ANSI T1A1 Contribution T1A1.5/94-128, March 28, 1994.
Edwin L. Crow
Abstract: Presents in detail the ANOVA methods for analysis of the subjective T1A1 video test data, especially with regard to any systematic effect a laboratory may have on the Mean Opinion Score (MOS) of any given Hypothetical Reference Circuit (HRC). The term HRC refers to a specific realization of a video transmission system that may include coders, digital transmission circuits, decoders, and even analog processing of the video signal. The experimental variables of the T1A1 subjective test plan may be summarized as follows: (1) 3 laboratories, X, Y, Z, (2) 25 HRCs, 1, 2,..., 25, (3) 25 scenes, a, b,..., y, (4) 625 HRC-scene combinations, or test combinations, (5) 30 accepted viewers in each lab, screened from about 36 initial viewers, some of whom may not pass a consistency check, broken into 3 teams of 10 each, (6) 3 sets of videotapes - Red (R), Green (G), Orange (O), each set of 4 tapes to be viewed by a corresponding team in each lab, each set including 10 HRCs (thus overlapping slightly), (7) 4 subteams within each team since each viewing session is limited to at most 3 viewers, (8) 4 sessions for each subteam to view the 4 tapes, each tape (and session) being limited to about 32 minutes, (9) 9 types (1, 2,..., 9) into which the 25 HRCs are classified, 1 to 4 in each type, (10) 5 content categories (A,B,C,D,E) of the 25 scenes, 3 to 6 in each category, (11) 5 possible ratings of test combination scene impairment by viewers on voting forms ranging from Imperceptible to Very Annoying, which will be translated into 5,4,3,2,1 in the data reduction. Test combinations are ordered on the tapes by a restricted randomization, that subteams are selected at random from the total viewers available (from a specified type of population), and that the four tapes are presented to the corresponding four subteams in random permutation orders.
Keywords: analysis; video; quality; subjective; ANOVA; statistical; inter-laboratory
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Margaret H. Pinson
Institute for Telecommunication Sciences
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