The quality assessment of impaired stereoscopic video is a key element in designing and deploying advanced immersive media distribution platforms. A widely accepted quality metric to measure impairments of stereoscopic video is, however, still to be developed. As a step toward finding a solution to this problem, this paper proposes a full reference stereoscopic video quality metric to measure the perceptual quality of compressed stereoscopic video. A comprehensive set of subjective experiments is performed with 14 different stereoscopic video sequences, which are encoded using both the H.264 and high efficiency video coding compliant video codecs, to develop a subjective test results database of 116 test stimuli. The subjective results are analyzed using statistical techniques to uncover different patterns of subjective scoring for symmetrically and asymmetrically encoded stereoscopic video. The subjective result database is subsequently used for training and validating a simple but effective stereoscopic video quality metric considering heuristics of binocular vision. The proposed metric performs significantly better than state-of-the-art stereoscopic image and video quality metrics in predicting the subjective scores. The proposed metric and the subjective result database will be made publicly available, and it is expected that the proposed metric and the subjective assessments will have important uses in advanced 3D media delivery systems.

No abstract

Abstract-Determining the best partitioning structure of a Coding Tree Unit (CTU) is one of the most time consuming operations in HEVC encoding. Specifically, it is the evaluation of the quadtree hierarchy using the Rate-Distortion (RD) optimization that has the most significant impact on the encoding time, especially in the cases of High Definition (HD) and Ultra High Definition (UHD) videos. In order to expedite the encoding for low delay applications, this paper proposes a Coding Unit (CU) size selection and encoding algorithm for inter-prediction in the HEVC. To this end, it describes (i) two CU classification models based on Inter N×N mode motion features and RD cost thresholds to predict the CU split decision, (ii) an online training scheme for dynamic content adaptation, (iii) a motion vector reuse mechanism to expedite the motion estimation process, and finally introduces (iv) a computational complexity to coding efficiency trade-off process to enable flexible control of the algorithm. The experimental results reveal that the proposed algorithm achieves a consistent average encoding time performance ranging from 55% -58% and 57% -61% with average Bjøntegaard Delta Bit Rate (BDBR) increases of 1.93% -2.26% and 2.14% -2.33% compared to the HEVC 16.0 reference software for the low delay P and low delay B configurations, respectively, across a wide range of content types and bit rates.

Abstract-It is well known that when the two eyes are provided with two views of different resolutions the overall perception is dominated by the high resolution view. This property, known as binocular suppression, is effectively used to reduce the bit rate required for stereoscopic video delivery, where one view of the stereo pair is encoded at a much lower quality than the other. There have been significant amount of effort in the recent past to measure the just noticeable level of asymmetry between the two views, where asymmetry is achieved by encoding views at two quantization levels. However, encoding artifacts introduce both blurring and blocking artifacts in to the stereo views, which are perceived differently by the human visual system. Therefore, in this paper, we design a set of psycho-physical experiments to measure the just noticeable level of asymmetric blur at various spatial frequencies, luminance contrasts and orientations. The subjective results suggest that humans could tolerate a significant amount of asymmetry introduced by blur, and the level of tolerance is independent of the spatial frequency or luminance contrast. Furthermore, the results of this paper illustrate that when asymmetry is introduced by unequal quantization, the just noticeable level of asymmetry is driven by the blocking artifacts. In general, stereoscopic asymmetry introduced by way of asymmetric blurring is preferred over asymmetric compression. It is expected that the subjective results of this paper will have important use cases in objective measurement of stereoscopic video quality and asymmetric compression and processing of stereoscopic video.

No abstract