1、 Recommendation ITU-R BT.1885(03/2011)Objective perceptual video quality measurement techniques for standard definition digital broadcast televisionin the presence of a reducedbandwidth referenceBT SeriesBroadcasting service(television)ii Rec. ITU-R BT.1885 Foreword The role of the Radiocommunicatio
2、n Sector is to ensure the rational, equitable, efficient and economical use of the radio-frequency spectrum by all radiocommunication services, including satellite services, and carry out studies without limit of frequency range on the basis of which Recommendations are adopted. The regulatory and p
3、olicy functions of the Radiocommunication Sector are performed by World and Regional Radiocommunication Conferences and Radiocommunication Assemblies supported by Study Groups. Policy on Intellectual Property Right (IPR) ITU-R policy on IPR is described in the Common Patent Policy for ITU-T/ITU-R/IS
4、O/IEC referenced in Annex 1 of Resolution ITU-R 1. Forms to be used for the submission of patent statements and licensing declarations by patent holders are available from http:/www.itu.int/ITU-R/go/patents/en where the Guidelines for Implementation of the Common Patent Policy for ITU-T/ITU-R/ISO/IE
5、C and the ITU-R patent information database can also be found. Series of ITU-R Recommendations (Also available online at http:/www.itu.int/publ/R-REC/en) Series Title BO Satellite delivery BR Recording for production, archival and play-out; film for television BS Broadcasting service (sound) BT Broa
6、dcasting service (television) F Fixed service M Mobile, radiodetermination, amateur and related satellite services P Radiowave propagation RA Radio astronomy RS Remote sensing systems S Fixed-satellite service SA Space applications and meteorology SF Frequency sharing and coordination between fixed-
7、satellite and fixed service systems SM Spectrum management SNG Satellite news gathering TF Time signals and frequency standards emissions V Vocabulary and related subjects Note: This ITU-R Recommendation was approved in English under the procedure detailed in Resolution ITU-R 1. Electronic Publicati
8、on Geneva, 2011 ITU 2011 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without written permission of ITU. Rec. ITU-R BT.1885 1 RECOMMENDATION ITU-R BT.1885 Objective perceptual video quality measurement techniques for standard definition digital broadca
9、st television in the presence of a reduced bandwidth reference (2011) Scope This Recommendation describes objective video quality assessment methods for standard definition digital broadcast television which can measure the perceptual video quality of mobile and stationary receiving conditions when
10、the features extracted from the reference video signal are readily available at the measurement point. The ITU Radiocommunication Assembly, considering a) that the ability to measure automatically the impairments of broadcast video signals has been desirable; b) that the perceptual video quality of
11、mobile reception may dynamically change depending on reception conditions; c) that objective measurement of perceived video quality may usefully complement subjective assessment methods; d) that three video quality measurement techniques for standard definition digital broadcast television in the pr
12、esence of a reduced reference have been proposed to ITU-R and they have been found to provide equivalent, well-aligned results; e) that objective perceptual video quality measurement techniques for standard definition digital broadcast television in the presence of a full reference have been specifi
13、ed in Recommendation ITU-R BT.1683, recommends 1 that any of the objective video quality models given in Annex 1 should be used for objective measurement of perceived video quality for standard definition digital broadcast television in the presence of a reduced bandwidth reference. 1 Introduction T
14、his RRNR-TV test addresses images as defined in Recommendation ITU-R BT.601-6 and two types of models: reduced reference (RR), and no reference (NR). RR models have limited bandwidth access to the source video, and NR models do not have access to the source video. The HRCs in each experiment encompa
15、ssed both coding only artefacts and coding with transmission errors. The coding schemes examined were MPEG-2 and H.264 (MPEG-4 part 10). The MPEG-2 coders were run at a variety of bit rates from 1.0 to 5.5 Mbit/s. The H.264 coders were run at a variety of bit rates ranging from 1.0 to 3.98 Mbit/s. E
16、ach experiment included 12 source sequences, of which two were secret source. Each experiment included 34 HRCs, and 156 processed video sequences (PVSs). Of these PVSs, 40 contained transmission errors and 116 contained coding only. 2 Rec. ITU-R BT.1885 1.1 Application This Recommendation provides v
17、ideo quality estimations for video classes TV3 to MM5B, as defined in ITU-T Recommendation P.911, Annex B. The applications for the estimation models described in this Recommendation include but are not limited to: 1. potentially real-time, in-service quality monitoring at the source; 2. remote dest
18、ination quality monitoring when side-channels are available for features extracted from source video sequences; 3. quality measurement for monitoring of a storage or transmission system that utilizes video compression and decompression techniques, either a single pass or a concatenation of such tech
19、niques; 4. lab testing of video systems. 1.2 Limitations The estimation models described in this Recommendation cannot be used to fully replace subjective testing. Correlation values between two carefully designed and executed subjective tests (i.e. in two different laboratories) normally fall withi
20、n the range 0.95 to 0.98. If this Recommendation is utilized to compare different codecs, it is advisable to use a quantitative method (such as that in ITU-T Recommendation J.149) to determine the models accuracy for that particular context. The models in this Recommendation were validated by measur
21、ing objective video quality that exhibits frame freezes up to 2 s. The models in this Recommendation were not validated for measuring objective video quality that has a steadily increasing delay (e.g. video which does not discard missing frames after a frame freeze). It should be noted that in case
22、of new coding and transmission technologies producing artefacts which were not included in this evaluation, the objective evaluation models may produce erroneous results. Here a subjective evaluation is required. 2 References The following ITU Recommendations and other references contain provisions,
23、 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 references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility
24、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 reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation
25、. 2.1 Normative references Recommendation ITU-R BT.500-12 Methodology for the subjective assessment of the quality of television pictures. ITU-T Recommendation P.910 (2008) Subjective video quality assessment methods for multimedia applications. ITU-T Recommendation P.911 (1998) Subjective audiovisu
26、al quality assessment methods for multimedia applications. Rec. ITU-R BT.1885 3 ITU-T Recommendation J.143 (2000) User requirements for objective perceptual video quality measurements in digital cable television. ITU-T Recommendation J.244 (2008) Full reference and reduced reference calibration meth
27、ods for video transmission systems with constant misalignment of spatial and temporal domains with constant gain and offset. 2.2 Informative references ITU-T Recommendation J.149 (1998) Subjective audiovisual quality assessment methods for multimedia applications. ITU-T Recommendation J.144 (2001) O
28、bjective perceptual video quality measurement techniques for digital cable television in the presence of a full reference. ITU-T Recommendation P.931 (1998) Multimedia communications delay, synchronization and frame rate measurement. ITU-T Recommendation J.148 (2003) Requirements for an objective pe
29、rceptual multimedia quality model. ITU-T Recommendation H.261 (1993) Video codec for audiovisual services at p x 64 kbits. ITU-T Recommendation H.263 (1996) Video coding for low bit rate communication. ITU-T Recommendation H.263 (1998) Video coding for low bit rate communication (H.263+). ITU-T Reco
30、mmendation H.264 (2003) Advanced video coding for generic audiovisual services. VQEG Validation of reduced-reference and no-reference objective models for standard definition television, Phase I, 2009. 3 Definitions 3.1 Terms defined elsewhere: This Recommendation uses the following terms defined el
31、sewhere: 3.1.1 subjective assessment (picture) (ITU-T Recommendation J.144): optional quoted definition. 3.1.2 objective perceptual measurement (picture) (ITU-T Recommendation J.144): optional quoted definition. 3.1.3 Proponent (ITU-T Recommendation J.144): optional quoted definition. 3.2 Terms defi
32、ned in this Recommendation This Recommendation defines the following terms: 3.2.1 Anomalous frame repetition: is defined as an event where the HRC outputs a single frame repeatedly in response to an unusual or out of the ordinary event. Anomalous frame repetition includes but is not limited to the f
33、ollowing types of events: an error in the transmission channel, a change in the delay through the transmission channel, limited computer resources impacting the decoders performance, and limited computer resources impacting the display of the video signal. 3.2.2 Constant frame skipping: is defined a
34、s an event where the HRC outputs frames with updated content at an effective frame rate that is fixed and less than the source frame rate. 3.2.3 Effective frame rate: is defined as the number of unique frames (i.e. total frames repeated frames) per second. 4 Rec. ITU-R BT.1885 3.2.4 Frame rate: is d
35、efined as the number of unique frames (i.e. total frames repeated frames) per second. 3.2.5 Intended frame rate: is defined as the number of video frames per second physically stored for some representation of a video sequence. The frame rate shall be constant. Two examples of constant intended fram
36、e rates are a BetacamSP tape containing 25 fps and a VQEG FR-TV Phase I compliant 625-line YUV file containing 25 fps; these both have an intended frame rate of 25 fps. 3.2.6 Live network conditions: are defined as errors imposed upon the digital video bit stream as a result of live network conditio
37、ns. 3.2.7 Pausing with skipping: is defined as events where the video pauses for some period of time and then restarts with some loss of video information. In pausing with skipping, the temporal delay through the system will vary about an average system delay, sometimes increasing and sometimes decr
38、easing. One example of pausing with skipping is a pair of IP Videophones, where heavy network traffic causes the IP Videophone display to freeze briefly; when the IP Videophone display continues, some content has been lost. Constant frame skipping and variable frame skipping are subsets of pausing w
39、ith skipping. A processed video sequence containing pausing with skipping will be approximately the same duration as the associated original video sequence. 3.2.8 Pausing without skipping: is defined as any event where the video pauses for some period of time and then restarts without losing any vid
40、eo information. Hence, the temporal delay through the system must increase. 3.2.9 Refresh rate: is defined as the rate at which the display is updated. 3.2.10 Simulated transmission errors: are defined as errors imposed upon the digital video bit stream in a highly controlled environment. Examples i
41、nclude simulated packet loss rates and simulated bit errors. 3.2.11 Source frame rate (SFR): is the intended frame rate of the original source video sequences. The source frame rate is constant. For the VQEG RRNR-TV test the SFR was either 25 fps or 30 fps. 3.2.12 Transmission errors: are defined as
42、 any error imposed on the video transmission. Example types of errors include simulated transmission errors and live network conditions. 3.2.13 Variable frame skipping: is defined as an event where the HRC outputs frames with updated content at an effective frame rate that changes with time. The tem
43、poral delay through the system will increase and decrease with time, varying about an average system delay. A processed video sequence containing variable frame skipping will be approximately the same duration as the associated original video sequence. 4 Abbreviations and acronyms This Recommendatio
44、n uses the following abbreviations and acronyms: ACR Absolute category rating (see ITU-T Recommendation P.910) ACR-HR Absolute category rating with hidden reference (see ITU-T Recommendation P.910) AVI Audio video interleave DMOS Difference mean opinion score FR Full reference FRTV Full reference te
45、levision HRC Hypothetical reference circuit Rec. ITU-R BT.1885 5 NR No (or Zero) reference PSNR Peak signal-to-noise ratio PVS Processed video sequence RMSE Root mean square error RR Reduced reference SFR Source frame rate SRC Source reference channel or circuit VQEG Video Quality Experts Group YUV
46、Colour space 5 Conventions None. 6 Description of the reduced reference measurement method The double-ended measurement method with reduced reference, for objective measurement of perceptual video quality, evaluates the performance of systems by making a comparison between features extracted from th
47、e undistorted input, or reference, video signal at the input of the system, and the degraded signal at the output of the system (see Fig. 1). Figure 1 shows an example of application of the reduced reference method to test a codec in the laboratory. FIGURE 1 Application of the reduced reference perc
48、eptual quality measurement method to test a codec in the laboratory 1885-01ReferencedecoderCoderInput/referencevideoObjective picturequality ratingFeature extractionsfor video qualitymeasurementVideo qualitymeasurementsystemThe comparison between input and output signals may require a temporal align
49、ment or a spatial alignment process, the latter to compensate for any vertical or horizontal picture shifts or cropping. It also may require correction for any offsets or gain differences in both the luminance and the chrominance channels. The objective picture quality rating is then calculated, typically by applying a perceptual model of human vision. Alignment and gain adjustment is known as normalization. This process is required because most reduced reference methods compare the features extracted from reference pictures and processed pictures on what
