1、 I n t e r n a t i o n a l T e l e c o m m u n i c a t i o n U n i o n ITU-T J.343.2 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (11/2014) SERIES J: CABLE NETWORKS AND TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS Measurement of the quality of service - Part 3 Hybrid-N
2、R objective perceptual video quality measurement for HDTV and multimedia IP-based video services in the presence of non-encrypted bitstream data Recommendation ITU-T J.343.2 Rec. ITU-T J.343.2 (11/2014) i Recommendation ITU-T J.343.2 Hybrid-NR objective perceptual video quality measurement for HDTV
3、and multimedia IP-based video services in the presence of non-encrypted bitstream data Summary Recommendation ITU-T J.343.2 provides hybrid no reference (Hybrid-NR) objective perceptual video quality measurement methods for HDTV and multimedia when non-encrypted bitstream data are available. The fol
4、lowing are example applications that can use this Recommendation: potentially real-time, in-service quality monitoring at the headend; video television streams over cable/IPTV networks including those transmitted over the Internet using Internet protocol; video quality monitoring at the receiver whe
5、n non-encrypted bitstream data are available; video quality monitoring at measurement nodes located between point of transmission and point of reception when non-encrypted bitstream data are available; quality measurement for monitoring of a transmission system that utilizes video compression and de
6、compression techniques, either a single pass or a concatenation of such techniques; lab testing of video transmission systems. This Recommendation includes an electronic attachment containing test vectors, including video sequences, bitstream files and predicted objective model scores. History Editi
7、on Recommendation Approval Study Group Unique ID* 1.0 ITU-T J.343.2 2014-11-29 9 11.1002/1000/12317 _ * To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000
8、/11830-en. ii Rec. ITU-T J.343.2 (11/2014) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent
9、organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes t
10、he topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-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 a
11、re prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommenda
12、tion may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation 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 us
13、ed to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTSITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellec
14、tual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property 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 received noti
15、ce of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers 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 2
16、015 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T J.343.2 (11/2014) iii Table of Contents Page 1 Scope . 1 1.1 Applications 2 1.2 Limitations 2 2 References . 3 3 Definitions 3 3.1 Terms defined el
17、sewhere 3 3.2 Terms defined in this Recommendation . 3 4 Abbreviations and acronyms 3 5 Conventions 4 6 Performance metrics . 4 7 Description of the hybrid no-reference methodology . 4 8 Models 4 Annex A YHyNR 5 A.1 Introduction 5 A.2 Hybrid-NR VQM computation . 5 Bibliography. 10 Electronic attachm
18、ent: Test vectors, including video sequences, bitstream files and predicted objective model scores. Rec. ITU-T J.343.2 (11/2014) 1 Recommendation ITU-T J.343.2 Hybrid-NR objective perceptual video quality measurement for HDTV and multimedia IP-based video services in the presence of non-encrypted bi
19、tstream data 1 Scope This Recommendation1 describes algorithmic models for measuring the visual quality of IP-based video services. The models are hybrid no-reference (Hybrid-NR) models, which use non-encrypted bitstream data and video image data captured at the video player. As output the models pr
20、ovide an estimate of visual quality on the 1,5 mean opinion score (MOS) scale, derived from five-point absolute category rating (ACR) as in ITU-T P.910. The models address low-resolution (VGA/WVGA) application areas, including services such as mobile TV, as well as high-resolution (HD) application a
21、reas, including services such as IPTV. This Recommendation is to be used with videos encoded using ITU-T H.264 and media payload encapsulated in RTP/UDP/IP packets for the low-resolution and encapsulated in MPEG-TS/RTP/UDP/IP for the high-resolution areas. The models in this Recommendation measure t
22、he visual effect of spatial and temporal degradations as a result of video coding, erroneous transmission or video rescaling. The models may be used for applications such as to monitor the quality of deployed networks to ensure their operational readiness or to benchmark service quality. The models
23、in this Recommendation can also be used for lab testing of video transmission systems. The models identified in this Recommendation have limited precision. Therefore, directly comparing model results can be misleading. The accuracy of models has to be understood and taken into account (e.g., using I
24、TU-T J.149). The validation test material consisted of video encoded using different implementations of ITU-T H.264. It included media transmitted over wired and wireless networks, such as WIFI and 3G mobile networks. The transmission impairments included error conditions such as dropped packets, pa
25、cket delay, both from simulations and from transmission over commercially operated networks. The following source reference channel (SRC) conditions were included in the validation test: 1080i 60 Hz (29.97 fps); 1080p (25 fps); 1080i 50 Hz (25 fps); 1080p (29.97 fps); SRC duration: HD: 10 s, VGA/WVG
26、A: 10 s or 15 s (rebuffering); VGA at 25 and 30 fps; WVGA at 25 and 30 fps. _ 1 This Recommendation includes an electronic attachment containing test vectors, including video sequences, bitstream files and predicted objective model scores. 2 Rec. ITU-T J.343.2 (11/2014) The following hypothetical re
27、ference circuit (HRC) conditions were included in the validation test for each resolution: Test factors Video resolution: 1920 1080 interlaced and progressive Video frame rates: 29.97 and 25 fps Video bitrates: 1 to 30 Mbit/s (HD), 100 kbit/s to 3 Mbit/s (VGA/WVGA) Temporal frame freezing (pausing w
28、ith skipping) of up to 50% of video duration Transmission errors with packet loss Rebuffering (VGQ/WVGA only): up to 50% of SRC Coding technologies ITU-T H.264/AVC (MPEG-4 Part 10) Tandem coding 1.1 Applications The applications for the estimation model described in this Recommendation include, but
29、are not limited to: potentially real-time, in-service quality monitoring at the headend; video television streams over cable/IPTV networks including those transmitted over the Internet using Internet protocol; video quality monitoring at the receiver when non-encrypted bitstream data and processed v
30、ideo sequence (PVS) are available; video quality monitoring at measurement nodes located between point of transmission and point of reception when non-encrypted bitstream data and PVS are available; quality measurement for monitoring of a transmission system that utilizes video compression and decom
31、pression techniques, either a single pass or a concatenation of such techniques; lab testing of video transmission systems. 1.2 Limitations The video quality estimation model described in this Recommendation cannot be used to fully replace subjective testing. When frame freezing was present, the tes
32、t conditions had frame-freezing durations up to 50% of SRC duration. The models in this Recommendation were validated for measuring video quality in a rebuffering condition (i.e., video that has a steadily increasing delay or freezing without skipping) only for VGA/WVGA. The models were not tested o
33、n other frame rates than those used in TV systems (i.e., 29.97 fps and 25 fps, in interlaced or progressive mode). If forward error correction techniques are employed, the models in this Recommendation may not be used. It is important that no additional transmission errors occur between the collecti
34、on point of the bitstream data and the capture point of the PVS. It should be noted that in case of new coding and transmission technologies producing artifacts, which were not included in this evaluation, the objective model may produce erroneous results. Here, a subjective evaluation is required.
35、Rec. ITU-T J.343.2 (11/2014) 3 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, the editions indicated were valid. All Recommendations and other re
36、ferences 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 currently valid ITU-T Recommendations is regularly published. The referen
37、ce to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T H.264 Recommendation ITU-T H.264 (2014), Advanced video coding for generic audiovisual services. ITU-T J.149 Recommendation ITU-T J.149 (2004), Method for specifying accurac
38、y and cross-calibration of Video Quality Metrics (VQM). ITU-T J.343 Recommendation ITU-T J.343 (2014), Hybrid perceptual bitstream models for objective video quality measurements. ITU-T P.910 Recommendation ITU-T P.910 (2008), Subjective video quality assessment methods for multimedia applications.
39、3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following term defined elsewhere: 3.1.1 hybrid no reference model ITU-T J.343: An objective video quality model that predicts subjective quality using the decoded video frames, packet headers, and video payload. Such models can b
40、e deployed in-service but cannot analyse encrypted video. 3.2 Terms defined in this Recommendation None. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: CODEC Coder-Decoder HRC Hypothetical Reference Circuit Hybrid-NR Hybrid No Reference LUT Look-Up Ta
41、ble MOS Mean Opinion Score MPEG Moving Picture Experts Group NR No (or Zero) Reference PES Packetized Elementary bitStream PVS Processed Video Sequence QP Quantization Parameter SRC Source Reference Channel (or Circuit) VQEG Video Quality Experts Group VQM Video Quality Metrics 4 Rec. ITU-T J.343.2
42、(11/2014) 5 Conventions None. 6 Performance metrics A summary of this and other hybrid models may be found in ITU-T J.343. See b-VQEG Hybrid for a complete analysis of the models included in this Recommendation. 7 Description of the hybrid no-reference methodology This Recommendation specifies objec
43、tive video quality measurement methods that use both processed video sequences and bitstream data. The bitstream data may be provided in the forms of elementary bitstream (ES), packetized elementary bitstream (PES) or packet video (Figure 1). Hybrid-NR models use only PVS and non-encrypted bitstream
44、 data, as shown in Figure 1 and Figure 2. Figure 1 Block-diagram depicts the core concept of hybrid perceptual bitstream models MOSp: predicted MOS by the model Figure 2 Block-diagram of the Hybrid-NR model 8 Models Annex A contains the full disclosure of the model included in this Recommendation. T
45、he model is YHyNR. Rec. ITU-T J.343.2 (11/2014) 5 Annex A YHyNR (Hybrid-NR model) (This annex forms an integral part of this Recommendation.) A.1 Introduction The YHyNR model first computes a video quality metrics (VQM) value using quantization parameter (QP) and the error area (log) using a predefi
46、ned look-up table (LUT). Then, post-processing is applied to reflect various impairments due to transmission errors. A.2 Hybrid-NR VQM computation A.2.1 Feature computation A.2.1.1 Quantization parameter and error area In ITU-T H.264/AVC, the QP is an important factor for video quality. The averaged
47、 QP and I frame QP are computed as follows: V id e o F r a m ea v e iQPN u m F ra m eQP 1 fr a m eIIfr a m e iQPN u m If ra m eQP 1 where NumFrame is the total number of frames and NumIFrame is the number of I frames. Figure A.1 Error areas due to transmission errors To reflect the effects of transm
48、ission errors, an error area can be calculated using an ITU-T H.264/AVC decoder (Figure A.1). The transmission error pixel may be categorized into two types. One is an error pixel due to erroneous packets and the other is the propagation of error pixels. The error pixels due to erroneous packet can
49、be directly calculated during decoding and the propagation error pixels are calculated using the reference frame index and motion vectors. First, an error map is produced as follows: o t h e r w i s e E r r o rkjiV i d e oifkjiE r r o r M a p 0 ,1,where ),( ji is a spatial index and k is temporal index. f r a m eji kjiE r r o r M a pkE r r o r F r a m e ),( ,Then, isolated error frames are removed, which may not affect overall p
