1、 International Telecommunication Union ITU-T G.1080TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (12/2008) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Multimedia quality of service and performance Generic and user-related aspects Quality of experience requirements for IP
2、TV services Recommendation ITU-T G.1080 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100G.199 GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS G.200G.299 INDIVIDUAL CHARACTERI
3、STICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES G.300G.399 GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES G.400G.449 COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY G.450G.499 TRANSMISS
4、ION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS G.600G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1000G.1999 TRANSMISSION MEDIA CHARACTERISTI
5、CS G.6000G.6999 DATA OVER TRANSPORT GENERIC ASPECTS G.7000G.7999 PACKET OVER TRANSPORT ASPECTS G.8000G.8999ACCESS NETWORKS G.9000G.9999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.1080 (12/2008) i Recommendation ITU-T G.1080 Quality of experience requirements
6、 for IPTV services Summary Recommendation ITU-T G.1080 defines user requirements for quality of experience (QoE) for Internet protocol television (IPTV) services. The QoE requirements are defined from an end user perspective and are agnostic to network deployment architectures and transport protocol
7、s. The QoE requirements are specified as end-to-end and information is provided on how they influence network transport and application layer behaviour. QoE requirements for video, audio, text, graphics, control functions and meta-data are provided. Compression coding schemes addressed in this Recom
8、mendation are examples, and detailed numeric values as performance targets, e.g., bit rate, packet loss rate, are also examples. The readers may appropriately choose or replace these parameter values in order to be consistent with the requirements of each IPTV service context to which they are inten
9、ded to be applied. Source Recommendation ITU-T G.1080 was approved on 7 December 2008 by ITU-T Study Group 12 (2009-2012) under Recommendation ITU-T A.8 procedure. Keywords IPTV, QoE, QoS. ii Rec. ITU-T G.1080 (12/2008) FOREWORD The International Telecommunication Union (ITU) is the United Nations s
10、pecialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on th
11、em with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-
12、T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used
13、 for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g., interoperability or applicability) and compliance with the R
14、ecommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of an
15、y party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Prope
16、rty Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, imp
17、lementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2009 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior writ
18、ten permission of ITU. Rec. ITU-T G.1080 (12/2008) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2 Terms defined in this Recommendation. 2 4 Abbreviations and acronyms 2 5 Introduction to QoE 4 6 QoE for video and audio. 6 6.1 Requirements for media comp
19、ression and synchronization. 6 6.2 Impact of network transmission on performance . 11 7 QoE for text and graphics. 12 7.1 Media component text 12 7.2 Media component graphics. 13 8 QoE for control functions . 14 8.1 QoE requirements for channel zapping time 14 8.2 QoE requirements related to VoD tri
20、ck mode 16 9 QoE for other IPTV services 16 9.1 QoE requirements for metadata 16 9.2 QoE requirements for browser . 17 9.3 QoE requirements for content navigation. 18 10 Accessibility requirements 18 11 Security considerations. 18 Appendix I Network QoS parameters affecting QoE . 19 Appendix II Non-
21、inclusive list of audio and video codecs. 20 II.1 Video codecs 20 II.2 Audio codecs 20 Appendix III Supplementary information related to the selected provisional performance parameters 21 III.1 Introduction 21 III.2 Standard definition TV (SDTV): General minimum objectives 21 III.3 Standard definiti
22、on (SD) TV: VoD and premium content objectives 23 III.4 High definition TV (HDTV): Objectives . 24 Appendix IV Impact of transmission impairments on quality 26 IV.1 Introduction 26 IV.2 Standard definition video . 28 iv Rec. ITU-T G.1080 (12/2008) Page IV.3 High definition TV . 30 IV.4 Plots of pack
23、et loss ratio vs bits sent 31 IV.5 Severe error limits for SDTV and HDTV services 33 Bibliography. 35 Rec. ITU-T G.1080 (12/2008) 1 Recommendation ITU-T G.1080 Quality of experience requirements for IPTV services 1 Scope This Recommendation defines user requirements for quality of experience (QoE) f
24、or IPTV services. The QoE requirements are defined from an end-user perspective and are agnostic to network deployment architectures and transport protocols. The QoE requirements are specified for the end-to-end service and information is provided on how they influence network transport and applicat
25、ion layer behaviour. Compression coding schemes addressed in this Recommendation are examples, and detailed numeric values given as performance targets, e.g., bit rate, packet loss rate, are also examples. The readers may appropriately choose or replace these parameter values in order to be consiste
26、nt with the requirements of each IPTV service context to which they are intended to be applied. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, th
27、e editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currentl
28、y valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T E.800 Recommendation ITU-T E.800 (1994), Terms and definitions related to quality of service and network per
29、formance including dependability. ITU-T F.700 Recommendation ITU-T F.700 (2000), Framework Recommendation for multimedia services. ITU-T H.262 Recommendation ITU-T H.262 (2000) | ISO/IEC 13818-2:2000, Information technology Generic coding of moving pictures and associated audio information: Video. I
30、TU-T H.264 Recommendation ITU-T H.264 (2005), Advanced video coding for generic audiovisual services. ITU-T P.10/Amd.1 Recommendation ITU-T P.10/G.100 (2006), Amd.1 (2007), New Appendix I Definition of Quality of Experience (QoE). ITU-T P.800 Recommendation ITU-T P.800 (1996), Methods for subjective
31、 determination of transmission quality. ITU-T T.140 Recommendation ITU-T T.140 (1998), Protocol for multimedia application text conversation. ITU-T Y.1541 Recommendation ITU-T Y.1541 (2006), Network performance objectives for IP-based services. ITU-R BT.500-11 Recommendation ITU-R BT.500-11 (2002),
32、Methodology for the subjective assessment of the quality of television pictures. ITU-R BT.601-6 Recommendation ITU-R BT.601-6 (2007), Studio encoding parameters of digital television for standard 4:3 and wide-screen 16:9 aspect ratios. 2 Rec. ITU-T G.1080 (12/2008) ITU-R BT.1359-1 Recommendation ITU
33、-R BT.1359-1 (1998), Relative timing of sound and vision for broadcasting. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following term defined elsewhere: 3.1.1 Quality of experience (QoE) ITU-T P.10/Amd.1: The overall acceptability of an application or service, as perceived
34、 subjectively by the end-user. NOTE 1 Quality of Experience includes the complete end-to-end system effects (client, terminal, network, services infrastructure, etc.). NOTE 2 Overall acceptability may be influenced by user expectations and context. 3.2 Terms defined in this Recommendation This Recom
35、mendation defines the following terms: 3.2.1 channel zapping: The act of quickly changing from one channel to another. 3.2.2 clean audio: Audio track of an IPTV service with background sounds removed. 3.2.3 group of pictures: The group of pictures (GOP) is a group of successive pictures within a MPE
36、G-coded film and/or video stream. Each MPEG-coded film and/or video stream consists of successive GOPs. From the MPEG pictures contained in it, the visible frames are generated. 3.2.4 triple play services: Services that include IPTV, VoIP, and Internet access. 3.2.5 VoD trick modes: Download and str
37、eaming video on demand (VoD) systems provide the user with a large subset of VCR functionality including pause, fast forward, fast rewind, slow forward, slow rewind, jump to previous/future frame, etc. These functions are usually referred to as “trick modes“. 4 Abbreviations and acronyms This Recomm
38、endation uses the following abbreviations and acronyms: A/V Audio Video AAC Advanced Audio Coding AC-3 Dolby digital audio (Advanced Codec 3) ARQ Automatic Repeat reQuest AVC Advanced Video Codec AVS Audio and Video coding Standard (Chinese) BER Bit Error Rate BML Broadcast Markup Language CBR Const
39、ant Bit Rate CPU Central Processing Unit DCT Discrete Cosine Transform DSCQS Double Stimulus Continuous Quality Scale DSL Digital Subscriber Line DVB Digital Video Broadcast Rec. ITU-T G.1080 (12/2008) 3 DVD Digital Video Disk ECG Electronic Content Guide EPG Electronic Program Guide FEC Forward Err
40、or Correction FFW Fast ForWard fps frames per second GOP Group of Pictures GWR GateWay Router HDTV High Definition TeleVision HG Home Gateway HTML HyperText Markup Language IGMP Internet Group Management Protocol IGP Interactive Gateway Protocol IP Internet Protocol IPG Interactive Program Guide IPT
41、V Internet Protocol TeleVision MOS Mean Opinion Score MP Measured Point MP3 MPEG-1 audio layer 3 MPEG Moving Pictures Expert Group MPLS MultiProtocol Label Switching NICAM Near Instantaneous Companded Audio Multiplex PAL Phase Alternating Line PC Personal Computer PDV Packet Delay Variation PHB Per-
42、Hop Behaviour PLR Packet Loss Ratio PTD Packet Transfer Delay QoE Quality of Experience QoS Quality of Service RFC Request For Comments SDH Synchronous Digital Hierarchy SDTV Standard Definition TeleVision SECAM SEquentiel Couleur A Mmoire (sequential color with memory) SMPTE Society of Motion Pictu
43、re and Television Engineers SONET Synchronous Optical NETwork STB Set-Top Box 4 Rec. ITU-T G.1080 (12/2008) TS Transport Stream VBR Variable Bit Rate VCR Video Cassette Recorder VoD Video on Demand VoIP Voice over IP 5 Introduction to QoE QoE is defined in ITU-T P.10/Amd.1 as the overall acceptabili
44、ty of an application or service, as perceived subjectively by the end-user. It includes the complete end-to-end system effects (client, terminal, network, services infrastructure, etc.) and may be influenced by user expectations and context. Hence in principle, QoE is measured subjectively by the en
45、d-user and may differ from one user to the other. However, it is often estimated using objective measurements. Differences in perceptual acuity and preference mean that QoE judgments obtained from different people may vary. Therefore, measurements of QoE are generally made using group data. Where th
46、e necessary studies have been done to calibrate the relationship with QoE, it may also be estimated using objective measurements. A number of system performance characteristics contribute to QoE of the media stream. For example, the codec and the encoding bit rate used, media resolution in the sourc
47、e and at the display, corruption or loss of information, and delay. Interactions among video content, the codec and bit rate used, and the specific bits corrupted and/or packets lost contribute to a high variability in the perceived quality of the video output. There are additional factors that can
48、influence the viewers response. Some of these affect the perception of quality, such as the context of the judgment (a particular image will be rated one way in the context of standard definition TV (SDTV), another in the context of high definition TV (HDTV), and still differently in the context of
49、a video clip on Internet), cultural background, motivation, attention related factors, emotional state, and so on. (Direct evaluations of QoE are designed to exclude these factors, since they are not generally under the control of a network operator and so do not contribute to equipment requirements.) Other factors influence the viewers judgment of acceptability. These include things like previous experience with the specific communication mode or related modes (for instance, experience with DVD quality will influence
