Optimal packetisation of MPEG-4 using RTP over mobile networks

The introduction of third-generation wireless networks should result in real-time mobile video communications becoming a reality. Delivery of such video is likely to be facilitated by the realtime transport protocol (RTP). Careful packetisation of the video data is necessary to ensure the optimal trade-off between channel utilisation and error robustness. Theoretical analyses for two basic schemes of MPEG-4 data encapsulation within RTP packets are presented. Simulations over a GPRS (general packet radio service) network are used to validate the analysis of the most efficient scheme. Finally, a motion adaptive system for deriving MPEG-4 video packet sizes is presented. Further simulations demonstrate the benefits of the adaptive system

3D video coding and transmission

The capture, transmission, and display of 3D content has gained a lot of attention in the last few years. 3D multimedia content is no longer con fined to cinema theatres but is being transmitted using stereoscopic video over satellite, shared on Blu-RayTMdisks, or sent over Internet technologies. Stereoscopic displays are needed at the receiving end and the viewer needs to wear special glasses to present the two versions of the video to the human vision system that then generates the 3D illusion. To be more e ffective and improve the immersive experience, more views are acquired from a larger number of cameras and presented on di fferent displays, such as autostereoscopic and light field displays. These multiple views, combined with depth data, also allow enhanced user experiences and new forms of interaction with the 3D content from virtual viewpoints. This type of audiovisual information is represented by a huge amount of data that needs to be compressed and transmitted over bandwidth-limited channels. Part of the COST Action IC1105 \3D Content Creation, Coding and Transmission over Future Media Networks" (3DConTourNet) focuses on this research challenge.peer-reviewe

Error-resilient performance of Dirac video codec over packet-erasure channel

Video transmission over the wireless or wired network requires error-resilient mechanism since compressed video bitstreams are sensitive to transmission errors because of the use of predictive coding and variable length coding. This paper investigates the performance of a simple and low complexity error-resilient coding scheme which combines source and channel coding to protect compressed bitstream of wavelet-based Dirac video codec in the packet-erasure channel. By partitioning the wavelet transform coefficients of the motion-compensated residual frame into groups and independently processing each group using arithmetic and Forward Error Correction (FEC) coding, Dirac could achieves the robustness to transmission errors by giving the video quality which is gracefully decreasing over a range of packet loss rates up to 30% when compared with conventional FEC only methods. Simulation results also show that the proposed scheme using multiple partitions can achieve up to 10 dB PSNR gain over its existing un-partitioned format. This paper also investigates the error-resilient performance of the proposed scheme in comparison with H.264 over packet-erasure channel

Performance evaluation of MPEG-4 video streaming over UMTS networks using an integrated tool environment

Universal Mobile Telecommunications System (UMTS) is a third-generation mobile communications system that supports wireless wideband multimedia applications. This paper investigates the video quality attained in streaming MPEG-4 video over UMTS networks using an integrated tool environment, which comprises an MPEG-4 encoder/decoder, a network simulator and video quality evaluation tools. The benefit of such an integrated tool environment is that it allows the evaluation of real video sources compressed using an MPEG-4 encoder. Simulation results show that UMTS Radio Link Control (RLC) outperforms the unacknowledged mode. The latter mode provides timely delivery but no error recovery. The acknowledged mode can deliver excellent perceived video quality for RLC block error rates up to 30% utilizing a playback buffer at the streaming client. Based on the analysis of the performance results, a self-adaptive RLC acknowledged mode protocol is proposed

Robust Adaptive Intra Refresh for Multiview Video

Transmission error propagation in wireless multimedia communication systems has become a recurring problem. This persistent problem has led to grave consequences on the visual quality of the decoded video. It is against this backdrop that, we present an adaptive intra refresh (AIR) error-resilient coding tool to mitigate the effect of transmission error propagation in 3D video communications. This work utilizes periodic insertion of intra macroblocks in badly error-infected frames temporally as well as related frames in the multi view video scheme. Our objective is to maximize the transmission efficiency while ensuring the transmission robustness of the coded bitstream. The selection of periodic macroblocks is based on areas with high motion above a pre-set threshold. The coding modes of the macroblocks are based on the distortion expectation due to transmission errors. Extensive simulation results show significant improvement in both objective and subjective video quality at different intra refresh rates