Institute for Telecommunication Sciences
the research laboratory of the National Telecommunications and Information Administration

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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Lilli Segre, Publications Officer
Institute for Telecommunication Sciences
(303) 497-3572
LSegre@ntia.gov

For technical information concerning this report, contact:

Margaret H. Pinson
Institute for Telecommunication Sciences
(303) 497-3579
mpinson@ntia.doc.gov


Disclaimer: Certain commercial equipment, components, and software may be identified in this report to specify adequately the technical aspects of the reported results. In no case does such identification imply recommendation or endorsement by the National Telecommunications and Information Administration, nor does it imply that the equipment or software identified is necessarily the best available for the particular application or uses.

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