Search

Dynamic adaptive streaming addresses user heterogeneity by providing multiple encoded representations at different rates and/or resolutions for the same video content. For delay-sensitive applications, such as live streaming, there is however a stringent requirement on the encoding delay, and usually the encoding power (or rate) budget is also limited by the computational (or storage) capacity of the server. It is therefore important, yet challenging, to optimally select the source coding parameters for each encoded representation in order to minimize the resource consumption while maintaining a high quality of experience for the users. To address this, we propose an optimization framework with an optimal representation selection problem for delay, power, and rate constrained adaptive video streaming. Then, by the optimal selection of source coding parameters for each selected representation, we maximize the overall expected user satisfaction, subject not only to the encoding rate constraint, but also to the delay and power constraints at the server. We formulate the proposed optimization problem as an integer linear program formulation to provide the performance upper bound, and as a submodular maximization problem with two knapsack constraints to develop a practically feasible algorithm. Simulation results show that the proposed weighted rate and power cost benefit greedy algorithm is able to achieve a near-optimal performance with very low time complexity. In addition, it can strike the best tradeoff both between the rate and power cost, and between the algorithm’s performance and the delay requirements proposed by delay sensitive applications. [ABSTRACT FROM AUTHOR]

Smart mobile phones are capable of performing video coding and streaming over wireless networks, but are often constrained by the end-to-end delay requirement and energy supply. To achieve optimal performance under the delay and energy constraints, in this paper we extend the traditional rate-distortion (R-D) model and the previously proposed delay R-D model to a novel delay-power-rate-distortion (d-P-R-D) model by including another two dimensions (the encoding time and encoder power consumption), which quantifies the relationship among source encoding delay, rate, distortion, and power consumption for IPPPP coding mode in H.264/AVC. We have verified the accuracy of our proposed d-P-R-D model through experiments. Based on the proposed d-P-R-D model, we develop a novel rate-control (RC) algorithm, which minimizes the encoding distortion under the constraints of rate, delay, and power. The experimental results demonstrate the superiority of the proposed RC algorithm over the existing scheme. Therefore, the d-P-R-D model and the model-based RC provide a theoretical basis and a practical guideline for the cross-layer system design and performance optimization in wireless video communication under delay and energy constraints. [ABSTRACT FROM PUBLISHER]