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Round trip delay | End system delay |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Gmin | RX config | JB nominal |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| JB maximum | JB abs max |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
block type (BT): 8 bits
A Video Stream Metrics Report Block is identified by the constant
<VSM>.
Frame type indicator (FT): 2 bits
This field is used to indicate the frame type to be reported.
Bits set to 01 if the Loss rate field and discard rate field
contain a I_frame report, 10 if the Loss rate field and discard
rate field contain a P frame report, 11 if the Loss rate field and
discard rate field contain a B frame report, 00 otherwise.
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
MUST be ignored by the receiver.
block length: 16 bits
The constant 8, in accordance with the definition of this field in
Section 3 of RFC 3611 [RFC3611].
SSRC of source: 32 bits
The SSRC of the RTP data packet source being reported upon by this
report block. in accordance with the definition of this field in
Section 3 of RFC 3611 [RFC3611].
The remaining fields are described in the following four sections:
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Packet Loss and Discard Metrics, Delay Metrics, Configuration
Metrics, and Jitter Buffer Parameters.
8.1. Packet Loss and Discard Metrics
It is very useful to distinguish between packets lost by the network
and those discarded due to jitter. Both have equal effect on the
quality of the video stream, however, having separate counts helps
identify the source of quality degradation. These fields MUST be
populated, and MUST be set to zero if no packets have been received.
Loss rate for I-Frame packets: 8 bits
The fraction of RTP data packets from the source lost since the
beginning of reception, expressed as a fixed point number with the
binary point at the left edge of the field. This value is
calculated by dividing the total number of I frame packets lost
(after the effects of applying any error protection such as FEC)
by the total number of packets expected, multiplying the result of
the division by 256, limiting the maximum value to 255 (to avoid
overflow), and taking the integer part. The numbers of duplicated
packets and discarded packets do not enter into this calculation.
Since receivers cannot be required to maintain unlimited buffers,
a receiver MAY categorize late-arriving packets as lost. The
degree of lateness that triggers a loss SHOULD be significantly
greater than that which triggers a discard.
Discard rate for I-Frame packets: 8 bits
The fraction of RTP data packets from the source that have been
discarded since the beginning of reception, due to late or early
arrival, under-run or overflow at the receiving jitter buffer.
This value is expressed as a fixed point number with the binary
point at the left edge of the field. It is calculated by dividing
the total number of I-Frame packets discarded (excluding duplicate
packet discards) by the total number of packets expected,
multiplying the result of the division by 256, limiting the
maximum value to 255 (to avoid overflow), and taking the integer
part.
Loss rate for P-Frame packets: 8 bits
The loss rate for P-Frame packets is similar to the loss rate for
I-Frame packets. The value is calculated by dividing the total
number of P frame packets lost (after the effects of applying any
error protection such as FEC) by the total number of packets
expected, multiplying the result of the division by 256.
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Discard rate for P-Frame packets: 8 bits
The discard rate for P-Frame packets is similar to the discard
rate for I-Frame packets. The value is calculated by dividing the
total number of P-Frame packets discarded (excluding duplicate
packet discards) by the total number of packets expected,
multiplying the result of the division by 256.
Loss rate for B-Frame packets: 8 bits
The loss rate for B-Frame packets is similar to the loss rate for
P-Frame packets. The value is calculated by dividing the total
number of B frame packets lost (after the effects of applying any
error protection such as FEC) by the total number of packets
expected, multiplying the result of the division by 256.
Discard rate for P-Frame packets: 8 bits
The discard rate for B-Frame packets is similar to the discard
rate for P-Frame packets. The value is calculated by dividing the
total number of B-Frame packet discarded (excluding duplicate
packet discards) by the total number of packets expected,
multiplying the result of the division by 256.
8.2. Burst Metrics
Loss Distance: 16 bits
The mean duration, expressed in milliseconds, of the loss
intervals that have occurred since the beginning of reception
[DSLF]. The duration of each loss distance is calculated based
upon the frames that mark the beginning and end of that period.
It is equal to the timestamp of the end frame, plus the duration
of the end frame, minus the timestamp of the beginning frame. If
the actual values are not available, estimated values MUST be
used. If there have been no burst periods, the burst duration
value MUST be zero.
Loss Period: 16 bits
The mean duration, expressed in milliseconds, of the burst loss
periods that have occurred since the beginning of reception
[DSLF]. The duration of each period is calculated based upon the
frame that marks the end of the prior burst loss and the frame
that marks the beginning of the subsequent burst loss. It is
equal to the timestamp of the subsequent burst frame, minus the
timestamp of the prior burst packet, plus the duration of the
prior burst packet. If the actual values are not available,
estimated values MUST be used. In the case of a gap that occurs
at the beginning of reception, the sum of the timestamp of the
prior burst packet and the duration of the prior burst packet are
replaced by the reception start time. In the case of a gap that
occurs at the end of reception, the timestamp of the subsequent
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burst packet is replaced by the reception end time. If there have
been no gap periods, the gap duration value MUST be zero.
Max Loss Duration of a single error: 16 bits
The maximum loss duration, expressed in milliseconds, of the loss
periods that have occurred since the beginning of reception. The
recommended max loss duration is specified as less than 16 ms in
[DSLF], which provides a balance between interleaver depth
protection from xDSL errors induced by impulse noise, delay added
to other applications and video service QoE requirements to reduce
visible impairments.
8.3. Delay Metrics
Similar to the delay metrics for audio stream defined in the section
4.7.3 of [RFC3611], the delay metrics for video stream fall into two
categories: end-system delay due to RTP payload multiplexing and
round trip delay due to multiplexing RTP frames within a UDP frame.
Round trip delay: 16 bits
As defined in Section 4.7.3 of [RFC3611].
End system delay: 16 bits
As defined in Section 4.7.3 of [RFC3611].
8.4. Configuration Parameter Metrics
Similar to the configuration metrics defined in the section 4.7.6 of
[RFC3611], the configuration metrics for video stream include Gmin,
receiver configuration byte, packet loss concealment, jitter buffer
adaptive, and jitter buffer rate.
Gmin: 8 bits
As defined in Section 4.7.6 of [RFC3611].
Receiver configuration byte (RX config): 8 bits
As defined in Section 4.7.6 of [RFC3611].
Jitter buffer adaptive (JBA): 2 bits
As defined in Section 4.7.6 of [RFC3611].
Jitter buffer rate (JB rate): 4 bits
As defined in Section 4.7.6 of [RFC3611].
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8.5. Jitter Buffer Parameters
Similar to the jitter buffer parameters defined in the section 4.7.7
of [RFC3611], the Jitter Buffer Parameters for video streams include
jitter buffer nominal delay, jitter buffer maximum delay and jitter
buffer absolute maximum delay.
Jitter buffer nominal delay (JB nominal): 16 bits
As defined in Section 4.7.7 of[RFC3611].
Jitter buffer maximum delay (JB maximum): 16 bits
As defined in Section 4.7.7 of[RFC3611].
Jitter buffer absolute maximum delay (JB abs max): 16 bits
As defined in Section 4.7.7 of[RFC3611].
9. Perceptual Quality Metrics Report Block
This block reports perceptual quality metrics beyond the information
carried in the standard RTCP packet format. Information is recorded
about Video MOS, Audio Video MOS, Video Service Transmission Quality,
Video Service Audio Quality, Video Service Multimedia Quality and
Video Service Picture Quality.
The report block contents are dependent upon a series of flag bits
carried in the first part of the header. Not all parameters need to
be reported in each block. Flags indicate which are and which are
not reported. The fields corresponding to unreported parameters MUST
be present, but are set to zero. The receiver MUST ignore any
Perceptual Quality Metrics Block with a non-zero value in any field
flagged as unreported.
The Perceptual Quality 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=TBD |I|S|T|A|M|P|Rsd| block length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MOS-V | MOS-AV |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VSTQ | VSAQ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VSMQ | VSPQ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Loss Period VSPQ | Loss Distance VSPQ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Block type (BT): 8 bits
The Perceptual Quality Metrics Block is identified by the constant
<PQM>.
Interval Metric flag (I): 1 bit
This field is used to indicate whether the Basic Loss/Discard
metrics are Interval or Cumulative metrics, that is, whether the
reported values applies to the most recent measurement interval
duration between successive metrics reports (I=1) (the Interval
Duration) or to the accumulation period characteristic of
cumulative measurements (I=0) (the Cumulative Duration).
MOS-V flag (S): 1 bit
Bit set to 1 if the MOS-V field and MOS-AV field contain a report,
0 otherwise.
Video Service Transmission Quality flag (T): 1 bit
Bit set to 1 if the VSTQ field contains a report, 0 otherwise.
Video Service Audio Quality flag (A): 1 bit
Bit set to 1 if the VSAQ field contains a report, 0 otherwise.
Video Service Multimedia Quality flag (M): 1 bit
Bit set to 1 if the VSMQ field contains a report, 0 otherwise.
Video Service Picture Quality flag (P): 1 bit
Bit set to 1 if the VSPQ field, Loss Period VSPQ, Loss Distance
VSPQ contains a report, 0 otherwise.
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Rsd.: 2 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
MUST be ignored by the receiver.
SSRC of source: 32 bits
As defined in Section 4.1 of [RFC3611].
MOS-V: 16 bits
The estimated mean opinion score for video quality (MOS-V) is a
video quality metric on a scale from 1 to 5, in which 5 represents
excellent and 1 represents unacceptable. This metric is defined
as not including the effects of audio impairments and can be
compared to MOS scores obtained from video quality tests. It is
expressed as an integer in the range 10 to 50, corresponding to
MOS x 10. For example, a value of 35 would correspond to an
estimated MOS score of 3.5.
A value of 127 indicates that this parameter is unavailable.
Values other than 127 and the valid range defined above MUST NOT
be sent and MUST be ignored by the receiving system.
MOS-AV: 16 bits
The estimated mean opinion score for Audio-Video quality (MOS-AV)
is defined as including the effects of delay and other effects
that would affect Audio-Video quality. It is expressed as an
integer in the range 10 to 50, corresponding to MOS x 10, as for
MOS-AV. A value of 127 indicates that this parameter is
unavailable. Values other than 127 and the valid range defined
above MUST NOT be sent and MUST be ignored by the receiving
system.
VSTQ: 16 bits
Video Service Transmission Quality (TBC)
VSAQ: 16 bits
Video Service Audio Quality (TBC)
VSMQ: 16 bits
Video Service Multimedia Quality (TBC)
VSPQ: 16 bits
Video Service Picture Quality (TBC)
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Loss Period VSPQ: 16 bits
Video Service Picture Quality during Loss Period (TBC)
Loss Distance VSPQ: 16 bits
Video Service Picture Quality during Loss Distance (TBC)
10. SDP Signaling
Six new parameters are defined for the six report blocks defined in
this document to be used with Session Description Protocol (SDP)
[RFC4566] using the Augmented Backus-Naur Form (ABNF) [RFC5234].
They have the following syntax within the "rtcp-xr" attribute
[RFC3611]:
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rtcp-xr-attrib = "a=rtcp-xr:"
[xr-format *(SP xr-format)] CRLF
xr-format = RTP-flows-syn
/ audio-video-syn
/ percept-quality-metrics
/ video-stream-metric
/ video-stat-summary
/ decodability-metric
RTP-flows-syn = "RTP-flows-syn"
["=" max-size]
max-size = 1*DIGIT ; maximum block size in octets
audio-video-syn = "audio-video-syn"
["=" max-size]
max-size = 1*DIGIT ; maximum block size in octets
percept-quality-metrics = "percept-quality-metrics"
["=" max-size]
max-size = 1*DIGIT ; maximum block size in octets
video-stream-metric = "video-stream-metric"
["=" max-size]
max-size = 1*DIGIT ; maximum block size in octets
video-stat-summary = "video-stat-summary"
["=" stat-flag *("," stat-flag)]
stat-flag = "I Frame loss and duplication"
/ "P Frame loss and duplication"
/ "B Frame loss and duplication"
decodability-metric = "decodability-metric"
["=" stat-flag *("," stat-flag)]
stat-flag = "Interval Metric"
/ "MOS-V and MOS-AV"
/ "VSTQ"
/ "VSAQ"
/ "VSMQ"
/ "VSPQ"
Refer to Section 5.1 of RFC 3611 [RFC3611] for a detailed description
and the full syntax of the "rtcp-xr" attribute.
11. IANA Considerations
New report block types for RTCP XR are subject to IANA registration.
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For general guidelines on IANA allocations for RTCP XR, refer to
Section 6.2 of [RFC3611].
This document assigns six new block type values in the RTCP XR Block
Type Registry:
Name: RFSD
Long Name: RTP Flows Synchronization Delay
Value <RFSD>
Reference: Section 4
Name: AVS
Long Name: Audio-Video Synchronization
Value <AVS>
Reference: Section 5
Name: VSS
Long Name: Video Statistics Summary
Value <VSS>
Reference: Section 6
Name: TDM
Long Name: TR 101 290 Decodability Metrics
Value <TDM>
Reference: Section 7
Name: VSM
Long Name: Video Stream Metrics
Value <VSM>
Reference: Section 8
Name: PQM
Long Name: Perceptual Quality Metric
Value <PQM>
Reference: Section 9
This document also registers six SDP [RFC4566] parameters for the
"rtcp-xr" attribute in the RTCP XR SDP Parameters Registry:
* "RTP-flows-syn"
* "audio-video-syn"
* "percept-quality-metrics"
* "video-stream-metric"
* "video-stat-summary"
* "decodability-metric"
The contact information for the registrations is:
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Qin Wu
sunseawq@huawei.com
101 Software Avenue, Yuhua District
Nanjing, JiangSu 210012 China
12. Security Considerations
TBC
13. Acknowledgements
The authors would like to thank Youqing Yang, Wenxiao Yu and Yinliang
Hu for their valuable comments and suggestions on this document.
14. References
14.1. Normative References
[ETSI] ETSI, "Digital Video Broadcasting (DVB); Measurement
guidelines for DVB systems", Technical Report TR 101 290,
2001.
[I-D.ietf-avt-rapid-rtp-sync]
Perkins, C. and T. Schierl, "Rapid Synchronisation of RTP
Flows", draft-ietf-avt-rapid-rtp-sync-11 (work in
progress), May 2010.
[I-D.ietf-avt-rtp-svc]
Wenger, S., Wang, Y., Schierl, T., and A. Eleftheriadis,
"RTP Payload Format for SVC Video",
draft-ietf-avt-rtp-svc-21 (work in progress), April 2010.
[ISO-IEC.13818-1.2007]
International Organization for Standardization,
"Information technology - Generic coding of moving
pictures and associated audio information: Systems",
ISO International Standard 13818-1, October 2007.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2250] Hoffman, D., Fernando, G., Goyal, V., and M. Civanlar,
"RTP Payload Format for MPEG1/MPEG2 Video", RFC 2250,
January 1998.
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[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, July 2003.
[RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control
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.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
14.2. Informative References
[DSLF] Rahrer, T., Ed., Fiandra, Ed., and Wright, Ed., "Triple-
play Services Quality of Experience (QoE) Requirements",
DSL Forum Technical Report TR-126, December 2006.
[RFC3357] Koodli, R. and R. Ravikanth, "One-way Loss Pattern Sample
Metrics", RFC 3357, August 2002.
Authors' Addresses
Qin Wu
Huawei
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
Email: sunseawq@huawei.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
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