Optimal Frame Rate Allocation and Quantizer Selection for Unicast and Multicast Wireless Scalable Video Communication

Abstract

In this paper, we present novel schemes for video quality maximization in the context of H.264 scalable video coding-based 4G wireless broadcast and multicast video transmission to heterogeneous multimedia wireless clients. In the first part, we address the issue of optimal frame rate allocation when the multimedia server is constrained by the processing overheads required for tasks such as video encoding, bit-stream extraction, packetization, etc. We demonstrate that the above problem of perceptual quality maximization is well represented by a constrained optimization framework. Based on the system model, we present a closed-form solution for frame rate allocation and a comprehensive algorithm for sum quality maximization. In the second part, we propose a novel rate partitioning-based optimal scalable video (RPSV) transmission framework. A typical wireless multicast group comprises of multimedia clients with varying wireless link qualities. Conventional multicast video transmission is constrained by the broadcast/ multicast group (BMG) subscriber with the worst link capacity. Hence, we propose the RPSV scheme for optimal partitioning of the multicast group for transmission of the H.264-coded base and enhancement scalable video layers. We demonstrate that the optimal wireless link quality-based BMG partition and the associated quantization, time-fraction parameters can be computed by solving a series of convex objective minimization problems and derive a closed-form solution for the convex problem at each step. We compare the results obtained using the above mentioned optimal frame rate allocation and quantization parameter selection schemes with the results obtained using conventional schemes and demonstrate the superiority of the proposed algorithms in both unicast and multicast scenarios.