This paper introduces a new high definition video quality database, referred to as BVI-HD, which contains 32 reference and 384 distorted video sequences plus subjective scores. The reference material in this database was carefully selected to optimise the coverage range and distribution uniformity of five low level video features, while the included 12 distortions, using both original High Efficiency Video Coding (HEVC) and HEVC with synthesis mode (HEVC-SYNTH), represent state-ofthe-art approaches to compression. The range of quantisation parameters included in the database for HEVC compression was determined by a subjective study, the results of which indicate that a wider range of QP values should be used than the current recommendation. The subjective opinion scores for all 384 distorted videos were collected from a total of 86 subjects, using a double stimulus test methodology. Based on these results, we compare the subjective quality between HEVC and synthesised content, and evaluate the performance of nine state-of-the-art, full-reference objective quality metrics. This database has now been made available online, representing a valuable resource to those concerned with compression performance evaluation and objective video quality assessment.

Subjective quality assessment is an essential component of modern image and video processing, both for the validation of objective metrics and for the comparison of coding methods. However, the standard procedures used to collect data can be prohibitively time-consuming. One way of increasing the efficiency of data collection is to reduce the duration of test sequences from the 10 second length currently used in most subjective video quality assessment experiments. Here, we explore the impact of reducing sequence length upon perceptual accuracy when identifying compression artefacts. A group of four reference sequences, together with five levels of distortion, are used to compare the subjective ratings of viewers watching videos between 1.5 and 10 seconds long. We identify a smooth function indicating that accuracy increases linearly as the length of the sequences increases from 1.5 seconds to 7 seconds. The accuracy of observers viewing 1.5 second sequences was significantly inferior to those viewing sequences of 5 seconds, 7 seconds and 10 seconds. We argue that sequences between 5 seconds and 10 seconds produce satisfactory levels of accuracy but the practical benefits of acquiring more data lead us to recommend the use of 5 second sequences for future video quality assessment studies that use the DSCQS methodology.

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