This figure presents the reference model for measuring end-to-end video performance parameters and summarizes the principles of the new measurement methodology detailed in ANSI T1.801.03, "American National Standard for Telecommunications - Digital Transport of One-Way Video Telephony Signals - Parameters for Objective Performance Assessment." This standard specifies a framework for measuring end-to-end performance parameters that are sensitive to distortions introduced by the coder, the digital channel, or the decoder as shown in the figure.
Performance measurement systems digitize the input and output video streams in accordance with ITU-R Recommendation BT.601 and extract features from these digitized frames of video. Features are quantities of information that are associated with individual video frames. They quantify fundamental perceptual attributes of the video signal such as spatial and temporal detail. Parameters are calculated using comparison functions that operate on two parallel sequences of these feature samples (one sequence from the output video frames and a corresponding sequence from the input video frames). The ANSI standard contains parameters derived from three types of features that have proven useful: (1) scalar features, where the information associated with a specified video frame is represented by a scalar; (2) vector features, where the information associated with a specified video frame is represented by a vector of related numbers; and (3) matrix features, where the information associated with a specified video frame is represented by a matrix of related numbers.
This measurement paradigm shown above is known internationally as "reduced-reference" video quality measurements (see International Telecommunications Union, Telecommunication Standardization Sector, ITU-T Recommendation J.143, "User requirements for objective perceptual video quality measurements in digital cable television").