1、 AMERICAN NATIONAL STANDARD FOR TELECOMMUNICATIONS ATIS-0100801.03.2003(R2013) Digital Transport of One-Way Video Signals Parameters for Objective Performance Assessment As a leading technology and solutions development organization, ATIS brings together the top global ICT companies to advance the i
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11、e of Disclaimer see Figure 1) is also not recommended until further independent validation tests can be performed. The General Model does not provide a comprehensive evaluation of two-way multimedia transmission quality. It only measures the effects of one-way video distortion. The effects of audio
12、distortion, audio delay, video delay, audio-video synchronization, and other impairments related to two-way interaction are not reflected in the General Model scores. Therefore, it is possible to have high General Model scores, yet poor quality of the multimedia connection overall. 2 Normative Refer
13、ences ITU-R Recommendation BT.601 (10/95), Studio Encoding Parameters of Digital Television for Standard 4:3 and Wide-Screen 16:9 Aspect Ratios. 22This document is available from the International Telecommunications Union, Radiocommunication Sector. 2 T1.801.03-2003 ITU-T Recommendation P.911 (12/19
14、98), Subjective Audiovisual Quality Assessment Methods for Multimedia Applications. 33 Definitions, Abbreviations, and Acronyms 3.1 Definitions 3.1.1 4:2:2: A Y, CB, CRimage sampling format where chrominance planes (CBand CR) are sampled horizontally at half the luminance (Y) planes sampling rate. S
15、ee Rec. 601 (clause 2). 3.1.2 Absolute Temporal Information (ATI): A feature derived from the absolute value of temporal information images that are computed as the difference between successive frames in a video clip. ATI quantifies the amount of motion in a video scene. See clause 7.5 for the prec
16、ise mathematical definition. 3.1.3 American National Standards Institute (ANSI): Administrator and coordinator of the United States private sector voluntary standardization system. 3.1.4 Alliance for Telecommunications Industry Solutions (ATIS): A North American standards body that develops telecomm
17、unications standards, operating procedures, and guidelines through its sponsored committees and forums. 3.1.5 Big YUV: The binary file format used for storing clips that have been sampled according to Rec. 601. In the Big YUV format, all the video frames for a scene are stored in one large binary fi
18、le, where each individual frame conforms to Rec. 601 sampling. The Y represents the luminance channel information, the U represents the blue color difference channel (i.e., CBin Rec. 601), and the V represents the red color difference channel (i.e., CRin Rec. 601). The pixel ordering in the binary f
19、ile is the same as that specified in SMPTE 125M 17. The full specification of the Big YUV file format is given in clause 5 and software routines for reading and displaying Big YUV files are given in 24. 3.1.6 Clip: Digital representation of a scene that is stored on computer media. 3.1.7 Clip VQM: T
20、he VQM of a single clip of processed video. 3.1.8 Chrominance (C, CB, CR): The portion of the video signal that predominantly carries the color information (C), perhaps separated further into a blue color difference signal (CB) and a red color difference signal (CR). 3.1.9 Codec: Abbreviation for a
21、coder/decoder or compressor/decompressor. 3.1.10 Common Intermediate Format (CIF): A video sampling structure used for video teleconferencing where the luminance channel is sampled at 352 pixels by 288 lines 11. 3.1.11 Feature: A quantity of information associated with, or extracted from, a spatial-
22、temporal sub-region of a video stream (either an original video stream or a processed video stream). 3.1.12 Field: One half of a frame, containing all of the odd or even lines. 3.1.13 Frame: One complete television picture. 3.1.14 Frames per Second (FPS): The number of original frames per second tra
23、nsmitted by the video system under test. For instance, an NTSC video system transmits approximately 30 FPS. 3.1.15 Gain: A multiplicative scaling factor applied by the hypothetical reference circuit (HRC) to all pixels of an individual image plane (e.g., luminance, chrominance). Gain of the luminanc
24、e signal is commonly known as contrast. 3This document is available from the International Telecommunications Union, Telecommunication Standardization Sector . 3 T1.801.03-2003 3.1.16 General Model: The video quality model, that is the subject of this standard (clause 9). The General Model was submi
25、tted to the phase-2 tests performed by the Video Quality Experts Group (VQEG). The VQEG Phase-2 final report describes the performance of the General Model (see 25, proponent H). 3.1.17 H.261: Abbreviation for ITU-T Recommendation H.261 11. 3.1.18 Hypothetical Reference Circuit (HRC): A video system
26、 under test such as a codec or digital video transmission system. 3.1.19 Input Video: Video before being processed or distorted by an HRC (see Figure 2). Input video may also be referred to as Original Video. 3.1.20 Institute for Radio Engineers (IRE) Unit: A unit of voltage commonly used for measur
27、ing video signals. One IRE is equivalent to 1/140 of a volt. 3.1.21 International Telecommunication Union (ITU): An international organization within the United Nations System where governments and the private sector coordinate global telecommunications networks and services. The ITU includes the Ra
28、diocommunication Sector (ITU-R) and the Telecommunication Standardization Sector (ITU-T). 3.1.22 Luminance (Y): The portion of the video signal that predominantly carries the luminance information (i.e., the black and white part of the picture). 3.1.23 Mean Opinion Score (MOS): The average subjectiv
29、e quality judgment assigned by a panel of viewers to a processed video clip. 3.1.24 Moving Picture Experts Group (MPEG): A working group of ISO/IEC in charge of the development of standards for coded representation of digital audio and video (e.g., MPEG-1, MPEG-2, MPEG-4). 3.1.25 National Television
30、 Systems Committee (NTSC): The 525-line analog color video composite system 18. 3.1.26 Offset or level offset: An additive factor applied by the HRC to all pixels of an individual image plane (e.g., luminance, chrominance). Offset of the luminance signal is commonly known as brightness. 3.1.27 Origi
31、nal Region of Interest (OROI): A Region of Interest (ROI) extracted from the original video, specified in Rectangle Coordinates. 3.1.28 Original Video: Video before being processed or distorted by an HRC (see Figure 2). Original video may also be referred to as input video since this is the video in
32、put to the digital video transmission system. 3.1.29 Original Valid Region (OVR): The Valid Region of an original video clip, specified in Rectangle Coordinates. 3.1.30 Output Video: Video that has been processed or distorted by an HRC (see Figure 2). Output video may also be referred to as Processe
33、d Video. 3.1.31 Over-scan: The portion of the video that is not normally visible on a standard television monitor. 3.1.32 Phase-Altering Line (PAL): The 625-line analog color video composite system. 3.1.33 Parameter: A measure of video distortion that is the result of comparing two parallel streams
34、of features, one stream from the original video and the corresponding stream from the processed video. 3.1.34 Processed Region of Interest (PROI): A Region of Interest (ROI) extracted from the processed video and corrected for spatial shifts of the HRC, specified in Rectangle Coordinates. 3.1.35 Pro
35、cessed Video: Video that has been processed or distorted by an HRC (see Figure 2). Processed video may also be referred to as output video since this is the video output from the digital video transmission system. 4 T1.801.03-2003 3.1.36 Processed Valid Region (PVR): The Valid Region of a processed
36、video clip from an HRC, specified in Rectangle Coordinates. The PVR is always referenced to the original video, so it is necessary to correct for any spatial shifts of the video by the HRC before computing PVR. Thus, PVR is always contained within the OVR. The region between the PVR and the OVR is t
37、hat portion of the video that was blanked or corrupted by the HRC. 3.1.37 Production Aperture: The image lattice that represents the maximum possible image extent in a given standard. The Production Aperture represents the desirable extent for image acquisition, generation, and processing, prior to
38、blanking. For Rec. 601 sampled video, the Production Aperture is 720 pixels x 486 lines for 525-line systems and 720 pixels x 576 lines for 625-line systems 19. 3.1.38 Quarter Common Intermediate Format (QCIF): A video sampling structure used for video teleconferencing where the luminance channel is
39、 sampled at 176 pixels by 144 lines 11. 3.1.39 Rec. 601: Abbreviation for ITU-R Recommendation BT.601 (clause 2), a common 8-bit video sampling standard that samples the luminance (Y) channel at 13.5 MHz, and the blue and red color difference channels (CBand CR) at 6.75 MHz. See clause 5 for more in
40、formation. 3.1.40 Rectangle Coordinates: A rectangular shaped image sub-region that is completely contained within the production aperture and that is specified by four coordinates (top, left, bottom, right). Numbering starts from zero so that the (top, left) corner of the sampled image is (0, 0). S
41、ee clause 5.3. 3.1.41 Reduced-Reference: A video quality measurement methodology that utilizes low bandwidth features extracted from the original or processed video streams, as opposed to using full-reference video that requires complete knowledge of the original and processed video streams 12. Redu
42、ced-reference methodologies have advantages for end-to-end in-service quality monitoring since the reduced-reference information is easily transmitted over ubiquitous telecommunications networks. 3.1.42 Reframing: The process of reordering two consecutively sampled interlaced fields of processed vid
43、eo into a frame of video. Reframing is necessary when HRCs do not preserve standard interlace field types (e.g., an NTSC field type one is output as an NTSC field type two and vice versa). See clause 6.1.2. 3.1.43 Region of Interest (ROI): An image lattice (specified in Rectangle Coordinates) that i
44、s used to denote a particular sub-region of a field or frame of video. Also see SROI. 3.1.44 Scene: A sequence of video frames. 3.1.45 Spatial Information (SI): A feature based on statistics that are extracted from the spatial gradients (i.e., edges) of an image or video scene. References 3 and 13 p
45、rovide a definition of SI based on statistics extracted from 3 x 3 Sobel-filtered images 16 while clause 7.2.2 of this standard provides a definition of SI based on statistics extracted from much larger 13 x 13 edge-filtered images (Figure 12). 3.1.46 Spatial Region of Interest (SROI): The specific
46、image lattice (specified in Rectangle Coordinates) that is used to calculate the VQM of a video clip. The SROI is a rectangular subset that lies completely inside the Processed Valid Region. For Rec. 601 sampled video, the recommended SROI is 672 pixels x 448 lines for 525-line systems and 672 pixel
47、s x 544 lines for 625-line systems, centered within the Production Aperture. This recommended SROI corresponds to approximately the portion of the video picture that is visible on a monitor, excluding the over-scan area. Also see ROI. 3.1.47 Spatial Registration: The process that is used to estimate
48、 and correct for spatial shifts of the processed video sequence with respect to the original video sequence. 3.1.48 Spatial-Temporal (S-T) Sub-Region: A block of image pixels in an original or processed video stream that includes a vertical extent (number of rows), a horizontal extent (number of col
49、umns), and a time extent (number of frames). See Figure 10. 3.1.49 Society of Motion Picture and Television Engineers (SMPTE): An industry-leading society for the motion picture and television industries devoted to advancing theory and application in motion imaging, including film, television, video, computer imaging, and telecommunications. The industry relies 5 T1.801.03-2003 on SMPTE to generate standards, engineering guidelines, and recommended practices to be followed by respective field professionals.
