Layered video coding as well as prioritized packet scheduling are two well-known methods that may improve the quality of service level in real-time applications with high bandwidth requirements, and are used over packet switched networks. However, it is often difficult to get an idea of, and to quantify, the actual gains that may be achievable, especially from an end-to-end perspective. In this...

ad hoc networks are multi-hop wireless networks without a pre-installed infrastructure. such networks are widely used in military applications and in emergency situations as they permit the establishment of a communication network at very short notice with a very low cost. video is very sensitive for packet loss and wireless ad-hoc networks are error prone due to node mobility and weak links. h...

Transmitting video data over wireless networks can be very unreliable due to packet-loss, leading to serious video quality degradation which is annoying to human perception. The lost packets not only affect the quality of current frame, but also lead to error propagation to subsequent frames due to motion-compensated prediction techniques used in standard video codecs. Adding error-resilience t...

Packet−based fidelity scalability (PFS) is a desirable feature in many video coding or transmission applications. Any realization of PFS in a hybrid video coding approach, however, requires suitable concepts for controlling drift and for generating sufficiently small increments in bit rate in order to allow progressive refinements of perceptual quality relative to a given base layer quality. Th...

The quality of real-time audio and video information transmitted via today’s Internet suffers severely from often significant packet losses. While this problem is well understood and solved for existing audio coding schemes, support from the video coding standards themselves is required for video streams. This paper presents the newly introduced error resilience mechanisms built into the second...

Image transmission via packet switched networks has a significant impact on encoded image data. To develop an efficient image codec for packet video, the goals of image coding are redefined and formulated as an optimization problem. Guided by these goals, a set of design requirements and a new segmentation based coding technique is developed. This approach features region based motion estimatio...

-We present a layered packet video coding algorithm based on a progressive transmission scheme. The algorithm provides good compression and can handle significant packet loss with graceful degradation in the reconstruction sequence. Simulation results for various conditions are presented.

The paper addresses the end-to-end QoS problem of MPEG4-FGS video streaming traffic delivery over a heterogeneous IP/UMTS network. It proposes and validates an architecture that explores the joint use of packet prioritization and scalable video coding together with the appropriate mapping of UMTS traffic classes to the DiffServ traffic classes. A set of simulation scenarios, involving eight dif...

Packet switching of variable-bit-rate real-time video sources is a means for efficient sharing of communication resources while maintaining uniform picture quality. Performance analysis for the statistical multiplexing of such video sources is required as a first step towards assessing the feasibility of packet video. This paper extends our earlier work in modeling video sources which have been...

This paper addresses the issue of cell loss and its consequent effect on video quality in a packet video system, and examines possible compensative measures. In the system's enconder, adaptive spectral separation is used to develop a two-layer coding scheme comprising a high priority layer to carry essential video data and a low priority layer with data to enhance the video image. A two-step er...