Khaled Shuaib

Robust compression and transmission of MPEG-4 video

This paper discusses issues related to the delivery of MPEG-4 video over the Internet and wireless channels. MPEG-4s built-in error resilience capabilities such as flexible re-synchronization markers, data partitioning, header protection, reversible VLCs, and forced intra-frame refresh are described. Methods for using these techniques to build a “smart” network decoder are discussed, and the decoders video quality is measured for various channel error conditions. The effectiveness and overheads of the various error resilience techniques are compared using both peak signal-to-noise ratio measurements and expert viewing. The use of forward error correcting strategies and the effects of packet sizes and boundaries on video quality are also examined.

Transmission of MPEG-2 video streams over ATM

Experiments investigated the relationship between MPEG video quality and ATM network performance. Preliminary results reveal the effects of network impairments on video quality for MPEG-2 transport streams delivered over ATM. The issues in mapping variable-rate MPEG to ATM are also examined, including the trade-off between bandwidth savings and video quality.

Dejittering in the transport of MPEG-2 and MPEG-4 video

Abstract. When multimedia information is transported over a packet-switched network, the quality of presentation can be degraded due to network delay variation or jitter. This paper presents a dejittering scheme that can be used in the transport of MPEG-4 and MPEG-2 video to absorb any introduced network jitter, thus preserving the presentation quality of transported media streams. The dejittering scheme is based on the statistical approximation of delay variation in the arrival times of video packets carrying encoded clock reference values and a filtering and re-stamping mechanism. In addition, a brief overview of the MPEG-4 system is presented.

Empirical evaluation of ATM CBR traffic transported under diverse operating conditions

Through an intensive experimental study, the characteristics of cell delay variation (CDV) and CTD in an ATM network transporting constant bit rate (CBR) traffic under diverse operating conditions are evaluated. We examine the effect of changing network parameters, such as the number of nodes and background load conditions, on the performance parameters of both CDV and CTD. Our results revealed the distributions of CTD and CDV could not be fit to any of the standard distributions (normal, gamma, etc.). The results also present, the autocorrelation behavior of CTD as a function of both load and number of travelled hops. A verification study of the square root law (SRL) of the ATM Forum, on estimating the CTD standard deviation with increasing number of network nodes is also presented. Our results indicate that the SRL reveal very close estimates only under the assumption of a uniform load conditions across all nodes in the network.

A cell loss padding technique for the transport of MPEG-2 transport stream over ATM/AAL

This paper investigates the sensitivity of MPEG-2 transport stream packets to communication network impairments such as bit errors and data loss. In the case of ATM, techniques for using the CRC and length fields in the AAL5 trailer for error detection are assessed, and their effect on received video quality is observed. A new cell loss padding technique that utilizes the length field in the case of AAL5 to conceal the impact of cell losses is proposed. The essence of the proposed technique is based on passing the incomplete PDU (PDLI with lost cells) and the length field to the decoder transport stream layer or to an AAL-SSCS where parsing and padding is performed based on the available information such as the type of incomplete TS packet. For AAL1 the sequence number is used for detection of lost cells, and padding is performed according to the position of the lost cells.

Performance of a hybrid terrestrial/satellite ATM network-experimental results for CBR traffic CTD and CDV QOS parameters

Through a comprehensive empirical study, the characteristics of CDV (jitter) and CTD of a hybrid terrestrial/satellite ATM network transporting CBR traffic were determined. In particular, the impact of a commercial, digital satellite modem on the two QoS parameters was examined. We found that the digital satellite link does not affect the end-to-end jitter regardless of the type of error correction or buffer size used by the satellite modem. However, the mean of the CTD is affected by the choice of error correction technique and the buffer depth in the modem. We also captured data showing that the auto-correlation function measuring the dependency between events (cells) is affected by the use of the satellite link. Analysis of the cells received from an ATM network with and without the satellite link showed different relationships among them for every tested modem configuration. Finally, our experiments revealed that a test signal passing through an ATM network supporting multiple speeds, has different CDV and CTD values depending on whether it was routed from high to low speed or vice versa. Although, this asymmetry is not directly related to the satellite equipment, it is of particular importance to satellite networks that may not always operate at the same speeds as the ATM networks they are connected to.

Bandwidth allocation and analysis of VBR MPEG video bit streams

This paper presents the benefits and challenges in the encoding and delivery of variable bitrate (VBR) MPEG video. The network resources required to transmit stored variable rate MPEG can be reduced by properly analyzing and smoothing the video stream before transmission. A scheduling technique is presented which selects a traffic contract for a pre-encoded MPEG video stream with the criteria of minimizing network resources and maintaining video quality. Several effective bandwidth metrics are discussed and used to model the potential saving in network resources for the shaped streams.

A de-jittering scheme for the transport of MPEG-4 and MPEG-2 video over ATM

A de-jittering scheme which can be used in the transport of MPEG-4 and MPEG-2 video to absorb any introduced network jitter is proposed. The essence of the de-jittering scheme is based on the statistical approximation of the delay variation in the arrival times of video packets carrying encoded clock reference values and a filtering and re-stamping mechanism. In addition, an overview of the MPEG-4 system is presented.

De-jittering in the transport of MPEG-4 and MPEG-2 video over ATM

In this paper a de-jittering scheme which can be used in the transport of MPEG-4 and MPEG-2 video to absorb any introduced network jitter is proposed. The essence of the de-jittering scheme is based on the statistical approximation of delay variation in the arrival times of video packets carrying encoded clock reference values and a filtering and re-stamping mechanism. In addition, a brief overview of the MPEG-4 system is presented.