This paper proposes the concept of perceptual pruning to improve the scalability of immersive video conferencing (IVC) systems. The aim of perceptual pruning is to enable servers to dynamically reduce the bit rate of videos on-the-fly in response to changes in virtual distance and orientation of videos with respect to the receiving client. It is shown that the video of each participant will have to undergo varying degrees of texture to pixel mapping before it is rendered by the client. By reducing the resolution of the video at the scale of each transform block in response to nuances of this mapping, the video bit rate could be reduced without any noticeable degradation of quality. This paper presents the results of experimental tests and also real-world scalability tests to quantify the impact of perceptual pruning. It is concluded that perceptual pruning will be of significant benefit, especially in those situations when the number of videos in the client's viewpoint is large.

This paper aims at minimising the video downstream bit rate of immersive video conferencing (IVC) applications by judiciously modifying the video quality based on the relative virtual positions of participants in the virtual environment. The paper reports on the results of a user study to assess the influence of participants' perspectives on the perceptual impact of relevant video parameters, such as resolution and frame rate. A mathematical model for video rate is proposed that expresses the total rate as the product of spatial resolution and frame rate. Results from the user study are combined with the proposed model to predict the rate parameters which will result in perceptually acceptable quality for a given user perspective. The simulation results show that by exploiting the proposed method, the downstream network load for the client can be significantly reduced with little or no impact on the perceived quality.