Optimal sequence duration for subjective video quality assessment

This paper reports an empirical investigation into increasing the efficiency of subjective data collection by reducing the length of test sequences below the recommended 10 seconds. Twenty-four observers viewed four 10 second reference sequences, in addition to four truncated versions of each: 7 seconds; 5 seconds; 3 seconds and 1.5 seconds. Results indicated that, compared to the 10 second sequences, the ability of observers to identify compression artefacts was significantly reduced only when viewing the 1.5 second sequences. These results indicate that, when using the DSCQS methodology, a significant benefit in the efficiency of subjective data collection can be gained by reducing the length of test sequences to potentially as low as 3 seconds, without a significant impact upon reliability.