martyn riley - Academia.edu (original) (raw)

Papers by martyn riley

International Broadcasting Conference IBC '95, 1995

The emerging standards for integrated broadband networks will change the communications infrastru... more The emerging standards for integrated broadband networks will change the communications infrastructure. Broadband asynchronous transfer mode (ATM) networks will enable a range of new communications applications. These applications will include multimedia communications, digital video broadcasting, interactive video and video on demand services. Multimedia communications and in particular digital video communications have challenging transmission requirements, such as high bandwidth and low delay. An important issue which must be addressed is that of quality of service (QOS) requirements for video and multimedia applications over broadband networks. Within an ATM network, QOS is negotiated for each connection. Typical QOS parameters include mean and peak bit rate requirements, delay tolerance and error tolerance. With the gradual introduction of broadband networks, the available network QOS may vary from connection to connection. The authors examine the QOS requirements for digital video transmission and the implications of these requirements for the design of broadband networks and video coding and transmission systems. >

5th IEE Conference on Telecommunications, 1995

Packet loss is widely used as an indication of network congestion over networks which do not prov... more Packet loss is widely used as an indication of network congestion over networks which do not provide bandwidth reservation. We use packet loss in conjunction with FEC as a means of congestion control for MPEG video sources. The receiver implements FEC to recover from packet loss. However, the level of packet losses are recorded and transmitted back to the source which acts on this information to adjust the compression ratio and thereby alleviate congestion. We describe a simulation study whereby a real MPEG video sequence with FEC is packetised into IP style datagrams and then transmitted through a simple network based on an output buffered multiplexor. We apply MPEG 1 video traffic sources with FEC to the simulated network using a novel rate based protocol to adapt the compression ratio of the video source to avoid unrecoverable packet loss due to network congestion. Packet loss is used as a measure of congestion at the receiving nodes. The receiving nodes periodically transmit this packet loss information back to the sending nodes. The FEC allows the receiving nodes to recover from the low levels of packet loss which occur at the onset of congestion thereby avoiding considerable video quality loss.

International Broadcasting Convention (IBC), 1996

We review the techniques available for the transmission of MPEG-2 compressed video over ATM netwo... more We review the techniques available for the transmission of MPEG-2 compressed video over ATM networks. The compressed video data is grouped into packets for transmission within the MPEG-2 systems layer. These packets are transmitted over one of a number of alternative ATM adaptation protocols and then over the ATM layer. MPEG-2 video requires an extremely high quality of service (QoS) from the transport system as it is extremely sensitive to cell losses. These requirements can be met by the network or by added functionality in the end systems. We consider how the end systems can, code the video to minimise the effect of errors, conceal errors, shape the traffic with rate control, perform forward error correction and implement scalable video coding. We discuss the advantages and disadvantages of the various approaches.

Fifth International Conference on Image Processing and its Applications, 1995

Page 1. 559 MPEG CODING FOR ERROR-RESILIENT TRANSMISSION IEG Richardson and M J Riley The Robert ... more Page 1. 559 MPEG CODING FOR ERROR-RESILIENT TRANSMISSION IEG Richardson and M J Riley The Robert Gordon University, UK 1. ABSTRACT We describe a novel layered coding scheme in which MPEG encoded ...

International Broadcasting Convention - IBC '94, 1994

Describes an experiment in which the authors investigate the effects of bit errors during network... more Describes an experiment in which the authors investigate the effects of bit errors during network distribution on coded video traffic. In this experiment, a video sequence is encoded using the progressive spectral selection mode of the JPEG international standard to produce a number of separate streams of coded video data. A simulation testbed is used to digitise and encode frames of video and to simulate the effect of transmission errors on the coded video data. The coded data is decoded to produce a number of re-animated video sequences. These sequences demonstrate the effects of bit errors on the separate streams of coded video data. The authors conclude that the separate streams have different tolerances to bit error effects and that the progressive spectral selection mode provides a flexible means of splitting encoded video data into separate streams in order to reduce the effects of bit errors on the received video data.

IEE Colloquium on ATM Professional and Consumer Applications, 1997

This paper provides a tutorial on the ATM adaptation layer (AAL) protocols in conjunction with a ... more This paper provides a tutorial on the ATM adaptation layer (AAL) protocols in conjunction with a discussion of quality of service (QoS) issues. We describe the various traffic classes and explain the relationship of the traffic classes to the various AAL protocols. We discuss the negotiation of a traffic contract prior to connection-set-up and the enforcement of this traffic contract during the connection. Then we present a short case study on the transmission of video across an ATM network by considering the various protocol options and modes of operation available and their advantages and disadvantages.

Integrated communications for multiservice workstations will have to support both asynchronous da... more Integrated communications for multiservice workstations will have to support both asynchronous data traffic and delay sensitive traffic such as real time video and voice. In an initial step towards this, a system providing a telephone service integrated into PCs and communicating over an IEEE 802.3 LAN has been demonstrated. The further development of this digital voice station into a full communicating multimedia workstation is considered.

Proceedings IEEE International Conference on Communications ICC '95, 1995

Page 1. Usage Parameter Control Cell Loss Effects on MPEG Video Iain EG Richardson and Martyn J R... more Page 1. Usage Parameter Control Cell Loss Effects on MPEG Video Iain EG Richardson and Martyn J Riley School of Electronic and Electrical Engineering The Robert Gordon University, Aberdeen, Scotland Abstract The effect ...

Visual Communications and Image Processing '95, 1995

In this paper we describe an 'intelligent' packetizing scheme in which MPEG coded video d... more In this paper we describe an 'intelligent' packetizing scheme in which MPEG coded video data is split into separate streams of ATM cells according to the picture coding type of each frame. We investigate the tolerance of each stream to cell losses and analyze the traffic characteristics of the separate streams. We conclude that this technique may provide a flexible means of splitting MPEG data into separate streams, each of which can accept a different Quality Of Service during transmission through an ATM network.

Digital Compression Technologies and Systems for Video Communications, 1996

We describe a novel approach to filtering coded video data. MPEG video is filtered to reduce fram... more We describe a novel approach to filtering coded video data. MPEG video is filtered to reduce frame rate and bandwidth by dropping coded B-pictures. The choice of B-pictures to be dropped is made based on an 'activity measure' which indicates the amount of motion within the video scene. We present preliminary results which indicate that this method produces a filtered

Digital Signal Processing for Communication Systems, 1997

Communication protocols for the PC such as the Internet transport protocol (TCP) have traditional... more Communication protocols for the PC such as the Internet transport protocol (TCP) have traditionally made use of ARQ techniques to perform error correction for data transmission applications. ARQ is not however a suitable error correction technique for real-time communications and especially for the transmission of compressed video traffic over networks with a high bandwidth-delay product. A number of International Standards are available for video compression including the ITU-T H.261 and emerging H.263 standards aimed at providing video conferencing at bit rates of n x 64 Kbit/s and below. Compressed video traffic is extremely sensitive to data loss during transmission [1] and many communication systems do not provide the relatively high Quality of Service required for digital video communications. In these circumstances error correction must be performed in the end systems and FEC is a more suitable technique than ARQ.

Computing & Control Engineering Journal, 1996

Providing high-quality cost-effective healthcare to patients in `remote' locations is an impo... more Providing high-quality cost-effective healthcare to patients in `remote' locations is an important requirement for today's health service. In an area such as Scotland, a significant proportion of the population live in rural areas, in many cases at a considerable distance from the nearest major hospital. Local health centres or general practice hospitals can provide effective care for many medical problems. However, patients may require urgent or specialist treatment that cannot be provided locally. Telemedicine can help solve this problem by providing local medical practitioners the means to consult with specialists based in the major hospitals via communications technology. This article introduces the concept of telemedicine and describes the components which make up a telemedicine system. It describes the SAVIOUR telemedicine project which involves the establishment of a telemedicine link between two hospitals in the North East of Scotland, discusses the technical and clinical issues highlighted by this project and examines some of the areas which must be addressed if telemedicine is to become an integrated part of the healthcare system.

2008 4th Southern Conference on Programmable Logic, 2008

A novel algorithm is proposed to reduce the power used performing the motion estimation and refer... more A novel algorithm is proposed to reduce the power used performing the motion estimation and reference frame loading operations required by a video encoder. The algorithm uses the results of the intra prediction encoding stage to determine the data propagation direction which minimises the data's transition activity. A motion estimation architecture which can adaptively change the direction data is propagated through it is proposed and the power saved using the algorithm is estimated. Results are given showing a power saving of upto 8%.

2007 3rd Southern Conference on Programmable Logic, 2007

The design of a platform based video streaming server using the Xilinx microblaze processor and a... more The design of a platform based video streaming server using the Xilinx microblaze processor and a custom H.263 hardware compression core is presented. The design uses a novel data structure to store the input images in external memory, allowing the H.263 core and the associated camera interface to utilise the external memory bandwidth more efficiently. The finished system is capable